Uwe Vroomen

Decision and Design Methodologies for the Lay-Out of Modular Dies for High-Pressure-Die-Cast-Processes

Within the project “Decision and design methodology for the lay-out of modular dies” which is part of the Cluster of Excellence “Integrative Production Technology for High-Wage Countries”, established and financed by the German Research Foundation (DFG), the main objective is setting guidelines for cost-effective and high quality high pressure die casting (HPDC) moulds. The strong increase in product variants and the growing demand for individualised products results in a growing complexity of all related products. The main objective of this project is bridging the existing gap between individual manufacturing and mass production. A new perspective on the value creation chain of HPDC-dies has to be established. First of all, the methodology for the lay-out of modular dies consists in an analysis of the already produced die cast moulds. For the development of modules, standard parts, and different die types, a wide range of HPDC-dies will be compared with each other and subsequently clustered along specific criteria such as size or number of core sliders. Another step consists in optimising setting-up time and maintenance. The as-is state in different companies will be examined. With this knowledge, new concepts will be developed, keeping a modular configuration of the different parts involved in mind. Concepts for modular core sliders, guides and ejectors will be developed and will be investigated for further use. Based on this information, the decision and design methodology for the lay-out of modular HPDC -dies will be examined and developed throughout the process.

Design methodology for modular tools

Serving individual customer needs at reasonable prices can be a profitable target market in high-wage countries. The dilemma between scale and scope-oriented production is one major research topic within the Cluster of Excellence “Integrative Production Technology for High-Wage Countries” at the RWTH Aachen University. One main objective of this project is to bridge the existing gap between individual manufacturing and mass production. Modularization is a widely accepted approach in tool-based manufacturing processes. In this paper, we propose a flexible design methodology for modular tools and dies. The methodology will assist the design engineer in setting up a series of modularized tools in a conceptually closed manner. The described methodology covers modularization in a broad sense, i.e. it includes hardware modularization as well as modularization of the construction process. The methodology consists of three phases: initiation, analysis and design phase.

Processing of High Pressure Die Casting Alloys and Engineering Polymers to New Hybrid Metal/Plastic Products in a Combined Process

Within the project “Advanced Processes for Hybrid Metal/Plastic Products” which is part of the Cluster of Excellence “Integrative Production Technology for High-Wage Countries”, established and financed by the German Research Foundation (DFG), new hybrid processes for the production of metal/plastic-composites will be developed. The activities of the Foundry Institute focus on the processing of structural parts with excellent mechanical properties and special integrated functions by combining two original mould operations. In the long term, the metal/plastic-composites are to be produced in a single step process, using one mould and one machine. Beside the combination of the two processes, high pressure die casting and injection moulding, preliminary test geometries will be manufactured in separate moulds. The operation using the two moulds consists in the production of the aluminium metal part in a pressure die casting mould, and subsequently the injection of the plastic component into an injection mould. The basics needed to define the adhesion mechanism between metal and plastic were investigated under experimental conditions in order to determine appropriate results for tests, carried out under the process conditions of high pressure die casting. It is proposed to find and to develop new concepts to join these two different materials. The best bonding mechanism will be chosen to obtain the first metal/plastic hybrid products in the so-called One-Step-Process. A selection of promising results concerning the bond strength of different joining concepts under application terms are presented in this paper.

Replication of Microscale Features via Investment Casting Using the Example of an Aluminium Intake Manifold of a Gasoline Engine with an Inner Technical Shark Skin Surface

Within the project “Functional Surfaces via Micro- and Nanoscaled Structures” an investment casting process to produce 3-dimensional functional surfaces down to a structural size of 1µm on near-net-shape-casting parts will be developed. The common way to realise functional microscale features on metallic surfaces is to use laser ablation, electro discharge machining or micro milling. The handicap of these processes is their limited productivity. In order to raise the efficiency, microscale features will be replicated by use of the investment casting process. The main research objective deals with the investigation of the single process steps with regard to the moulding accuracy. Actual results concerning making of the wax pattern and the ceramic mould as well as the casting of an Aluminium alloy will be presented. By using the example of an intake manifold of a gasoline race car engine a technical shark skin surface was defined in order to reduce the drag of the in-coming air. Possible process stategies to realise microscale features on an inner surface of a casting part were developed.

Mold-Based Production Systems

Mold-based production systems are vastly common in mass production processes, due to the high investment costs of production equipment. In order to address the challenge of a strong tendency towards individualized customer demands, companies in high-wage countries are forced to react towards these changes. This chapter describes recent advances in the field of individualized production for mold-based production systems regarding plastics profile extrusion and high-pressure die casting. A holistic methodology for an integrated product and mold design is presented based on the principles of simultaneous engineering. In addition, recent advances in the field of numerical optimization are shown. The advances in numerical optimization will be carried out based on the processes mentioned above. The monitoring and simulation of the viscoelastic swell will be shown for plastics profile extrusion. For the field of high-pressure die casting the strategy to optimize the entire process will be outlined and current experimental results shown. For both application cases the potential benefit of additive manufacturing technologies—such as Selective Laser Melting (SLM)—will be evaluated and validated inasmuch as possible.

Multi-technology products

Development of technical solutions that lead to widening the use of multi-technological products as well as in assessing ecological and economic potentials of multi-technological products have not yet been studied intensively. The activities conducted in the context of this research area focus on these aspects. The aforementioned aspects have been examined, evaluated and quantified on the basis of three example products resulting from the first funding period. The research activities conducted on the example components deliver the basis for the layout of different integrated multi-technology production systems. Technical solutions that enable coupling of different process steps with each other as well as the integration of different functionalities and different materials in final multi-technology products have been proposed. The complex interdependencies of the products themselves and their associated production processes have been researched and evaluated intensively. Finally, a profitability assessment of the proposed solutions was conducted and future research topics identified.

Multi-Component High Pressure Die Casting (M-HPDC): Influencing Factors on the Material Temperature During the Joining of Metal-Plastic-Hybrids

M-HPDC is an In-Mold manufacturing process combining High Pressure Die Casting (HPDC) and Injection Molding (IM) within one manufacturing plant. The biggest influence within a metal-plastic-bond realized by micro bracing is ascribed to a suitable temperature management in the die. Therefore a suitable temperature control concept for a sample die, made to manufacture an overlap shear tensile sample, will be presented. In order to investigate the temperature influence, the die provides several options to influence the actual temperature. A number of independent cooling circuits, an alternating temperature management unit and a contour adapted heating cartridge are integrated. Besides that, the temperature within the joining area can be raised by exchangeable die inserts for the usage of either an inductor or a heating ceramic. For the purpose of quantification, the temperature will be monitored by thermocouples close to the actual cavity surface. The die concept and first results of the simulative approaches will be shown.

On relation of development of speed of ultrasound in hardening polyurethane coldbox binders

Abstract The relationship between the change in sound propagation and mechanical properties of a gas hardening polyurethane coldbox bound sand core was studied. A novel test rig was constructed to achieve that goal. The sound propagation properties are quantitatively different in every trial of the experiments. Defining criteria for the start and end of the hardening reaction by the first time derivative render two points that correlate well with the start and end of the development of the mechanical hardness of the sand core.

Replication of specifically microstructured surfaces in A356-alloy via lost wax investment casting

A common way of realizing microstructural features on metallic surfaces is to generate the designated pattern on each single part by means of microstructuring technologies such as e.g. laser ablation, electric discharge machining or micromilling. The disadvantage of these process chains is the limited productivity due to the additional processing of each part. The approach of this work is to replicate microstructured surfaces from a master pattern via lost wax investment casting in order to reach a higher productivity. We show that microholes of different sizes (∅ 15–22 µm at depths of 6–14 µm) can be replicated in AlSi7Mg-alloy from a laser-structured master pattern via investment casting. However, some loss of molding accuracy during the multi-stage molding process occurs. Approximately 50% of the original microfeatures heights are lost during the wax injection step. In the following process step of manufacturing a gypsum-bonded mold, a further loss in the surface quality of the microfeatures can be observed. In the final process step of casting the aluminum melt, the microfeatures are filled without any loss of molding accuracy and replicate the surface quality of the gypsum mold. The contact angle measurements of ultrapure water on the cast surfaces show a decrease in wettability on the microstructured regions (75°) compared to the unstructured region (60°).