Quality Of Plastic Parts Research Articles

Integrating Machine Learning with Machine Parameters to Predict Plastic Part Quality in Injection Moulding

The plastic injection moulding process is a critical manufacturing technique renowned for its high productivity, cost-effectiveness, and ability to produce intricate plastic components for various industries including medical and aerospace. The quality of the manufactured parts is influenced by several parameters, such as machine settings and mould characteristics, particularly thermal aspects. This paper specifically investigates the influence of primary machine parameters on part quality, excluding considerations of time, mould features, and cooling channel geometries. By focusing on the machine parameters and employing advanced machine learning methods, a comprehensive understanding is developed on how these factors can be utilised to predict the quality of the parts produced. The findings provide valuable insights into optimising the injection moulding process to enhance product quality and consistency.

INFLUENCE OF PROCESSING MODES ON ACCURACYAND SHRINKAGE OF THREADED PLASTIC PARTS OF OILFIELD EQUIPMENT

The study of the operating conditions of oil equipment made it possible to identify a set of indicators that most fully characterize the quality of plastic parts. It is known that the quality of parts of products made of various materials is a combination of mechanical, physical and operational indicators of any equipment. It is partially formed during their manufacturing process, depending on their materials and manufacturing method. And plastic parts are very different from metals depending on the area of application. This is due to the technologies for manufacturing structural products and individual parts from them. When manufacturing technologically complex parts from polymer materials, it is possible to achieve the required quality by controlling production modes depending on the grade of materials and the design of the parts being manufactured. Production of a thread of plastic details is rather difficult, than on metals. It is connected with the physical-mechanical processes coming in the course of production of concrete thread details from plastic by method of pressing and casting under pressure. Also mechanics of formation of plastic threads on details of the oil-field equipment on the specific properties differ from the threads received by a machining method on metals. As thread surfaces on plastic details are formed in compression molds depending on materials and the modes: temperatures, pressure and time of production. These regime parameters and guided parameters play a part at a guaranty of physical- mechanical properties of details in the course of production. In this regard, it in this article influences of technological parameters of production on quality of thread details oil-field equipment are considered. At the same time, in a wide range of operating parameters, the achievable boundaries of quality indicators for parts operating in the designs of exploration, drilling and operation equipment in the oil and gas industry are investigated. Mathematical relationships are established between the quality indicators (shrinkage and strength) of parts on the pressing temperature. Keywords: thread plastic details, accuracy, shrinkage, pressing pressure.

Development of variotherm extrusion blow molding technology to produce high-gloss automotive spoilers

Abstract The surface quality of plastic parts produced by the conventional extrusion blow molding (EBM) process is usually poor, especially for those made of engineering thermoplastics. To achieve a high-gloss appearance, some costly and pollutive post-treatments (e.g., painting, polishing, etc.) have to be employed to hide or eliminate surface defects. Herein, a variable mold temperature EBM (i.e., variotherm EBM) technology with electric heating and water cooling, which has the potential to directly yield high-gloss parts, was developed. First, the process principle was designed and presented. Then, an complex industrial plastic part, i.e., automotive spoiler, was selected as a molding case to be studied, in which the variotherm blow mold of the spoiler was designed and especially the design rationality of the mold electric-heating and cooling systems was then examined by numerically evaluating the mold thermal response in the respect of cavity surface heating/cooling efficiencies and uniformity. Finally, the variotherm EBM experiments based on the manufactured prototype spoiler mold were conducted. The results showed that the developed technology can realize high-temperature blow molding with both the molding cycle time and energy consumption in an acceptable range compared with the conventional EBM. Moreover, the surface quality of the molded spoilers is largely improved and the surface defects that are generally appearing in the conventional EBM process can be fully eliminated. Thus, the feasibility and effectiveness of developed technology in yielding high-gloss blow-molded parts are demonstrated.

QUALITY STUDIES OF PLASTIC PARTS OILFIELD EQUIPMENT

The article considers the quality of plastic parts of oilfield equipment depending on the modes of manufacturing their various designs and the composition of press materials. By adjusting the regime parameters in the manufacture of parts, quality indicators are determined: tensile strength, hardness of parts, and others. The use of parts made of plastic materials for the development of the oil field equipment industry can be considered efficient from a technical and economic point of view. Also, in order to improve the quality, strength and longevity, plastic masses, which are an alternative product to metals and non-metals, have started to be used. Studying the performance indicators of the used plastic materials is considered mandatory. The quality of details made of plastic masses depends on many factors, and the indicators of these factors appear during operation. The quality indicators of products made of plastic materials in oil field equipment are distinguished by the presence of unlimited possibilities, greater than structural materials. Parts made of such materials have high performance indicators and are used in the preparation of parts with different constructions using uncomplicated processing methods. For the development of the oil industry, ways to increase the durability and longevity of the equipment used in this industry should be investigated. Based on the results, an experimental-theoretical method for determining the main quality criteria (shrinkage deformation and other quality indicators, strength, hardness, surface roughness) of plastic parts is proposed. The developed technique for the design of plastic parts makes it possible to estimate the expected life of parts, taking into account their operating conditions. Keywords: quality, plastic parts, press materials, performance, shrinkage.

Multi-Objective Optimization of Liquid Silica Array Lenses Based on Latin Hypercube Sampling and Constrained Generative Inverse Design Networks.

Injection molding process parameters have a great impact on plastic production quality, manufacturing cost, and molding efficiency. This study proposes to apply the method of Latin hypercube sampling, and to combine the response surface model and "Constraint Generation Inverse Design Network (CGIDN)" to achieve multi-objective optimization of the injection process, shorten the time to find the optimal process parameters, and improve the production efficiency of plastic parts. Taking the LSR lens array of automotive LED lights as the research object, the residual stress and volume shrinkage were taken as the optimization objectives, and the filling time, melt temperature, maturation time, and maturation pressure were taken as the influencing factors to obtain the optimization target values, and the response surface models between the volume shrinkage rate and the influencing factors were established. Based on the "Constraint-Generated Inverse Design Network", the optimization was independently sought within the set parameters to obtain the optimal combination of process parameters to meet the injection molding quality of plastic parts. The results showed that the optimal residual stress value and volume shrinkage rate were 11.96 MPa and 4.88%, respectively, in the data set of 20 Latin test samples obtained based on Latin hypercube sampling, and the optimal residual stress value and volume shrinkage rate were 8.47 MPa and 2.83%, respectively, after optimization by the CGIDN method. The optimal process parameters obtained by CGIDN optimization were a melt temperature of 30 °C, filling time of 2.5 s, maturation pressure of 40 MPa, and maturation time of 15 s. The optimization results were obvious and showed the feasibility of the data-driven injection molding process optimization method based on the combination of Latin hypercube sampling and CGIDN.

Closed-Loop Control Applied to the Injection Moulding Process—An Industry 4.0 Refurbishment Case Study

Injection moulding process stability is a key issue in ensuring suitable quality of plastic parts. External factors such as processing equipment malfunctions, environmental variations, or tool misuse require qualified professionals to handle the issue or diagnosing systems to detect them at an early stage to avoid production in unsuitable processing conditions. The process control system was developed to provide a solution to these problems, whether by introducing automatic self-corrections to processing conditions or providing key performance indicators (KPI) for operation, maintenance, production, and quality control, with a local or remote interface. The system gathers processing and operating data from the mould and from the processing equipment to provide an overall process view. The data collected are obtained from several sensors located on the mould, placed at strategic locations, and real-time information is provided by the injection equipment or its peripherals. These data are processed in near real-time by the process control system and corrections for processing parameters, if required, are transferred to the injection equipment to be implemented in the subsequent injection cycles. Preliminary results from this case study proved that this solution provided suitable responses to the imposed processing variations, resulting in optimized plastic parts.

Molecular Insights into the Wall Slip Behavior of Pseudoplastic Polymer Melt in Nanochannels during Micro Injection Molding

Wall slip directly affects the molding quality of plastic parts by influencing the stability of the filling flow field during micro injection molding. The accurate modeling of wall slip in nanochannels has been a great challenge for pseudoplastic polymer melts. Here, an effective modeling method for polymer melt flow in nanochannels based on united-atom molecular dynamics simulations is presented. The effects of driving forces and wall–fluid interactions on the behavior of polyethylene melt under Poiseuille flow conditions were investigated by characterizing the slip velocity, dynamics information of the flow process, and spatial configuration parameters of molecular chains. The results indicated that the united-atom molecular dynamics model could better describe the pseudoplastic behavior in nanochannels than the commonly used finitely extensible nonlinear elastic (FENE) model. It was found that the slip velocity could be increased with increasing driving force and show completely opposite variation trends under different orders of magnitude of the wall–fluid interactions. The influence mechanism was interpreted by the density distribution and molecular chain structure parameters, including disentanglement and orientation, which also coincides with the change in the radius of gyration.

Application of Expert Adjustable Fuzzy Control Algorithm in Temperature Control System of Injection Machines.

The stability and accuracy of temperature control of the injection molding machine is one of the keys to determine the quality and appearance of plastic parts. Due to the temperature control system of water-cooled injection molding machine has the characteristics of coupling, nonlinearity, and hysteresis, the traditional proportion-integral-derivative (PID) method to control the barrel temperature of injection molding machine will yield temperature overshoot and oscillation, affecting the product and appearance quality. In order to improve the effect of barrel temperature control, in this paper, an expert adjustable fuzzy control strategy (EAFCA) is designed to optimize the barrel temperature control system through the combination of expert control, fuzzy control, and PID control. The expert control rules are designed according to the barrel temperature deviation e and its change rate ec. The expert rules are used to adjust the mapping range of the fuzzy universe in real time for the input and output variables of the fuzzy controller and finally to realize the accurate adjustment of the PID controller parameters. In terms of control systems, the distributed control system (DCS) monitoring system of injection molding machine is designed with Siemens CPU315-2PN/DP and industrial computer as the hardware core and Step7 and windows control center (WinCC) as the software platform to complete the tool plastic production monitoring system. The DCS improves the operability, data management convenience, and plastic production efficiency of the injection molding machine monitoring system. The Simulink simulation and field test show that the EAFCA method can increase the adjustment speed by approximately 34 s and reduce the overshoot by nearly 3.1%, which significantly improves the stability and accuracy of the barrel temperature and improves the quality of plastic parts.

Optimization to Assist Design and Analysis of Temperature Control Strategies for Injection Molding-A Review.

Injection molding (IM) is the most widespread and economical way to obtain high-quality plastic components. The process depends, however, to a great extent, on the quality and efficiency of the injection molding tools. Given the nature of the IM process, the temperature control system (TCS), its design, and its efficiency are of utmost importance for achieving the highest possible quality of plastic parts in the shortest possible time. For that reason, the implementation of additive manufacturing (AM) in novel IM temperature control strategies has gained considerable interest in academia and industry over the years. Conformal cooling channels (CCCs) are TCSs that have already demonstrated great potential when compared to conventional gun-drilling systems. Nevertheless, despite the recent advances, the design of these systems is still an open field of study and requires additional research in both aspects deemed as critical: thermo-mechanical models and the application of optimization techniques. This review paper tackles all the relevant, available papers on this topic, highlighting thermo-mechanical models developed by TCS designers and the optimization techniques used. The articles were thoroughly analyzed, and key points on the design of new TCS and new opportunities were identified.

Overview of injection molding process optimization technology

Injection molding process parameters have a very important influence on the molding quality of plastic parts. In this paper, the application of injection molding parameter optimization technology in the study of injection molding process is reviewed. The basic principles and characteristics of various optimization techniques are described. Optimization techniques mainly include: Optimization based on Taguchi method, Optimization of numerical simulation based on CAE technology, Optimization based on genetic algorithm, Optimization based on artificial neural network. The application types of optimization problems applicable to various optimization techniques are discussed.

Multi-objective optimization of injection-molded plastic parts using entropy weight, random forest, and genetic algorithm methods

Abstract The qualities of injection-molded parts are affected by process parameters. Warpage and volume shrinkage are two typical defects. Moreover, insufficient or excessively large clamping force also affects the quality of parts and the cost of the process. An experiment based on the orthogonal design was conducted to minimize the above defects. Moldflow software was used to simulate the injection process of each experiment. The entropy weight was used to determine the weight of each index, the comprehensive evaluation value was calculated, and multi-objective optimization was transformed into single-objective optimization. A regression model was established by the random forest (RF) algorithm. To further illustrate the reliability and accuracy of the model, back-propagation neural network and kriging models were taken as comparative algorithms. The results showed that the error of RF was the smallest and its performance was the best. Finally, genetic algorithm was used to search for the minimum of the regression model established by RF. The optimal parameters were found to improve the quality of plastic parts and reduce the energy consumption. The plastic parts manufactured by the optimal process parameters showed good quality and met the requirements of production.

Simplex space-time meshes in thermally coupled two-phase flow simulations of mold filling

The quality of plastic parts produced through injection molding depends on many factors. Especially during the filling stage, defects such as weld lines, burrs, or insufficient filling can occur. Numerical methods need to be employed to improve product quality by means of predicting and simulating the injection molding process. In the current work, a highly viscous incompressible non-isothermal two-phase flow is simulated, which takes place during the cavity filling. The injected melt exhibits a shear-thinning behavior, which is described by the Carreau-WLF model.Besides that, a novel discretization method is used in the context of 4D simplex space-time grids [1]. This method allows for local temporal refinement in the vicinity of, e.g., the evolving front of the melt [2]. Utilizing such an adaptive refinement can lead to locally improved numerical accuracy while maintaining the highest possible computational efficiency in the remaining of the domain. For demonstration purposes, a set of 2D and 3D benchmark cases, that involve the filling of various cavities with a distributor, is presented.

A quantitative evaluation of the appearance quality of weld lines in RHCM parts

The appearance quality of plastic parts in weld lines can be improved significantly through the rapid heating cycle molding (RHCM) process. However, there is no evaluation method for measuring the appearance quality of weld lines to determine whether they are in a good or bad condition. In this study, RHCM parts were molded with electric heating and the total color difference dE of the Commission Internationale de l’Eclairage (CIE) Lab system was employed as the quantitative evaluation method for the appearance quality of weld line. The dE of weld lines under different heating temperature conditions was analyzed. The results indicate that the mold heating temperature significantly influences the appearance quality of weld lines and the CIE Lab system accurately assesses the appearance quality of weld lines. Moreover, the experimental results further demonstrate that the lightness difference ΔL has a significant influence on the dE of weld lines in plastic parts, whereas the color differences Δa and Δb have only a slight influence.

금속 열순환 성형에서 수지의 점도와 윤활유가 유리 섬유 강화 고분자의 기계적 물성과 표면에 미치는 영향

Conventional injection molding (CIM) and rapid heat cycle molding (RHCM) methods are used to prepare ABS and (acrylonitrile-butadiene-styrene)/glass fiber copolymer (ABS/GF) plastic parts. Pentaerythritol stearate (PETS) and silicon particles are chosen as lubricants. Effect of resin viscosity and lubricants on properties of plastic parts was investigated. The results show that resin viscosity has some effect on surface quality of plastic parts in CIM process but no effect in RHCM process. ABS/GF plastic parts molded in RHCM process exhibit higher tensile, higher flexural strength and lower impact strength. Silicon is more effective in RHCM process than in CIM process.

Automated and robust multi-objective optimal design of thin-walled product injection process based on hybrid RBF-MOGA

An automated and robust multi-objective optimal design system has been developed and carried out on the optimization of injection process parameters. A hybrid multi-objective optimization of process parameters in plastic injection molding (PIM) is implemented for a synchronous decrease in multi objectives. The main defects indicating plastic part quality including warpage, volume shrinkage, and weldline are the objectives of optimization. Melt temperature, injection time, cooling time, mold temperature, packing pressure, and packing time are considered as optimization parameters. Orthogonal array-Latin hypercube sampling (OA-LHS) method is adopted to generate the initial set of parameter points. Metamodeling technique, radial basis functions (RBF), is utilized to construct the response surface fitting process parameters and simulation responses. RBF replaces expensive simulation experiments and reduces the time and computation cost. For a quick search of optimal point, Pareto-ranking-based multi-objective genetic algorithm (MOGA) is performed to make a trade-off among three objectives. Accuracy analysis shows a lower prediction error of the proposed algorithm, and sensitivity analysis identifies the parameters which have significant influence on response. Simulation experiments are implemented for verification of the optimization. The proposed optimization is automated with the help of visual basic scripts, python, Applications Programming Interface (API) of Moldflow and Dakota. The system is applied to an industrial application in thin-walled automobile air-conditioner vent injection process which increases efficiency and accuracy in optimal design compared to conventional trial-and-error design process.

Influence of clamping force on tie-bar elongation, mold separation, and part dimensions in injection molding

In injection molding, the magnitude of clamping force may affect the quality of plastic parts. A small clamping force may produce defects such as flashes and poor geometrical accuracy, whereas a large force could result in insufficient air venting during mold filling/packing, leading to the generation of short shot. Traditionally, clamping force is set at the highest machine specification, which may lead to additional energy consumption. Moreover, heavy loading at the tie bars is detrimental to the durability of processed molds and the machine itself. In this study, we developed a measuring system for recording tie-bar elongation and mold separation during injection molding at each corner of the mold. To determine the consequences of proper and improper clamping force settings on the quality of injection-molded parts, we systematically evaluated the effects of relevant parameters such as cavity layout and gate location on cavity pressure distribution during packing and the reactive force from cavity pressure acting on mold walls. Correlation analysis on experimental results depicted that the maximum increase in tie bar elongation and the maximum mold separation during injection molding are highly correlated with the thickness of plastic parts, and we suggested that the two features are good indicators of part quality. Moreover, cavity layout of generating diverse filling patterns and the distribution of cavity pressure is influential to mold separation as well as tie-bar elongation during mold filling. This phenomenon is further change the degree of mold separation at each corner of the injection mold and should be concerned in practice.

Numerical and experimental investigations on polymer melt flow phenomenon in a vario‐thermal mold cavity

ABSTRACTMold temperature is one of the key factors affecting the morphology and quality of plastic parts. This article explores the melt flow phenomena in a vario‐thermal mold cavity. A coupled numerical method, considering the conjugate heat transfer between the mold and melt, is developed for the melt flow simulation. Mold temperature variations and melt flow phenomena for short shot injection in an electrical heated mold cavity are numerically studied and verified by experiments. The results indicate that the melt flow length and cavity filling ratio increase significantly with the elongation of the preheating time before injection. Melt filling ratio increased nearly linearly with the increasing of electric heating time. The smaller the injection pressure is, the bigger the relative filling ratio increment is. Therefore, polymer melt can flow much longer or the mold cavity can be filled up with a smaller injection pressure when the cavity is preheated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45193.

Development of the comprehensive method forquality assessment of plastic parts

In present work we constructed the tree of quality indicators of plastic parts. A generalized algorithm is proposedto estimatethe quality level of plastic parts, which is the basis for the developmentof method forassessing the quality level of plastic parts. The designed algorithm, in contrast to those existing, includes a stage for the estimation of error in quality level, which will make it possible to improveaccuracy of determining thequality level of plastic parts. We devised acomprehensive method for evaluating quality of plastic parts. Its essence is in the fact that the obtained method allows us to determine anintegratedindicator of quality of plastic part, which includesa proposed nomenclature of quality indicators, represented in the form of the tree and the proposed generalized indicator of quality of plastic part. The developed comprehensive method differs from those existing by the proposed additional stage – the estimation of error in quality. Its essence is that it is necessary to determine: error in the number of properties that characterize quality; error in determiningthe weight coefficients;wear and aging of the materials that the MD are made of; error in the calculations of quality indicators;and permissible instrument errors. All these components will in turn make it possible to increase accuracy in the quality assessment of plastic parts. Results of present researchinto quality indicators ofpart’s PMdemonstrated that for the selected part, one part of the values of relative quality indicators is larger than unity, and another part is lower, which does not make it possible to unambiguously estimate the quality level for the givenpart. The designed method is useful in the development of mathematical and CAD software for technological equipment. It might be applied in the fabrication of thermoplastic parts for radio-electronic equipment.

Design of Injection Mold and Research of Process for Plastic Parts Based on CAE Analysis

The injection molding of plastic parts was simulated and analyzed by MOLDFLOW. Based on the result of mold flow analysis, we can optimize the structure of the mold, select equipment, determine parameters of process, and predict potential defects. The CAE technology could improve mold design ability, shorten plastic parts development cycle, improve the quality of plastic parts, reduce costs, and strengthen competitive power.

Implementation of Conformal Cooling & Topology Optimization in 3D Printed Stainless Steel Porous Structure Injection Molds

This work presents implementation of numerical analysis and topology optimization techniques for redesigning traditional injection molding tools. Traditional injection molding tools have straight cooling channels, drilled into a solid body of the core and cavity. The cooling time constitutes a large portion of the total production cycle that needs to be reduced as much as possible in order to bring in a significant improvement in the overall business of injection molding industry. Incorporating conformal cooling channels in the traditional dies is a highly competent solution to lower the cooling time as well as improve the plastic part quality. In this paper, the thermal and mechanical behavior of cavity and core with conformal cooling channels are analyzed to find an optimum design for molding tools. The proposed design with conformal cooling channels provides a better alternative than traditional die designs with straight channels. This design is further optimized using thermo-mechanical topology optimization based on a multiscale approach for generating sound porous structures. The implemented topology optimization results in a light-weight yet highly effective die cavity and core. The reduction in weight achieved through the design of dies with porous structures is meant to facilitate the adoption of additive manufacturing for die making by the tooling industry.