超声清洗机吊运机械手设计【三维UG和CATIA图】【8张CAD图纸和毕业论文 含开题报告和翻译】

超声清洗机吊运机械手设计【三维UG和CATIA图】【8张CAD图纸和毕业论文 含开题报告和翻译】

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超声清洗机吊运机械手设计[3D-UG][3D-CATIA].rar
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153.CATPart
ban.CATPart
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chilun.CATPart
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falan.CATPart
huakuaiSBR35UU.CATPart
huakuaizuoguntong.CATPart
huakuaizuozhouchengdanyuan LV16M.CATPart
jian.CATPart
jixieshoujia-1.CATAnalysis
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kuangjiazhuangpeitu.CATProduct
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luoding.CATPart
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luogan.CATPart
Part212.CATPart
Part213.CATPart
Part29.CATPart
qingxilan.CATPart
shangxialiaojigouzhpt.CATProduct
shangxialiaojijia.CATPart
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ban.prt
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cao700.prt
chilun.prt
chilun100.prt
congdonglianlun.prt
daogui 50.prt
dianjijia.prt
dianjilianlun.prt
diaogou.prt
duanluogan.prt
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【温馨提示】 购买原稿文件请充值后自助下载。全部文件 那张截图中的文件为本资料所有内容,下载后即可获得。预览截图请勿抄袭,原稿文件完整清晰,无水印,可编辑。有疑问可以咨询QQ:414951605或1304139763摘  要   超声波清洗始于20世纪50年代初,随着科技的发展应用日益扩大。现在已普遍用于电器领域、电子管零件、清洗半导体器件、继电器、印刷电路、滤波器和开关等;机械领域中用于清洗轴承、齿轮、燃油过滤器、油泵油嘴偶件、阀门和他机械零件,小到手表零件,大到发动机和导弹部件;再如医疗器械方面和光学用于清洗眼镜及框、各种透镜、医用针管玻璃、器皿等。该系统是综合运用了机电一体化技术,在电控方面主要用到PLC进行控制,PLC具有可靠性高、抗干扰能力强,灵活性好,编程方便等特点,总的系统使原来复杂的动作变成相当简单操作,电气系统采用三菱PLC控制,控制电子元件均采用新材料或进口名牌元件,经久耐用,噪音低,系统的可靠性和可操作性都有所提高。关键词:超声波;清洗机;PLC。AbstractUltrasonic cleaning began in the early 1950s, with the development of technology application widening. Currently has been widely used in electronic industry, semiconductor device, cleaning tube parts and printing circuit, relays, switches and filter; etc. Mechanical industry for the cleaning gears, bearings, diesel oil, fuel filter, valves and other mechanical parts, such as engine and missile components, such as watch of small parts, Again, such as optical and medical equipment used for washing various aspects lens, glasses and frame, glassware, medical and surgical instruments, etc.;The system is the integrated use of mechatronics technology, mainly used in the electronic control PLC control, PLC has high reliability, strong anti-interference ability, good flexibility, easy programming, the overall system of the original complex action into a fairly simple operation, the electrical system with Mitsubishi PLC control, control electronics are made of new materials or imported brand-name components, durable, low noise, reliability and operability of the system are improved.Key words: ultrasonic, Cleaner,PLC.目录摘  要 IIIAbstract IV目录 V1 绪论 1   1.1 课题的来源及其意义 11.1.1 课题的来源 11.1.2 课题的意义 12 超声波清洗 32.1.1 什么是超声波? 32.1.2 超声波清洗的原理 32.1.3 影响超声波清洗效果的因素及选择 32.1.4 超声波清洗的特点 62.1.5 超声波清洗技术在我国的发展及现状 103 超声波清洗机的结构设计 113.1 清洗机总体结构的设计 113.2 传动部分的设计 123.2.1 方案的选择 123.2.1 电机的选择 133.2.2 链轮的设计选择 143.2.3齿轮齿条的选择和校核 153.3 机械手执行件的设计 183.3.1 提升架的设计 183.3.2 其它零部件的设计 193.4 其它部件说明 213.4.1技术参数说明 213.4.2 设备主要装置 264 电气部分设计 274.1 电器元件 274.1.1 增量式编码器 274.1.2 温控器 274.1.3 变频器 284.1.4 触摸屏 294.2  PLC控制系统简介 294.3  PLC的安装,调试,及系统的维护 314.4  PLC 控制系统的设计 334.3.1 控制流程的拟订 334.3.2 PLC控制电路元器件的选用及电气原理图的绘制 344.3.3 PLC程序的编制 345 总结 36    致谢 37参考文献  38 1 绪论1.1 课题的来源及其意义  1.1.1 课题的来源本课题由生产厂家提出,能达到实际加工要求。超声清洗机吊运装置是用于物料输送的专用设备,设备的传动将由机械系统完成,电气控制由PLC完成。本课题既能达到锻炼学生设计能力,且为机电综合的设计水平,特别是机械及电控的设计制造。又能熟悉如何从图纸到实际工作完成的整个过程,并经实际的动手完成真正能正常工作的设备。  1.1.2 课题的意义   工业清洗的范畴包括工业生产劳动过程中涉及到的超声波清洗机清洗:造纸业、印刷业、纺织业、交通运输业、石油加工业、金属加工业、电力工业、机械工业、汽车制造、电子工业、仪器仪表、邮电通讯、医疗仪器、光学产品、军事装备、航空航天、家用电器、原子能工业等都涉及运用到超声清洗机清洗技术。     一般工业超声波清洗机清洗包括车辆、飞机、轮船表面的清洗,一般仅仅能去除较大的污垢;超精密超声清洗机清洗包括精密工业生产过程中对电子元件、光学部件机械零件、等的超精密清洗,以清除超微小污垢颗粒为目的;精密工业超声清洗机清洗包括设备表面的清洗和各种材料,各种产品加工生产过程中的清洗等,以去除微小的污垢粒子为目的。根据超声清洗机清洗方法的不同,还可以分为物理超声清洗机清洗和化学超声清洗机清洗。利用声学、电学、热学、力学、光学的原理,凭借外在能量的作用,如机械摩擦、高压冲击、超声波、紫外线、负压、蒸汽等除去物体表面污垢的方法叫物理清洗超声清洗机清洗;凭借化学反应的作用,利用化学药品或其它溶剂除去物体表面污垢的方法叫化学超声清洗机清洗,如用各类有机酸或无机去除物体表面的水垢、锈迹,用氧化剂去除物体表面的色斑,用消毒剂、杀菌剂杀灭微生物并去除霉斑等。物理清洗和化学清洗都各有优缺点,同样还具有很好的互补性的特点。实际生活应用过程,一般都是把两者有机的结合起来,以达到更好的超声波清洗机清洗效果。     根据超声波清洗机清洗媒介的不同,又可以分为干式清洗和湿式清洗。一般在气体介质中进行的清洗称为干式超声波清洗机清洗,将在液体介质中进行的清洗称为湿式超声波清洗机清洗。通常的清洗方式大多为湿式清洗,而人们比较容易接触的干式清洗也就是吸尘器。但随着技术的飞速发展,干式清洗发展飞速如干冰清洗紫、外线清洗、激光清洗、离子清洗等,在高端工业技术领域得到快速发展。近几年,新技术也不断得被开发于清洗技术之中,例如生物技术的领域,越来越多的微生物和酶在超声波清洗机清洗技术中被利用,这结合的是生物化学反应;在水和空气净化处理过程中,活性炭的使用也越来越普遍,这利用的是吸附作用;另外电解清洗也同样被利用等。现在,清洗涵盖当前清超声波清洗机洗技术飞速发展的现实状况工业超声波清洗机清洗与各类工业活动联系紧密,有些只是产品生产工艺的一个构件,清洗不创造最终的产品,而是许多工业生产过程中的一个部分工序、辅助活动或工艺。在一些基础工业中,清洗已经被大家简单的看作是小过程或常识,往往被人们忽视,事实上清洗的优劣决定最终产品的质量和性能。尤其是在当代的高科技发展中,超声清洗机清洗技术的作用特别明显。新型的超声波清洗机清洗技术和设备渐渐得到开发和应用,如等离子清洗、真空清洗、紫外臭氢清洗,激光清洗等初现优势,展示了良好的用途和未来前景。2 超声波清洗       2.1 超声波清洗        2.1.1 什么是超声波?  超声波是人耳听不到声波,频率在20KHz以上的声波。超声波具有频率高,方向性强,穿透能力大,特别是在液体中能产生空化现象等特点,被广泛应用于许多行业。超声波生活应用技术很多,主要包括医学超声,检测超声,高频超声和功率超声等,超声波清洗技术是最普遍的一种功率超声应用。超声波清洗技术有时也被叫做称无刷清洗,把工件放入超声清洗机中,无需任何清洗动作,污物“自动”从工件表面脱离,很快就焕然一新,让人叹为观止。超声波的两个主要参数: 频率20KHz33KHz 功率密度=发射功率(W)/发射面积(CM2) 超声清洗的换能器有两种类型:磁致伸缩换能器和压电换能器。磁致伸缩换能器这种换能器的电声效率比较低。而且金属镍材料价格昂贵,制造工艺复杂,所以目前很少采用。还有一种用铁氧体材料做成的磁致伸缩换能器,虽然其电声效率比较高,但机械强度低,所能承受的电功率容量小,因而目前我国也很少应用。
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超声 清洗 机吊运 机械手 设计 ug catia
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摘  要
  超声波清洗始于20世纪50年代初,随着科技的发展应用日益扩大。现在已普遍用于电器领域、电子管零件、清洗半导体器件、继电器、印刷电路、滤波器和开关等;机械领域中用于清洗轴承、齿轮、燃油过滤器、油泵油嘴偶件、阀门和他机械零件,小到手表零件,大到发动机和导弹部件;再如医疗器械方面和光学用于清洗眼镜及框、各种透镜、医用针管玻璃、器皿等。该系统是综合运用了机电一体化技术,在电控方面主要用到PLC进行控制,PLC具有可靠性高、抗干扰能力强,灵活性好,编程方便等特点,总的系统使原来复杂的动作变成相当简单操作,电气系统采用三菱PLC控制,控制电子元件均采用新材料或进口名牌元件,经久耐用,噪音低,系统的可靠性和可操作性都有所提高。

   关键词:超声波;清洗机;PLC。
 Abstract
   Ultrasonic cleaning began in the early 1950s, with the development of technology application widening. Currently has been widely used in electronic industry, semiconductor device, cleaning tube parts and printing circuit, relays, switches and filter; etc. Mechanical industry for the cleaning gears, bearings, diesel oil, fuel filter, valves and other mechanical parts, such as engine and missile components, such as watch of small parts, Again, such as optical and medical equipment used for washing various aspects lens, glasses and frame, glassware, medical and surgical instruments, etc.;The system is the integrated use of mechatronics technology, mainly used in the electronic control PLC control, PLC has high reliability, strong anti-interference ability, good flexibility, easy programming, the overall system of the original complex action into a fairly simple operation, the electrical system with Mitsubishi PLC control, control electronics are made of new materials or imported brand-name components, durable, low noise, reliability and operability of the system are improved.

   Key words: ultrasonic, Cleaner,PLC.


目录

摘  要 III
Abstract IV
目录 V
1 绪论 1
  1.1 课题的来源及其意义 1
1.1.1 课题的来源 1
1.1.2 课题的意义 1
2 超声波清洗 3
2.1.1 什么是超声波? 3
2.1.2 超声波清洗的原理 3
2.1.3 影响超声波清洗效果的因素及选择 3
2.1.4 超声波清洗的特点 6
2.1.5 超声波清洗技术在我国的发展及现状 10
3 超声波清洗机的结构设计 11
3.1 清洗机总体结构的设计 11
3.2 传动部分的设计 12
3.2.1 方案的选择 12
3.2.1 电机的选择 13
3.2.2 链轮的设计选择 14
3.2.3齿轮齿条的选择和校核 15
3.3 机械手执行件的设计 18
3.3.1 提升架的设计 18
3.3.2 其它零部件的设计 19
3.4 其它部件说明 21
3.4.1技术参数说明 21
3.4.2 设备主要装置 26
4 电气部分设计 27
4.1 电器元件 27
4.1.1 增量式编码器 27
4.1.2 温控器 27
4.1.3 变频器 28
4.1.4 触摸屏 29
4.2  PLC控制系统简介 29
4.3  PLC的安装,调试,及系统的维护 31
4.4  PLC 控制系统的设计 33
4.3.1 控制流程的拟订 33
4.3.2 PLC控制电路元器件的选用及电气原理图的绘制 34
4.3.3 PLC程序的编制 34
5 总结 36
   致谢 37
参考文献  38


     1 绪论
   1.1 课题的来源及其意义
     1.1.1 课题的来源
   本课题由生产厂家提出,能达到实际加工要求。超声清洗机吊运装置是用于物料输送的专用设备,设备的传动将由机械系统完成,电气控制由PLC完成。本课题既能达到锻炼学生设计能力,且为机电综合的设计水平,特别是机械及电控的设计制造。又能熟悉如何从图纸到实际工作完成的整个过程,并经实际的动手完成真正能正常工作的设备。
     1.1.2 课题的意义
      工业清洗的范畴包括工业生产劳动过程中涉及到的超声波清洗机清洗:造纸业、印刷业、纺织业、交通运输业、石油加工业、金属加工业、电力工业、机械工业、汽车制造、电子工业、仪器仪表、邮电通讯、医疗仪器、光学产品、军事装备、航空航天、家用电器、原子能工业等都涉及运用到超声清洗机清洗技术。
        一般工业超声波清洗机清洗包括车辆、飞机、轮船表面的清洗,一般仅仅能去除较大的污垢;超精密超声清洗机清洗包括精密工业生产过程中对电子元件、光学部件机械零件、等的超精密清洗,以清除超微小污垢颗粒为目的;精密工业超声清洗机清洗包括设备表面的清洗和各种材料,各种产品加工生产过程中的清洗等,以去除微小的污垢粒子为目的。根据超声清洗机清洗方法的不同,还可以分为物理超声清洗机清洗和化学超声清洗机清洗。利用声学、电学、热学、力学、光学的原理,凭借外在能量的作用,如机械摩擦、高压冲击、超声波、紫外线、负压、蒸汽等除去物体表面污垢的方法叫物理清洗超声清洗机清洗;凭借化学反应的作用,利用化学药品或其它溶剂除去物体表面污垢的方法叫化学超声清洗机清洗,如用各类有机酸或无机去除物体表面的水垢、锈迹,用氧化剂去除物体表面的色斑,用消毒剂、杀菌剂杀灭微生物并去除霉斑等。物理清洗和化学清洗都各有优缺点,同样还具有很好的互补性的特点。实际生活应用过程,一般都是把两者有机的结合起来,以达到更好的超声波清洗机清洗效果。
        根据超声波清洗机清洗媒介的不同,又可以分为干式清洗和湿式清洗。一般在气体介质中进行的清洗称为干式超声波清洗机清洗,将在液体介质中进行的清洗称为湿式超声波清洗机清洗。通常的清洗方式大多为湿式清洗,而人们比较容易接触的干式清洗也就是吸尘器。但随着技术的飞速发展,干式清洗发展飞速.如干冰清洗紫、外线清洗、激光清洗、离子清洗等,在高端工业技术领域得到快速发展。近几年,新技术也不断得被开发于清洗技术之中,例如生物技术的领域,越来越多的微生物和酶在超声波清洗机清洗技术中被利用,这结合的是生物化学反应;在水和空气净化处理过程中,活性炭的使用也越来越普遍,这利用的是吸附作用;另外电解清洗也同样被利用等。现在,清洗涵盖当前清超声波清洗机洗技术飞速发展的现实状况.工业超声波清洗机清洗与各类工业活动联系紧密,有些只是产品生产工艺的一个构件,清洗不创造最终的产品,而是许多工业生产过程中的一个部分工序、辅助活动或工艺。在一些基础工业中,清洗已经被大家简单的看作是小过程或常识,往往被人们忽视,事实上清洗的优劣决定最终产品的质量和性能。尤其是在当代的高科技发展中,超声清洗机清洗技术的作用特别明显。
   新型的超声波清洗机清洗技术和设备渐渐得到开发和应用,如等离子清洗、真空清洗、紫外/臭氢清洗,激光清洗等初现优势,展示了良好的用途和未来前景。
   2 超声波清洗
          2.1 超声波清洗
           2.1.1 什么是超声波?
     超声波是人耳听不到声波,频率在20KHz以上的声波。超声波具有频率高,方向性强,穿透能力大,特别是在液体中能产生空化现象等特点,被广泛应用于许多行业。超声波生活应用技术很多,主要包括医学超声,检测超声,高频超声和功率超声等,超声波清洗技术是最普遍的一种功率超声应用。超声波清洗技术有时也被叫做称无刷清洗,把工件放入超声清洗机中,无需任何清洗动作,污物“自动”从工件表面脱离,很快就焕然一新,让人叹为观止。
   超声波的两个主要参数:
   频率20KHz~33KHz
   功率密度=发射功率(W)/发射面积(CM2)

    超声清洗的换能器有两种类型:磁致伸缩换能器和压电换能器。磁致伸缩换能器这种换能器的电声效率比较低。而且金属镍材料价格昂贵,制造工艺复杂,所以目前很少采用。还有一种用铁氧体材料做成的磁致伸缩换能器,虽然其电声效率比较高,但机械强度低,所能承受的电功率容量小,因而目前我国也很少应用。


内容简介:
超声清洗机吊运机械手设计 无锡太湖学院信机系91班周剑 设计课题依据及意义 超声清洗机吊运机械手是为无锡美极超声公司设计的产品 本设计的最大特色是 机电一体化 能极大的锻炼学生的动手能力 总体方案设计 设计要点简介 机械手的设计 电控系统的设计 机械手的设计包括以下几个方面 机械手三维化设计 机械手二维图的设计3 提升架的有限元分析 控制系统的设计 难点 动作流程图的绘制 为了对整套流水有更加清晰的认识 我用CATIA对整套设备的动作进行了动画仿真设计 已放过动画 电气原理图的设计 选择合适的PlC控制器 电气原理图的绘制 难点 PLC梯形图的编制 采用三凌的编程 演示如下 重点 这次设计的最大特点是机电液一体化 可以说是对四年学习的一个很好的总结与深化 从中我学到了很多 未来需要我们既要懂机 也要懂电 我会向着这个方向发展的 无锡太湖学院毕业设计(论文)开题报告题目:超声清洗机吊运机械手设计 信机系 机械工程及其自动化专业学 号: 0923048 学生姓名: 周 剑 指导教师: 林承德 (职称:教 授 ) (职称: ) 2012年11 月 课题来源本课题由生产厂家提出,能达到实际加工要求。超声清洗机吊运装置是用于物料输送的专用设备,设备的传动将由机械系统完成,电气控制由PLC完成。本课题既能达到锻炼学生设计能力,且为机电综合的设计水平,特别是机械及电控的设计制造。又能熟悉如何从图纸到实际工作完成的整个过程,并经实际的动手完成真正能正常工作的设备。科学依据(包括课题的科学意义;国内外研究概况、水平和发展趋势;应用前景等)一般工业超声波清洗机清洗包括车辆、轮船、飞机表面的清洗,一般只能去掉比较粗大的污垢;精密工业超声波清洗机清洗包括各种产品加工生产过程中的清洗,各种材料及设备表面的清洗等,以能够去除微小的污垢粒子为特点;超精密超声波清洗机清洗包括精密工业生产过程中对机械零件、电子元件,光学部件等的超精密清洗,以清除极微小污垢颗粒为目的。根据超声波清洗机清洗方法的不同,也可以分为物理超声波清洗机清洗和化学超声波清洗机清洗。利用力学、声学、光学、电学、热学的原理,依靠外来能量的作用,如机械摩擦、超声波、负压、高压冲击、紫外线、蒸汽等去除物体表面污垢的方法叫物理清洗;依靠化学反应的作用,利用化学药品或其它溶剂清除物体表面污垢的方法叫化学清洗,如用各种无机或有机酸去除物体表面的锈迹、水垢,用氧化剂去除物体表面的色斑,用杀菌剂、消毒剂杀灭微生物并去除霉斑等。物理清洗和化学清洗都存在着各自的优缺点,又具有很好的互补性。在实际应用过程中,通常都是把两者结合起来使用,以获得更好的超声波清洗机清洗效果。研究内容1达到技术指标所规定要求,满足实际工作需要。2PLC全自动控制,要有较高的工作可靠性;安全性。3主机部件需作有限元应力分析,以及相应的运动学分析。4工作时定位准确,启停无冲击。5工作时噪音小,发热较小,工作可靠。实习地点:无锡。主要技术指标: 满足用户提出的书面技术要求。 工作量要求: 1 总装图:机械手装配图0#;整机装配图0#。2 主要部装图:设备动作流程图2#,电气原理图0#,3 重要零件图:电气布置图1#;。4 重要零件的应力应变分析; 整机三维装配图,机械手三维装配图,动作流程 模拟动画仿真,PLC程序的编制5 完整的设计及使用说明书(电气选型;PLC程序) 。 拟采取的研究方法、技术路线、实验方案及可行性分析本设计中主要分三个阶段:1 零部件的设计,主要包括传动装置的设计和机架的设计。2 电气设计,主要包括气动原理图,PLC控制的图及流程图。3 程序的调试,在三菱编程的环境下进行模拟运行。因为本设计已经生产为实物了,而且它也已经被广泛的使用了,所以它的可行性是毋庸置疑的。研究计划及预期成果研究计划:2012年11月14日-2012年12月2日:按照任务书要求查阅论文相关参考资料,填写毕业设计开题报告书。2013年1月7日-2013年1月20日:学习并翻译一篇与毕业设计相关的英文材料。2013年1月29日-2013年3月3日:填写毕业实习报告。2013年3月4日-2013年3月10日:按照要求修改毕业设计开题报告。2013年3月18日-2013年3月24日:零部件的设计,主要包括传动装置的设计和机架的设计。2013年3月25日-2013年3月31日:电气设计,主要包括气动原理图,PLC控制的图及流程图。2013年4月1日-2013年4月7日:程序的调试,在三菱编程的环境下进行模拟运行。2013年4月8日-2013年5月25日:毕业论文撰写和修改工作。预期成果:既能达到锻炼学生设计能力,且为机电综合的设计水平,特别是机械及电控的设计制造。又能熟悉如何从图纸到实际工作完成的整个过程,并经实际的动手完成真正能正常工作的设备。 特色或创新之处该系统是综合运用了机电一体化技术,在电控方面主要用到PLC进行控制,PLC具有可靠性高、抗干扰能力强,灵活性好,编程方便等特点,总的系统使原来复杂的动作变成相当简单操作,电气系统采用三菱PLC控制,控制电子元件均采用新材料或进口名牌元件,经久耐用,噪音低,系统的可靠性和可操作性都有所提高。该设计的最大的特点是密切联系实际,可以极大的锻炼我们的动手能力和解决问题的能力。已具备的条件和尚需解决的问题 已具备的条件:零部件的设计,电气方面的原理图以及电气接线图都已经达到预期的设计要求。尚需解决的问题:1、 本设计的工作流程有九步,所以要九个槽体,设备本身就比较的庞大。零件放在槽体里面都要花一次的时间清洗,所以一个流程所花的时间比较的长。指导教师意见 指导教师签名: 年 月 日 教研室(学科组、研究所)意见 教研室主任签名: 年 月 日系意见 主管领导签名: 年 月 日 机械手动作流程:前手(原始位置在进料区上方)A进料10S-前手降5S-前手退2S(钩住)-前手升5S-前手进10S-前手降5S(1槽酸洗开始)-180S到-前手升5S-前手进10S-前手降5S(2槽水洗开始)- 20S到-前手升5S-前手进10S-前手降5S(3槽酸洗开始)- 30S到-前手升5S-前手进10S-前手降5S(4槽酸洗开始)- 30S到-前手升5S-前手进10S-前手降5S(5槽水洗开始)-前手进(松开)3S-前手升5S-前手退30S(在进料区上方)-周而复始。后手(原始位置在6槽上方)。B后手退10S-后手降5S-后手退(钩住)3S-后手升5S-后手进10S-后手降(6槽碱洗开始)5S-60S到-后手升5S-后手进10S-后手降5S(7槽水洗开始)-30S到-后手升5S-后手进10S-后手降(8槽防锈开始)5S-180S到-后手升5S-后手进10S-后手降5S(9槽防锈开始)-30S到-后手升5S-后手进10S-后手降5S(出料区)-后手升5S-后手退30S(在6槽上方)-周而复始。C出料5S-风切泵开;接通气路,气缸带动风刀往复运动-延时30S-风切泵停;断开气路,风刀停止-出料电机转5S;闪光提醒工件清洗完毕。1英文原文Process Planning and Concurrent EngineeringProcess Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gags. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Concurrent engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of an aluminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Term used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines.Organizational Changes in DFM/A. Effective implementation of DFM/A involves making changes in a companys organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a products design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants.Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTThe product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gages. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Concurrent engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of an aluminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Term used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines.Organizational Changes in DFM/A. Effective implementation of DFM/A involves making changes in a companys organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a products design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants.Design Principles and Guidelines. DFM/A also relies on the use of design principles and guidelines for how to design a given product to maximize manucturability and assembility. Some of these are universal design guidelines that can be applied to nearly any product design situation. There are design principles that apply to specific processes, and for example, the use of drafts or tapers in casted and molded parts to facilitate removal of the part from the mold. We leave these more process-specific guidelines to texts on manufacturing processes.The guidelines sometimes conflict with one another. One of the guidelines is to “simplify part geometry, avoid unnecessary features”. But another guideline in the same table states that “special geometric features must sometimes be added to components” to design the product for foolproof assembly. And it may also be desirable to combine features of several assembled parts into one component to minimize the number of parts in the product. In these instances, design for part manufacture is in conflict with design for assembly, and a suitable compromise must be found between the opposing sides of the conflict.Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTThe product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gages. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Concurrent engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of an aluminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Term used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines.Organizational Changes in DFM/A. Effective implementation of DFM/A involves making changes in a companys organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a products design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants.Design Principles and Guidelines. DFM/A also relies on the use of design principles and guidelines for how to design a given product to maximize manucturability and assembility. Some of these are universal design guidelines that can be applied to nearly any product design situation. There are design principles that apply to specific processes, and for example, the use of drafts or tapers in casted and molded parts to facilitate Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTThe product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gages. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Concurrent engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of an aluminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Term used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines.Organizational Changes in DFM/A. Effective implementation of DFM/A involves making changes in a companys organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a products design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants.Design Principles and Guidelines. DFM/A also relies on the use of design principles and guidelines for how to design a given product to maximize manucturability and assembility. Some of these are universal design guidelines that can be applied to nearly any product design situation. There are design principles that apply to specific processes, and for example, the use of drafts or tapers in casted and molded parts to facilitate removal of the part from the mold. We leave these more process-specific guidelines to texts on manufacturing processes.Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTThe product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gages. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTThe product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process Planning Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planners knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning. .Interpretation of design drawings. The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure. .Process and sequence. The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared. .Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment. .Tools, dies, molds, fixtures, and gages. The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted.Methods analysis. Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area.Work standards. Work measurement techniques are used to set time standards for each operation.Cutting tools and cutting conditions. These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsFor individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.A typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.Once the geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. When finishing is required, it is usually the final step in the processing sequence.Processing Planning for Assemblies The type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out.Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the companys own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchased externally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.There are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the companys own plant in themanufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the companys own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision. The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the companys own plant for $28.00. The components of making the part are as follows: Unit raw material cost = $8.00 per unit Direct labor cost =6.00 per unit Labor overhead at 150%=9.00 per unit Equipment fixed cost =5.00 per unit _ Total =28.00 per unit Should the component by bought or made in-house?Solution: Although the vendors quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.Make or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process Planning There is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPP systems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following:.Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality. .Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners.Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation. .Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets. .Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingConcurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizational counterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.Fig.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringBy contrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new products function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.Concurrent engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of an aluminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Term used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines.Organizational Changes in DFM/A. Effective implementation of DFM/A involves making changes in a companys organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a products design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants.Design Principles and Guidelines. DFM/A also relies on the use of design principles and guidelines for how to design a given product to maximize manucturability and assembility. Some of these are universal design guidelines that can be applied to nearly any product design situation. There are design principles that apply to specific processes, and for e
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