Heat Transfer and Fluid Flow Theory Application in Automotive Casting Redesign 2003-01-0440
The requirements of automotive die casting are high in terms of quality, integrity, volume, and tight delivery. Historically OEM customers normally do not consider the casting process and manufacturing capability. Therefore this inexperience creates high scrap rates with poor design for manufacturability features.
A high quality design must apply scientific and technological knowledge; such as fluid flow, heat transfer and metallurgy. It must also involve the casting process experience and computer tools. In other words, casting design not only requires casting geometry and mechanical function, but also castability.
Heat transfer and fluid flow theory have been successfully used in the automotive casting design. Combining 3-D fluid mechanics equations with heat conduction and convention equations, good casting design criteria are developed. Some of the criteria are free surface tracking, flow separation and re-circulation detection, poor fill detection, isothermal solidification contour, metal freezing range impact, thermal gradient pattern, cooling rate pattern, hot cracking elimination, and alloy shrinkage porosity detection. These criteria are able to guide the casting design.
This paper presents some positive and negative experiences in automotive casting system design. It applies real castings with the gating design techniques associated with North American die casting design rules and process modeling tools. Casting examples used are aluminum transmission housing and magnesium bracket.