OPTIMIZING LOW PRESSURE DIE CASTING PARAMETERS USING SIX SIGMA TO MINIMIZE POROSITY IN THE FACE MILLING AREA OF TYPE A CYLINDER HEADS AT PT XYZ

Abstract

Cylinder head manufacturing is a critical process in the automotive industry where product reliability and production efficiency are highly dependent on casting quality. One of the most persistent quality issues in this process is the occurrence of porosity defects, which compromise structural integrity and engine performance. To address this problem, the present study applied the six-sigma methodology to systematically reduce porosity defect levels. The research employed a Design of Experiments (DoE) approach through a full factorial design, testing three process parameters, aluminium temperature, pressure, and press-up time each at three levels (low, medium, high). The analysis followed the DMAIC (Define, Measure, Analyze, Improve, Control) framework, the study identified root causes, prioritized improvements, and optimized machine settings. The experimental results revealed that the optimal parameter combination aluminium temperature of 700 °C, pressure of 18,000 Pa, and press-up time of 8 seconds. The research results show that by using these parameters the resulting porosity defect is 0,64% and the six-sigma level value is 2,49. These findings demonstrate that structured process optimization using six-sigma can significantly enhance casting quality and reduce porosity defects in cylinder head production.