Using Quality Control Techniques to Analyze Products Defects in an Aluminium Manufacturing Industry

Abstract

This presents the application of quality control techniques to reduce product defects in an aluminium sheet/rolls production company. The data on defective products from 2016 to 2019 was obtained from the quality control department of the case study company. One hundred and twenty samples were collected in a period of thirty 30 days per year for 4 years (2016 to 2019) for study. Quality control techniques, P- charts, C-charts, and Pareto charts were applied for data analysis. Analysis of variance was also used to investigate the impacts of the defect type on the number of defects identified during the period under investigation. Results from P-chart and C-chart showed that the highest defects (182defects) were experienced in the year 2018, while 2019 had the least number (162 defects) of recorded defectives items. More still, the results of both P-chart and C-chart indicated that in the year 2016 and 2019, two data points each were out of control, while in 2017 and 2018 three points each were out of control. The results from the Pareto analysis showed that 10% of the defects experienced occurred on the fifth day of investigation, which indicated an early part of the year. For the year 2017, 9 % of the defects occurred on the 23rd, which represents the latter part of the year and for 2019, 11 % of the experienced defects happened on the 11th of the sampled days. Pareto results also showed that 25 % of the total defects are to be given attention each year to enhance the greatest improvement. Analysis of variance results showed that sheet thickness has no significant effect on the number of defects experienced per batch produced. Further analysis was conducted through P-chart and C-chart brought in control of the system after the out-of-control points were eliminated. However, results revealed that C-chart was more effective for that purpose compared to P-chart. The company should adapt C-chart and Pareto chart as control techniques.