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外文翻译--对通过塑料注射成型零件的选择性激光融化生产得到的功能梯度材料插入棒的评估英文版.pdf

多用角架搁板的注塑模具设计及其仿真加工设计【9张图纸】【优秀】

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关键词：: 多用角架搁板注塑模具设计及其仿真加工设计图纸多用角架搁板

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多用角架搁板的注塑模具设计及其仿真加工设计

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凸模.dwg

凹模.dwg

动模固定板.dwg

塑件.dwg

外文翻译--对通过塑料注射成型零件的选择性激光融化生产得到的功能梯度材料插入棒的评估中文版.doc

外文翻译--对通过塑料注射成型零件的选择性激光融化生产得到的功能梯度材料插入棒的评估英文版.pdf

多用角架搁板.doc

多用角架搁板的注塑模具设计及其仿真加工设计.doc

定模座板.dwg

导套.dwg

拉料杆A4.dwg

浇口套.dwg

装配图.dwg

QQ截图20140126132653.gif

凹模.gif

导套.gif

定模座板.gif

动模固定板.gif

浇口套.gif

拉料杆A4.gif

全部文件.gif

塑件.gif

凸模.gif

装配图.gif

摘要I

AbstractII

1 绪论1

1.1模具工业的地位和发展前景1

1.2课题内容和意义1

2塑件成型工艺性分析3

2.1塑件结构分析3

2.2塑件的工艺性分析3

2.2.1塑件材料的选择3

2.2.2 塑件的壁厚5

2.2.3 塑件的表面质量5

2.2.4 塑件的精度等级6

2.2.5 塑件的脱模斜度6

2.3 PP塑件的注射工艺7

3 分型面的选择9

3.1 分型面位置的确定9

3.2 型腔数目的确定10

4 注射机型号的选择11

4.1 体积质量的计算11

4.2 注射机的选择11

4.3 注射机相关参数的校核12

5 注射过程与模流分析14

5.1 MoldFlow分析软件简介14

5.2 网格划分14

5.3 塑件的最佳浇口位置分析15

5.4 塑件的流动性分析16

5.4.1 气穴和熔接痕16

5.4.2 注射位置处压力17

5.4.3充填时间17

5.4.4 锁模力18

5.5塑件的冷却分析18

5.6 MoldFlow分析总结19

6 浇注系统的设计20

6.1 浇注系统的设计原则20

6.2 主流道的设计和计算20

6.3 浇口的设计21

6.4校核主流道的剪切速率21

7注塑模具成型零件及模具体的设计22

7.1成型零件的结构设计22

7.2成型零件钢材的选用22

7.3成型零件工作尺寸的计算22

7.3.1凹模径向尺寸的计算22

7.3.2凹模深度尺寸的计算23

7.3.3凸模径向尺寸的计算23

7.3.4 凸模高度尺寸的计算23

7.4 合模导向机构的设计23

7.5 脱模机构的设计24

7.5.1脱模力的计算24

7.5.2塑件脱出机构25

7.6 模架的确定26

7.7模架各尺寸的校核26

8冷却系统及排气系统设计27

8.1 冷却系统的设计27

8.1.1 模具温度调节的必要性27

8.1.2 冷却系统的设计原则27

8.1.3 冷却水道的设计27

8.2排气和引气系统的设计29

9模具的装配与调试31

10 基于Mastercam X2的仿真加工33

10.1 Mastercam X2软件简介33

10.2 多用角架搁板凸模加工34

10.2.1 加工坯料及对刀点的确定34

10.2.2规划曲面挖槽粗加工刀具路径34

10.2.3 工件参数设置35

10.2.4 曲面挖槽粗加工实体加工模拟35

10.2.5规划分型面浅平面精加工刀具路径36

10.2.6分型面浅平面精加工实体加工模拟36

10.2.7规划等高外形精加工刀具路径37

10.2.8 曲面等高外形精加工实体加工模拟37

10.2.9 规划3圆鼻刀曲面平行精加工刀具路径38

10.2.10曲面平行精加工实体加工模拟39

10.2.11 规划顶面平行铣削精加工刀具路径39

10.2.12 顶面平行铣削精加工平行铣削实体加工模拟40

10.3生成加工NC代码40

结论42

致谢43

参考文献44

摘要

　　　注射模具是模具工业的重要发展方向，也是衡量一个国家产品制造水平高低的重要标志。模具 CAD/CAE/CAM 技术的应用从根本上改变了传统的产品开发和模具生产方式，大大提高了生产效率、产品品质以及企业自身的竞争力。

　　　本文根据多用角架搁板实物模型进行了模型特征重构，在此基础上基于 PRO/E软件设计出一套合理的注射模具。首先分析了多用角架搁板制件的工艺特点，包括材料性能、结构工艺性、成型特性与条件等，并选择了成型设备。然后介绍了香皂盒注射模的分型面选择、型腔数目及布置形式，重点介绍了浇注系统、成型零件、冷却系统、脱模机构的设计。然后选择模架，并对注射机的工艺参数进行了校核。在此基础上，本文讲诉了如何运用Mastercam软件对多用角架搁板凸模进行仿真加工。　　

关键词注射模具；PRO/E；Mastercam；仿真加工

1 绪论

1.1模具工业的地位和发展前景

塑料注射成型所用的模具称为注射成型模，简称注射模。它是实现注射成型工艺的重要工艺装备。塑料模具为模具总量近 40％，而且这个比例还在不断上升。这类模具主要是两类：一类是大型模具，一类是精密模具。大型模具主要是以汽车仪表板，保险杠和家电产品模具为代表的成型模具。精密模具是以集成电路、塑封模具为代表的成型模具。注射模具被欧美等发达国家誉为“磁力工业”。很大部分工业产品依赖注射模具才得以规模生产、快速扩张，由于注射模具对社会生产和国民经济的巨大推动作用和自身的高附加值，世界模具工业，尤其是注射模具工业发展较快，当前全球模具工业的产值已经达到 600 亿~650 亿美元，是机床工业产值的两倍，其中注射模具工业的产值已经达到 240 亿至 260 亿。

纵观发达国家对模具工业的认识与重视，我们感受到制造理念陈旧则是我国模具工业发展滞后的直接原因。模具技术水平的高低，决定着产品的质量、效益和新产品开发能力，它已成为衡量一个国家制造业水平高低的重要标志。因此，模具是国家重点鼓励与支持发展的技术和产品，现代模具是多学科知识集聚的高新技术产业的一部分，是国民经济的装备产业，其技术、资金与劳动相对密集。目前，我国模具工业的当务之急是加快技术进步，调整产品结构，增加高档模具的比重，质中求效益，提高模具的国产化程度，减少对进口模具的依赖。

现代模具技术的发展，在很大程度上依赖于模具标准化、优质模具材料的研究、先进的设计与制造技术、专用的机床设备，更重要的是生产技术的管理等。21世纪模具行业的基本特征是高度集成化、智能化、柔性化和网络化。追求的目标是提高产品的质量及生产效率，缩短设计及制造周期，降低生产成本，最大限度地提高模具行业的应变能力，满足用户需要。

在科技发展中，人是第一因素，因此我们要特别注重人才的培养，实现产、学、研相结合，培养更多的模具人才，搞好技术创新，提高模具设计制造水平。在制造中积极采用多媒体与虚拟现实技术，逐步走向网络化、智能化环境，实现模具企业的敏捷制造、动态联盟与系统集成。我国模具工业一个完全信息化的、充满着朝气和希望而又实实在在的新时代即将到来。

1.2课题内容和意义

本次设计的课题设计内容主要包括以下几点：

1.进行多用角架搁板塑件的三维造型设计；

2.从塑料品种、塑件形状、尺寸精度、表面粗糙度等方面考虑注塑成型工艺的可行性和经济性，进行塑件成型的工艺性分析；

3.根据塑件的质量和模具型腔数大致确定模具的结构，初步确定注射机型号，了解注射机与模具有关的技术参数；

4.考虑塑件成型位置及分型面选择，模具型腔数，型腔的排列，流道布局及浇口位置设置来进行凸、凹模零件设计；

5.将模具三维模型导入CAM软件中，进行注塑成型模具三维型面的数控仿真加工；

6.由模具三维结构图绘制出二维装配图，依据装配图完成模具主要零件的设计和图样绘制。

本次毕业设计通过对注塑成型模具的设计，可了解常用塑料的性能、塑料制品的设计原则及方法，掌握注射模具常用结构的组成、特点及应用场合，并由此熟悉注射成型工艺及仿真加工的全过程。通过学习现代化的设计制造方法，积极开展CAD/CAM技术在注射模具设计中的推广应用, 从而提高自己进行模具设计的工作能力。

内容简介：: Evaluating the use of functionally graded materialsinserts produced by selective laser melting on theinjection moulding of plastics partsV E Beal1*, P Erasenthiran2, C H Ahrens1, and P Dickens21Universidade Federal de Santa Caterina, Floriano polis, Brazil2Wolfson School of Mechanical Engineering, Loughborough University, Loughborough, UKThe manuscript was received on 19 October 2006 and was accepted after revision for publication on 9 March 2007.DOI: 10.1243/09544054JEM764Abstract:The demand for productivity and shape complexity on the injection mouldingindustry necessitates new research to improve tool design, material, and manufacturing.A research field is the development of functionally graded materials (FGMs) to build injectionmoulds. For example, moulds built with the FGMs technique can have distinctive regionswith higher heat conduction. Higher rates of heat transfers from thicker regions of theinjected part can be useful to produce better and cheaper injection moulded polymer parts.It is possible to obtain moulds with differential conductivity by adding locally, during thefabrication of the mould, copper to the mould base material such as tool steel. In this work,an investigation into the effect of FGM copper (Cu)-tool steel mould insert over polymerinjected parts is presented. The work is divided in two parts: a numerical thermal analysiscomparison between Cu-tool steel graded and tool steel inserts and an injection mouldingexperiment with comparisons between mould surface temperature and degree of crystallinityof polypropylene parts. The numerical model was used to compare different behaviour of themould heat transfer according to the mould insert material. Thereafter, a bolster was built tohold FGMs and tool steel inserts obtained by a selective laser fusion process. Polypropylenewas injected over the inserts to compare with the numeric results. To observe the effect ofthe cooling rate in the polypropylene parts using the graded inserts, the degree of crystallinityof the parts was measured by differential scanning calorimetry (DSC) test. The temperatureof the mould was also evaluated during the injection cycles. The results showed that thegraded Cu-tool steel inserts tested had lower capacity to store heat energy. As Cu was addedto the tool steel, the mixture proved to transfer heat more efficiently but it had less capacityto absorb heat.Keywords:functionallygradedmaterials,injectionmoulding,rapidmanufacturing,polypropylene crystallinity1INTRODUCTIONThe benefit of injection moulded parts depends onthree general aspects: tool cost, injection mould-ing raw material, and productivity of the tool. Thistrio makes it difficult to change part/mould designwithout affecting productivity and material. Hence,durability of the tool, productivity, and costs must beachieved by the optimal material raw selection andpart and mould designs 1. Unfortunately, there arerestraints that make it difficult to find the best com-promising solution. As the complexity of a moderninjection mould is high, the mould designers concernis how to solidify the part without causing distortionsand keeping the mould with high rates of parts pro-duced per hour. A complex channels network isdesigned to enable cooling liquid to extract the heatfrom the mould. The design of the channels is difficultas it is necessary to keep the ejection system in place.*Corresponding author: Engenharia Meca nica CIMJECT,Universidade Federal de Santa Catarina, Caixa Postal 476,Campus Universita rio Trindade, Floriano polis, SantaCatarina 88040-900, Brazil. email: valterbealJEM764? IMechE 2007Proc. IMechE Vol. 221 Part B: J. Engineering Manufacture945Ejector pins, slides, and air stream gates are used toeject the part from the mould cavity avoiding marksin the aesthetic side of the part. Depending on thecomplexity and shape of the part, the space left bythe cooling system is small and it is not feasible tomanufacture without leaving marks in the mould imp-ression. In many cases, when the heat extraction equi-librium for homogeneously extracting the heat fromcavity and productivity are not achieved, it might benecessary to redesign the part geometry to fit mouldlimitations. An alternative to solve complex thermalissues is the use of copperberyllium (CuBe) inserts1. As CuBe inserts have higher thermal conductivitythan the usual steel alloys, they are used to extractheat from regions where the cooling channels do nothave an effect during the injection moulding cycles.Nevertheless, they are not environmentally friendly,as beryllium is cited as a highly carcinogenic element2. Another limitation is that inserts in the mouldimpression might leave marks in the part as the mouldsurface has a visible interface between the basematerial and the insert. In addition, the insert featuresthat are needed to attach it to the base contribute toreducing the space left for the cooling channels.In the mid 1980s, new manufacturing technologiesknown as SFF (solid free-form fabrication) emerged3. The main difference of these technologies, as oppo-sed to the traditional ones, was that they were basedon the layer additive principle. Also known as rapidprototyping (RP), these technologies can produceparts in low-volume production in virtually anyform or material. The variety of available materialsis limited; however, RP processes can build parts inmetals, ceramics, and polymers 3. RP technologiesare highly automated and they are also called three-dimensional (3D) printers as the machines almostprint solid parts from data generated from compu-ter software. Designers and engineers can build andverify designed parts without misunderstandings,inaccuracies, and delays. The basic principle of RPtechnologies is to build, layer-by-layer, material cor-responding to the data of the designed part. Rawmaterials can be liquid resins, wires, pastes, powders,and sheets. The way to shape these materials andbond layers can be diverse including ultravioletlasers, lamps, power lasers, spray of glue, depositionof fused material, and others. These additive-layeredmanufacturing technologies (LMTs) have also beenused to produce tools for injection moulding. Depend-ing on the technology and material used in cons-truction, the complexity of the mould impression(injected part), and the injected material, thesemoulds can be competitive to traditional cast/milledmoulds. It is possible to build moulds from 12 to10000 parts according to the technology, material,and application 4, 5. One interesting techniqueused with SFF to build injection moulds is conformalcooling channels. The channels are designed in themould impression without the concerns of the lim-itations from the traditional manufacturing method.The conformal cooling channels might follow themould impression surface, passing by the ejector sys-tem with fewer limitations than the usual moulds.Unfortunately, they are still limited by the ejectionsystem and some part features such as deep grovesmight not be affected by the cooling capabilities ofthe channels. To overcome some of these constraints,it is possible to use functionally graded materials(FGMs) to build injection moulds by SFF technologies.FGMs have been the subject of research for the last25 years 6. Most of the natural materials such asminerals and tissues have a gradual change fromone functional region to another. This example ofnature inspires integrated form and function designall in the same component/unit. FGM is not comple-tely new to the manufacturing processes, but it wasonly after the 1980s that it started to receive moreattention and to be classified as a specific researchsubject. The basic idea of FGM is to improve theproperties of the part by varying the quantity of aningredient in specific regions in order to achieve dif-ferential properties. An ingredient could be a basicelement such as carbon being used to increase thehardness of a steel part only at the surface. Anotherexample is the porosity variation from the outside tothe inside of the mammals bones. The low porosityfrom the outside increases the stiffness of the bonebut provides interconnectivity to the inside. Thecore of the bone is porous, thereby allowing weightefficiency. By using this variation from one materialto another, optimized components can be obtained.Reduced number of joints and fasteners, weightreduction, structural enhancement, differential heatextraction, thermal barriers, embedded sensors, andbiocompatible implants are some of the potentialadvantages of using FGM 68. FGMs also couldgradually join dissimilar materials with differentproperties in the same component. The principle issimilar to composite materials. The difference isthat composites have distinctive phases and do notvary their composition in the volume of the compo-nent. Despite the idea of FGMs being very simple,most of the potential FGM applications are restric-ted to technological limitations and high cost. Diffi-culties in controlling and depositing the gradientcomposition and producing complex shapes withcomputer-aided design (CAD), computer-aided man-ufacturing (CAM), and finite element analysis (FEA)integration are some of the causes for restrictionsof use.The use of RP technologies to produce FGM partshas been investigated by many researchers 9. SinceRP technologies can produce free-form parts and canhandle different materials, it is possible to use them946V E Beal, P Erasenthiran, C H Ahrens, and P DickensProc. IMechE Vol. 221 Part B: J. Engineering ManufactureJEM764? IMechE 2007to produce FGM components. Most of the research-ers investigating the fabrication of FGM by LMTs pro-cess the materials with the heat source delivered by alaser beam. As lasers can be easily automated andcan deliver high-energy densities with precision andspeed, they can process almost any material 10.Another aspect of FGM and RP is the frequent useof materials in the form of powder to be fused orpre-sintered under a laser spot. The main issue forusing rapid processing and manufacturing technolo-gies for producing FGM parts is the local compositioncontrol (LCC). This regards the principle for addingand joining the materials by controlling their percen-tages on each region of the part or layers. Someresearchers 11, 12 used miniature hopper-nozzlesand capillary tubes to control the deposition of pow-ders in the layer. Ensz et al. 13 studied the optimiza-tion of two powder flows in the laser engineering net-shaping (LENS?) process to build gradients fromH13 to M300 steel alloys. In addition, computationalmethods to represent the graded geometry havebeen the subject of study. Cho et al. 14 investigatedthe LLC for the 3D printing process after obtaininggeometry and material data from finite element andvoxel space geometries. By this method, it was possi-ble digitally to represent the 3D part with differentvolumetric gradients.The idea of adding an extra functional material toa base material to produce a FGM injection mouldhas been researched in previous work 15. A multi-compartment hopper was used to produce gradedstructures of H13 tool steel and Cu. The H13 iscommonly used as material for injection moulds asit has dimensional stability, toughness, and wearresistance at high temperature. Nevertheless theheat conduction of this material is low comparedwith Cu (kH13: 24.3W/m K; kCu: 385W/mK 16, 17).Elemental Cu powder was mixed with H13 in propor-tions of 12.5, 25, 37.5, and 50%wt to produce FGMbars. The method for producing these bars was theselective laser fusion/melting (SLF or SLM) using ahigh-powder Nd:YAG pulsed laser. The laser pro-cessed the multi-composition powder bed that waspreviously loaded with powders from the multi-compartment hopper. As the laser scanned thepowder bed, the powder was fused and bonded tothe previous added layers. After processing a layer,the powder bed was lowered and the powders werespread over the previous layer and the laser was setto fuse the powder to form a new layer. This processwas numerically controlled and continued until thecompletion of the part. The fusion process, usingthis laser, left a rough superficial aspect and requiredsome post processing including the removal of thesubstrate that was used to bond the first layers ofthe part to the powder bed platform. At the end ofthe process, graded parts of H13 and Cu could beobtained. Therefore, FGMs could be used on injec-tion moulds to create high heat conductivity regionsto improve heat extraction. As the cooling/heatingchannels can be limited by manufacturability andthe ejector system, some regions of the impressioncould be over heated. This differential heat extractionfrom the part might cause warpage, sink and coldwelding marks, and poor surface quality, and couldreduce the production rate of the part. Anotherapplication of FGM on moulds is to build the cavityedges with gradients of tool steel and tungsten car-bide. This could improve the part quality by red-ucing defects such as flashing caused by wear in themould edges 1.The use of FGM to obtain performance injectionmoulds was one of the stimuli for this research.Despite the limitations of the laser and layer deposi-tion systems used in this work, these experimentswere planned to evaluate the influence of the Cuaddition to the H13 matrix. The effect of the additionof Cu on the mould temperature and on the injectedpolymer part crystallinity degree, compared with theH13 base material, was analysed. In theory, the addi-tion of Cu would increase the thermal conduct-ivity of the mould. The work was divided in twoparts: numerical modelling of the heat transfer andexperimental injection moulding. The first part pre-sents the numerical model of the heat transfer fromthe injected part to the mould and the metallicinserts. The model evaluated the temperature timestamp, simulating mould inserts in different materi-als: H13, Cu, and H1350%Cu. In the injectionmoulding experiment, FGM bars (mould inserts)were manufactured by laser fusion and placed in astereolithography (SL) mould. Polypropylene (PP)parts were produced by injecting the polymer overthese metallic inserts. Two outputs were analysedfrom this experiment: temperature of the mould sur-face and crystallinity degree of the PP parts. Thetemperature of the mould was measured by thermo-couples in the exact same position taken in thenumerical model. The degree of crystallinity of theparts, moulded with different inserts, was analysedby differential scanning calorimetry (DSC). The DSCtest was performed to identify if the parts mouldedover different inserts had different cooling rates. As aconsequence, the degree of crystallinity of the partscould be different too. The lower the cooling rate,the greater is the organization of the polymer chainsreflecting in the crystallinity degree of the PP. A rapidcooling rate helps the polymer to hold an amorphousstructure. When heating a plastic, more heat will benecessary to dissolve the crystals (more stable andlower energy state) until the plastic is completelymelted. This phenomenon can be seen in the DSCcurves measuring the energy absorbed by the samplebefore melting 18.Evaluating the use of functionally graded materials inserts947JEM764? IMechE 2007Proc. IMechE Vol. 221 Part B: J. Engineering Manufacture2METHODOLOGY2.1Numerical modelThe injection moulding cycle is a transient phenom-ena and thermal conductivity is not the only materialproperty that counts when analysing the heat trans-fer. Density and specific heat capacity also determinethe capability of the material to store or to transportenergy 19. Considering volume control, the energystate is obtained by the balance of the energy that isabsorbed, generated, and lost. This variation of theenergy accumulated by the mass inside the volumecan be modelled by equation (1). The energy thatenters (_Ein) plus the energy generated (_Egen) insidethe volume minus the energy lost (_Eout) to the sur-roundings is equal to the variation of energy (E) ofthe mass inside the volume with respect to time (t)._Ein?_Eout_EgendEdt?vc1In the case of a mould, in the moments after themelted material fills the mould impression, there isno heat generated in defined volume control. Consid-ering the heat transfer in one direction, equation (1)becomes further simplified for the heat flux throughan area A, generating equation (2). Simplifying thearea, equation (3) is generated. In these equations, q00represents the heat fluxes, r is the material density,cpsymbolizes the specific heat, T is the temperature,and x is the axis of the direction of the heat flux.qin00A ? qout00A 0 ZxrcpTtAdx2qin00? qout00ZxrcpTtdx3The temperature in the mould, away from theimpression, could be considered constant. Takingthis into consideration, in a very short period theheat fluxes can be considered constant and can bedescribed as in equation (4), where k is the heatconduction coefficient.q00 kTx?x4There is no easy solution for solving equations (3)and (4) and a numerical model is usually necessaryto solve them for complex shapes. A two-dimensional(2D) model of an injection moulded part inside a SLmould in contact with a metallic insert is shown inFig. 1. This model considered no contact resistancebetween the parts, moulds, and insert surfaces. Theinitial conditions were that the temperature in thenodes inside the area that represents the hot PPinjected part was 195C and the temperature for allother nodes, including the connected nodes of thepart with other areas, was 20C. Temperature was cal-culated by employing a quadrangular mesh formedby planar four-node elements. The nodes chosen tobe analysed are indicated in Fig. 1. Thermocoupletemperature, Ttc, matched the same position in theexperimental work and insert surface temperature,Tis, matched the region from where DSC sampleswere taken in the PP part. The model and analysiswere performed using Ansys software.For inputting the material properties (density,specific heat, and thermal conductivity) in the numer-ical model, tabled values were used for the H13 16.However, the H1350 per cent material propertiesvalues were estimated based on the Voight and Reussrules of mixtures 5, 6. The basic rule of mixtures(Voight) is presented in equation (5). An equivalentproperty () of the mixture formed by a and b phasesis calculated by the summation of the property ofeach phase and the volume fraction (V) of the phasesin the mixture, resulting in a linear variation betweeneach phase value property. The second rule expressedin equation (6) is more elaborate, but neither rulecounts the phase interaction, phase geometry, spacedistribution, and other factors that affect the finalproperty of the mixture. Nevertheless, the secondrule is more conservative than the first one. The mate-rial properties used in the numerical model arepresented in Table 1.Voight Vaa Vbb5ReussbaVab Vba6Intotal,sixsimulationsofthetimeversustemperature in the nodes Ttcand Tis(refer to Fig. 1)were made using different insert materials specifiedin Table 1. The first four simulations were performedFig. 12D model for the heat transfer of an injected part incontact with a metallic insert in a SL mould (initialtemperature indicated for each area of the model)948V E Beal, P Erasenthiran, C H Ahrens, and P DickensProc. IMechE Vol. 221 Part B: J. Engineering ManufactureJEM764? IMechE 2007with all node temperature being time dependent.The other two simulations were calculated consider-ing that the nodes in the back surface of the insertwere kept at a constant temperature of 20C, withoutchanges with respect to time. This was made tosimulate the case of using a cooling channel in theback of the insert. The numerical simulations arelisted in Table 2.2.2Injection moulding experimentTo investigate the effect that FGM had on injectionmoulded parts, graded inserts of H13 and Cu weremanufactured using SLM and a multi compartmenthopper. The laser scanned tracks over a graded pow-der bed. This graded powder bed was spread by thehopper with different blends of powders. The laserenergy melted the powder building a graded struc-ture layer-by-layer. A basic sketch of the process isshown in Fig. 2.To produce the inserts, bimodal-sized mixturesof H13 and Cu powders were used. The powderswith H1312.5%Cu, H1325%Cu, H1337.5%Cu,and H1350%Cu (weight fractions) and pure H13powder were placed on ceramic ball mills for pro-per mixing of the powders. The average ratio bet-ween the diameter of large and fine particles ofpowders was 6.6:1. This is close to 7:1, which is sug-gested in the literature for increasing the apparentdensity (packing) of powder consisting of sphericalparticles 22. The large particles of Cu and H13were within the range 105150mm. The small particlesof Cu were less than 22mm in diameter size and theH13 particles less than 38mm. The AISI H13 tool steelalloy (BS EN ISO 4957:2000 XV40CrMoV5-1) composi-tion was, in percentage weight: Fe 90.8%, C 0.320.42%, Cr 4.755.25%, Mn max. 0.4%, Mo 1.251.75%,Si 0.851.15%, and V 0.91.1% and the copper powderwas 99.99% Cu oxygen free (OHFC) 23.The different compositions of powder were used tofill the multi-compartment hopper and spread over amild steel substrate. The computer numerically con-trol (CNC)-laser-guided system melted the powder,layer-by-layer, using a specific scan strategy patterndeveloped for this technique and described in detailin reference 15. This strategy was divided in to twostages. In the first step, the laser was set to fusespaced lines of powder leaving a gap between thelines. A refill of powder between these solidifiedlines was executed with the hopper sliding the pow-der bed (without moving the platform). In the secondstep of the scanning strategy, the laser was set tomelt the new powder deposited in the gaps. The laserprocessing parameters were: energy pulse 10J, pulsewidth 20ms, repetition rate 2Hz, and scan speedTable 2Conditions of the numerical simulationsCondition ofthe insertInitial temperatureof the injected partInitial temperature ofthe moulds and insertsTemperature at theback surface of the insertH13195C20CInitial 20CCuH1350Cu VoightH1350Cu ReussH13195C20CConstant 20C(cooling system)H1350Cu ReussTable 1Material properties used in the numerical modelDensityHeatcapacityHeatconductionModel area Material(g/cm3) (J/g.C)(W/mK)SL mouldRenShape 7580resin 201.222.00*0.2*PartPolypropylene 211.00y2.000.13InsertH13 167.800.46024.3Cu 178.960.385385.0H1350%Cu Voight 8.340.425192.2H1350%Cu Reuss8.300.42243.1*estimatedyaverageFig. 2The selective laser fusion process and the multi-compartmenthopperforspreadingx-gradedpowder bedEvaluating the use of functionally graded materials inserts949JEM764? IMechE 2007Proc. IMechE Vol. 221 Part B: J. Engineering Manufacture5mm/s.Thelayerthicknessusedwas250mmand argon (Ar) was used to reduce oxidation. Afterbuilding the specimens, they were post processedby cutting off the substrate and grinding its surfaces.The final dimensions of the graded insert and the dis-tribution of the gradient are presented in Fig. 3. Eachdifferent mixture of Cu and H13 was 3.5mm wide.A pure H13 insert was made from stock annealedH13 by cutting and grinding and had the samedimensions as the FGM specimen.An injection mould was designed specifically tohold and swap the inserts. The design of the impres-sion consisted of a simple slab 30 60 2.5mm(Fig. 4). The SL process was used to build the mould.This choice was taken because SL resins have lowthermal conductivity and can work as an insulator.Therefore, the influence of the metallic inserts wouldbe more distinctive. The mould design consideredalso the placement in the mould of two thermo-couples to read the mould surface temperatureduring the injection cycles. The positions of thethermocouples are shown in Fig. 4.The mould was built using a 3D Systems SLA7000stereolithography machine in Huntsman RenShape7580 resin. The K-type thermocouples were positionedand glued to the moulds surface using a commercialepoxy bi-compound resin (Araldite). After the epoxyglue hardened, it was sanded until the thermocoupletips were exposed. Figure 5 shows in detail the mouldfinished and assembled in the bolsters ready to bemounted in the injection moulding machine. Theinjection moulding machine used was a BattenfeldTM750/210 and thermocouples were connected toa CR10X data logger from Campbell Scientific. Datawere collected each 5s and the room temperaturewas 20C. The injection moulding material was theSolvay Eltex-P HY202 PP.Theinjectionmouldingprocedurestartedbyplacing the FGM insert in the first slot and the H13in the second slot. After 20 injection cycles, the insertswere swapped and the FGM insert was placed inthe second slot, the H13 in the first slot, and a further20 cycles were performed. Table 3 shows the injectionmoulding cycle and the insert position on each slotcorresponding to Fig. 4.Fig. 5Injection mould (above) and the interchangeableinserts in detail (below)Fig. 3FGM insert and the disposition of the gradientsFig. 4Position of the thermocouples in the cavity950V E Beal, P Erasenthiran, C H Ahrens, and P DickensProc. IMechE Vol. 221 Part B: J. Engineering ManufactureJEM764? IMechE 2007Between each mould opening, a delay of 120s wastaken to allow the inserts to cool down. A releaseagent was not necessary as the geometry was simpleand an ejection draft angle was used in the mouldimpression surfaces to make part ejection easier(1.5).Theinjectionmouldingparameterswerekept constant and they are presented in Table 4.The low injection and holding pressures are typicallyused in SL moulds. Most of the SL resins becamesoft above 80C and high pressures and temperatureshad to be avoided in order to increase the mouldslife.Samples from PP parts obtained in the second andsixteenth cycles of the A and B injection moulding ser-ies were taken from the DSC test. The apparatus usedfor these tests was a Shimadzu DSC-60. The sampleswere taken from the same position for all parts andmatched the face in contact with the inserts (FGMand H13) on the same region where the thermo-couples were placed. Figure 4 indicates these regionsfrom sampling. The PP samples, having masses bet-ween 5 and 7mg, were inserted on aluminium pansfor DSC, covered, and placed in the apparatus. Thetests were performed from room temperature (1921C) to 300C with a heating rate of 10C/min. Theresults were analysed using the Shimadzu ta60 version1.51 analysis software. As explained earlier, the mainobjective of the DSC tests was to compare the degreeofcrystallinity ofa partobtained using different insertsin the injection moulding impression. The percentageof crystallinity can be calculated by equation (7). DH isthe heat of fusion for the polymer tested and theDH100%is the heat of fusion for the same polymerwith 100 per cent crystallinity 24.x% DHDH100%73RESULTS3.1Numerical analysis resultsFrom the numerical simulations it was possible toplot the temperature against the time for the areas(nodes) that represented the thermocouples and sur-face of the inserts. The calculated temperature in thenode that represents a thermocouple (Ttc) is shownin Fig. 6. For the simulations without cooling system(H13; Cu; H1350Cu Voight; H1350Cu Reuss)the curves of Fig. 6 showed that there was no differ-ence between the cooling rate, although the materialof the insert was different. For the simulations withthe cooling channel (temperature of the back surfaceof the insert constant at 20C), it showed that thecurves for the two tested insert materials (H13 andH1350Cu) had a more accelerated cooling effectcompared with the inserts without cooling. Neverthe-less, it showed no difference in the cooling ratebetween them.The results from the other node that representedthe insert surface temperature were relevantly differ-ent. Figure 7 shows the temperature plotted againsttime for node Tis. The heating and cooling rates ofthe insert surface without simulation of the coolingsystemshowedthattherewerenosignificantchanges in the cooling rate although the materialsproperties were different. For the other two analysesthat simulated the cooling system in the back surfaceof the insert, the results showed that the materialaffected the cooling rate. In Fig. 7 the curves of H13and H1350Cu, estimated by the Reuss equation,had higher cooling rates than the other simulatedconditions and it demonstrated that the insert simu-lating the FGM (H1350Cu Reuss) would have afaster cooling rate than the insert of pure H13.Table 4Injection moulding parametersParameterSettingClamping force64kNInjection pressure160barInjection speed10ccm/sInjection temperature195C (nozzle)Holding pressure60bar (during 1s)Cooling time30sTime before next injection (open mould)120sTable 3Injection moulding order and position of theinsertsFirst slotSecond slotInjection moulding A series (IMA)FGM insertH13 insertInjection moulding B series (IMB)H13 insertFGM insertFig. 6Estimated temperature of the thermocouple (Ttc,mould surface) plotted against the time simulatingdifferent material properties for the insertEvaluating the use of functionally graded materials inserts951JEM764? IMechE 2007Proc. IMechE Vol. 221 Part B: J. Engineering Manufacture3.2Injection moulding experiment resultsThe temperatures measured from the thermocouplesduring typical injection moulding cycles are plottedin Fig. 8. This figure shows that the temperature forthe FGM inserts was higher than the temperaturefor inserts made of only H13. This behaviour wasindependent from the order of the slot as shown inFig. 8. Also, the temperature of the mould surfacefor the position of the FGM insert was considerablyhigher than the H13 insert. In addition, the tempera-ture for H13 inserts was similar to the numericalmodel. On the other hand, the FGM temperaturewas considerably higher than the numerical resultsobtained.The DSC results reflected the behaviour of thetemperature measured with the thermocouples. TheFGM insert presented higher temperature and lowercapacity to absorb the heat from the part. This wasidentifiable by the higher energy necessary to dis-solve the more crystalline samples moulded overthe FGM insert. The curves of the DSC shown inFig. 9 also reveal that with a hotter mould, sixteenthcycle, a higher crystallinity could be observed in thesamples. Table 5 shows the difference between theenergy per gram that was necessary to melt the sam-ples. Also, the percentage crystallinity is calculatedbased on equation (7). The reference for 100 percent crystalline polypropylene was 209J/g 25.4DISCUSSION AND CONCLUSIONSThe measured temperature of the mould surfaceshowed different results from those obtained fromthe numerical experiments. The temperatures inthe mould surface were higher than the simulatedresults. In addition, analysis of the curves dropdownshowed that the cooling rate of the simulation washigher than the real readings. The difference mightbe from different causes. The model did not considerphase and property changes of the polymer during itssolidification. Additionally, the fittings of the insertsin the rough SL bolster do not provide a perfect con-tact surface, as considered in the numerical model.Another source affecting the results was that thecomputational model was based on estimations ofFig. 9Calorimetric plot of the samples taken from PPparts of the second injection moulding cyclesover the first slot (H13 2nd and FGM 2nd) andover the second slot in the 16th cycles (H13 16thand FGM 16th)Fig. 7Temperature of the insert surface (Tis) plottedagainst the time simulating different material pro-perties for the insertFig. 8Temperature of the mould surface, Ttc, during theinjection mouldingTable 5DSC summary of the PP samples analysedSlotInjectionmouldingseriesInsertPeaktemperature(C)Heat(mJ)Heat/mass(J/g)Crystallinitydegree(%)1stIMAFGM167.22635.10 109.50 52.4IMBH13165.28548.0994.50 45.22nd IMBFGM166.69464.5776.16 36.4IMAH13165.99382.8563.81 30.5952V E Beal, P Erasenthiran, C H Ahrens, and P DickensProc. IMechE Vol. 221 Part B: J. Engineering ManufactureJEM764? IMechE 2007properties of the graded material. The FGM materialhas its porosity and internal cracks from the buildprocess. The rules of mixtures did not consider thesevoids in the material. The stock H13 insert presentedless difference between the injection moulding andnumerical results as it did not present these voidsinside its microstructure. Confirming this theory,the comparison between the results showed that thebehaviour of the cooling curves was equivalent, butthere was a small distinction between the H13 andFGM curves in the results from the numerical model.For the real data measurements, it was possible toidentify that the H13 was more efficient than theFGM inserts in absorbing and storing the heat. Thedifference between the inserts performance showeda temperature peak around 7 degrees lower for theH13 insert. As the objective of the addition of Cu tothe H13 was to increase conductivity it was necessaryto simulate a condition to compare the heat beingtransferred through the inserts. Consequently, thenumerical results simulating the cooling channelsin the back surface of the inserts showed that the50%CuH13 insert had better capacity to transportthe heat away from the part than the pure H13 insert.The DSC results showed no surprise as the tem-perature studies in the numerical and practicalexperiments had shown that the FGM mould wasabsorbing the heat slower than the pure H13 insert.Although the properties of the 50%CuH13 mixturewere unknown, it is reasonable to say that theseproperties are lower than the expectation comparingthe thermal performance of pure Cu. Some of the fac-tors that might be affecting the results have alreadybeen identified in previous work 15. Porosity andcracks in the microstructure of the different propor-tions of Cu and H13 affected the thermal properties.Optimization in the building process can reducethese voids and increase material properties.Although the results that the conductivity of theCuH13 mixtures was lower than expected, it showedthat it could be used for achieving different coolingrates in the mould using cooling channels. The com-bination of FGM with conformal cooling can bringclear benefits to improve heat extraction, especiallyin cases of deep grooves, thin walls, and highly com-plex parts. Higher proportions of Cu in the gradientmight increase the thermal heat transfer capabilitiesof these regions. Even so, care must be taken as themechanical properties are not characterized and itwould be expected that the material would be softerand less tough.ACKNOWLEDGEMENTSThe authors would like to thanks to Capes andCNPq (Ministries of Education and Science andTechnology, Brazil) for funding support. Also a spe-cial thanks to Juliano Heidrich, Naguib Saleh, BobTemple, and Rod Springthorpe.REFERENCES1 Menges, G. and Mohren, P. How to make injectionmolds, 2nd edition, 1993 (Hanser, Munich).2 Center for Epidemiologic Research. Former berylliumworkers medical surveillance program. Oak Ridge Insti-tute for Science and Education, Oak Ridge, Tennessee,USA,availableonlineat/cer/BMSP_pro/be-home.htm (accessed December 2005).3 Jacobs, P. F. Stereolithography and other RP&M tech-nologies, 1996 (RPA/ASME Press, New York).4 Ahrens, C. H., Ribeiro, A. S., and Beal, V. E. An alterna-tive cooling technique for stereolithography moulds.ProceedingsofTime-compressiontechnologies2001Conference, Manchester, UK, 2627 September 2001.5 Dalgarno, K. and Stewart, T

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