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CA6140车床拨叉[831007] 加工工艺及铣φ40外圆上端面夹具设计1[含CAD图纸和文档所见所得]

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本科生毕业设计选题审批表毕业设计题目CA6140车床拨叉加工工装设计指 导 教 师职 称学生具备条件熟练做图的能力、演算的能力,以及独立分析问题的能力选题完成形式毕业设计说明书和图纸内 容 简 要:车床变速用拨叉是某企业产品的主要零件之一。于是需要设计关键工序的专用夹具及加工用组合机床,而且夹具采用液压驱动,组合机床采用液压滑台。工艺设计以保证质量稳定、生产可靠为原则。对工件进行加工时,为了保证加工要求,首先要使工件相对于刀具及机床有正确的位置,并使这个位置在加工过程中不因外力的影响而变动。为此,在进行机械加工前,首先要将工件装夹好。用夹具装夹工件有下列优点:能稳定地保证工件的加工精度;能提高劳动生产率;能扩大机床的使用范围;能降低成本。 系主任签字: 年 月 日 院长签字: 年 月 日2选题的依据及意义(包括课题的理论价值和实践价值;国内外的研究概况等):机械制造技术是研究产品设计、生产、加工制造、维修服务乃至回收再生的整个过程的工程学科,是以提高质量、效益、竞争力为目标,包含物质流、信息流和能量流的完整的系统工程。随着社会的发展,人们对于产品的要求也发生了很大的变化,要求品种要多样、更新要快捷、质量要高当、使用要方便、价格要合理、外形要美观、售后服务要好、要满足人们越来越高的要求,就必须采用先进的制造技术。机械自动化,主要指在机械制造业中应用自动化技术,实现加工对象的连续自动生产,实现优化有效的自动生产过程,加快生产投入物的加工变换和流动速度。机械自动化技术的应用与发展,是机械制造业技术改造、技术进步的主要手段和技术发展的主要方向。机械自动化的技术水准,不仅影响整个机械制造业的发展,而且对国民经济各部门的技术进步有很大的直接影响。近年来,我国的制造业不断采用先进制造技术,但与工业发达国家相比,仍然存在一个阶段性的整体上的差距。工业发达国家较广泛的采用高精密加工、精细加工、微细加工、微型机械和微米/纳米技术、激光加工技术、电磁加工技术、超塑加工技术以及复合加工技术等新型加工方法。我国普及率不高,尚在开发、掌握之中。与工业发达国家相比,我国的机械制造仍存在阶段性的差距。集中表现为制造技术的落后在设计方法和手段、制造工艺、制造过程自动化及管理技术诸方面都明显落后于工业发达国家。制造技术的落后严重制约了机械工业的进一步发展,使我国机械传动工业的技术来源大部分依赖引进国外技术,全员劳动生产率低,机械产品质量差,可靠性低,缺乏竞争力。本课题研究内容拨叉是一种辅助零件,通过拨叉控制滑套与旋转齿轮的接合。滑套上面有凸块,滑套的凸块插入齿轮的凹位,把滑套与齿轮固连在一起,使齿轮带动滑套,滑套带动输出轴,将动力从输入轴传送至输出轴。摆动拨叉可以控制滑套与不同齿轮的结合与分离,达到换档的目的。分析这种动力联接方式可知,车换档时要减速,这样可以减少滑套与齿轮之间的冲击,延长零件的使用寿命。题目给定的零件是CA6140拨叉它位于车床变速机构中,主要起换档,使主轴回转运动按照工作者的要求进行工作。本课题研究方案零件材料为HT200灰铸铁,考虑到零件需加工表面少,精度要求不高,有强肋,且工作条件不差,既无交变载荷,又属于间歇工作,故选用金属型铸件,以满足不加工表面的粗糙度要求及生产纲量要求。零件形状简单,因此毛坯形状需与零件的形状尽量接近,又因内孔很小,不可铸出。该拨叉用在CA6140的主轴上,和其他零件配合,在改变转速的时候承受轻微的载荷,所以应该保证本零件的重要工作表面符合技术要求。研究的创新之处(1)应用了新型材料(2)应用了新的夹紧机构 研究过程(含完成期限)第5周查阅资料,拟订课题第6周查阅相关车床拨叉机械的设计资料,并进行概述和文献综合。第7-9周完成设计并绘制零件图。第10-12周完成装配图。第13周完成所有的图纸并进一步修改。第14-15周在以上基础上完成毕业设计说明书一篇。第16周修改设计,并定稿。第17周答辩,提交相关材料,结束设计。指导教师意见 指导教师签名:年 月 日教研室意见 教研室主任签名:年 月 日院系意见 主管领导签名: 年 月 日毕业设计成绩单院系专业入学时间学号学生姓名班级周数起止日期指导教师职称论文(设计)题目CA6140车床拨叉加工工装设计指导教师评语建议成绩指导教师签名 年 月 日评阅人评语建议成绩评阅人签名 年 月 日答辩与评分综合成绩答辩小组负责人签名 年 月 日本成绩单一式二份,一份装订在毕业论文(设计)中,一份入学生学籍档案。优秀毕业设计推荐表论文题目CA6140车床拨叉加工工装设计学生姓名刘汉清学 号 27专 业机械设计制造及其自动化学 院信息学院指导教师王双喜审稿说明:1.对论文内容、论文质量、学术水平(含文字、图表、公式)的评价。2.对论文具体说明推荐的理由。3.推荐的论文稿件是否符合编写规范要求。推荐人意见: 推荐人签字: 年 月 日 院长签字: 年 月 日本科生毕业设计开题报告题 目CA6140车床拨叉加工工装设计学院名称 专业名称 年 级 学生姓名 学 号 指导教师 职 称 年 月 日毕业设计外文资料翻译系部: 专 业: 姓 名: 学 号: 外文出处: Process Planning and Concurrent Engineering 附 件: 1.外文资料翻译译文;2.外文原文。 指导教师评语: 签名: 年 月 日附件1:外文资料翻译译文工序制订与并行工程产品设计是用于产品,及它的部件装配的计划。为了把产品设计转化成一个实际存在的物体,这需要一个制造计划。而制订一个这样的计划的行动就叫做工序制订。它是产品设计和制造之间的连接。工序制订包括决定加工顺序和制造产品所必须完成的装配步骤。在这篇文章中,我们将对工序制订和他的一些相关的主题进行解释。首先,我们应该区别在这篇文章中被反复提到的工序制订和生产计划。工序制订与如何制造产品和它的零件等工程技术问题有关。制造零件和装配产品需要什么样的设备和工具?工序制订与产品制造物流管理有关系。它在工序制订后面与原料分类及获得满足制造充分数量产品要求的资源有关。工序制订工序制订包括决定最适当的制造及装配步骤和顺序,可计划的工序范围和多样性通常由于公司车间可用设备和技术能力而受到限制。在公司内部不能够制造的零件必须到外部市场购买。工序制订所提及的工序选择同样也受到详细设计资料的限制。我们稍后将会回到这一点。工序制订通常是由制造工程师完成的。(工业工程师拥有其他权利。)工序制订者必须熟悉工厂中详细可用的制造流程并且能够说明工程图。基于制订者的知识,技术和经验,用于制造每个零件的工序步骤以最合乎逻辑的顺序被发展制订。下列各项是在工序制订范围里的许多决定和详细资料:.设计图的说明. 在工序制订的开始,产品设计的这一部分(材料、尺寸、公差、表面处理、等等)必须进行分析。.工序和顺序. 工序制订者必须选择哪一个工序是必需的及必需工序的序列。此外还必须准备好一个简短的工序步骤描述。.设备选择. 大体上,工序制订者必须逐步展开利用工厂现有机器的计划。另外,组件必须被购买或在新设备上的投资必须被制定。.工具、冲模、铸模、夹具、量具. 工序必须决定每个工序需要什么工具。这些工具的实际设计和制造通常通过委派工具设计部门和工具库或者联系专攻那种工具制造的外面厂商来完成。.方法分析. 车间规划、小工具、提升重物的提升间、甚至在一些人工操作情景中的肢体动作也被指定。.操作步骤. 工作测量技术被用来为每个操作设定时间标准。.切削工具和切削条件. 这些必须对加工操作通过推荐标准手册来进行详细说明。零件工序制订对于单个零件,加工顺序通过一种被称为进路表的表格来进行文件证明备份。 (不是所有的公司使用进路表这个名字;另外的一个名字是“操作说明书。”)就如工程图被用于详细说明产品设计一样,进路表被用于详细说明工序计划。他们是类似的,一个用于产品设计,另一个用于制造。典型的进路表,如图21.1 中举例,包括下列信息:(1)所有工作部分要执行的操作都按照他们应当被执行的顺序列出来;(2)一个指出关于零件图尺寸公差必须完成加工的每个操作的简短描述;(3)用于完成这个操作的特定设备;(4)象冲模,钻模,切削刀具,钻夹具或夹具,和量具这样的特定工具。一些公司还包括时间设置,周期标准和其他数据。他被称为进路表是因为工序顺序规定了零件在工厂中必须遵循的路线。如表21-1中,列出了在准备一个进路表时所需要的一些指导方针。进路表包含 XYZ在内的机械工厂零件号081099材料 1050 H18 A1序号零件名称发电机轴 产品尺寸 60mm diam,206mm length操作内容面向末端(0.003mm).粗车直径至52.00mm.在50.00mm处结束车削面向并车削长15.00mm直径为42.00mm的轴肩退刀结束.表面加工至200.00mm长.粗车直径到52.0mm.至50.mm车削结束.钻4个直径为7.5mm的孔铣6.5mm深x方向5.00mm宽的槽在对面铣宽10.00mm的槽制订者MPGroover校核: N.Needed日期08/12/xx页数 1/1注释加工方法设备装备时间设置操作时间1020304050latheL45DrillMillMillL45G0810D09M32F630G08100.7hrJ555F6621.5hr1.0hr3.0min.0.5hr0.7hr4.8min5.2min3.2min6.2min图 21.1 详细说明工序计划的典型进路表表21-1 准备一个进路表的典型指导方针连续操作步骤的操作序号应该以10,20,30,等形式列出。如果必要的话这允许插入新的操作。当一个工件从一个工作站到另一个工作站, 新的操作和序号必须进行详细说明。当一个工件从一个夹具到另一个夹具,尽管有可能在同一设备上,新的操作和序号也必须进行详细说明。当在一条生产线上如果一个工件从一个工人到另一个工人,新的操作和序号也必须进行详细说明。开始原料基础工序二级工序特性加强工序最后工序完成零件特性加强工序不一定是必须的在特性加强之后,有时需要一些二级工序图21.2 在零件制造中的典型工序顺序 制造单个零件的典型加工顺序包括:(1)一个基本工序,(2)二级工序,(3) 提高物质特性工序,和(3)最后工序。在图21.2中显示了这种序列。一个基本工序决定了工件的起始造型。金属铸件,塑料成型,金属精炼是基本工序中的实例。 起始造型常常必须通过改变起始造型操作(或者接近于最终造型)的二级工序来精制。二级工序习惯于和基本工序一起提供起始造型。当砂型铸造是基本工序,车加工通常是二级工序。当轧钢厂制造金属片是基本工序,冲压操作象冲裁和弯曲通常是二级工序。当塑料注入成型是基本工序时,二级工序通常是不必要的,因为他的大多数几何特征制造通过别的方式如成型制造来完成。塑料成型和其他操作的二级工序被称为净成型工序的并发二级工序。需要一些但并不多的二级工序的操作就是所提到的近似净成型工序。许多有印象的摸锻件就是这一类。这类零件能够经常在锻造(初级工序)阶段被成型,因此减少了必要的加工(二级工序)。 一旦模型被建立,许多零件的下一步是改良它们的机械物理性能。提高特性工序并不改变零件模型,然而,它却能改变零件的物理特性。金属零件的热处理操作就是最普通的实例。类似的如玻璃通过热处理来制造钢化玻璃。对于大多数零件的制造来说,这些特性加强工序如在图21.2指出的可选择路径那样在加工工序中并不需要。 最后工序通常对零件(或装配体)的表面提供一个涂层。例如电镀,薄膜沉积技术,涂漆。表面处理的目的是改善外观,改变颜色,或者表面保护防止腐蚀和磨损等等。在很多零件中最后工序是并不需要的;例如,塑料成型就很少需要最后程序。当必须需要最后程序,他通常是加工顺序的最后一步。表21-2列出了一些普通原料加工的典型加工顺序:表21-2 一些典型加工顺序基本工序开始原料二级工序最后成型加强工序最后工序砂型铸造 砂型铸件加工车加工零件(可选择)涂漆拉摸铸造拉摸铸件(净成型)拉摸铸造(可选择)涂漆玻璃铸造玻璃锭挤压 ,吹塑法玻璃器皿 热处理(无)注塑成型 模型制品(净成型)成型塑料(无)(无)轧扎金属片l切割模弯曲模冲压(无)电镀 喷漆轧扎金属片l深冲压冲压(无)电镀 喷漆锻造 锻件(净成型) 加工机加工件(无)电镀 喷漆轧扎和 棒材拉拔 棒料磨削加工机加工件热处理电镀 喷漆挤压铝压出型材切削挤压零件(无)阳极电镀 喷漆雾化金属粉末挤压PM 零件烧结喷漆粉碎陶器粉末挤压陶器烧结上釉锭拉拔矽块锯和碾磨硅片清洗锯 和 磨削矽块氧化,CVD,PVD蚀化IC芯片表面处理装配工序制订一个既定产品的典型装配方法由以下因素决定的:(1)预期产品数量;(2)装配产品的复杂性,例如,不同组件的数量;和(3)常用装配工序,例如,机械定位焊接。对于小数量产品,通常在人工装配线上进行装配。对于大量制造的一打或这样组件的简单零件,要采用适当的自动化装配线。无论如何,这里有一个工作必须被完成的优先顺序。这个优先需求经常用一个优先表来进行图表描绘。装配工序制订包括装配指令的发展,但是更详细地,对于小批量生产,在一个岗位完成整个装配。对于一个装配线上的大批量生产,工序制订由一种分配工作条件到装配线个别工位并被叫做人工投入线性平衡法的程序组成。这种装配线按照装配线平衡解决方案决定的顺序发送工作单元到个别工位。在个别组成,任意工具或夹具的工序制订时,一条装配线的决定,设计,和制造必须被完成,并且工作站的必须被列出来。制造或购买决定在工序制定过程中出现的一个重大问题是一个特定零件应该在公司内部的工厂内生产还是从外部销售商处购买,并且这个问题的答案被认为是制造或购买决定。如果公司没有技术设备或制造零件所必须的详细制造工序中的专门技术,那么答案就很明显了:因为没有其他选择零件必须购买。然而,在很多例子中,零件既可以在利用现有设备在内部制造或者可以从外部拥有相似制造能力的生产销售商处购买。在我们的关于制造或购买的决定的讨论中,他应该认识到在开始几乎所有的制造者从供应商那里购买原料。一个机械加工厂从一个金属经销商购买他的起动柄原料或从一个铸造厂购买他的砂型铸件。一个塑料成型厂从一个化工厂购买他的模塑料。一个冲压厂可以去经销商或直接从轧钢厂购买金属片。很少的公司能够在操作中从原料一直进行垂直整合,这看来至少购买一些也许在他的工厂可以另外制造的零件是合理的。也有可能为公司使用的每一个组成要求制造或购买决定。这里有许多影响制造或购买决定的因素。在表21-3中列出一列影响决定的因素和结果。一个人可能认为成本是决定是购买还是制造零件的最重要的因素。如果一个外部经销商比公司工厂更精通于制造零件的工序,因而公司内部生产成本可能比经销商赚取成本后的价格还要高。可是,如果购买决定导致公司工厂设备和劳动的闲置,可是购买零件的表面优势就会丧失。考虑以下例子,例21.1制造或购买决定为一个特定零件被引述的价格是100个单位的每单位$20.00。制造零件的成分如下所示: 单位原料成本=每单位$8.00 直接劳动成本=每单位6.00 劳动加班150%=每单位9.00 设备修理成本=每单位5.00 总计=每单位28.00表21-3制造或购买决定因素因素在制造或购买决定的说明和效果零件成本是如何比较的?这也许被看作是在制造或购买决定的最重要的因素。然而,成本比较并不明显,如例21.1这种加工可以在内部使用吗?如果一个给定工序的设备和专门技术在内部不能用,那么购买是显而易见的决定。经销商经常适合精通特定工序,这使得他们在内外比较中有较强的成本竞争力。然而,如果公司不发展在对于制造该类型产品的重要特定工序的专门技术,这将影响公司的长期成本运算。什么是产品总产量?必需的单位总数在产品的生命上是主要因数。如果总生产量增大,这用意支持制造决定。较低的生产量支持购买决定。什么是产品预期寿命?较长的产品寿命趋向于支持这种决定组成是不是一个标准项目?标准目录项目(举例来说,硬件项目如螺栓,螺钉,螺母,和其他标准件)由那些专门制造这种产品的厂商以低成本制造。在标准件上,成本比较几乎一直支持一个购买决定供应商是否值得信赖?一个经销商在关键零件的交货延误将导致公司总装配厂的停工。拥有保证交货期和质量报告的供应商比那些有较少报告的供应商要受到优先考虑的。公司工厂是不是已经全能力操作?在最高要求周期中,公司也许被迫从外部经销商购买一部分必需的产品来增大列出工厂设备能力。公司需要一个其它可能的供给来源吗?公司有时为他们的生产工厂从外部经销商购买的零件来维持可选择的货源。附件2:外文原文Process Planning and Concurrent Engineering The 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. At the outset ,we should distinguish between process planning and production planning ,which is covered in the following chapter. Process planning is concerned with the engineering and technological issues of how to make the products and its parts. What types of equipment and tooling are required to fabricate the parts and assemble the product ? Production planning is concerned with the logistics of making the product .After process planning is concerned with ordering the materials and obtaining the resources required to make the product in sufficient quantities to satisfy demand for it.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 .(Other titles include in industrial engineer.) 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 parts For individual parts,the processing sequence is documented on a form called a route sheet .(Not all companies use the name route sheet ;another name is “operation 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 route sheet ,illustrated in Fig.21.1,includes the following information: (1) all operations to be performed on the work part ,listed in the order in which they should be performed ; (2) a brief description of each operation indicating the processing to be accomplished,with references to dimensions and tolerances on the part drawing; (3) the specific machines on which the work to be done; and (4) special tooling such as dies molds ,cutting tools,jigs or fixtures ,and gages.Some companies also include setup times ,cycle time standards,and other data.It is called a route sheet because the processing sequence defines the route that the part must follow in the factory .Some of the guidelines in preparing a route sheet are listed in Table 21-1. Decisions on process to be used to fabricate a given part are based largely on the starting material for the part .This starting material is selected by the product designer.Once the material has been specified ,the range of the possible processing operation is reduced considerably .The product designers decisions on starting material are based primarily on functional requirements ,although economics and manufacturability a role in the selection.Route SheetXYZ Machine Shop,Inc.Part no.081099Material 1050 H18 A1No.Part name Shaft ,generatorStock size 60mm diam,206mm lengthOperation descriptionFace end (approacx.3 mm).Rough turn to 52.00 mm diam Finish turn to 50.00 mm diam.Face and turn shoulder to 42.00 mm diam.and 15.00 mm lenghthReverse end.Face end to 200.00mm length.Rough turn to 52.00mm diam.Finish turn to 50.00mm diam Drill 4radial holes 7.50mm diamMill 6.5 mm deep X 5.00 mm wide slotMill 10.00 mm wide flat ,opposite side.PlannerMPGrooverCheck by: N.NeededDate 08/12/xxPage 1/1CommentsDeptMachineToolingSetupSdt1020304050latheL45DrillMillMillL45G0810D09M32F630G08100.7hrJ555F6621.5hr1.0hr3.0min.0.5hr0.7hr4.8min5.2min3.2min6.2min Fig.21.1 Typical routes sheet for specifying the process plan Table 21-1 Typical Guidelines in Preparing a Route Sheet .Operation numbers for consecutive processing steps should be listed as 10,20,30,etc This allows new operations to be inserted if necessary. .A new operation and number shouled be specified when a work part leaves one workstation and is transferred to another station. .A new operation and number should be specified if a part is transferred to another workholder(e.g.,jig or fixture),even if it is on the same machine tool. .A new operation and number should be specified if the work part is transferred from one worker to another ,as on a production line. Starting raw materialBasic processSecondary process Property-enhancing processesFinishing operations Finished partProperty-enhancing processes not always required Additionary secondary processes sometimes required following property enhancement Fig.21.2 Typical sequence of processes required in part fabrication 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.The sequence is shown in Fig.21.2. A basic process determines the starting geometry of the workpart.Metal casting ,plastic molding ,and roling 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 ,as indicated by the alternative arrow path in Fig.21.2. Finally finish operations usually provide a coat on the work parts (or assembly )surface. Examples inclued 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 .Table 21-2 presents some typical processing sequences for common materials used in manufacturing . In most cases,parts and materials arriving at the factory have complete their basic process.Thus ,the first operation in the process plan follows the basic process that has provided the starting geometry of the part .For example ,machined parts begain as bar stock or castings or forgings,which are purchased from outide vendors.The process plan begains with the machining operations in the companys own plant .Stempings begin as sheet metal coils or strips that are bought from the rolling mill.These raw materials are supplied outside sources so that the secondary processes,property-enhancing operations ,and finishing operatios can be performed in the companys own factory. In addition to the route sheet ,a more detailed description of eac operation is usually prepared. This is filed in the particular production department office where the operation is performed.It lists specific details of the operation ,such as cutting conditionsand toolings(if the operation is machining )and other instructions that may be useful to the amchine operator.The desciptions often include sketches of the machine setup. Table 21-2 Some Typical Process SequenceBasic ProcessStarting MaterialSecondary processesFinal shapeEnhancing ProcessesFinishing ProcessesSand casting Sand castingMachiningMachined part(optional)PaintingDie casting Die casting(Net shape)Die casting(optional)PaintingCasting of glassGlass ingotPressing ,blow moldingGlass ware Heat treatment(None)Injection modeling Molded part(Net shape)Plastic Molding(None)(None)RollingSheet metalBlanking punching bending formingStamping(None)Plating paintingRollingSheet metalDeep drawingDrawing(None)Plating paintingForging Forging(near net shape) MachiningMachined part (None)Plating paintingRolling and bar drawing Bar stockMachining grindingMachined partHeat treatmentPlating paintingExtrusion of aluminum ExtrudateCutoffExtruded part(None)Painting anodizingAtomizeMetal powdersPressPM partSinterPaintComminutionCeramic powderspressCeramic wareSinterGlazeIngot pullingSilicon bouleSawing and grindingSilicon waferCleaningSawing and grindingSilicon bouleOxidation,CVD,PVDetchingIC chipCoatingProcessing 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,and built;and the workstation arrangement must be laid out.Make or Buy Decision An 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 .We have complied a list of the factors and issues that affect the decision in Table 21-3 .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 the manufacturing 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 .Example 21.1 Make or Buy Decision The quoted price for a certain
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