Injection Moulding Manufacturing Research Articles

Overprinting of TPU onto PA6 Substrates: The Influences of the Interfacial Area, Surface Roughness and Processing Parameters on the Adhesion between Components.

The hybridisation of injection moulding (IM) and additive manufacturing (AM) offers the opportunity to combine the high productivity of IM and the high flexibility of AM into a single process. IM parts can be overprinted through fused filament fabrication (FFF) to allow for the customisation of parts or to add new functionalities. However, the right material pair must be chosen, and processing parameters must be optimised to achieve suitable adhesion between the components. The present study dealt with the investigation of the influence of the interfacial area, substrate surface roughness and overprinting processing parameters on the adhesion between the polyamide 6 (PA6) substrate and thermoplastic polyurethane (TPU) rib overprinted via FFF. PA6 substrates were produced through the IM of plates into a mould with different textures to obtain substrates with three different surface roughnesses. The ribs with varied interfacial areas were overprinted onto produced substrates using a desktop FFF 3D printer. To study the effect of overprinting processing parameters, the ribs were overprinted under varying printing and substrate temperatures and printing speeds according to the Box-Behnken design of experiments (DoE). The chemical composition and thermal properties of used materials were determined via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The surface properties of prepared substrates were studied via digital optical microscopy (OM), through surface roughness measurements using a confocal microscope, through contact angle (CA) measurements and through the determination of free surface energy (SFE). The adhesion between the components was determined by evaluating the tear-off strength using a universal testing machine (UTM). With an increasing interfacial area, the tear-off strength decreased, while substrate surface roughness had no statistically significant effect. Overprinting parameters influenced the tear-off strength in the order of printing speed > printing temperature > substrate temperature. High values of tear-off strength were found for the lowest printing speed, while there were no important differences found between the middle and upper values. With increasing printing and substrate temperatures, the tear-off strength increased linearly. The highest value of tear-off strength (0.84 MPa) was observed at a printing temperature, substrate temperature and printing speed of 250 °C, 80 °C and 2 mm/s, respectively.

Comparison between Micro-Powder Injection Molding and Material Extrusion Additive Manufacturing of Metal Powders for the Fabrication of Sintered Components

Original compositions based on iron micro-powders and an organic binder mixture were developed for the fabrication of sintered metallic elements with micro-powder injection molding (µPIM) and material extrusion additive manufacturing of metal powders (MEX). The binder formulation was thoroughly adjusted to exhibit rheological and thermal properties suitable for µPIM and MEX. The focus was set on adapting the proper binder composition to meet the requirements for injection/extrusion and, at the same time, to have comparable thermogravimetric characteristics for the thermal debinding and sintering process. A basic analysis of the forming process indicates that the pressure has a low influence on clogging, while the temperature of the material and mold/nozzle impacts the viscosity of the composition significantly. The influence of the Fe micro-powder content in the range of 45–60 vol.% was evaluated against the injection/extrusion process parameters and properties of sintered elements. Different debinding and sintering processes (chemical and thermal) were evaluated for the optimal properties of the final samples. The obtained sintered elements were of high quality and showed minor signs of binder-related flaws, with shrinkage in the range of 10–15% for both the injection-molded and 3D printed parts. These results suggest that, with minor modifications, compositions tailored for the PIM technique can be adapted for the additive manufacturing of metal parts, achieving comparable characteristics of the parts obtained for both forming methods.

Additive manufacturing and numerical modeling of injection mold for fabricating NdFeB magnets

Additive manufacturing and numerical modeling of injection mold for fabricating NdFeB magnets

Comparative Techno-economic Assessment of NdFeB Bonded Magnet Production: Injection Molding versus Big-Area Additive Manufacturing

Comparative Techno-economic Assessment of NdFeB Bonded Magnet Production: Injection Molding versus Big-Area Additive Manufacturing

The effects of cooling rate (mould temperature) on HDPE gears produced through injection moulding

The effects of mould temperature (cooling temperature) on molten HDPE (Hostalen GC 7260) during manufacture, is evaluated in this paper. HDPE gears were produced at varying mould temperatures using Injection Moulding. Optimised injection values for melt temperature, injection volume, hold pressure, and hold time were obtained, and then held constant while the mould temperature was altered.Analysis on how the mould temperature affected peak melting points and crystallinity were then carried out using differential scanning calorimetry (DSC). These revealed that crystallinity improved as the mould temperature was increased from 22 °C to 65 °C. Gears produced at similar cooling temperatures were then meshed on a gear test rig and run at 1000 rpm, using different torque loadings. Their wear rates, and modes of failure were then analysed, and comparisons were made to ascertain how the differing mould temperatures employed during the injection moulding manufacturing process affected their wear characteristics. Topographical analysis of worn gear teeth was performed using scanning electron microscopy (SEM). It was noted that gear tooth wear and failure was dependent on the mould temperature employed during the manufacturing process. Gears produced at 65 °C showed improved tooth surface wear resistance at lower loads (0.5 Nm and 1 Nm) compared to those produced at 22 °C, but were more likely to fail through tooth fracture at the pitch line due to excessive material removal. Gears produced at lower mould temperatures, on the other hand, exhibited better wear resistance for higher loads (3 Nm and 4 Nm), compared to those produced at higher mould temperatures, and were more likely to fail due to material flow. The results show a correlation between mould temperature, crystallinity, and gear performance. Based on wear rate responses of gears produced at differing mould temperatures to the application of varying torque loadings, a Mould Temperature to Torque Reference Chart for HDPE is presented.

Laser Polishing and Annealing Injection Mold Using Dual-Beam Laser System

One of the challenges regarding the application of laser polishing in injection mold manufacturing is to eliminate the tensile residual stress on a polished cavity surface without the extra expenses of an annealing vacuum furnace. This study aims to develop a fast laser annealing method using a dual-beam laser system by which a mold cavity can be laser-polished and then laser-annealed. Fourteen mold steel specimens were laser-polished by a dual-beam laser, resulting in a roughness reduction from the initial state, Sa 1.11 μm, to Sa 0.16 μm, a smoother surface finish. A numerical simulation of laser annealing using the current CW laser was implemented to optimize the laser annealing parameters to guide the experiment of CW laser annealing. XRD measurement results showed that the tensile residual stress dropped from an initial 638 MPa to 10 MPa in an annealing cycle time of 40 min at 750 °C; therefore, fatigue cracks or stress corrosion cracks (SCC) on the mold cavity will no longer occur. Confocal microscopy, X-ray diffraction, and scanning electron microscopy were used to obtain the microstructure and phase composition of the microstructures, demonstrate that laser polishing and laser annealing by a dual-beam laser is a fast and effortless technique which can be effectively employed in injection mold manufacturing.

Microstructural characteristics and material removal mechanisms in nano-scale finished surface of mirror-like injection mould fabricated by laser metal deposition and post treatments

The manufacture of injection moulds with mirror-like surfaces by laser metal deposition is a state-of-the-artdevelopment trend in manufacturing industries. The high surface quality and long-term service performance are two critical demands for laser-metal-deposited injection moulds. In this paper, the microstructure and material removal mechanisms of laser-metal-deposited moulds after nano-scale surface finishing and post treatment were analyzed. Our results confirmed that the differences in temperature gradient and melting composition during solidification would result in both columnar and equiaxial dendritic αʹ-Fe grains distributed in the mould surfaces, and the surface defects of the moulds after nano-scale finishing were directly related to the aggregation of brittle M23(C,B)6 networks stripped out from inhomogeneous αʹ-Fe matrices. Both laser-surface-heat and vacuum-furnace-heat post treatments were beneficial to the microstructural homogenization. The former could achieve directional solidification microstructures with columnar αʹ-Fe dendrites and well-distributed M23(C,B)6 networks, effectively relieve stress concentration during finishing and successfully enhance surface quality and performance. The latter would produce the formation of retained γ-Fe and M2(C,B) particles, weakening surface quality of moulds. Therefore, the laser-surface-heat post treatment seemed to be one of the most promising ways to address microstructural homogenization of laser metal deposited moulds.

Additive Surface Graining in Prototype Tooling for Injection Molding

Surface properties of injection molded parts have a strong effect on the visual and haptic perception of the parts by customers. Especially for injection molded automotive interior parts, grained surfaces can often be found. In conventional tooling, graining requires separate process steps. This makes the realization of grained injection molded prototype parts very complex. By additive manufacturing of injection molds in prototype tooling, it is possible to print micro structures into the mold surface in one printing operation. An injection mold with four different graining structures varying in depth and distance was designed and additively manufactured. The specification regarding the surface graining was analyzed by means of roughness measurements of the CAD model, injection mold and injection molded parts. Results show the feasibility of highly controllable additive surface graining.

Performance study of different EDM Electrode Materials for machining of honeycomb cavities of plastic injection molds

Electro Discharge Machining (EDM) is an extremely prominent machining process among newly developed non - traditional machining techniques for “difficult to machine” conducting materials such as heat treated tool steels, composites etc. In EDM, the material removal of the electrode is achieved through high frequency sparks between the tool and the work-piece immersed into the dielectric. The Material Removal Rate (MRR), Tool Wear Rate (TWR) and surface integrity are some of the important performance attributes of the EDM process. This is widely used in machining intricate cavities in Aluminum HPDC Dies, Tyre mold manufacturing and Plastic Injection mold manufacturing. In Plastic injection mold manufacturing, especially for machining narrow cavities of honeycomb structures, the tool wears faster and machining becomes costly. This study compares performance of three materials viz. Copper, Graphite and Copper impregnated Graphite used as EDM electrodes and evaluates their performances based in lower Tool Wear Rates (TWR)

Penggunaan Kaedah Aliran Angin untuk Mengatasi Masalah Kecacatan Produk Plastik

The product from plastic has occurred many defects and caused more difficulties to the worker in the injection moulding manufacturing sectors. There are some of few samples of defected plastic product such as shot short, burn mark, flashing, warping, bubbles and et cetera. Air vent is the marking line was designed on the mould. This air vent line has constructed in the centre of the ejector rod. Air vent also invented at the block in the mould or suitable places. This airflow line will occur during, while or after setting up a new mould installation processes. The position and size of the airflow line will determine the analysis of flow rate for raw material. Other factors also counted such as working experience and trial and error concepts. If the injection time is lesser than the from recommended timing (S<sup>2</sup> > S<sup>1</sup>), will cause the gases to emit from melting material will be trapped into the mould. This scenario will occur defects to the products. According to the journal papers, four (4) cases were practically addressed about plastic products defects. All study has presented and addresses cases, many benefits were obtained in terms of time and number of defected products. But this process only can be controlled if the mould maintenance and mould lifespan where repaired. Hence the cost of operation and the number of defected products is significantly decreased as well as increased the number of products.

Metal Additive Manufacturing of Plastic Injection Molds with Conformal Cooling Channels.

Conformal cooling channels (CCCs) are widely used in the plastic injection molding process to improve the product quality and operational performance. Tooling that incorporates CCCs can be fabricated through metal additive manufacturing (MAM). The present work focuses on the MAM of a plastic injection mold insert with different CCC types that are circular, serpentine, and tapered channels with/without body-centered cubic (BCC) lattices. The entire manufacturing process of the mold insert is explained from the design step to the final printing step including the computational thermal & mechanical simulations, performance assessments, and multiobjective optimization. Compared to the traditional channels, conformal cooling channels achieved up to 62.9% better cooling performance with a better thermal uniformity on the mold surface. The optimum mold geometry is decided using the multiobjective optimization procedure according to the multiple objectives of cooling time, temperature non-uniformity, and pressure drop in the channel. Direct Metal Laser Sintering (DMLS) method is used for manufacturing the molds and the quality of the printed molds are analyzed with the X-ray Computed Tomography (X-ray CT) technique. The errors between the design and the printed parameters are less than 5% for the circular and tapered channels while the maximum deviation of the strut diameters of the BCC is 0.06 mm.

Effects of Different Mold Materials and Coolant Media on the Cooling Performance of Epoxy-Based Injection Molds.

Metal additive manufacturing techniques are frequently applied to the manufacturing of injection molds with a conformal cooling channel (CCC) in order to shorten the cooling time in the injection molding process. Reducing the cooling time in the cooling stage is essential to reducing the energy consumption in mass production. However, the distinct disadvantages include higher manufacturing costs and longer processing time in the fabrication of injection mold with CCC. Rapid tooling technology (RTT) is a widely utilized technology to shorten mold development time in the mold industry. In principle, the cooling time of injection molded products is affected by both injection mold material and coolant medium. However, little work has been carried out to investigate the effects of different mold materials and coolant media on the cooling performance of epoxy-based injection molds quantitatively. In this study, the effects of four different coolant media on the cooling performance of ten sets of injection molds fabricated with different mixtures were investigated experimentally. It was found that cooling water with ultrafine bubble is the best cooling medium based on the cooling efficiency of the injection molded parts (since the cooling efficiency is increased further by about 12.4% compared to the conventional cooling water). Mold material has a greater influence on the cooling efficiency than the cooling medium, since cooling time range of different mold materials is 99 s while the cooling time range for different cooling media is 92 s. Based on the total production cost of injection mold and cooling efficiency, the epoxy resin filled with 41 vol.% aluminum powder is the optimal formula for making an injection mold since saving in the total production cost about 24% is obtained compared to injection mold made with commercially available materials.

Exploring the Applicability of Sinterjoining to Combine Additively Manufactured Ceramic Components

This paper examines the general applicability of sinterjoining for combining the advantages of Ceramic Injection Molding (CIM) and Additive Manufacturing (AM) as well as different AM processes. To do so, the geometric tolerance, the pre-sintering temperature and the co-sintering time are varied exemplarily on samples produced by vat photopolymerization (VPP) to minimize the force required for inserting the bodies and to maximize the degree of sintering. The results show that degrees of sintering larger 90 % can be obtained reproducibly. Thus, sinterjoining can be considered as a promising approach for combining the advantages of several ceramic manufacturing processes.

MAYA – MAnufacturing of the lining panel using hYbrid technologies; Additive manufacturing, injection moulding and thermoforming

MAYA aims at developing innovative manufacturing routes integrating standard thermoplastic processes (such as injection moulding) and additive manufacturing to produce fuselage composite lining panels. These panels basically consist on sandwich structures with sheets reinforced with fibre-glass hold to the aircraft frame by a set of brackets. The high productivity rate of thermoplastic injection moulding associated to the design freedom of 3D printing will lead to an enhancement of the manufacturing process of the panel-bracket assembly resulting in lighter and less expensive panels with improved overall performance. The work carried out by the research group AMADE focuses on the experimental analysis for interface characterisation, material selection and validation of designs. The first stage of the experimental campaign includes the initial characterisation of the interface bonding of dissimilar materials with different thicknesses obtained by direct 3D printing on the composite skin or by using adhesives under mode I, static and fatigue, and mode II, static, to obtain the best material candidates and design properties. The second part of the work is based on the experimental analysis of the union between the composite skin and small-scale brackets under pull-out and shear-out conditions. Lastly, the final designs of the brackets, both for injection moulding and additive manufacturing, and the corresponding interface bonding with the sandwich panels are validated in large-scale tests under static and fatigue conditions simulating the in-use forces applied to the panels. In this work, the characterisation of the interface bonding of dissimilar materials is presented.

Retos tecnologicos de la implementacion de la inyección de pasticos en piezas aeronauticas

The potential implementation in the aeronautical industry of the injection moulding manufacturing process with short fiber reinforced plastics was studied on different parts with low structural responsability within horizontal and vertical stabilizers thanks to the atractive recurent cost and hi-rate production widely demostrated within automotive industry. The present work shows the different activities performed in the frame of engineering and manufacturing  with the aim to assess the feseability for the aplication of the technology. These activities go from design, stress and mechanical testing, study of the different injection strategies and the implications in the mold design to evolve from conventional plastic to reinforced mateials mainly due to the high temperatures and anisotropy of the material Previous developments are included  in the project FACTORIA, funded by the Ministerio de Economía y Competitividad, by means of the Centro Tecnológico Industrial (CDTI), in the Strategic Programme CIEN 2018

Breaking The Mould?

Nick Allen, managing director of 3DPRINTUK looks at the likely futures for injection moulding and additive manufacturing.

Conceptual Design of Glass/Renewable Natural Fibre-Reinforced Polymer Hybrid Composite Motorcycle Side Cover

This paper presents the development process relating to the conceptual design of glass/renewable natural fibrereinforced polymer hybrid composite motorcycle side cover. Motorcycle side cover is a component frequently made from plastic or steel that functions on covering the motorcycle parts, components and systems such as frame, battery, electrical systems and mechanical systems. Function Analysis Systems Techniques (FAST) is used to identify the functions of motorcycle side cover. The right-side cover of motorcycle model SYM E-Bonus 110 has been physically studied to identify the competitive benchmarking criteria. The functions and competitive benchmarking criteria are then compiled and integrated with the environmental requirements to identify the Product Design Specifications (PDS). The coir fibre has been selected from six identified dominant renewable natural fibre used for automotive component through integration of Ranking Method and Quality Based Selection (QBS). Then the polypropylene matrix is selected after shortlisting the existing thermoplastic that is used with coir fibre and has high suitability for injection moulding manufacturing. The polypropylene matrix is then evaluated using Weighted Evaluation Matrix (WEM) by comparing to benchmark material which is Acrylonitrile Butadiene Styrene (ABS). After that, the conceptual design development of glass/renewable coir fibre-reinforced polypropylene motorcycle side cover is carried out using an integrated Theory of Inventive Problem Solving (TRIZ) and Morphological Chart, followed by final conceptual design selection using integration of Pugh Scoring Method and QBS. The conceptual design development intended on improving the biodegradability to reduce pollution to the environment. However, the usage of glass/coir fibre-reinforced polypropylene hybrid composite may increase the weight due to higher density. Four innovative design concepts have been developed and the selected final concept design has the most minimum number of ribs and minimum thickness with the same ratio of glass fibre and natural fibre composition.

A current state of art applied to injection moulding manufacturing process – A review

Abstract Injection moulding (IM) appears to be one of the most important techniques for manufacturing plastics products worldwide. As IM is a complicated process, so it is technically very difficult to take into account all the changes taking place during the process. To enhance efficiency of the process and to have consistent product quality, proper input parameter’s setting is critically important. The numbers of input process parameters are: melt temperature, mold temperature, injection pressure, injection speed, injection time, holding pressure, holding time and cooling time. The responses/output may be mechanical properties, defects e.g., warpage, shrinkage, sink mark, residual thermal stress etc., and aesthetic requirement for example surface finish/roughness. Literature review shows that most of the researchers have optimized the process parameters and established a correlation between the parameters and the behavior of the material under investigation. Others performed optimization research regarding some specific areas of IM viz. cooling channel design, location of the gate, runner system design etc. Some of the studies were focused on monitoring control system to monitor the process during production to ensure quality and minimize the defects. Researchers have used many different techniques to model and optimize the IM manufacturing process. These techniques include mathematical modelling, simulation, design of experiments (DOE) and artificial intelligence (AI). Some of the examples of these techniques are Taguchi method, evolutionary algorithm (EA), artificial neural networks (ANN), genetic algorithms (GA), fuzzy logic, response surface methodology (RSM), particle swarm optimization (PSO), analysis of variance (ANOVA) etc. This paper aims to review and present the various studies concerning the process parameters and their influence over the quality of product. Throughout this review, the process parameters, response, material used and the technique applied to optimization research in the field of IM are highlighted.

Rheological Behaviour of Highly Filled Materials for Injection Moulding and Additive Manufacturing: Effect of Particle Material and Loading

Within this paper, we are dealing with a mixture of thermoplastic polymer that is filled with inorganic fillers at high concentrations up to 60 vol.%. A high number of particles in the compound can substantially change the rheological behaviour of the composite and can lead to problems during processing in the molten state. The rheological behaviour of highly filled materials is complex and influenced by many interrelated factors. In the present investigation, we considered four different spherical materials: steel, aluminium alloy, titanium alloy and glass. Particles with similar particle size distribution were mixed with a binder system at different filling grades (30–60 vol.%). We showed that the rheological behaviour of highly filled materials is significantly dependent on the chemical interactions between the filler and matrix material. Moreover, it was shown that the changes of the particle shape and size during processing lead to unexpected rheological behaviour of composite materials as it was observed in the composites filled with glass beads that broke at high contents during processing.

Chapter 2 Manufacturing of Injection Mold

Chapter 2 Manufacturing of Injection Mold