Polymer Injection Moulding Research Articles

Effects of injection Moulding Parameters on the Produced Parts

The publication deals with an innovative technology called powder-based metal injection moulding, which is a combination of traditional polymer injection moulding and powder metallurgy. With the technology, it is possible to produce metal components with complex geometry in large series. There is an extremely large selection of materials that can be used, mostly steel, copper, titanium or nickel-based alloys. In this research, the material used is type 17-4PH, martensitic corrosion-resistant steel, and since it is a widely used material, it is examined in many international articles and research studies, and it is also common in industry, so it is advisable to use this type of material for further comparability. Little information can be found in the literature about spraying parameters and their effects, which is why this research focusses on this. On the other hand, these data can also serve as useful information for the industry. During the production of so-called green products, the effects of product shrinkage were measured by changing the most important parameters and comparing the effects of these parameters to traditional polymer injection moulding.

PMMA Lens Arrays for Micro Concentrator Solar Cells Produced by Hot Embossing

The rising energetical needs of modern society have been increasingly pushing for the improvement in energy efficiency. Thin-film solar cell technology encompasses several types of devices whose purpose is to gather energy emitted from a luminous source and convert it into usable electrical energy for a variety of applications, particularly low-powered devices. Micro concentrator solar cells are promising devices to solve the materials availability problem and address the power conversion efficiency simultaneously. Since the energy conversion efficiency for this type of solar cell is not particularly high, it stands out to benefit greatly from using an optical concentrator element to increase the light intensity reaching the active surface. The micro-concentrator element is comprised of a micro-lens array, which can be manufactured by different technologies, such as polymer injection moulding, extrusion, or hot embossing. In this work, we explore how hot embossing can be used to inexpensively produce spherical lenses with Ø 1 mm in an array according to micro concentrator solar cell requirements. A simple compression system coupled with an infrared lamp heat chamber was used to emboss PMMA disks. Different mould insert manufacturing technologies were used and different hot embossing parameters were assessed. The process replicability of the micro-lens cavities was determined by infinite focus microscopy and optical microscopy. The most promising lens array was achieved with a mould insert produced by μ-EDM (with Ra and Rz values of 0.6 μm and 4.58 μm, respectively).

Influence of the Sintering Conditions on the Structure, Phase Composition, and Porosity of Titanium Alloy VT6 Parts Formed by Powder–Polymer Injection Molding

Influence of the Sintering Conditions on the Structure, Phase Composition, and Porosity of Titanium Alloy VT6 Parts Formed by Powder–Polymer Injection Molding

Controlling the geometry of laser ablated microneedle cavities in different mould materials and assessing the replication fidelity within polymer injection moulding

Microneedle arrays are minimally invasive devices which enable self-administration of drugs in a straightforward and efficient way. Recently, a low-cost mass production method to produce solid polymer microneedles using laser ablated moulds in an injection moulding process has been developed. In this context, it is key to understand how the geometry of the microneedle cavities can be changed and what parameters affect the replication fidelity during injection moulding. In this study, two laser scanning parameters, being the programmed base diameter and the number of layers were varied in four levels and their effects on the geometry of the microneedle cavities were evaluated in tool steel, copper alloy, and aluminium alloy inserts. Afterwards, the microneedle cavities were replicated in polypropylene and polycarbonate using injection moulding. The study showed how the depth and base diameter of the microneedle cavity can be changed by varying laser scanning parameters. Moreover, the moulds in the three materials exhibited different microneedle cavity shapes and dimensions, due to differences in material properties. As to the injection moulding process, strong linear relationships were found between the aspect ratio of the microneedle cavities and the replicated thermoplastic microneedles, where a higher aspect ratio resulted in a lower replication. The replication fidelity for the polypropylene microneedles was in all cases higher compared to the polycarbonate needles. Between the three mould materials, a comparable replication fidelity was found for tool steel and copper alloy and a lower replication for the aluminium alloy, due to differences in thermal and wetting properties.

Hybrid Process Chain for the Integration of Direct Ink Writing and Polymer Injection Molding.

The integration of additive manufacturing direct-writing technologies with injection molding provides a novel method to combine functional features into plastic products, and could enable mass-manufacturing of custom-molded plastic parts. In this work, direct-write technology is used to deposit conductive ink traces on the surface of an injection mold. After curing on the mold surface, the printed trace is transferred into the plastic part by exploiting the high temperature and pressure of a thermoplastic polymer melt flow. The transfer of the traces is controlled by interlocking with the polymer system, which creates strong plastic/ink interfacial bonding. The hybrid process chain uses designed mold/ink surface interactions to manufacture stable ink/polymer interfaces. Here, the process chain is proposed and validated through systematic interfacial analysis including feature fidelity, mechanical properties, adhesion, mold topography, surface energy, and hot polymer contact angle.

Investigation of a Short Carbon Fibre-Reinforced Polyamide and Comparison of Two Manufacturing Processes: Fused Deposition Modelling (FDM) and Polymer Injection Moulding (PIM).

New technologies are offering progressively more effective alternatives to traditional ones. Additive Manufacturing (AM) is gaining importance in fields related to design, manufacturing, engineering and medicine, especially in applications which require complex geometries. Fused Deposition Modelling (FDM) is framed within AM as a technology in which, due to their layer-by-layer deposition, thermoplastic polymers are used for manufacturing parts with a high degree of accuracy and minimum material waste during the process. The traditional technology corresponding to FDM is Polymer Injection Moulding, in which polymeric pellets are injected by pressure into a mould using the required geometry. The increasing use of PA6 in Additive Manufacturing makes it necessary to study the possibility of replacing certain parts manufactured by injection moulding with those created using FDM. In this work, PA6 was selected due to its higher mechanical properties in comparison with PA12. Moreover, its higher melting point has been a limitation for 3D printing technology, and a further study of composites made of PA6 using 3D printing processes is needed. Nevertheless, analysis of the mechanical response of standardised samples and the influence of the manufacturing process on the polyamide’s mechanical properties needs to be carried out. In this work, a comparative study between the two processes was conducted, and conclusions were drawn from an engineering perspective.

Review on the Reduction of Defects and Optimization of Cycle Time for Polymer Injection Molding

Review on the Reduction of Defects and Optimization of Cycle Time for Polymer Injection Molding

Review on the Reduction of Defects and Optimization of Cycle Time for Polymer Injection Molding

Review on the Reduction of Defects and Optimization of Cycle Time for Polymer Injection Molding

Development of Mold for Demolding Resistance Measurement in Polymer Injection Molding

Development of Mold for Demolding Resistance Measurement in Polymer Injection Molding

Multiobjective Optimization Method for Polymer Injection Molding Based on a Genetic Algorithm

To solve the quality problem of polymer injection parts, a quality prediction and multiobjective optimization method is established. In this method, the parameters that have an important effect on the part quality are selected using an orthogonal testing method, and then a central composite design experiment is performed using these parameters. A mathematical model considering an objective and impact factors is developed using the response surface method. The optimal combination of the impact parameters is determined using a multiobjective genetic algorithm. The injection molding of a typical interior trim part of a car, i.e., the seat belt cover plate, is used as an example to demonstrate the method. The two most troublesome problems in this process—the sink marks and warpage—are multiobjectively analyzed using the established method, and the optimal combination of impact parameters that minimized the defects is determined. The errors of the sink marks and warpage between the experimental and theoretical values were 7.95% and 0.2%, respectively. The optimized parameters were tested in actual injection molding. The results show that the shrinkage and warpage of the parts are obviously improved by optimization using the proposed method, allowing the parts to satisfy the requirements of assembly and appearance.

Electricity Consumption Estimation of the Polymer Material Injection-Molding Manufacturing Process: Empirical Model and Application

Polymer injection-molding is one of the most used manufacturing processes for the production of plastic products. Its electricity consumption highly influences its cost as well as its environmental impact. Reducing these factors is one of the challenges that material science and production engineering face today. However, there is currently a lack of data regarding electricity consumption values for injection-molding, which leads to significant errors due to the inherent high variability of injection-molding and its configurations. In this paper, an empirical model is proposed to better estimate the electricity consumption and the environmental impact of the injection-molding process. This empirical model was created after measuring the electricity consumption of a wide range of parts. It provides a method to estimate both electricity consumption and environmental impact, taking into account characteristics of both the molded parts and the molding machine. A case study of an induction cooktop housing is presented, showing adequate accuracy of the empirical model and the importance of proper machine selection to reduce cost, electricity consumption, and environmental impact.

Energy-efficiency and Robustness in a Hybrid Process of Hydroforming and Polymer Injection Molding

The combination of hydroforming and polymer injection molding is an efficient solution to shorten the manufacturing process chain and to generate potential cost-savings, especially in medium to high production volumes. A promising approach for the evaluation of the energy-efficiency and the robustness of process chains for resource-efficient manufacturing of hybrid components will be shown. The investigations are especially focused on the process chain for manufacturing hybrid profiles by applying different semi-finished products. As a result the determination of the process robustness and the energy consumption is possible, two essential aspects of sustainable manufacturing. Finally, improvement potential for an efficient process design will be demonstrated.

Simulation of Polymer Injection Molding: A New Practical Approach to Improve Computation Accuracy

Simulation of injection molding of polymeric materials is still a series scientific and engineering problem. The quality of the input data is crucial for computation accuracy. The original, relatively simple tool has been designed to validate simulations. This allows a fast identification of the critical input data, and next their proper adjustment to computations. FEM simulations have been compared with directly registered pictures of cavity filling process in a special injection mold with a sight-glass.

Modelling the deformations during the manufacturing of nanostructures on non-planar surfaces for injection moulding tool inserts

This paper presents a new manufacturing process for transferring nanostructures from a glass wafer to a curved aluminium insert for polymer injection moulding. A nanostructure consisting of sinusoidal cross-gratings with a period of 426 nm is successfully transferred to hemispheres with different radii via an embossing process. The embossing is done into a glass-like resist called HSQ, using a 50 μm thick nickel foil, manufactured with electroforming. During the imprinting process the nickel foil is stretched due to the curved surface of the aluminium substrate and it is experimentally possible to characterize this stretch by counting the periods of the cross-gratings via SEM characterization. A numerical model for simulating the deformation of the nickel foil during nanoimprint is also developed, utilizing non-linear material and geometrical behaviour. Good agreement between measured and numerically calculated stretch ratios on the surface of the deformed nickel foil is shown, and from the model it is also possible to predict the limiting boundary of the nanostructures on the curved surfaces, with decreasing radii.

Data characterizing tensile behavior of cenosphere/HDPE syntactic foam.

The data set presented is related to the tensile behavior of cenosphere reinforced high density polyethylene syntactic foam composites “Processing of cenosphere/HDPE syntactic foams using an industrial scale polymer injection molding machine” (Bharath et al., 2016) [1]. The focus of the work is on determining the feasibility of using an industrial scale polymer injection molding (PIM) machine for fabricating syntactic foams. The fabricated syntactic foams are investigated for microstructure and tensile properties. The data presented in this article is related to optimization of the PIM process for syntactic foam manufacture, equations and procedures to develop theoretical estimates for properties of cenospheres, and microstructure of syntactic foams before and after failure. Included dataset contains values obtained from the theoretical model.

Energy-efficiency in a Hybrid Process of Sheet Metal Forming and Polymer Injection Moulding

Hybrid processes are an efficient solution for shortening process chains and improving performance. As an example a process combination of sheet metal forming and polymer injection molding is introduced and investigated. The merging of forming and moulding processes into a single step process allows generating potential cost-savings, especially for medium to large production volumes. Based on the technological comparison between the conventional and the new process chain, the determination of the energy consumption and the detected impacts concerning the process efficiency are presented, showing that approx. 20% less energy is required due to using only one tempered tooling and reduction of handling operation.

Micro-injection Moulding of Polymer Locking Ligation Systems

In recent years, there has been an increment on micro-components for medical purposes, diseases treatment and surgical equipment, requiring biocompatible materials such as some engineering polymers. Nonetheless, the micro size of these parts impose challenges for fabrication using high production processes, like polymer injection moulding submitted to high cooling rates and variability of the process, in addition to the complex design of precise mould micro-cavities. This paper presents the development of a complete mould for a polymer locking ligation system fabrication, a medical device selected as a case study for micro-injection moulding tooling. This development includes the prediction of appropriate injection parameters and process conditions using computer simulations and a comparison with real values of pressure and temperature during the process, due to data acquisition with piezoelectric sensors. The results show a moderate error between experimental and simulated results, in terms of pressure (0.05% prediction error) and average cycle temperature at the sensor location (13% prediction error), which proves that the proposed approach can be used for precision micro-injection moulding applications.

An analysis of Digital ABS as a rapid tooling material for polymer injection moulding

Rapid tooling (RT) is an important application of additive manufacturing (AM). However, applications in this field are very dependent on the material that is available for use in AM processes. This work investigates the application of the new Digital ABS material from Stratasys in RT, focusing primarily on dimensional and surface stability during the injection process, and the influence the material has on the properties of the final moulding. Digital ABS was used to make inserts to inject standard specimens, which were compared with specimens produced using inserts made of two metallic materials (SAE 1045 steel and Zamak 8). Polypropylene (PP) was used to produce the specimens (50 shots). Insert surface quality and dimensional variations during injection were analysed. The influence of the material used on moulding properties was assessed by tensile, bending, impact and hardness tests and by measuring the crystallinity of the mouldings. The results show that in terms of dimensional and surface quality, the behaviour of Digital ABS during injection moulding was stable. The properties of mouldings produced with inserts made from digital ABS were only slightly different from those produced with inserts made from SAE 1045 steel and Zamak 8.

Simulation and modelling of sintering process for 316L stainless steel metal injection molding parts

The metal injection moulding (MIM) process allows the manufacturing of small and very complex metallic components. MIM processing combines the shaping capability of polymer injection moulding with the large material variety of metals and ceramics. This paper discusses in detail the development of a numerical model capable of simulating micro-structural evolution and macroscopic deformation during sintering of complex powder compacts. A sintering model based on elastic–viscoplastic constitutive equations was proposed and the corresponding parameters such as bulk viscosity, shearing viscosity and sintering stress were identified from dilatometer experimental data. The constitutive model was then implemented into the finite element software in order to perform the simulation of the sintering process. The numerical simulation methods have been compared against the results of the sintering experiments. The experimental data were obtained from sintering of 316L stainless steel powders.

Replication fidelity assessment of large area sub-μm structured polymer surfaces using scatterometry

The present study addresses one of the key challenges in the product quality control of transparent structured polymer substrates, the replication fidelity of sub-μm structures over a large area. Additionally the work contributes to the development of new techniques focused on in-line characterization of large nanostructured surfaces using scatterometry. In particular an approach to quantify the replication fidelity of high volume manufacturing processes such as polymer injection moulding is presented. Both periodic channels and semi-spherical structures were fabricated on nickel shims used for later injection moulding of Cyclic-olefin-copolymer (COC) substrate were the sub-μm features where ultimately transferred. The scatterometry system was validated using calibrated atomic force microscopy measurements and a model based on scalar diffraction theory employed to calculate the expected angular distribution of the reflected and the transmitted intensity for the nickel surfaces and structured COC and, respectively.