A Study on Reducing Casting Defects Leading to Water Leakage of Sand Casted Water Pump

Casting is one of the useful processes in producing products from utensils to machinery components. However, major disadvantage of this process is accompanying of casting defects, which bring great loss to the industry. Casting defects occur due to various parameters which are hard to control under the industrial environment. Many researchers have conducted investigations to find the best combination of process parameters which causes minimum casting defects. Some of them have successfully reduced the casting defects below 5% by varying the moulding sand properties. Local pump manufacturers are currently suffering from drawbacks in production of grey cast iron water pump casings due to high rate of sand casting defects that is around 10% which leads to water leakage. This research focuses on analysis of these casting defects quantitatively and qualitatively, and their causes and suggesting effective solutions. It was found that shrinkage and blowholes are two critical defects leading to water leakage of water pump casing. Generally, it is well known that moulding sand properties, metal pouring temperature, design of gating system and chemical composition of the raw material are vital factors that lead to the formation of casting defects. The influence of these major factors on formation of shrinkage and blowholes was studied. The experimental results showed that improper design of gating system and deviation of the moulding sand properties relative to the moulding sand prepared for castings dominantly affect the shrinkage and blowhole defects.