Influence of key process parameters on the quality of semi-solid metal cast aluminum components

Semi-solid metal casting is now being used on three continents for the commercial production of aluminum alloy components for the automotive, industrial and recreational goods industries. This paper attempts to set out some process guidelines derived from practical experiences. By using a real-time controlled casting machine, it was possible to study die filling sequences under real processing conditions. There are a number of design and process parameters that must be controlled to produce quality semi-solid metal castings. This study examined the impact of two parameters, gate velocity and slug temperature, on the manner in which semi-solid aluminum alloy A356 filled a plate-shaped die cavity. The results indicated the gate velocity must be maintained at or below 5 meters per second, and the slug temperature above 575 degrees C in order to fill the die with a planar, stable semi-solid meniscus required to avoid air entrapment and so obtain high quality castings.