Todor Ivanov

Hybrid Production Systems

While virtual product development allows great freedom in terms of design, actual development processes are rather restricted. Those boundary conditions are at best hardly possible to exert influence on. Therefore, future research has to focus both on the realisation of the concept of one-piece-flow while simultaneously increasing flexibility and productivity and on the technological advancement. Hence, hybridisation of manufacturing processes is a promising approach, which often allows tapping potentials in all the aforementioned dimensions.

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.

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.

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°).