PT A manufactures high-quality bolts, screws, and keeling nails for widespread use in industry and manufacturing. The production process applied by the company is made to order, where the number of products produced is based on customer demand and specifications from customers. Based on the company's monthly production report, the average percentage of defects for Bolt Welding 6 x 12 is 2.62% where the percentage of defects has exceeded the company's disability tolerance limit of 2%. Solving disability problems can be done using the Six Sigma method with Define, Measure, Analyze, Improve, and Control (DMAIC) stages to improve the quality of production. At the Define stage, SIPOC Diagrams are created and critical to quality (CTQ) determinations are made. At the Measure stage, control map calculation, DPMO calculation, and sigma level are performed. At the Analyze stage, a Pareto Diagram was created to find out the most dominant causes of disability, an Ishikawa diagram to find out the root cause of the most dominant disability problem, and MAFMA method to know the main problem of disability causes prioritized to be fixed based on the greatest weight. At the Improve stage brainstorming is done to increase effectiveness and productivity. At the Control stage, an evaluation of the improvement process has been implemented. DPMO value after the implementation of improvement of 6100 with sigma level of 0.0263 so that it can be known that there is an increase of 0.0263 from sigma level before the implementation of improvement.