Quality Control
Duy Duong-Tran; Romina Dastoorian; Lee Wells
Abstract
Exponential Weighted Moving Average (EWMA) control charts have been widely used in Statistical Process Control (SPC) to detect small and persistent process shifts. In theory, EWMA control limits monotonically increase over time to account for the continual growth of the EWMA statistic’s variance. ...
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Exponential Weighted Moving Average (EWMA) control charts have been widely used in Statistical Process Control (SPC) to detect small and persistent process shifts. In theory, EWMA control limits monotonically increase over time to account for the continual growth of the EWMA statistic’s variance. However, these control limits are often assumed constant and are set to their respective asymptotic limits to simplify the process of applying and analyzing EWMA control charts. One-sided EWMA charts are often implemented when it is only desirable to detect shifts in a specific direction. When using one-sided EWMA charts, reflecting boundaries (resets) can be used to prevent the statistic from drifting too far from the chart’s control limit, which can delay shift detection. There have been several research efforts into designing and studying the performance of one-sided EWMA charts with reflecting boundaries. However, these efforts have maintained the constant control limit assumption. When implementing a reflecting boundary, the EWMA statistic’s variance is constantly being reset to zero, which may significantly affect the constant control limit assumption’s validity. The focus of this paper is to understand behavior of the one-sided EWMA control charts with constant and time-varying limit assumption through simulation studies.
Quality Control
Hernadewita Hernadewita; Diky Herdiawan; Afriyuddin Afriyuddin; Hermiyetti Hermiyetti
Abstract
As one manufacturing industry which has engaged in the textile industry and produced zippers, the painting process at zipped production has a number of problems, as on zipper sticks to each other, uneven paint, etc. In this discussion, the improvements that will be made are related to the painting process. ...
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As one manufacturing industry which has engaged in the textile industry and produced zippers, the painting process at zipped production has a number of problems, as on zipper sticks to each other, uneven paint, etc. In this discussion, the improvements that will be made are related to the painting process. Quality Control Circle (QCC) method is applied to reflect the support of the continuous improvement program in the company. The painting process is the finishing process of a zipper that serves as a coating to be resistant to corrosion and enhance the zipper appearance. The results of the study, it is found the main problem in the zipper painting process, which are Abbeku or sticking. This is due to the factors, such as machinery, methods, and materials. Of the three factors, there is one of the biggest problem factors, namely the position of non-standard spray gun. The focus of the improvement that will be made is the modification of the spraygun holder so that the fix position does not change. The results after an improvement in the modification of the spray gun holder are Abbeku (sticking) loss on the painting production which is originally 23 lots. As a conclusion, it eliminates the biggest loss factor in the painting process, replaced the position of the spraygun that is not fixed.
Quality Control
Hernadewita Hernadewita; Mahefud Ismail; Mohamad Nurdin; Lien Kusumah
Abstract
Quality control is an important thing that must be done by the company to minimize defective products. The company can analyze product defects by using the Six Sigma method, by formulating Define, Measure, Analyze, Improve, and Control (DMAIC) that occurs. PT. XYZ as a large company that prints magazines ...
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Quality control is an important thing that must be done by the company to minimize defective products. The company can analyze product defects by using the Six Sigma method, by formulating Define, Measure, Analyze, Improve, and Control (DMAIC) that occurs. PT. XYZ as a large company that prints magazines often faces the problem of quality defects in its printouts, resulting in the cost losses due to production defects every year is not small, as a result of not being sold. The Six Sigma method is an approach method to help control the quality of production. This study conducts to determine the level of sigma from the current production process, the types of defects that are a priority to be addressed, and the causes of disability. From the results of the study, the sigma value of current production is 3.6 or DPMO of 15919.63613. The type of defect that occurs is blurred by 59%, does not register at 29% and paper cut by 12%. To achieve Six Sigma it is necessary to take corrective steps using the results of the analysis.