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The quality control of plastic products is an essential aspect of the plastic injection molding (PIM) process. However, the warpage and shrinkage deformations continue to exist because the PIM process is easily interfered with by several related or independent process parameters. Thus, great efforts have been devoted to optimizing process parameters to minimize the warpage and shrinkage deformations of products during the last decades. In this review, we begin by introducing the manufacturing process in PIM and the cause of warpage and shrinkage deformations, followed by the mechanism about how process parameters, like mold temperature, melt temperature, injection rate, injection pressure, holding pressure, holding and cooling duration, affect those defects. Then, we summarize the recent progress of the design of experiments and four advanced methods (artificial neural networks, genetic algorithm, response surface methodology, and Kriging model) on optimizing process parameters to minimize the warpage and shrinkage deformations. In the end, future perspectives of quality control in injection molding machines are discussed.

This book has long been at the forefront of advanced materials research, owing to their exceptional strength-to-weight ratio, corrosion resistance, and high-temperature performance. Their determinative role in aerospace, automotive, biomedical, and other industrial applications underscores the importance of continuous advancements in titanium-related technologies. This special edition aims to provide a comprehensive overview of recent research results and achievements in three key areas: titanium aluminides, titanium matrix composites, metal injection moulding and sinter-based additive manufacturing. Researchers and engineers will find this special edition useful for understanding the latest advancements and prospects in titanium technology.

This book covers a wide range of applications and uses of simulation and modeling techniques in polymer injection molding, filling a noticeable gap in the literature of design, manufacturing, and the use of plastics injection molding. The authors help readers solve problems in the advanced control, simulation, monitoring, and optimization of injection molding processes. The book provides a tool for researchers and engineers to calculate the mold filling, optimization of processing control, and quality estimation before prototype molding.

Thermosets such as silicone are ubiquitous. However, existing manufacturing of thermosets involves either a prolonged manufacturing cycle (e.g., reaction injection molding), low geometric complexity (e.g., casting), or limited processable materials (e.g., frontal polymerization). Here, we report an in situ dual heating (ISDH) strategy for the rapid 3D printing of thermosets with complex structures and diverse rheological properties by incorporating direct ink writing (DIW) technique and a heating-accelerated in situ gelation mechanism. Enabled by an integrated Joule heater at the printhead, extruded thermosetting inks can quickly cure in situ, allowing for DIW of various thermosets with viscosities spanning five orders of magnitude, printed height over 100 mm, and high resolution of 50 μm. We further demonstrate DIW of a set of heterogenous thermosets using multiple functional materials and present a hybrid printing of a multilayer soft electronic circuit. Our ISDH strategy paves the way for fast manufacturing of thermosets for various emerging fields. ‘Thermosets are ubiquitous but existing manufacturing of thermosets involves either a prolonged manufacturing cycle, low geometric complexity, or limited processable materials. Here, the authors report an in situ dual heating strategy for the rapid 3D printing of thermosets with complex structures and diverse rheological properties by incorporating direct ink writing (DIW) technique and a heating-accelerated in situ gelation mechanism

Polylactide (PLA) is known as one of the most promising biopolymers as it is derived from renewable feedstock and can be biodegraded. During the last two decades, it moved more and more into the focus of scientific research and industrial use. It is even considered as a suitable replacement for standard petroleum-based polymers, such as polystyrene (PS), which can be found in a wide range of applications—amongst others in foams for packaging and insulation applications—but cause strong environmental issues. PLA has comparable mechanical properties to PS. However, the lack of melt strength is often referred to as a drawback for most foaming processes. One way to overcome this issue is the incorporation of chemical modifiers which can induce chain extension, branching, or cross-linking. As such, a wide variety of substances were studied in the literature. This work should give an overview of the most commonly used chemical modifiers and their effects on rheological, thermal, and foaming behavior. Therefore, this review article summarizes the research conducted on neat and chemically modified PLA foamed with the conventional foaming methods (i.e., batch foaming, foam extrusion, foam injection molding, and bead foaming).

Volume shrinkage and warpage deformation are very critical quality indicators in the plastic injection molding (PIM) of box-shaped thin-walled plastics. These two performance indexes are greatly affected by the molding parameters. Therefore, in this paper, six optimization algorithms and inverse-deformation designs (IDD) are used to reduce volume shrinkage and warpage deformation. Firstly, six important molding parameters, namely filling time (A), plasticity temperature (B), mold temperature (C), holding time (D), maximum holding pressure (E) and cooling time (F), are determined, and the L 25 (5 6 ) orthogonal experimental design (OED) is established. Taguchi grey correlation (TGC) theory analysis is used to determine the optimal combination of molding parameters. Secondly, different combinations of Box-Behnken design (BBD) response surface method, BP neural network (BPNN) training, and NSGA-II genetic algorithms are used to generate four combined optimization algorithms, in order to perform multi-objective optimization of the six molding parameters. The result shows that the effectiveness of four optimization analyses are ranked as follows: BPNN-BBD-NSGA-II > BPNN-BBD > BBD-NSGA-II > BBD. The BPNN-BBD-NSGA-II method holds the best prediction results. Finally, a global optimization platform based on NX/Moldex3D is established considering the IDD theory to simulate the molding process. Optical scanning instruments are used to examine the molding quality. The result proves that the warpage deformation in box-shaped thin-walled injection-molded products is almost completely eliminated and a high molding quality can be achieved. This research is favorable for designing the molding process and guiding the molding of box-shaped thin-walled injection-molded products.

During the clamping process in an injection-molding machine, the mold’s movement is directly driven by the velocity of the crosshead. The form of the adjustment on the crosshead’s kinematics can influence the final dynamics of the mold, which can contribute to the stability of the clamping duration further. This article is aimed at investigating the kinematics analysis and the stability management strategy of the mold in the early design stage for the clamping mechanism. The two different velocity-controlled forms of the crosshead, constant and variable kinematics adjustments, are applied and compared in the clamping analysis. Three factors of the crosshead, the maximum velocity, the acceleration/deceleration stage adjustment, and the multi acceleration/deceleration process, are validated for the stability control of the mold’s motion in the injection molding process. The results show an extra “fast” process is detected in the constant condition when compared to the variable crosshead’s kinematics adjustment. Furthermore, by the reasonable adjustment of the maximum velocity and two special positions of the crosshead during the acceleration and deceleration stages, the maximum acceleration fluctuation of the mold is decreased by more than 50%, allowing the mold to move more steadily.

Spherical titanium alloy powder is an important raw material for near-net-shape fabrication via a powder metallurgy (PM) manufacturing route, as well as feedstock for powder injection molding, and additive manufacturing (AM). Nevertheless, the cost of Ti powder including spherical Ti alloy has been a major hurdle that prevented PM Ti from being adopted for a wide range of applications. Especially with the increasing importance of powder-bed based AM technologies, the demand for spherical Ti powder has brought renewed attention on properties and cost, as well as on powder-producing processes. The performance of Ti components manufactured from powder has a strong dependence on the quality of powder, and it is therefore crucial to understand the properties and production methods of powder. This article aims to provide a cursory review of the basic techniques of commercial and emerging methods for making spherical Ti powder. The advantages as well as limitations of different methods are discussed.

In this paper, cooling performance of conformal cooling channel in plastic injection molding (PIM) is numerically and experimentally examined. To examine the cooling performance, cycle time and warpage are considered. Melt temperature, injection time, packing pressure, packing time, cooling time, and cooling temperature are taken as the design variables. A multi-objective optimization of the process parameters is then performed. First, the process parameters of conformal cooling channel are optimized. Numerical simulation in the PIM is so intensive that a sequential approximate optimization using a radial basis function network is used to identify a pareto-frontier. It is found from the numerical result that the cooling performance of conformal cooling channel is much improved, compared to the conventional cooling channel. Based on the numerical result, the conformal cooling channel is developed by using additive manufacturing technology. The experiment is then carried out to examine the validity of the conformal cooling channel. Through numerical and experimental result, it is confirmed that the conformal cooling channel is effective to the short cycle time and the warpage reduction.

Injection molding, in addition to extrusion, is the most important technology in the polymer processing industry. When modeling injection molding, the global approach is necessary to take into account the solid polymer transport, polymer melting and the polymer melt flow. The model of polymer melting is fundamental for the development of such a global injection molding model. In the paper, the state-of-the-art of modeling and experimentation of the flow and melting in injection molding machines has been presented and discussed. It has been concluded that the existing mathematical models have no strong experimental basis. Therefore, experimentation of the polymer flow and melting in the injection molding machine has been performed, and the effect of processing conditions: the screw speed, the plasticating stroke and the back pressure on the process course has been investigated. Starving in the beginning sections of the screw has been observed, which was not presented in the literature so far. The novel concepts of injection molding modeling have been discussed.