P T. Bukaka Teknik Utama is one of the companies that engages in infrastructure and heavy equipment. Machining Gear Shop division of PT. Bukaka Teknik Utama is one of the divisions in the company which produces part-part from pumping unit products. The quality is the most considered thing by the company in production activity, therefore if there is a problem then the company must suddenly find out the source of the problem and solve it with the proper methods. In the beginning research that had been done, there is a problem in the perforation process of part housing wrist pin_ The obstacle that is still faced is laid on the perforation process of part housing wrist pin by using CNC Milling machine. The core of the problem is there is often found the range result between each hole which does not match with the desired beginning specification. From the direct research result in the field, the obstacle in the Milling process is caused by the factor of machine setting that is not optimal yet on the CNC Milling machine. This CNC Milling machine is also the machine the company has bought and operated so the operator has not had the experience and good machine setting on the characteristic of this CNC Milling machine. This research only focuses on the perforation process or part housing wrist pin Milling process. The objective of this research is to get optimum setting of the machine so that it produces the products whith are comkatible with specification, because based on the interview with the operator that the factor from the machine setting influences on the result of cutting. This research use statistical process controlling method and experiment planning which involve controlling process by using SPC and factorial planning of order I for factor filtering and machines optimization. In the beginning research, it is found out that the score of capability process still needs revision because there are still many unmatched perforation results. After conducting data analysis and processing, there are two factors that have the most influence from the three available factors, which are Machine Pre-heating Time (A) factor and Cutting Feed (C) factor. After conducting research, there is a finding that machine optimum setting of factor Machine Pre-heating Time (A) = 13 min, factor Spindle Speed (B) = 500 Rpm, and factor Cutting Feed (C) = 11.2 mm/min. Then it is conducted implementation on machine setting as a comparison with the machine setting before doing the experiment. It is found out that there is an improvement from the score of capability process. For the vertical range variable, it is obtained the score of Cp is 1.08 and for horizontal range variable the Cp score is 1.08.