Quantitative study of shrinkage and warpage behavior for microcellular and conventional injection molding

This research investigated the effects of processing conditions on the shrinkage and warpage (S&W) behavior of a box‐shaped, polypropylene part using conventional and microcellular injection molding. Two sets of 2^6‐1 fractional factorial design of experiments (DOE) were employed to perform the experiments and proper statistical theory was used to analyze the data. After the injection molding process reached steady state, molded samples were collected and measured using an optical coordinate measuring machine (OCMM), which had been evaluated using a proper R&R (repeatability and reproducibility) measurement study. By analyzing the statistically significant main and two‐factor interaction effects, the results show that the supercritical fluid (SCF) content (nitrogen in this case, in terms of SCF dosage time) and the injection speed affect the S&W of microcellular injection molded parts the most, whereas pack/hold pressure and pack/hold time have the most significant effect on the S&W of conventional injection molded parts. Also, this study quantitatively showed that, within the processing range studied, a reduction in the S&W could be achieved with the microcellular injection molding process. POLYM. ENG. SCI., 45:1408–1418, 2005. © 2005 Society of Plastics Engineers     

薄壁塑件注射成型工艺参数优化

在注射成型过程中将计算机模拟技术和实验优化设计相结合,以相机外壳为例利用MoldFlow对各工艺参数进行注射成型过程的模拟.通过分析塑件体收缩变形和翘曲变形的原因,得出熔体温度是影响塑件体收缩变形的主要因素,而保压压力对翘曲变形起主导作用力.并在正交试验的指导下优化工艺参数,使收缩率和翘曲变形分别降为原来的75.9%和87.0%.     

注射成型薄壁制品收缩与翘曲因素

介绍了薄壁注射成型的充填、保压、冷却和残余应力的数值模型,并将集成的模拟程序对收缩翘曲问题进行定量地模拟分析.采用Taguchi 实验优化设计理论,用L₂₇（3¹³）正交表设计实验并进行了统计分析.研究了因素如熔体温度、模具温度、保压时间、保压压力、浇口尺寸和注射速率对收缩与翘曲的影响的显著性.得出优化工艺参数如熔体温度、模具温度、保压时间和压力能减少残余热应力;保压压力和熔体温度是影响收缩与翘曲的最显著因素.     

Optimal process conditions of shrinkage and warpage of thin‐wall parts

Optimal process conditions of thin‐wall injection molding of a cellular phone cover were investigated with the consideration of interaction effects between process parameters. L₂₇ experimental tests based on Taguchi's method were performed, and then Cyclone Scanner, PolyCAD and PolyWorks were used to measure the shrinkage and warpage of the thin‐wall injected parts to determine the optimal process conditions. Based on the results of the analysis of variables and the F‐test, interaction effects for each observed factor were determined. The results indicated that the packing pressure was the most important process parameter affecting the shrinkage and warpage of the thin‐wall part. The optimal process conditions were different for the shrinkage and the warpage. This was because during the injection process, the mechanisms affecting shrinkage or warpage were different. Compared with the results obtained with simplified thin‐wall parts in the literature, it was found that the geometry of a real commercial part did affect the optimal process conditions and the order of influence of process parameters. The optimal process conditions determined by Taguchi's method for reducing the shrinkage and warpage were verified experimentally in this work. Polym. Eng. Sci. 44:917–928, 2004. © 2004 Society of Plastics Engineers.     

采用RFR-GA算法的薄壁注塑件质量多目标优化

汽车内饰件可由注塑加工获得,但成型过程中塑件产生的翘曲、体积收缩较大,针对该问题,以某汽车薄壁注塑件为例,研究了其注塑工艺参数的优化方法.通过以注塑过程中的最小翘曲和最小体积收缩率为目标函数,以注塑温度、模具温度、注射压力、保压压力、保压时间以及冷却时间等参数作为设计变量,构建了多目标全局优化模型.利用Moldflow...     

基于CAE和DOE技术的注射成型工艺优化

以打印机上盖为例,以体积收缩率、翘曲量和沉降斑指数为考察指标,结合CAE和DOE技术研究了模具温度、熔体温度、注射时间、保压压力和保压时间五个工艺参数对考察指标的影响,用DOE软件回归拟合得到体积收缩率、翘曲和沉降斑指数的预测模型,并运用该模型求解最佳的工艺参数,通过试验验证了该方法的可行性.     

注射成型工艺对制品收缩与翘曲的不同影响

以PP盒形制品为例,设计了一种测量方案使得收缩与翘曲可以独立度量,分别考察了这两者在不同工艺水平下的变化。使用单因素方差分析表确定熔体温度、保压压力等注射成型工艺参数对收缩与翘曲的影响程度,并以置信区间图示出各参数对收缩与翘曲的影响规律。通过对实验数据的总结发现,保压压力对收缩影响最为显著,而模具温度对翘曲影响最显著。制品收缩与翘曲随工艺参数变化呈3种不同特征：收缩与翘曲呈相反的变化趋势,提高注射速率或熔体温度,制品收缩率减小而翘曲增大;随保压压力升高收缩率单调减少而翘曲呈“U”形曲线变化;调整其他工艺参数,收缩与翘曲有相同的变化趋势。这些影响规律的总结为减小注射成型中塑料制品的收缩与翘曲提供依据。     

Exfoliation of Kaolinite Nanolayers in Poly(methylmethacrylate) Using Redox Initiator System Involving Intercalating Component

Injection molding is one of the most widely employed methods for the fabri- cating of polymer articles, being characterized by high production rates and accurately dimensioned products. The process includes the flow of polymer melt through a runner system and gates followed by injection into a cold mold, packing under high pressure, and subsequent cooling to solidification. Accordingly, during the injection-molding process the polymer undergoes simultaneous mechanical and therma! influences while in fluid, rubbery, and glassy states. Such effects introduce residual stresses and strains into the final product [1,2], resulting in highly anisotropic mechanical behavior [3–9] and warpage and shrinkage [10–13]. Thus, understanding the factors governing the residual-stress development during molding is of great importance.     

注塑成型保压阶段的分析

本文主要研究二维矩形模腔的非等温、可压缩无定形聚合物的保压阶段。流体是广义牛顿型的，可压缩行为服从Ｔａｉｔ的ｐ—ｖ—Ｔ状态方程。本文在展示保压阶段速度、压力的分布，密度沿着厚度方向的变化的基础上，讨论了保压阶段压力和密度的分布对最终产品的内应力、收缩和翘曲的影响。研究结果表明，保压阶段是注塑成型过程中一个非常复杂的阶段，其压力、温度、速度、密度的变化强烈地依赖于熔体的粘度和模腔的边界条件     

基于CAE的厚壁塑件注塑工艺参数优化

利用Moldflow软件对某厚壁塑料制件的注射成型过程进行分析,选取反映制品收缩与翘曲的多个评价指标,结合正交实验法,优化充填时间、熔体温度、保压时间、保压压力、冷却时间等工艺参数,通过均值分析与极差分析研究各因素对各评价指标的影响,并通过综合评分法得到一组最佳的工艺参数。结果表明,增加保压时间与保压压力能减小产品的收缩和翘曲,且得出的最佳工艺组合为注射时间为2.5 s,熔体温度为280 ℃,保压时间为130 s,保压压力为110 MPa,冷却时间为40 s,该工艺下产品的质量疏松度、体积收缩率、平面误差、翘曲分别降低了6.66 %、7.90 %、12.5 %、20.83 %,产品整体成型品质得到有效提高。     

注塑成型工艺参数对汽车保险杠翘曲变形的影响研究

结合Moldflow模拟分析软件和正交实验设计,通过对汽车保险杠的注射成型过程的数值模拟,系统分析了熔体温度、模具温度、注射时间、保压压力和保压时间等工艺参数对制件翘曲变形的影响规律.研究得到了最佳工艺参数组合方案,导人Moldflow软件分析后发现保险杠的翘曲变形得到明显改善;并通过实际的注塑成型实验验证了Moldflow分析结果.     

Review on the Effects of Process Parameters on Strength,Shrinkage, and Warpage of Injection Molding Plastic Component

Injection molding process causes differences between designed shape and real parts, all of them associated to shrinkage and warpage phenomena. Temperature, pressure distribution, and other injection parameters during molding process originate local shrinkage and the internal stresses depending on the relative stiffness of each part area. The aim of this work is to review and report the influence of injection molding process parameters on the postmolded strength, shrinkage, and warpage of injection molded parts. It is also to investigate the influence of injection molding process parameters on the postmolding shrinkage and warping of parts made of polypropylenes.     

保压方式对塑件翘曲影响的CAE分析

针对洗衣机底板在注射成型中产生的翘曲问题,利用CAE软件进行计算机数值模拟。结果表明影响翘曲变形的主要因素为收缩不均,并分别通过二级保压方式和根据材料的PVT曲线进行等比容保压来减小翘曲,对比两种保压方式,后者得到的塑件的翘曲量更小。     

基于CAE的注塑模浇口与保压优化设计

通过Moldflow软件，对平板形塑料件注塑过程中的流动、翘曲情况进行数值模拟。通过设置不同的浇口数量、位置和保压压力、保压时间，分析了注塑压力、熔接线分布、翘曲变形量和缩水缺陷等情况，优化了浇口数量、位置和保压压力、保压时间以减少注塑缺陷和塑料件变形；并结合分析结果指导模具设计及注塑过程工艺参数的设定。     

工艺参数对注塑制品翘曲影响的CAE分析

通过对注塑制品翘曲原因的深入分析,得出注射成型中制品翘曲模拟的主要方法,为优化注塑制品的翘曲提供了前提。结合实验设计方法,通过CAE对具体的注塑制品进行翘曲分析,得出最佳的工艺条件设置,得知影响翘曲的显著因素有保压压力、冷却时间、保压时间、熔体温度及其与模具温度的交互作用等,并分析了各单一因素对翘曲的影响趋势及其原因。     

Optimization and numerical simulation analysis for molded thin‐walled parts fabricated using wood‐filled polypropylene composites via plastic injection molding

Plastic injection molding is discontinuous and a complicated process involving the interaction of several variables for control the quality of the molded parts. The goal of this research was to investigate the optimal parameter selection, the significant parameters, and the effect of the injection‐molding parameters during the post‐filling stage (packing pressure, packing time, mold temperature, and cooling time) with respect to in‐cavity residual stresses, volumetric shrinkage and warpage properties. The PP + 60 wt% wood material is not suitable for molded thin‐walled parts. In contrast, the PP + 50 wt% material was found to be the preferred type of lignocellulosic polymer composite for molded thin‐walled parts. The results showed the lower residual stresses approximately at 20.10 MPa and have minimum overpacking in the ranges of ?0.709% to ?0.174% with the volumetric shrinkage spread better over the part surface. The research found that the packing pressure and mold temperature are important parameters for the reduction of residual stresses and volumetric shrinkage, while for the reduction of warpage, the important processing parameters are the packing pressure, packing time, and cooling time for molded thin‐walled parts that are fabricated using lignocellulosic polymer composites. POLYM. ENG. SCI., 55:1082–1095, 2015. © 2014 Society of Plastics Engineers     

基于灰色关联分析的注塑工艺多目标优化及PSO–SVM预测模型的建立

针对某电器活动上盖翘曲变形及体积收缩问题,对相关注塑工艺参数进行正交实验设计,在Moldflow中模拟分析,并对翘曲变形量及体积收缩率进行信噪比优化处理.利用灰色关联分析法得到翘曲变形量和体积收缩率的灰色关联度,通过对灰色关联度进行极差分析得到各注塑工艺参数对塑件综合目标(翘曲变形量及体积收缩率同时较小)的影响程度为:...     

基于CAE的注塑件翘曲变形优化研究

运用Moldflow软件进行某后盖产品的翘曲变形分析,结合Moldflow软件的翘曲变形分析理论,将影响注塑件的翘曲变形因素分为3类:冷却不均、收缩不均及取向因素。然后针对翘曲变形不同的影响因素提出冷却优化、结构优化、保压优化及反变形设计等优化方案。分析结果表明:提出的这几种优化方案能极大地改善注塑件的翘曲变形,为注塑制品企业在控制产品尺寸、满足装配质量要求、改善翘曲变形等方面提供优化思路及工艺参考。     

带金属嵌件的手机外壳注塑成型翘曲变形分析

在Moldflow模拟分析的基础上,通过正交试验研究了熔体温度、模具温度、注射时间、保压压力、保压时闻和冷却时间等工艺参数对带金属嵌件的手机外壳注塑成型翘曲变形的影响,并优化了成型工艺.结果表明,保压时间和保压压力对翘曲变形的影响最大,最佳工艺组合为:熔体温度310℃,模具温度120℃,注射时间0.3 s,保压压力14...     

注塑工艺参数对聚碳酸酯车灯面罩翘曲变形的影响

采用正交实验方法,利用Moldflow软件对汽车的车灯面罩进行注塑模拟,系统地分析了注塑中熔体温度、模具温度、注射时间、保压压力和保压时间等工艺参数对聚碳酸酯（PC）车灯面罩翘曲变形的影响规律和机理,并确定了车灯面罩的最佳工艺参数值。将所确定的最佳工艺参数导入Moldflow软件进行分析,发现车灯面罩的翘曲变形量明显下降。