AA STUDY OF MACHINE PARTS LIFETIME EXTENSION BASED ON RELIABILITY

Abstract

The company in this case study had a tough policy of process continuous improvement. Every employee had to initiate the improvement unless overall equipment effectiveness (OEE) was near 100%. It was found that the OEE of plastic chips producing machine was 89.07%. Availability level of machine was the lowest compare to the other OEE components. The objective of this study was to improve the OEE of plastic chips maker by improving machine availability. During the 5 months, there were variety of losses such as chips cutting blade change time loss, start up loss and quality loss. Specially cutting blade change, there were average losses about 12.13 tons per month. Time to failure (TTF) of chips cutting blade was used to calculated the Weibull distribution shape parameter and scale parameter by using Rank Regression and Correlation method. The study showed that the shape parameter was less than 1.0. This suggested us that the lifetime of chips cutting blades were shorter than usual due to various factors. Both Weibull parameters were used to calculate the mean time between failure (MTBF) of chips cutting blade. MTBF was only 38.79 hours in service. The physical phenomena and mechanism analysis (P-M analysis) was held to find out the complex causes of failure. Various improvement led to the increasing of MTBF of both chips cutting blade and OEE. It was be able to improve the MTBF to 279.41 hours and OEE was increased to 97.82%