Plastic Parts Research Articles

A Study on Over-Molded Copper-Based Flexible Electronic Circuits.

Over-molding has been proposed in recent years as an integrated functional flexible circuit board in a plastic part. This method uses the conventional process for film insert technology. Over-molding has attracted significant attention across many industries due to its potential to deliver different electrical functions in a variety of different part geometries, especially in automotive interiors and home appliances. While it has great application potential, manufacturing challenges continue throughout foil fabrication and injection molding. This raises challenges for designers and researchers responsible for maintaining the reliability of such electronic flexible circuits. Therefore, the purpose of this research paper is to improve some of the over-molding process parameters. On 0805 and 1206 over-molded zero-ohm resistors, electrical, mechanical, and failure characterization was performed. Those components were mounted in parallel, perpendicular, and 45° angled arrangements on two different polymer substrates, polyimide (PI) and polyethylene terephthalate (PET) using lead-free solder, low-melt solder, and conductive adhesive paste. Moreover, as an over-molding material, polycarbonate (PC) with medium viscosity was used. The effect of using different mold shapes (corner mold, 2 mm flat mold, and 3 mm flat mold) and injection molding process parameters (injection speeds and melt temperature) was studied.

3D Printing as a Disruptive Technology for the Circular Economy of Plastic Components of End-of-Life Vehicles: A Systematic Review

The automotive industry is frequently associated with high polluting manufacturing systems, which raise concern owing to the current environmental frame. For this reason, new alternative manufacturing technologies with lower environmental impact have been proposed and tested, such as additive manufacturing (AM). Since AM technologies produce almost no waste, they can represent a huge opportunity for the automotive industry to become greener. In this sense, the object of the present review is to explore the challenges and strategies of 3D printing, recycling, and circular economy in the automotive industry. Therefore, to achieve the aim of the study, a systematic review methodology was used in five stages: (1) defining the targets; (2) extraction of papers from Scopus; (3) text mining and corpora text analysis of relevant documents from the platform; (4) identification of the dominant categories of the research topics; and (5) discussion and control of obtained results and provision of recommendations for future studies. The analysis of 14 relevant articles revealed that 3D printing technology represents an opportunity to empower small-scale producers of polymers, recycle ELV materials, and decentralize the supply chains of plastic articles. The possibility to include plastic parts produced by AM technology has been pointed out as an innovative option for car manufacturers. Unfortunately, till the present day, poor information was found in this regard. Findings highlighted the need for strategies to turn polymeric automotive components into more eco-friendly and safer materials, improve the supply chain of polymers, perform sustainability assessments, and reformulate waste policies for ELVs.

A sustainable recycling process for end-of-life vehicle plastics: A case study on waste bumpers

End-of-life vehicle (ELV) recycling has considerable potential value and a wide range of applications. Plastics form an increasing percentage of the total weight of automobiles as their lightweight. Recycling plastics from automobiles is important for achieving the overall recycling goal from a sustainability standpoint. In this study, the whole recycling process of automotive plastic parts was explored, using waste bumpers as an example, in which paint removal and recycled polypropylene (RPP) modification were the important links. First, LS-Dyna was used to run simulations to determine the best paint removal process parameters for surface coating treatment, and experiments were then conducted to confirm the paint removal effect. Second, component, morphological, and Gel Permeation Chromatography (GPC) analyses were conducted. As per the results, the degradation was primarily caused by surface oxidation of the ELV bumper, and the molecular weight of RPP was lower than that of new PP. Finally, the thermal and mechanical properties of RPP, modified RPP, and the new bumper were compared. The addition of nano-montmorillonite(nano-MMT), virgin PP, and a compatibilizer could improve the thermal and mechanical properties of RPP while satisfying the application requirements of the new bumper. This process provides a valuable idea for the sustainable recycling of used ELV plastics.

Topology optimization-driven design of added rib architecture system for enhanced free vibration response of thin-wall plastic components used in the automotive industry

A relentless paradigm switch in the automotive industry is being witnessed, where traditional combustion engines are progressively replacing with electric counterparts. In order to compensate for heavy electric engine technology, plastic components used in the interior parts of electric vehicles seems to be a reasonable strategy aligned with the lightweight trend as the automotive industry’s top priority. Extremely thin plastic components (ultra-lightweight) attached to ribs-based architectures have been identified as an adequate solution offering a good balance between lightweight and structural/vibrational response of the overall composition. Still, they may yield detrimental features regarding thermal-induced deformations (i.e., warpage and shrinkage) associated with the typical mold injection process for their manufacturing. This paper uses topology optimization to determine the precise location of the added rib architecture system for enhanced vibration response of the overall plastic component (thin original plastic part and ribs architecture). Following a constant mass criterion, the topology optimization-driven design of the additional material is replaced with a more convenient ribs-based architecture component, showing a reasonable similarity from a vibration standpoint. The component in its initial state (without some ribs-based architecture) shows a vibration response of 16.69 Hz. Once the topology optimization is applied, a significant improvement is observed since a value of 26.05 Hz is obtained. At a postprocessing stage, the design is analyzed and subjected to typical static loading cases to verify its stiffness properties, getting a significant displacement reduction from 7.68 to 3.51 mm. Finally, the design implementation of a warpage and shrinkage analysis confirmed that the final design was not adversely affected according to standard considerations.

Simulation of micro cracks introduced by environmental stress in amorphous plastics

Environmental stress crack resistance (ESCR) is a major problem especially for amorphous polymers. The interaction between aggressive substances and both mechanical external and residual stresses can lead to a fracture of the plastic part. In a previous study, a method was developed to measure the ESCR. The specimens are bent over a circular jig to introduce external stresses and a softener is applied as aggressive substance. After a certain time, the samples fracture giving a measure for the ESCR. In this study, this method is under further investigation using the example of acrylonitrile butadiene styrene. Before the sample fractures, there are several micro cracks visible on the surface. The growth of these micro cracks was measured by dye penetrant testing and the shape of the cracks was determined with computer tomographic measurements. From these measurements, artificial samples were constructed for a simulation. Through the simulation, the stresses in the samples were determined to get an insight into the failure mechanism of the samples. It has been shown that the number of the micro cracks in a sample is constant at all times even though there is a great variation in the number of cracks in the different samples. The cracks grow almost linearly with time. This means that all cracks initiate in one specimen at the same time and in the following phase these cracks grow while no more new cracks initiate. This can be explained by the simulation showing that the stress accumulates at the tips of the cracks and the tensile stress at the surface of the specimens decreases. These results were compared with the results from a stress relaxation test which also showed a decrease in the tensile stress at the surface with time, hence verifying the simulative results.

Heat Dissipation Plays Critical Role for Longevity of Polymer-Based 3D-Printed Inserts for Plastics Injection Moulding

Injection moulding is a polymer processing method of choice for making plastic parts on industrial scale, but its traditional mould is made from tooling steel with time-consuming and costly production. Additive manufacturing technologies arise as an alternative for creating mould inserts at lower costs and shorter lead times. In this context, this study describes a series of stereolithography (SLA)-printed injection mould inserts fabricated from two photopolymer resins, utilised to mould standard tensile specimens of a commercial-grade polypropylene, aiming to evaluate effects on the polymer’s thermal and mechanical properties. Our results demonstrated that the glass fibre-filled resin inserts withstood more moulding cycles before failure, had superior mechanical properties, higher Tg and greater thermal conductivity. Calorimetric data revealed that PP thermal properties and degree of crystallinity were little affected, while mechanical testing suggests a significant effect in the elongation at break. Thus, these findings highlight the importance of adequate heat extraction during injection moulding and endorse further application of SLA mould inserts for the manufacturing of injection-moulded plastic parts in the case of prototypes or small batches, provided suitable cooling is made available, contributing to the feasibility and affordability of employing this approach for an industrial setting.

Modelling and Simulation of MuCell®: The Effect of Key Processing Parameters on Cell Size and Weight Reduction.

Microcellular injection moulding is an important injection moulding technique to create foaming plastic parts. However, there are no consistent conclusions on the impact of processing parameters on the cell morphology of microcellular injection moulded parts. This paper investigates the influence of the main processing parameters, such as melt temperature, mould temperature, injection pressure, flow rate, shot volume and gas dosage amount, on the average cell size and weight reduction of a talc-reinforced polypropylene square part (165 mm × 165 mm × 3.2 mm), using the commercial software Moldex 3D. The effect of each parameter is investigated considering a range of values and the simulation results were compared with published experimental results. The differences between numerical and experimental trends are discussed.

New Metal-Plastic Hybrid Additive Manufacturing for Precise Fabrication of Arbitrary Metal Patterns on External and Even Internal Surfaces of 3D Plastic Structures.

Constructing precise metal patterns on complex three-dimensional (3D) plastic parts allows the fabrication of functional devices for advanced applications. However, it is currently expensive and requires complex processes. This study demonstrates a process for the fabrication of 3D metal-plastic composite structures with arbitrarily complex shapes. A light-cured resin is modified to prepare the active precursor allowing subsequent electroless plating (ELP). A multimaterial digital light processing 3D printer was newly developed to fabricate the parts containing regions made of either standard resin or active precursor nested within each other. Selective 3D ELP processing of such parts provided various metal-plastic composite parts having complicated hollow structures with specific topological relationships with the resolution of 40 μm. Using this technique, 3D devices that cannot be manufactured by traditional methods are possible, and metal patterns can be produced inside plastic parts as a means of further miniaturizing electronics. The proposed method can also generate metal coatings exhibiting improved adhesion of metal to substrate. Finally, several sensors composed of different functional materials and specific metal patterns were designed and fabricated. The present results demonstrate the viability of the proposed method and suggest potential applications in the fields of 3D electronics, wearable devices, and sensors.

Study on in situ visualization crystallization behavior and secondary nucleation model of polypropylene under supercritical N2

The crystal morphology and crystallization kinetics of polymers under supercritical N2 have an important impact on the polymers’ melt strength as well as the microstructure and properties of microcellular plastic parts. Herein, the self-made in-situ high pressure microscopy system was employed to study the spherulite morphology and crystal growth behavior in high pressure N2. It was found that PP spherulites were significantly refined under supercritical N2. As the N2 pressure was augmented to 20.69 MPa at 130 °C, the spherulite size was reduced to 48.41 μm, refined by 35.84%, indicating that the crystallization behavior of PP can be controlled by pressure regulation. The new growth pattern for spherulite under supercritical N2 was discovered by atomic force microscope (AFM) for the first time. In addition, the spherulite growth rate exhibited a phenomenon that was inhibited first and then promoted. To explore the re-promoting effect of supercritical N2, a secondary nucleation model that considered the effect of additional free energy induced by high-pressure N2, was established. The re-promotion of spherulite growth rate at elevated N2 pressure is attributed to the augment in translational free energy induced by N2, i.e., entropy-driven crystallization. The calculated results of secondary nucleation model achieved a good agreement with the experimental results, and the variation trend of PP spherulite growth rate could be well predicted under supercritical N2.

OPTIMIZATION OF INJECTION MOLDING QUALITY BASED ON BP NEURAL NETWORK AND PSO

An electronic product shell is prone to uneven shrinkage, warpage and sink marks, resulting in a large number of unqualified products and increased costs. Therefore, volumetric shrinkage, warpage deformation and sink mark index are selected as optimization goals. Based on the orthogonal test and entropy weight method, a multi-objective optimization was transformed into a comprehensive evaluation optimization. A BP neural network combined with a particle swarm optimization algorithm was used to obtain the optimal combination of process parameters, simulated by Moldflow to reduce volumetric shrinkage to 3.46 %, warpage deformation to 2.538 mm, and the sink mark index to 1.87 % so as to improve the injection molding quality of the plastic parts and meet the requirements of qualified parts. The combination of the BP neural network and particle swarm optimization algorithm can prevent the defects such as large shrinkage, warpage and sink marks

Design recommendation for thermal conductive plastic parts in automotive industry

In this paper we will present a mechanical study made on the design of thermal conductive plastic parts. Out of our study derived new design rules that are useful for mechanical design engineers that have to create parts built from this type of materials. We used Catia V6 software for modelling the parts and ANSYS Moldflow software to simulate the behaviour of real components. The solutions resulted from our trials are improving the quality of the parts built from thermal conductive plastics. The test and simulation results lead us to new rules for designing screw domes and rivets for thermal conductive plastic parts and reducing warpage effect with 75% on this kind of parts.

How micro‐AM is impacting time‐to‐market for precision plastic parts

PhotonicsViewsVolume 19, Issue 5 p. 44-46 Additive ManufacturingFree Access How micro-AM is impacting time-to-market for precision plastic parts Reducing product development costs and stimulating design optimization – three case studies First published: 17 October 2022 https://doi.org/10.1002/phvs.202270510AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Some thirty years ago now, additive manufacturing (AM) — which back in the day was more typically known as rapid prototyping — disrupted (as the name suggests) the prototyping stage of product development. Now, it targets the reign of micromolding. Volume19, Issue5October/November 2022Pages 44-46 RelatedInformation

Cooling solutions by matching plastic and metal in automotive industry

In this paper it is presented a mechanical study made on prototype parts created from aluminium and thermal conductive plastic. The scope is to replace full metal parts used for cooling electronic control unit in automotive industry and save costs. We used aluminium plates and thermal conductive plastic parts for this study. The permanent bonding of two materials, without any glue or additional additives, can be obtained by applying heat on an aluminium plate until around 300 degrees Celsius and pressing the plate on a thermal conductive plastic part. This solution has the following advantages: it can be used to cool local spots and bring around 30% savings by replacing full aluminium housings with parts built from plastic and local aluminium plates. Where the heat dissipation cannot be made without forced air convection, a solution is to combine plastic housing with an aluminium heat sink. The assembly solution is innovative. Our tests prove the efficiency of this solution to be around 20% lower than a full aluminium housing, from cooling effect point of view.

Optimization of the injection moulding process for plastics parts by using FEA

The paper presented the process of injection moulding for plastics with their innovative technologies and moulded plastic materials. The main goal of this research is to present a practical method for analysing the optimization parameters process of plastic injection moulding, such as filling time, melt temperature, mould temperature, maximum injection pressure, injection volume, cooling time, cycle, etc., The simulation was applied on a PC+ABS BAYBLEND T65 XF sample by using the FEA of Moldex3D Program.

Use of principles from axiomatic design in the case of equipment for studying abrasion resistance

The last two decades have highlighted the expanding use of plastic parts obtained by 3D printing processes. This expansion has facilitated the development of research on the various physical and mechanical properties of materials embedded in parts made by 3D printing. Such a property is the abrasion resistance of the plastics. The problem of designing simple equipment to facilitate experimental research on the abrasion resistance of test pieces obtained from plastics by 3D printing has been formulated. It was appreciated that the design of the equipment for the study of abrasion resistance could be performed using some axiomatic design principles. Specific steps have been considered to use axiomatic design to achieve a simple equipment solution for abrasion resistance testing. The functional requirements have been formulated, and appropriate solutions have been identified for the design parameters corresponding to the intended equipment. The axiomatic design facilitated the design of equipment for testing abrasion resistance.

Stress-adapted fiber orientation along the principal stress directions for continuous fiber-reinforced material extrusion

A proven method to enhance the mechanical properties of additively manufactured plastic parts is the embedding of continuous fibers. Due to its great flexibility, continuous fiber-reinforced material extrusion allows fiber strands to be deposited along optimized paths. Nevertheless, the fibers have so far been embedded in the parts contour-based or on the basis of regular patterns. The outstanding strength and stiffness properties of the fibers in the longitudinal direction cannot be optimally utilized. Therefore, a method is proposed which allows to embed fibers along the principal stresses into the parts in a load-oriented manner. A G-code is generated from the calculated principal stress trajectories and the part geometry, which also takes into account the specific restrictions of the manufacturing technology used. A distinction is made between fiber paths and the matrix so that the average fiber volume content can be set in a defined way. To determine the mechanical properties, tensile and flexural tests are carried out on specimens consisting of carbon fiber-reinforced polyamide. In order to increase the influence of the principal stress-based fiber orientation, open-hole plates are used for the tensile tests, as this leads to variable stresses across the cross section. In addition, a digital image correlation system is used to determine the deformations during the mechanical tests. It was found that the peak load of the optimized open-hole plates was greater by a factor of 3 and the optimized flexural specimens by a factor of 1.9 than the comparison specimens with unidirectional fiber alignment.

Fatigue life evaluation for notched single-crystal Ni-based superalloys considering inhomogeneous rafting microstructure

Hot-section components made by single crystal (SC) Ni-based superalloys with geometrical discontinuities such as film holes suffer from spatially inhomogeneous rafting of the γ'/γ microstructure due to harsh circumstances. Therefore, low cycle fatigue (LCF) life prediction is critical for ensuring the safety of engineering structures. Within this regard, an energy-based LCF life model is proposed based on the concept of the strain energy gradient by introducing the effect of rafting into the plastic and elastic parts of the strain energy density. The inhomogeneous microstructure degradation of a centre-hole specimen is depicted by stress-assisted rafting and stress-free isotropic coarsening, whereas the inelastic deformation behaviour of materials near the central hole is simulated by a microstructure-sensitive constitutive model. Combined with the concepts of modified strain energy density, effective damage zone and weight function, the proposed life model achieves a good prediction accuracy in ± 2 scatter bands against the experimental data of the centre-hole specimens with different rafting treatments. Finally, the uncertainty of the proposed life prediction model induced by the statistical dispersion of the microstructure is estimated. The results show that the uncertainty of the predicted lifetimes decreases with the rafting extent and fatigue life, even though the distribution of the γ channel width of the alloy with heavily rafting alloys is highly dispersed.

Novel Method for Failure Modes Detection in UV-Cured Clear Coated Polymer for Automotive Interior Mechatronic Devices.

Plastic parts used in automotive interior are difficult to coat, due to their low surface energies as well as their sensitivity to temperature and solvents, rendering the development of coating systems for such substrates challenging. Automotive customer requirements are explicit and clear, mainly focused on functional and surface defects. A new failure modes detection methodology of UV clear coated polymers for automotive interior, obtained by a multi-step manufacturing process, is proposed. The polymer complex parts analyzed in this paper are manufactured in various steps as follows: two components plastic injection molding, primer coating, laser engraving, and UV-cured clear coating. The failure modes detection methodology of the parts within each process step is investigated using different tests and analyses as follows: surface tension test, painting adhesion test, optical 3D measuring, energy dispersive X-ray analysis (EDX), and microscopy. A design of the experiments (DoE) based on the Taguchi technique with the aim to detect the influence of the main factors that lead to surface defects was performed. The proposed methodology is validated by a case study. The results showed that the mold temperature and the laser engraving current have a significant influence on the surface defect occurrence. Additionally, a possible contamination of the molding tool can generate the defects. A solution to reduce the occurrence of the failures was proposed, reducing the defect rate from 50% to 0.9%.

Assessment of thermal effect on the fracture toughness of granite

The effect of temperature on rock properties has attacked wide attention with the development of deep earth engineering. The change of temperature results in brittle-ductile transformation and makes the fracture toughness different. In the current study, a modified elastic–plastic damage model is proposed to predict the constitutive relation of granite in tension at different temperatures. The model is applied to predict the J-integral of a double-edge-notched plate. Unloading at the point where slope of the secant line is 0.95 times of the initial linear segment slope, the elastic and plastic part of the J-integral can be distinguished. It is noted that the J-integral decreases with elevated temperature and the downward trend changes obviously at around 600 °C. The plastic part takes 57–73 % of the total J-integral for quasi-brittle materials at different temperatures. The fracture toughness predicted based on different methods is compared, it shows that the fracture toughness predicted by the J-integral method is about 1.43 times of the ASTM load-based method.

Mechanical Joining with Aluminum Part by 3D Printing of Polylactic Acid and Acrylonitrile-Butadiene-Styrene Parts for Fabrication of Multi-Material Parts

In this study, the manufacturing process of multi-material parts by simultaneous mechanical joining and three-dimensional (3D) printing of plastic parts was developed. In this process, a metal part with a hole sets on a lower 3D printed plastic part having a projection, and an upper plastic part is deposited on the metal part, while caulking is formed by a 3D printer. The effect of 3D printing conditions and a dimension of caulking on the joint strength was evaluated through the tensile shear and three-point bending tests. It was observed that squashing the projection while printing the upper part effectively improved the strength. The strength decreased as the clearance increased, whereas the shape of the projection was changed to a cylinder and a cone to ease positioning while preventing a decrease in the strength.