Enhancing Sustainability and Quality Performance in the Rubber Industry Through Six Sigma–Driven Process Optimization

The rubber manufacturing process plays a crucial role in various sectors, including the automotive industry. The rising production of motor vehicles has increased the demand for rubber-based components, such as those produced by PT MC, which manufactures motorcycle tires and tube. In tube production, the defect rate reached average 0.31%, exceeding the company's target of 0.30% due to variations in rubber stick length. The analysis was conducted using the Six Sigma DMAIC and Statistical Quality Control methods, capability analysis, and hypothesis testing. Improvements were made by modifying the Tube Extruder machine and adding a specialized drive motor for the take-away conveyor. The drive motor reduces the pulling that occurs during the rubber stick's cooling process after the extruder process. Verification using the paired sample T-test resulted in a P-value of 0.015, indicating a significant improvement. Rubber stick length variation became more controlled, standard deviation decreased from 11.61 to 2.88, Cp and Cpk values improved (0.57 and 0.55 to 2.31 and 2.27), and defect percentage reduced from 0.31% to 0.17%. The Sigma Level increased from 4.738 to 4.911, enhancing customer confidence and reducing costs due to lower defect rates.