Sand Sintering Problem on Bronze Castings
A research has been carried out on surface defects of castings. The problem of sand sintering on castings of ferrous and non ferrous metals is a well known surface defect, which may lead to poor quality product and a huge economic loss for finishing and cleaning. The problem occurs on a 32 kg closed type tin bronze impellers used for water works. The objective of this paper is to analyze the causes of the surface defect and develop the methods of sand sintering protection on the tin bronze impeller body and internal surfaces. The research method used includes green sand molding, data analysis, physical observation, photographic analysis, grinding and fish bone diagram. The causes, effects and remedial actions required to improve the quality of casting with regard to impeller is presented in this paper. By using the remedial methods applied to prediction time of the impeller reduced to about 35minutes to 1 hr and the total cost for finishing total impellers exposed to sand sintering reduced to 15-20 USD.
Key words: Sand casting, Sand sintering, Impeller, Burn on, Bentonite