Injection molding: Process, design, and applications
Abstract
Injection molding is one of the most versatile and important manufacturing processes, capable of mass-producing complicated plastic parts in a variety of complex shapes with high dimensional precision. It is a major processing technique for converting thermoplastic and thermosetting materials with the aid of heat and pressure into complicated parts, consuming worldwide approximately 32% of all plastics. This book presents current research data in the study of injection molding from across the globe, including an overview of injection molding as a manufacturing technique for pharmaceutical applications; melt/solid weldline in over injection molding; metal injection molding of Co for biomedical applications; and the application of ultrasonic technology in the injection molding process.
... Ultrasonic measurement of temperature is an indirect measurement method that requires a model specific to the material that the measurement should be conducted on (Kariminejad et al., 2021;Kauffer, 2011). The principle works by sending an ultrasonic pulse through the plastic material. ...
In running production the measurement of process and material properties in-line, is a requirement to design and implement effective process control in injection moulding. This work presents a structured thorough analysis and review of the research concerned with in-line measurements of selected processes and material properties on the injection moulding machines. This review sets the current state of art within a range of process and material properties, and identifies areas for future research. The process and material property measurements reviewed are; Viscosity, Melt temperature, pvT and Melt density. It is identified that the largest research effort has been placed on the measurement of viscosity and melt temperature, whereas pvT and melt density measurement are less developed. Finally, gaps within the literature are identified and the proposal of a direction within the field is stated.
... Injection molding is a major processing technique for converting thermoplastic and thermosetting materials, consuming worldwide approximately 32% of all plastics [9].The injection molding process is done on injection molding machines (Fig. 4). It is considered the dominant process in plastics processing. ...
The article deals with issues related to quality management and quality assessment in production of plastic articles in injection moulding. Expert knowledge collected in textbooks and literature allows to get acquainted with the characteristics of plastic article production and product quality defects arising in such processes. The characteristics and technology of plastics processing are discussed, the most frequent quality defects occurring in the production of articles made of plastics by injection molding are listed. On the basis of expert knowledge collected in the literature, a series of actions leading to the elimination of each of the mentioned quality defects has also been proposed.
... Molding (PIM) is one of the most widely used industrial technologies in polymer processing capable of producing parts with complex shapes at a relatively low cost. Many daily use products, e.g., electronic devices, appliances, and packaging, rely on the technology and production of the PIM industry 3 , which covers approximately 32% of all plastic components 4,5 . PIM process consists of four different phases, namely, plastication, injection, packing, and cooling 6 . ...
The multi-stage sequential process with multi-objective is a complex problem to address as the decision made at a particular stage influences the subsequent stage and vice versa. In this article, the effects of input variables of plastic injection, mold, and different plating stages were investigated on different output responses, namely weldline, warpage, length, and various metal plating thicknesses. This paper investigates a real-time industrial data of manufacturing an automotive exterior part made of ABS material. A D-optimal experimental layout with 55 experiments was generated for eight input factors each at three levels. Nine different output responses in each experiment were normalized into a weighted grey relational grade using grey relational analysis coupled with principal component analysis. The solutions obtained by the analysis of variance on weighted grey relational grade, and by the desirability analysis of D-optimal were compared and validated. The confirmation experiments recorded an average improvement in cumulative process outputs as 40.56% by grey relational analysis and 38.50% by desirability analysis.
... The ability to produce parts in a wide range of polymers with good physical and mechanical properties has resulted in IM being one of the most widely used polymer processing techniques, equating to 35% by weight of polymers consumed worldwide [1][2][3]. ...
Purpose
Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts.
Design/methodology/approach
A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues.
Findings
Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time.
Originality/value
This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.
... Plastic injection molding is a versatile process that uses heat and pressure to convert thermoplastic and thermosetting materials into a variety of complex shapes with high-quality surface finish and dimensional precision (Kauffer, 2011). The design of tooling for plastic injection is considered critically important for the quality of the product that influences the business to a great extent. ...
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.
... Fig. (4). is a rendering of an injection moulding machine. The interested reader can readily find comprehensive publications on this topic [32][33][34]. Many of our everyday items are manufactured through this process as it offers a range of possible designs, from small to large and from simple to intricate. ...
Non-degradable polymers have an important function in medicine. Solid dosage forms for longer term implantation require to be constructed from materials that will not degrade or erode over time and also offer the utmost biocompatibility and biostability. This review details the three most important non-degradable polymers for the production of solid dosage forms - silicone elastomer, ethylene vinyl acetate and thermoplastic polyurethane. The hydrophobic, thermoset silicone elastomer is utilised in the production of a broad range of devices, from urinary catheter tubing for the prevention of biofilm to intravaginal rings used to prevent HIV transmission. Ethylene vinyl acetate, a hydrophobic thermoplastic, is the material of choice of two of the world's leading forms of contraception - Nuvaring® and Implanon®. Thermoplastic polyurethane has such a diverse range of building blocks that this one polymer can be hydrophilic or hydrophobic. Yet, in spite of this versatility, it is only now finding utility in commercialised drug delivery systems. Separately then one polymer has a unique ability that differentiates it from the others and can be applied in a specific drug delivery application; but collectively these polymers provide a rich palette of material and drug delivery options to empower formulation scientists in meeting even the most demanding of unmet clinical needs. Therefore, these polymers have had a long history in controlled release, from the very beginning even, and it is pertinent that this review examines briefly this history while also detailing the state-of-the-art academic studies and inventions exploiting these materials. The paper also outlines the different production methods required to manufacture these solid dosage forms as many of the processes are uncommon to the wider pharmaceutical industry.
This review explores significant advancements in polymer science and fabrication processes that have enhanced the performance and broadened the application scope of microfluidic devices. Microfluidics, essential in biotechnology, medicine, and chemical engineering, relies on precise fluid manipulation in micrometer-sized channels. Recent innovations in polymer materials, such as flexible, biocompatible, and structurally robust polymers, have been pivotal in developing advanced microfluidic systems. Techniques like replica molding, microcontact printing, solvent-assisted molding, injection molding, and 3D printing are examined, highlighting their advantages and recent developments. Additionally, the review discusses the diverse applications of polymer-based microfluidic devices in biomedical diagnostics, drug delivery, organ-on-chip models, environmental monitoring, and industrial processes. This paper also addresses future challenges, including enhancing chemical resistance, achieving multifunctionality, ensuring biocompatibility, and scaling up production. By overcoming these challenges, the potential for widespread adoption and impactful use of polymer-based microfluidic technologies can be realized.
The benefits of additive manufacturing (AM) are widely recognised, boosting the AM method’s use in industry, while it is predicted AM will dominate the global manufacturing industry. Alas, 3D printing’s growth is hindered by its sustainability. AM methods generate vast amounts of residuals considered as waste, which are disposed of. Additionally, the energy consumed, the materials used, and numerous other factors render AM unsustainable. This paper aims to bring forward all documented solutions in the literature. The spotlight is on potential solutions for the Powder Bed Fusion (PBF) AM, focusing on Selective Laser Sintering (SLS), as these are candidates for mass manufacturing by industry. Solutions are evaluated critically, to identify research gaps regarding the recyclability of residual material. Only then can AM dominate the manufacturing industry, which is extremely important since this is a milestone for our transition into sustainable manufacturing. This transition itself is a complex bottleneck on our quest for becoming a sustainable civilisation. Unlike previous reviews that primarily concentrate on specific AM recycling materials, this paper explores the state of the art in AM recycling processes, incorporating the latest market data and projections. By offering a holistic and forward-looking perspective on the evolution and potential of AM, this review serves as a valuable resource for researchers and industry professionals alike.
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