Six Sigma’s problem-solving methodology DMAIC has been one of several techniques used to improve quality. The work follows the DMAIC methodology to investigate defects, root causes and provide a solution to reduce/eliminate these defects. The analysis from employing Six Sigma and DMAIC indicated that the metal melting temperature, die temperature and die holding time influenced the number of defective items produced. In particular, the design of experiments (DOE) and two-way analysis of variance (ANOVA) techniques were combined to statistically determine the correlation of the metal melting temperature, die temperature and die holding time with defects as well as to define their optimum values needed to reduce/eliminate the defects. As a result, a reduction of 16.93 % to 10.04 % in the terminal cover and 16.62 % to 8.97 % in the din based cover was achieved, which helped the organisation studied to reduce its defects per million opportunities (DPMO) and thus improve its Sigma level from 2.53 to 2.79 for the terminal cover and 2.55 to 2.85 for the din based cover.