IMPLEMENTATION OF SIX SIGMA APPROACH IN QUALITY CONTROL OF METAL CASTING PRODUCTS MADE FROM GRAY CAST IRON TYPE FC 250: A CASE STUDY IN SMALL AND MEDIUM ENTERPRISES IN INDONESIA

The ?X? company is one of the modern small and medium industries engaged in metal casting in Indonesia. One of the main ingredients used is gray cast iron (ferro carbon) or FC 250. At this time the level of product defects is still at the level of 10.8%. This value is relatively still high enough from the company's decision that is no more than 10% of product defects. This study aims to control product quality through the implementation of the Six Sigma steps. From the results of the study, five types of critical to quality defects have been identified, including: Porous, Displaced Core, Misrun defects, Cleft defects and Cracks. The measurement results have also obtained a level of product disability of one million opportunities (DPMO) on an average of 106,667. This value is equivalent to the Sigma level of 2.76 which indicates that the level of company quality control is still below the average national quality standard. Some recommendations are proposed, among others, through the proper application of standard operating procedures, selection and control of raw materials, improvement of the work environment and improvement of employee performance.