Analysis of Production Quality Control in Minimizing Product Defects with the Six Sigma Method (Case Study at PT. Jaykay Files Indonesia)

- PT. JayKay Files Indonesia is a company engaged in the industry that produces files and drills. Where the products have been exported to various countries and the quality is well received by various overseas customers. PT. JayKay Files Indonesia is certified with ISO 9001:2008, OHSAS 18001:2007 and ISO 14001-2004 environmental management system. However, to maintain this quality, the company must control the existing defective products. Then the research was carried out using the Six Sigma DMAIC (Define Measure Analyze Improv Control) stage. And produced 4 (four) types of defects in the Define stage, with the calculation of the sigma value of 3.8 with 3.8% damage at the measure stage, then Analyze which occurs because there are several causes using a fishbone diagram, namely machine, human, method and environmental factors. At the improve stage, there are several recommendations for improvement so that for control, supervision is carried out at the dept. Quality control.


II. RESEARCH METHODS
The implementation time of this practical work is from January to February 2020. The place where this research was carried out was at PT. JayKay Files Indonesia Semarang. The method used in the quality data processing process uses the Six Sigma method using the Six Sigma method (define, measure, analyze, and improve). is the theoretical basis in accordance with this research. The type of data used in this study is quantitative data which is data that can be calculated, namely data in the form of numbers and supporting information in the form of production cost data of PT JayKay Files Indonesia, which is primary data, namely data obtained from companies and interviews. directly with company employees who are considered related to this research.  From the results of the calculation table above, Based on the table above, it is known that the highest probability of defects is on the 17th day of observation, which is 0.4328 and the lowest probability of defects is on the 22nd day, which is 0.0689. For the control limit, the result is 0.1915, the upper control limit is 0.1994 and the lower control limit is 0.1836. Next, a P Control Map is made which can be seen in the P control chart image on the next page. Based on the picture of the control chart p above, it can be seen that the data obtained are not entirely within the control limits that have been set, even many are out of the control limits, only 1 (one) point is within the control limits, so it can be said that the process is not under control. In the picture above, it can be seen that the 27 samples taken fall into the control limits. The highest value is on the 17th day and the lowest is on the 22nd day. This indicates that there is a high deviation. It states that quality control at PT. JayKay Files Indonesia needs improvement. Because there are very high and irregular fluctuating points which indicate that the production process is still experiencing deviations.
The next calculation is the measurement of sigma performance with the aim of knowing the current level of work (performance baseline). The DPMO value is converted to a sigma value using Microsoft excel with the calculation formula: DPMO Value Conversion = NORMSINV((1,000,000-DPMO)/1,000,000)+1,5 The following is a table of the results of the calculation of DPO, DPMO and Sigma Value: In the table above, it can be seen that the production of Slim Taper at PT. JayKay Files Indonesia has an average production rate of 25617 pcs per day with an average defect or damage rate of 4905 Slim Tapers per day or a probability of 0.1960. The DPMO value is 12252, which means that the probability of damage per 1 million units is 12252. For the sigma value, the result is 3.8, which means that in each production process there will be no defects or damage of more than 3.8%. Based on these results it can be seen that PT. JayKay Files Indonesia needs to improve the production process so that the level of defects or damage can be minimized. The following is a table of the level of achievement of the sigma value.

Analyze
This stage is carried out by analyzing Pareto diagrams based on data that has been processed to determine the percentage of types of defective products and the order of types of damage that occur from the lowest to the highest in the Slim Taper production process at PT. JayKay Files Indonesia. The following is a table for calculating the percentage of types of defects: Source: Results of proving data for January From the Pareto diagram above, it can be seen that the type of defect L (Crack) is the type of defect with the highest percentage of 21.15%, the second is k (Soft) with a percentage of 13.59% and the third is E (Edging Damage) with a percentage of 12, 91% and so on as in the table above. After knowing the type of defect, the next step is to identify the cause of the type of defect using a fishbone.
There are four main causes of several types of defects that can occur due to machine, human, method and environmental factors. The following is an explanation of each of the factors that cause defects:

Machine
Machine factors that affect defective products are matters relating to the use of equipment or machines and their reusability such as the age of the machine which is no longer economical and the lack of maintenance for machine maintenance.

Man
Human factors are related to labor or personnel aspects such as lack of skills, lack of experience, and physical fatigue.

Method
Factors regarding work methods and procedures that can result in defective products include SOP errors and lack of training.

Environment
Work environment factors also affect the quality of the product. A good environment will make workers more comfortable and minimize defective products. Environmental factors that affect, among others, noise, and vibration.

Improve
At the improve stage, recommendations for improvement of each cause of defects that have been made through fishbone diagrams are given. The following are recommendations for improvements that can be made by PT. JayKay Files Indonesia in an effort to improve the quality of Slim Taper products:

Control
The last stage is controlling the improvement recommendations that have been given. Supervision needs to be carried out to see if there are differences in the quality of Slim Taper before and after the implementation of several recommendations. PT. JayKay Files Indonesia, especially the Quality Control Department, tries to implement some of the recommendations given so that the increase in sigma value can be achieved so that the quality of Slim Taper products at PT. JayKay Files Indonesia has increased and the percentage of defective products can be reduced.

IV. CONCLUSIONS AND SUGGESTIONS Conclusion
1. The results of the calculation of the quality control of Slim Taper products at PT. JayKay Files Indonesia with the Six Sigma method: a. Based on the processed data, the results of the DPMO calculation are 12252, which means that there is a probability of a defective product of 12252 out of one million possibilities and a sigma value of 3.8 is obtained which means that in each production process there will be no defects or damage of more than 3 ,8%. b. The types of damage or defects that often occur in the production of Slim Taper PT. JayKay Files Indonesia is caused by Crack as much as 21.15%, the second is Soft with a percentage of 13.59% and the third is Edging Damage with a percentage of 12.91%. 2. The application of the six sigma method in calculating the quality control of Slim Taper products produces complete, precise and accurate data according to the data needs of the Quality Control department.

Suggestions
1. Companies need to use the six sigma method to be able to find out the types of damage that often occur and the factors that cause it. Thus the company can immediately take preventive action to reduce the occurrence of product defects. 2. Based on the analysis using the six sigma method that has been carried out, the company can make quality improvements by focusing on repairs to types of damage that have a large or dominant number in production, which are caused by factors such as; people, machines, methods, and the environment.