Design for Six Sigma to optimise the process parameters of a foundry

Six Sigma is an organised and systematic method for strategic process improvement that relies on statistical and scientific methods to reduce the defect rates and achieve significant quality upgradation. A case study is carried out for a foundry, where Six Sigma tools are applied for the defect reduction. It analyses various significant process parameters of the casting process of a foundry, located in north India. In the first stage, a set of process parameters that contribute various casting defects are identified. An orthogonal array, the signal‐to‐noise ratio and analysis of variance criterion are used to analyse the effect of selected process parameters and their levels on the casting defects of the cast iron (grade‐25) differential housing cover castings. In the second stage, the optimised parameters are considered to perform the practical run for the differential housing cover castings. Proposed techniques optimised control factors, resulting in superior quality and stability.