Moulding characteristics of sand mixture with partial vacuum suction techniques

The compaction of moulding sand mixture is critical for dimensional accuracy and surface finish of castings. This paper reports the moulding characteristics of resin bonded sand mixture under negative pressure formed by partial vacuum suction process. The main factors such as the volume and the predetermined vacuum pressure of the vacuum tank, the opening rate of venting holes on the pattern plate and on the suction plate, the size of the mould, the suction time and the mould density distribution along the vertical direction in the sand flask were examined. The optimised range of technical parameters and potential improving methods were also suggested. Based on the analysis of experimental results, a new concept, compacting impulse, was suggested to evaluate the compaction of moulding sand mixture.