IMPROVING PROCESS OF CUTTING PLY IN MACHINE TTO USING STATISTICAL PROCESS CONTROL (SPC) AT PT WOW

Abstract

Consider of having both Cp and Cpk index greater than 1 will give beneficial effect to many kinds of quality aspect. PT WOW as one of tire manufacture currently deals with problem regarding to process capability in machine TTO. Since cutting ply is one of the major process in making tire, having unstable process of cutting will affect to defect occurrence, tire performance reduction, and also cost. Using Statistical Process Control (SPC), cutting process in machine TTO is monitored to maintain its precision. Quality tools such as Cause-and-effect diagram, Cause-and-effect matrix, and 5 whys analysis are used to identify the proper improvements. One of the improvement includes with One-way ANOVA method. The purpose of implementing this method is to determine proper setting that produce the best result as well as to analyze the interaction between several levels of width setting and the average width of ply. After all improvements have been conducted, a continue process control is conducted to maintain the capability of process and also to become the initiator for continuous improvement. As for the result, Cpk index is increased by 81.21% and the variation of cutting is decreased by 21.65% for standard deviation and 28.57% for maximum range.