Contribution to eurolite 2007

Transcription

1 Contribution to eurolite 2007 Innovative lightweight design solutions thanks to multi-material components Compound casting less weight, greater costeffectiveness The lightweight construction philosophy is based on the principle of making the best possible use of the material. Vehicle construction and aerospace in particular demand solutions which save as much weight as possible while fulfilling identical or even greater requirements with regard to component properties, and which can be produced at low cost. Compound casting meets a wide range of requirements within one component by combining different materials. In addition to saving weight, it has the added advantage of reducing bonding processes. In the product creation process, lightweight construction solutions can be implemented in the design phase, the construction phase itself and the manufacturing phase. The construction phase also offers great weightsaving potential through the selection of the right material. Often, however, different things are required of a component or the material used with regard to strength, corrosion or heat resistance for instance. Components constructed using a hybrid method have proven to offer a useful approach. Compound casting multi-material construction with savings potential One variant which is becoming ever more important in series production is compound casting. Through the combination of various materials, this compound casting process can help components meet the most diverse of requirements. And with the hybrid construction process, the material bond is created by recasting separate hot or cold bonding/jointing processes are not necessary. This in turn reduces the number of production steps needed in the manufacturing process. A good example 1

2 of applications in this field is the manufacturing of engine blocks. As a pure sheet steel solution, it consists of numerous individual parts which are joined to one another. In contrast, the compound casting solution makes it possible to produce this component as a single piece. The intelligently designed casting made from an aluminium or magnesium alloy ensures the high functional integrity of flanges and bearing carriers, for instance. In difficult areas, a carefully positioned insert such as a semi-finished product made of steel or an aluminium alloy provides the necessary strength. "In comparison with conventional diecasting, the manufacture of a compound casting piece requires additional handling, for example manipulation of inserts or perhaps pretreatment of the surfaces", explains Werner Fragner, head of casting technology at ARC LKR Ranshofen GmbH (Austria). Considering compound casting in the design phase In order to optimise the weight-saving aspect and strength of the component with as little manufacturing work as possible, the compound casting design must be taken into consideration as early as the design phase of a mixed-material component. The simulation of the casting process and the evaluation of the compound strength using structural FEM calculations make it possible to precisely tailor the manufacturing process and the properties of the component to suit requirements. "In addition to finding the optimal design of the geometries and parameters for the casting process, parameters can be determined for calculating the component strength. This prevents critical flaws in the components", explains the expert in lightweight construction. Three types of multi-material compound With form closure, force closure and adhesive bonding, compound casting enables three different types of multi-material connection. While form closure is ensured by the geometric design of the workpiece to be cast, force closure is based on the solidification shrinkage of the casting material and generates a press fit. The adhesive bond is created by a chemical reaction between the liquid material and the insert and ensures 2

3 a smooth transition between the materials. "Ideally, at least two of the connection types are combined in the design of the compound casting parts", says Fragner. Each of these material connections has its advantages and disadvantages. The ideal connection must therefore be defined individually for each component to be designed. A form closure may lead to a loosening of the connection under dynamic loads, yet it has great static strength. A force closure is only possible if the component can be completely transfused. With adhesive bonding, the properties of the intermetallic phases play an essential part in the quality of the material bond. Assessing the material bonds The project "Austrian Light Weight Structures" (ALWS), managed by LKR, deals with the assessment of these material bonds. It examines the potential and the challenges faced throughout the entire product lifecycle, from manufacturing with innovative designs to specially designed recycling. In addition to design guidelines, the aspects of corrosion protection, which is particularly important when two or more different metallic materials are used, manufacturing parameters, usability and mechanical and dynamic properties play an important role. For form closure, for instance, the optimal suitability of different geometries is examined; with force closure the length and thickness of the connection points are optimised; and with adhesive bonding the kinetics and morphology of the chemical bond are characterised. Compound casting in use Compound casting parts are already used in vehicle construction for parts of the chassis, such as the engine block, shock strut supports and gearbox casing, as well as bodywork components, for example A- and B-columns, door frames and connection supports and as dashboard mounts in the interior. And according to information from the automotive industry, multi-material components are on the increase. This is proven 3

4 by compound cast parts such as the 6-cylinder magnesium engine with aluminium insert from BMW and other components which are undergoing development but have not yet been announced. The aircraft industry, too, is relying more and more on compound cast materials. Info box eurolite, international specialist trade fair for lightweight design The eurolite international specialist trade fair for lightweight design is the industry- and technology-independent trade fair platform for the forward-looking growth market of lightweight construction. The exhibition portfolio covers software for calculation, simulation and lightweight construction methods, materials, prototype and model construction, manufacturing technologies, bonding and connection technology as well as surface technology, component tests and series production of lightweight components and semi-finished products. The lightweight construction trade fair, where LKR will be appearing, is the only one of its kind in Europe and will be held from 26 to 28 June 2007 in Salzburg. For more information, visit The geometry for form-closed multi-material components in compound casting is optimised using the finite element method. 4

5 Prototype casts with close-to-production casting machines enable the insert and casting parameters to be optimised. The development of the thickness of intermetallic phases in aluminiumsteel composites. 5

6 Contact addresses: ARC Leichtmetallkompetenzzentrum Ranshofen GmbH Werner Fragner Postfach 26 A-5282 Ranshofen, Austria Tel: +43 (0) Fax: +43 (0) H & K Messe GmbH & Co. KG Wieland Kniffka Kaiserstraße D Karlsruhe, Germany Tel: +49 (0) Fax: +49 (0) w.kniffka@hundkmesse.de SCHULZ. PRESSE. Text Doris Schulz Martin-Luther-Straße 39 D Korntal, Germany Tel: +49 (0) Fax: +49 (0) ds@pressetextschulz.de 6