Moulding Tools Research Articles

The effects of machining strategies of magnetic assisted roller burnishing on the resulted surface structure

The aim of this paper is to investigate the effect of different burnishing strategy on a C45 steel machining. Burnishing is a well-known, cold working surface improving technology, it is usually applied for cylindrical workpiece. In the reported research a novel developed magnetic assisted ball burnishing (MABB) tool was applied which was designed for MABB machining of flat and harmonic surfaces. To increase its efficiency, different types of machining strategies were applied. After the burnishing process the machined surfaces were measured by surface roughness tester to determine the most important Rsk and Rku tribological parameters. According to the results it can be stated that all different burnishing strategies have special application areas where they can be used efficiently (e.g. sliding surface, moulding tool and after- or pre-machining for ultra-precision machining).

Surface‐treated kaolin minerals as a complement or substitute to glass fibers in thermoplastics

Glass fiber (GF)‐related mold abrasion and tool wear make it undesirable for certain thermoplastics applications. Furthermore, fiber attrition during processing and orientation sensitivity raise concerns over compromised performance. In this study, kaolin minerals with varying properties and surface‐treatments are tested to potentially replace GFs in nylon composites. Composites are melt‐compounded and injection molded using lab‐scale and industrial‐scale equipment. Mechanical properties (tensile, flex, impact), heat distortion temperature, and thermal decomposition using thermogravimetric analysis (TGA) are used to comparatively characterize kaolin composite formulations against 30% weight GF composites. Kaolin minerals with high aspect ratio and good interfacial contact are found to show strength and modulus improvements up to 80% that of GF. Additionally, low aspect ratio kaolin composites were found to surpass GF composites in impact strength. A synergistic effect is found between high and low aspect ratio kaolin that can potentially lead to further enhancement in properties with the added possibility of blending minerals to customize composite performance. Such findings suggest that kaolin minerals can be used to customize the properties of composites in manners previously unattainable through GF usage alone. Scale up trials show potential for kaolin to replace GFs at industrial levels. POLYM. ENG. SCI., 59:E330–E338, 2019. © 2018 Society of Plastics Engineers

Replication integrity of micro features using variotherm and vacuum assisted microinjection moulding

Micro features on surfaces are critical for the functionality of a product, such as micro channels for a microfluidic chip and micro lens arrays for an artificial compound eye lens. In the present work, we design a series of microfluidic and microstructured surface patterns to evaluate the influence of variotherm and vacuum venting on replication integrity of micro features. By using a process monitoring system, including machine process and cavity pressure/temperature measurements, the influence of warm and cold circuit settings, and vacuum venting are characterised in terms of injection pressure, cavity pressure and mould–polymer interface temperature. These are then correlated with the replication integrity of micro features by assessing feature replication height, cross-section area and surface morphology. The performance of anti-stick coatings on a micro mould tool insert was also characterised in terms of moulding cycles. After a series experiments and optimisation, we have significantly enhanced feature replication with 100% replication of proposed features without either significant distortion or tearing, which cannot easily be achieved using conventional injection moulding. Additionally, we have successfully moulded features having good integrity and a maximum aspect ratio of up to 10 at a width of less than 8μm over areas as large as 5.25mm2.

Epoxy infiltrated 3D printed ceramics for composite tooling applications

The use of additive manufacturing (AM) provides an opportunity to fabricate composite tooling molds in a rapidly and cost effectively manner. This work has shown the use of a polymer based infiltrated ceramics produced via binder jetting for producing composite tooling molds. Here, molds based on silica sand as well as zircon sand have been printed on a S-Max 3D printer unit and subsequently impregnated with an epoxy system for yielding functional molds in the range of autoclave temperatures around 150–177 °C. The mechanical properties of the infiltrated 3D printed materials have been investigated and it was observed that the polymer-infiltrated systems resulted in a compressive and flexural strength one order of magnitude higher than the non-infiltrated printed ceramic material. A thermal analysis was also performed on both the infiltrated and non-infiltrated printed samples, and it was recorded that the incorporation of the polymer resulted in a larger coefficient of thermal expansion on the infiltrated systems. Here, a carbon fiber reinforced composite was manufactured with the infiltrated composite tooling molds printed in the S-Max unit, and it was observed that the assembled molds are capable of producing a successful composite material. The present work has demonstrated that a binder jetting process, is a feasible technology for producing thermostable low cost composite tooling molds.

Optimization for Reducing Warpage in Injection Moulding

Injection molding is a standout technique utilized for the fabrication of thermoplastic parts in industry due to short product cycles, high part quality, good mechanical properties and low cost for large scale manufacturing. In molded case circuit breaker (MCCB), Trip-bar is one of the most critical components as safety is concerned which is manufactured by injection molding process. To get it manufactured within the specified warpage and deformities free, number of mold flow simulations is carried out using Creo-MoldFlow. The outcomes of the simulation are used to design the mold tool and the process parameters for injection molding are optimized. For process parameter optimization Taguchi based experimental design and ANOVA analysis is done. The objective of this work is to optimize the injection molding process parameters such as filling time, melt temperature and mold temperature to minimize the warpage. CAE flow simulation software is used to simulate the process and Grey Relational Analysis (GRA) is used to find out optimum process parameters.

Additive Ambition

Andrew Allcock discovers three companies employing 3D printing to support mould tool or pattern manufacturing activities. But while they have advantages for their users, in the case of the mould tool making examples, he doesn’t anticipate a rush for others to follow in their footsteps

Investigation of the Integrity of aC:H Coatings on Stainless Steel Micro-Moulds during Thermal Cycling

Micro-injection moulding (µIM) is a key technology for scaling down larger geometry components and can include functional features at the micrometre scale and as far as the sub-micrometre length scale. Thermal cycling of amorphous hydrogenated carbon (aC:H) coated Stainless Steel (SS) has been investigated to simulate long-term micro-injection moulding (µIM) wearing and damage. Micro indentations and cracks were made into the mould and predictions of the crack behaviour were made using thermal expansion models. Validation of the results was performed with multiple heating and cooling cycles along with hardness measurements of the damage to the coating. The undamaged surfaces showed no major deformation but the cracks were shown to propagate and change in behaviour. The first two heat cycles of the testing had the most significant effect on the substrate with varying thermal expansions of materials being the main cause. The aC:H is shown to have excellent properties for mould tool applications but delamination could occur in areas susceptible to damaged and periodic surface inspection will be required preserve tool life.

Status-quo and Development of Cutting-tool Industry in Taiwan and China

Cutting plays a very important role in the manufacturing industry. The global industries of general machinery, automobile, aviation and aerospace, energy, medical, rail transit, mold and machine tools, etc. cannot do without cutting-tool equipment. Modern efficient cutting-tools focus on high accuracy, high efficiency, high reliability and customization. The type numbers and varieties of cutting-tools produced in Taiwan and China are becoming rich day by day. Therefore, this research explored the cutting-tool industry in Taiwan and China, and employed expert interview, five forces analysis, and PEST analysis to analyze the industry. This study offered conclusions based on the research results and provide specific, substantial business improvement, policy formulation and other related recommendations for relevant industry, government-related units and academic research.

Combination of short and ultrashort pulse laser processing for productive large scale structuring of 3D plastic mould steel

Surface functionality is an increasing and crucial factor for the success and acceptance of a product. Through structured surfaces, products can gain additional functions: for example, friction reduction in combustion engines and bearings or optimizing lighting efficiency in light-emitting diodes. Furthermore, not only technical properties but also optical and haptic functions can be generated by surface structuring. Especially in the area of consumer products, these functions determine essentially the product quality. The most common way to create surface functionality in mass production is replication processes via structured mold tools. Currently used manufacturing processes for tool structuring like photochemical etching are limited in precision (manual preparation and execution) and in flexibility (limited design). This is the reason why laser ablation with (ultra-) short laser radiation is becoming an increasingly important technology that is able to generate structure sizes in the range of several hundred nanometers to several hundred micrometers. In this paper, the possibility of combining nanosecond (ns) pulsed laser radiation with picosecond (ps) pulsed laser radiation for microstructuring is investigated. This approach promises an increase of the productivity of the manufacturing process, similar to the strategy of roughing and finishing in milling processes. Within a first laser process, the workpiece is pretreated by short nanosecond laser pulses and a large amount of the volume is removed. A second, following laser process using picosecond pulses is utilized to ablate the remaining volume and to finish the surface by fabricating precise microstructures. This combination brings the advantages of both processes together: (comparable) short processing time (short pulses = roughing) while achieving high precision (ultrashort pulses = finishing). Main research activities presented are different approaches for combination strategies, discussions about achievable and from industrial site acceptable processing times, and accessible surface qualities for the combined process.

Design of Family Mould Tool for Plastic Box

Design of Family Mould Tool for Plastic Box

Determining the Effect of Material Hardness During the Hard Turning of AISI4340 Steel

In the present manufacturing industries hardened steels are most widely used in the applications like tool design and mould design. It enhances the application range of hard turning of hardened steels in manufacturing industries. This study discusses the impact of workpiece hardness, feed and depth of cut on Arithmetic mean roughness (Ra), root mean square roughness (Rq), mean depth of roughness (Rz) and total roughness (Rt) during the hard turning. Experiments have been planned according to the Box–Behnken design and conducted on hardened AISI4340 steel at 45, 50 and 55 HRC with wiper ceramic cutting inserts. Cutting speed is kept constant during this study. The analysis of variance was used to determine the effects of the machining parameters. 3-D response surface plots drawn based on RSM were utilized to set up the input–output relationships. The results indicated that the feed rate has the most significant parameter for Ra, Rq and Rz and hardness has the most critical parameter for the Rt. Further, hardness shows its influence over all the surface roughness characteristics.

Optimal integration of pneumatic artificial muscles with vacuum-jammed surfaces to characterise a novel reconfigurable moulding system

Producing mould tooling systems is a considerable proportion of manufacturing cost and time, especially for low volume productions. Producing a reconfigurable mould to shape surfaces into complex geometries with multiple curvatures would obviate the need to design and fabricate individual moulds for different products. Current reconfigurable mould tooling systems are mainly variations on a ‘bed of pins’ design through differing patterns of actuated pins. These systems are heavy, mechanically complex and expensive to manufacture. Soft pneumatic actuators such as Mckibben muscles, also known as pneumatic artificial muscles (PAMs) are recognised for their high strength to weight ratio, ease of manufacture and low cost. In this work, PAMs are used to influence a soft elastomeric surface, allowing the formation of spatial curved profiles. This thin, hollow surface is packed with a granular medium that exhibits jamming under the negative pressure of a vacuum. This allows the flexible surface to transform to a rigid surface of greatly increased stiffness with a specific geometry for moulding purposes. This paper presents the design, experimental development and experimental performance of two sample prototypes to actualizes the idea of such adaptable moulding tools. The prototypes contain different actuator arrangements to form jamming surfaces into diverse, simple-to-complex 3D profiles. In addition, the kinematic performance for one of the prototypes is shown by a numerical model. Future work on this system will tailor it for production of fibre carbon composites.

Monitoring of Injection Molding Tool Corrosion and Effects of Wood Plastic Compound's Moisture on Material Properties

Abstract Before injection molding, wood polymer composites (WPC) normally have to be dried to achieve optimal quality of the injected parts as well as to avoid corrosion of the mold. Based on a literature study, there are currently no published investigations dealing with the dependency of WPC properties on the initial moisture content of the compound's pellets. Further, it is known that water and wood in combination with high temperatures can lead to corrosion of steel parts, but a systematic analysis of the impact of WPC injection molding on tool corrosion has not been found in the literature. For the present study, a compound with 68 wt% (weight percent) polypropylene, 30 wt% wood flour and 2 wt% coupling agent was produced and tested in injection molding trials. Specimens according to ISO 527-2 were produced from WPC with defined moisture contents, respectively. Compound moisture, already at very low contents, had significant negative effects on the tested mechanical properties, namely tensile modulus and strength, unnotched and notched Charpy impact strength and heat deflection temperature. Corrosion trials were performed for different tool steel qualities. The severity of corrosion correlates with the amount of chromium (Cr) in the alloys tested.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Path Planning of Cooperating Industrial Robots Using Evolutionary Algorithms

Nowadays, aerospace components made of carbon fiber reinforced plastics (CFRP) which are manufactured by a dry-fiber depositing process are produced almost exclusively by hand. In this type of process, hundreds of textile blanks with different contours are stored in a tool mould. For large components such as an aircraft fuselage, it is also necessary to transport the flexible blanks with cooperating robots. For this purpose, a system was developed which allows to generate robot paths on the basis of Computer Aided Design (CAD) data, which is automatically extended by information such as pickup and drop points for the robot. The system has already been successfully tested with sampling-based algorithms on a robot system with two KUKA KR210 R3100 robots on a common linear axis. However, the use of sampling-based algorithms a heuristic must be developed to solve the redundancy of linear axis which is usually only functional for the current scenario and must be adapted for another one. Evolutionary algorithms offer the advantage that they are also able to find a solution for the linear axis independent of the scenario. In this work. A path planning system that uses evolutionary algorithms to calculate collision-free paths reliably for cooperating robots on a common linear axis will be presented.

Research and Implementation on Critical Technology of Precision Compression Molding Tool

Research and Implementation on Critical Technology of Precision Compression Molding Tool

Thermal Comparison of Conventional and Conformal Cooling Channel Designs for a Non-Constant Thickness Screw Cap

Complex parts are manufactured with high production rates using plastic injection. Defects in injection moulded parts are typically caused by non-uniform cooling. The design of cooling channels is a key step in the mould tool design process. Laser sintering allows for the direct fabrication at reasonable price, complex 3D tools with integrated cooling channels without the need of fixtures. This technique allows the designer to optimise the position of cooling channels relative to the heat source. This paper presents a simulation study for a non-constant thickness threaded screw cap. Results comparing conventional to conformal cooling channel show that the range between the highest and the lowest part surface temperatures is reduced by 18.8%. On the other hand, there is only a decrease of 3.9% for the maximum temperature in the interior of the threaded screw cap. Conformal cooling using laser sintering in tool manufacturing achieves an improved heat transfer leading to a better part quality.

Identification of Residual Stress in the Production of Molding Tools by Turn-Milling Technology

AbstractThis article describes how to plan the tool path and analyze the surface of the machined part by working simultaneously on two basic operations such as milling and turning. New machine tools allow parallel processing of both multi-axis tools at the same time, it is a production technology in which the workpiece and the tool are simultaneously rotating. This relatively new turnmilling technology could be an alternative to increasing productivity in many applications. Especially in cases involving heavy-duty materials or large diameters of machined surface. The aim of this study is to explore this new technology, especially with regard to the increased precision and quality of the surface of the workpiece. Experimental results show that the combination of these two operations is suitable for precise machining of rotationally symmetrical workpieces with high surface finish.

Environmental and Economic Implications of Distributed Additive Manufacturing: The Case of Injection Mold Tooling

SummaryAdditive manufacturing (AM) holds great potentials in enabling superior engineering functionality, streamlining supply chains, and reducing life cycle impacts compared to conventional manufacturing (CM). This study estimates the net changes in supply‐chain lead time, life cycle primary energy consumption, greenhouse gas (GHG) emissions, and life cycle costs (LCC) associated with AM technologies for the case of injection molding, to shed light on the environmental and economic advantages of a shift from international or onshore CM to AM in the United States. A systems modeling framework is developed, with integrations of lead‐time analysis, life cycle inventory analysis, LCC model, and scenarios considering design differences, supply‐chain options, productions, maintenance, and AM technological developments. AM yields a reduction potential of 3% to 5% primary energy, 4% to 7% GHG emissions, 12% to 60% lead time, and 15% to 35% cost over 1 million cycles of the injection molding production depending on the AM technology advancement in future. The economic advantages indicate the significant role of AM technology in raising global manufacturing competitiveness of local producers, while the relatively small environmental benefits highlight the necessity of considering trade‐offs and balance techniques between environmental and economic performances when AM is adopted in the tooling industry. The results also help pinpoint the technological innovations in AM that could lead to broader benefits in future.

Rotational moulding of PEEK polymer liners with carbon fibre/PEEK over tape-placement for space cryogenic fuel tanks

PEEK polymers are investigated as replacement materials for metallic liners in composite overwrapped pressure vessels (COPVs) for fuel tank applications in space. A novel, integrally heated, rotational moulding tool has been developed to produce PEEK polymer liners, samples of which have then been overwrapped using CF/PEEK in a laser assisted tape-placement (LATP) process to produce demonstrator samples of a polymer lined COPV. Helium permeability testing has shown that the designs are capable of resisting leakage to acceptable levels for fuel storage, while X-ray CT scanning and cryogenic cycling have shown that the current design is capable of resisting crack growth over multiple cycles. Nano-indentation testing has shown that the LATP process has created a region of reduced modulus in the PEEK polymer at the surface of the liner where the CF/PEEK has been tape-laid. This laser-affected zone of reduced polymer modulus in the composite interface region has enabled an enhanced resistance to crack growth formations from thermal residual stresses in comparison to hot plate moulded test samples.