INVESTIGATION OF CASTING DEFECTS IN NIGERIAN FOUNDRY INDUSTRY (A Case Study of Lagos and Ogun States)

Abstract

Casting that does not meet the quality standard or agree with the laid down technical specifications is said to contain Cast Defect since it cannot be used directly without necessary corrections. In this work, attempt is made to study the level of cast defects in foundries in Lagos and Ogun States. The study revealed that 35.7% of defects recorded are blow holes; 31% short run, shrinkage 7% and porosity 6% other various types of defects are less than 20%. This high percent of blow holes, which is caused by high moisture content, improper drying and inadequate vent and permeability of the moulding materials, can be attributed to the fact that a large number of our foundries employ sand casting process. Majority of casting without defect are obtained from non-ferrous metals using permanent moulds. Most casting defects are recorded in ferrous metals and alloys (steel and cast iron).