An investment casting process to produce 3-dimensional functional surfaces down to a structural size of 1 μm on near-net-shape-casting parts will be developed. The common way to realise functional microstructures on metallic surfaces is to use laser ablation, electro discharge machining or micro milling. The handicap of these processes is their limited productivity. The approach of this project to raise the efficiency is to use the investment casting process to replicate microstructured surfaces by moulding from a laser-microstructured grand master pattern. The main research objective deals with the investigation of the single process steps of the investment casting process with regard to the moulding accuracy. Actual results concerning making of the wax pattern, suitability of ceramic mould and core materials for casting of an AISi7Mg0.3 alloy as well as the knock-out behaviour of the shells will be presented. Using the example of an intake manifold of a gasoline race car engine, a technical shark skin surface will be realised to reduce the drag of the intake air. The intake manifold consists of an air-restrictor with a defined inner diameter which will be microstructured with technical shark skin riblets. For this reason the inner diameter cannot be drilled after casting and demands a very high accuracy of the casting part. A technology for the fabrication and demoulding of accurate microstructured castings will be shown. Shrinkage factors of different moulding steps of the macroscopic casting part as well as the microscopic riblet structure will be examined.%介绍一种生产尺寸达到1μm的三维功能表面的近净形铸件的精密铸造技术.通常,在金属表面形成功能微观结构的方法是激光烧蚀、电火花加工或者微铣削,但这些方法的生产效率低.采用精密铸造工艺来提高效率的方法,从具有激光微观结构的母模复制微观表面,主要研究精密铸造每一个步骤的造型精度.文中对AlSi7Mg0.3合金给出了蜡模制作,陶瓷型和型芯材料的适应性以及型壳的落砂性的实际结果.以赛车汽油发动机进气歧管为例,形成的鲨鱼皮形内表面可以减少进气阻力.进气歧管由具有规定内径的空气节流器组成,节流器内表面具有鲨鱼皮式沟槽结构,为此,内孔铸造后不能再进行钻加工,要求铸件精度非常高.介绍了具有精确微观结构铸件的制造和脱模技术,还考察了宏观铸件不同制型阶段的收缩特性以及微观沟槽结构.
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