LCD后背板的注射成型参数正交优化设计

针对注射成型过程中最常见的制件翘曲问题,尝试以LCD后背板为研究对象,对影响薄壳塑件翘曲变形的因素(如模具温度、熔体温度、注射时间、保压压力、保压时间、冷却时间)进行分析,以正交实验法找出最佳工艺参数组合,通过极差分析,确定实现低翘曲变形的最优方案为:模具温度85℃,注射时间0.6s,保压压力100%。     

基于Taguchi方法的塑件工艺参数优化

注塑制品的使用性能和外观质量主要取决于注塑模具的质量和注塑成型过程。为了得到最优的工艺产品,工程技术人员往往需要多次修模改模、反复调整工艺参数或更换材料,传统的试错法应用范围窄且成本高、效率低。通过采用Taguchi 试验和数值模拟相结合的方法,对注塑成型过程进行模拟分析,得到熔体温度、模具温度、注射时间、保压压力和保压时间对翘曲量和体积收缩率的影响,其中保压压力和时间对翘曲量和体积收缩率的影响程度较大,由此得到一组最优工艺,减少了调整工艺参数的时间,提高了注塑件设计效率。     

基于灰色理论的顺序注射成型工艺参数优化

汽车保险杠是大型薄壁塑件,采用传统注射成型很难消除其表面的熔接痕,热流道顺序注塑是解决熔接痕,提高表面质量的一种很好的成型方法。以汽车保险杠为例,采用针阀式浇口,5点进浇,可以使熔接痕控制在产品边缘,但是其翘曲度偏大。根据分析,翘曲度的大小与针阀开启时机密切相关,以保压过程中的压力和针阀开启时刻为主要因素进行正交实验。运用灰色理论,计算出各试验的灰色关联度,并通过极差分析,获取最佳工艺参数值组合。将该最优参数组合在Moldflow软件中进行验证,该产品3个方向的最大翘曲度分别为0.973%,1.12%,1.33%,都小于1.5%,满足生产要求,这种热流道顺序注射成型方法成功的解决了塑件熔接痕的问题,同时对针阀开启时机的优化成功的控制了塑件的翘曲度的大小,这种成型优化方法可以在实际的生产中进行推广应用。     

塑料卡板成型的流动分析

MPI/Flow的流动分析功能能够模拟聚合物在模具中的流动,并能够帮助设计人员优化模腔的布局、材料的选择、填充和压实的工艺参数,获得最佳保压阶段设置,从而尽可能降低由保压引起的制品收缩和翘曲等质量缺陷.在产品允许的强度范围和合理的充模情况下,设计人员可以适当减少模腔的壁厚,把熔接线和困气定位于结构和外观允许的位置上,并且定义个范围较宽的工艺条件,而不必考虑生产车间条件的变化.MPI/Flow能够从塑件设计、模具设计到成型工艺等方面,对注塑成型提供全面的、并行的解决方案.     

注塑CAE技术在模具设计和开发中的应用

海信模具公司为了增强模具设计的可靠性,引进了美国Moldflow/MPI料流分析软件进行注塑过程模拟分析(CAE),包括填充、保压、气辅、翘曲等各个阶段.通过把注塑CAE技术与公司多年从事模具开发所积累的丰富实践经验相结合,在确定模具浇注系统和气辅工艺方案、帮助客户改进产品设计、预测并改善注塑缺陷等方面发挥了十分显著的作用,大大提高了模具开发的可靠性系数,取得了显著的经济效益.     

Moldflow技术在注塑成形过程中的应用

一、 前言注塑成形CAE技术是根据高分子流变学、弹性力学和计算机技术,采用有限元计算方法来模拟整个注塑过程及这一过程对注塑成形产品质量的影响,他可以模拟塑料制品在注塑成形过程中的流动、保压和冷却过程以及预测制品中的应力分布、分子取向、收缩和翘曲变形等,帮助设计人员及早发现问题,及时修改模具设计,提高一次试模成功率,帮助企业缩短产品上市周期,增强市场竞争能力。美国Moldflow公司是专业从事注塑成形的CAE软件和咨询公司,是塑料成形分析软件的创造者,自1976年发行了世界上第一套流动分析软件以来,一直主导着塑料…     

Moldflow在某大型薄壁异形件注塑成型模拟分析中的应用

Moldflow注塑成型与模拟软件系列用于帮助制件设计者和模具设计者检测其设计的工艺性.Moldflow软件在注塑模设计中的作用主要体现在以下三个方面,首先可以优化塑料制品,运用Moldflow软件,可以得到制品的实际最小壁厚,从而优化制品结构,降低材料成本,缩短生产周期,保证制品能全部充满;其次运用Moldflow软件可以优化模具结构,可以得到最佳的浇口数量与位置、合理的流道系统与冷却系统,并对型腔尺寸、浇口尺寸、流道尺寸和冷却系统尺寸进行优化,在计算机上进行试模、修模,大大提高模具质量,减少修模次数;最后通过Moldflow软件,用户可以非常方便地优化注塑工艺参数,用户可以确定最佳的注射压力、保压压力、锁模力、模具温度、熔体温度、注射时间、保压时间和冷却时间,以注塑出最佳的塑料制品.     

基于支持向量机的复合材料力学性能预测

通过建立材料力学性能与工艺参数相关的预测模型,可以减少试验次数、实现工艺优化,提高产品质量;该文提出利用支持向量机建立材料性能影响因素到力学性能的非线性映射;以麦杆增强复合材料为例,建立其力学性能预测的支持向量机模型,对材料的注塑工艺参数进行分析,得出其注塑成型的最佳工艺参数;结果表明所建模型具有较好的学习和泛化能力,对于优化成型工艺参数具有可行性,在材料性能研究领域有着较好的应用和推广价值.     

通过模具CAE技术改善LED面板变形研究

本文以LED面板为例,阐述CAE软件在改善塑料产品变形中的应用.研究表明,采用CAE软件进行变形分析可以在试模之前找到翘曲变形的主要原因,如产品结构和壁厚、注射工艺参数设定、浇口位置和顺序等,将问题可视化,最终确定优化方案,减少试模次数和提高一次试模成功率.     

基于Moldflow软件的薄壁零件直流和随形冷却通道分析

一、前言 注射成型工艺有四个阶段,即加料、塑化、冷却和脱模,这些阶段中,冷却阶段对成型周期时间和成型件质量影响非常大.注射模冷却通道设计会影响冷却时间和所生产成型塑件质量,翘曲是薄壁件常见的一种缺陷,有效的冷却通道能减小成型件的收缩不均和翘曲.为提高注射模工艺冷却阶段的冷却效率,提出随形冷却通道.     

Simulation and experimental study in determining injection molding process parameters for thin-shell plastic parts via design of experiments analysis

This paper deals with the application computer-aided engineering integrating with statistical technique to reduce warpage variation depended on injection molding process parameters during production of thin-shell plastic components. For this purpose, a number of Mold-Flow analyses are carried out by utilizing the combination of process parameters based on three level of L₁₈ orthogonal array table. In the meantime, apply the design of experiments (DOE) approach to determine an optimal parameter setting. In addition, a side-by-side comparison of two different approaches of simulation and experimental is provided. In this study, regression models that link the controlled parameters and the targeted outputs are developed, and the identified models can be utilized to predict the warpage at various injection molding conditions. The melt temperature and the packing pressure are found to be the most significant factors in both the simulation and the experimental for an injection molding process of thin-shell plastic parts.     

Grey optimization of injection molding processing of plastic optical lens based on joint consideration of aberration and birefringence effects

Microsystem Technologies - The optical performance of injection molded plastic lenses is seriously degraded by the warpage and residual stress induced during the molding process. In particular,...     

Numerical and experimental investigation of process parameters optimization in plastic injection molding using multi-criteria decision making

In plastic injection molding (PIM), the process parameters such as packing pressure, melt temperature, and cooling time should be adjusted and optimized for high product quality and high productivity. Warpage is one of the major defects in the PIM and should be minimized for high quality. Cycle time should be minimized for the high productivity. In addition to the warpage and the cycle time, clamping force affects the product both the quality and the productivity. Therefore, for the high product quality and the high productivity, it is important to minimize the warpage, the cycle time and the clamping force simultaneously. In this paper, a multi-objective optimization of process parameters in PIM for minimizing three objectives is performed. Numerical simulation in the PIM is generally so intensive that a sequential approximate optimization using radial basis function network is adopted to determine the optimal process parameters. The radar chart is used to perform the trade-off analysis among three objective functions. In addition, the better and worse solution are newly introduced for the trade-off analysis. It is found through the trade-off analysis that all objective functions of the conformal cooling channel are well improved in comparison with the ones of the conventional cooling channel. Therefore, 43% warpage reduction, 1,7% clamping force reduction, and 47% cycle time reduction can successfully be achieved using the conformal cooling channel. Based on the numerical result, the experiment using PIM machine (GL30-LP, Sodick) is carried out. The conformal cooling channel is developed by the metal 3D printer (OPM250L, Sodick). Through the numerical and experimental result, the validity of the proposed approach is examined.     

General frameworks for optimization of plastic injection molding process parameters

Plastic injection molding is widely used for manufacturing a variety of parts. Molding conditions or process parameters play a decisive role that affects the quality and productivity of plastic products. This work reviews the state-of-the-art of the process parameter optimization for plastic injection molding. The characteristics, advantages, disadvantages, and scope of application of all of the common optimization approaches such as response surface model, Kriging model, artificial neural network, genetic algorithms, and hybrid approaches are addressed. In addition, two general frameworks for simulation-based optimization of injection molding process parameter, including direct optimization and metamodeling optimization, are proposed as recommended paradigms. Two case studies are illustrated in order to demonstrate the implementation of the suggested frameworks and to compare among these optimization methods. This work is intended as a contribution to facilitate the optimization of plastic injection molding process parameter.     

Effect of micro tensile sample’s cross section shape on the strength of weld line in micro injection molding process

As a suitable mass and cost efficiency fabrication method, micro injection molding is doing a very good performance in micro plastic parts production. The mold design is an important part affecting micro parts properties. In this study, a micro injection mold with multi cavities of micro tensile bar is used. These micro cavities are fabricated by a micro milling process in different cross section shapes (semicircle R = 0.5 mm, equilateral triangle D = 0.3 mm, and trapezoid D = 0.336 mm t = 0.2 mm bottom angle = 95°). With an Arburg^® 320C injection molding machine, micro tensile test sample are prepared in different processing parameters so that a correlation between the cross section shapes with micro weld line strength in different conditions could be investigated by tensile test. Final results show that when the cross section shape is different, their corresponding weld line strength is also different. Equilateral triangle cross section is leading to strongest weld line, and then followed by trapezoid, semi-circle is the last. By analysis of these tensile test results, the quantitative factor a is defined as the ratio of perimeter to area of cross section shape, and higher a value is corresponding stronger weld line. After weld line strength comparison in different processing conditions, the results show that higher injection pressure induced to lower weld line strength whatever the cross section shape is. By higher mold and melt temperature, equilateral triangle cross section gives improved weld line strength. But mold and melt temperature affect weld line strength negative for other cross section shapes.     

Influence of processing parameters on micro injection molded weld line mechanical properties of polypropylene (PP)

As a hot fabrication technology for micro scale parts, micro injection molding is receiving increasing market attention. Improving mechanical properties of micro parts should be an important issue in the micro injection molding process. The relation between weld line strength in micro injection molding parts and processing parameters is investigated. A visual mold with variotherm unit is designed and constructed, in which the micro tensile specimen with weld line are prepared. Polypropylene (PP) is used as the research material in this study, and six processing parameters were chosen as investigating factors, which were melt temperature, mold temperature, injection pressure, packing pressure, ejection temperature and injection speed. In order to achieve optimized processing parameters and their order of significance, Taguchi experiment method was applied in this presented study. The prediction formulation of the strength of micro weld line was built up by multiple regression analysis based on Chebyshev orthogonal polynomial. The results showed the influencing significance order of parameters from strong to week separately are mold temperature, melt temperature, injection speed, ejection temperature, packing pressure and injection pressure. And the tolerance of micro weld line prediction formulation was found to be lower than 21% through confirmation experiments.     

Effects of Fabrication Process Parameters on the Properties of Cyclic Olefin Copolymer Microfluidic Devices

Among the materials used for fabricating microfluidic devices, plastics have been increasingly employed in the past few years. Although several methods for fabricating plastic devices have appeared in the literature, reports typically indicate one set of conditions that yield functional devices; little data are available detailing how results are affected by their changes in the process variables. We report in this paper a systematic study of fabrication process parameters including compression rate, molding temperature, and the force used by a hydraulic press, as well as their effects on the device properties. Using cyclic olefin copolymers as the molding material, we found that the device thickness decreased when the molding temperature and compression force increased. Fidelity in the pattern transfer from a master to a device was confirmed by the reproduction of nanostructures and channel depth/shape. Pattern transfer fidelity appeared to be independent of the molding temperature and compression force, at least in the range of conditions we investigated. Stress whitening (or crazing) on the device surface was found to be related to the molding temperature and the cooling rate of the mold/device assembly. The bond strength between the layers of a laminated device was determined to be a function of the lamination temperature. In addition, we demonstrated the utility of a plastic microfluidic device by separating proteins. 1678     

Self-organizing fuzzy controller for injection molding machines

Most plastic parts are manufactured using an open-loop injection molding machine (IMM). However, this process produces parts with poor dimensional precision and may result in product shrinkage, residual stress and other effects depending on the complexity of parts’ geometric shape, size, or a combination of both. To improve the performance of the IMM, in this study, we modified the IMM’s control structure from open-loop to closed-loop. The IMM has clearly complicated and nonlinear characteristics. Thus, it is difficult to design model-based controllers for manipulating the IMM. To solve the problem, a model-free self-organizing fuzzy controller (SOFC) was developed to control the IMM and its control performance was evaluated. Experimental results demonstrated that the SOFC exhibits better control performance than the fuzzy logic controller or the proportional-integral-derivative (PID) controller in controlling the injection-screw velocity of the IMM and the injection-nozzle holding pressure of the IMM.     

Injection molding and injection compression molding of three-beam grating of DVD pickup lens

The objective of this paper is to investigate the application of injection molding and injection compression molding processes to produce diffraction gratings. A mold was designed to produce a diffraction rating connected with the fixed bushing. The combined part was verified to have a good diffraction performance. Integrated grating eliminates the assembly cost and error. Photolithography was applied to make the mold insert. The Taguchi method and parametric analysis were applied to study the effects of molding parameters on grating quality. The design, fabrication of structured mold surfaces and the results of the replication by injection molding (IM) and injection compression molding (ICM) are presented and compared. The diffraction angle of ICM grating is more accurate than that of IM grating. Grating made by ICM has a much smaller warpage than that made by IM. The diffraction pattern shows that ICM is a better process than IM to replicate a diffraction grating.