After heat treatment, cast aluminum can be used as recycled material. Before loading the furnace, the aluminum parts should be cleaned up to eliminate surface oil stains and dirt. Aluminum parts should be classified according to trademark, overall size, wall thickness of castings and heat treatment process standards. Aluminum parts should be heated slowly. If there are messy castings, they should be put into a low temperature furnace and heated to quenching temperature for about 2 hours. After reaching the specified temperature, heat preservation should be carried out.