Analysis of the Causes of Defect and Proposed Improvements with Fault Tree Analysis Method in the Drawing Process at PT. XYZ

Abstract

PT. XYZ is a manufacturing company that produces various types of metal-based products with a make to
order system. One of them is the Back Top Plate 450/456 (BTP 450/456) part which is a component of
refrigerators. In the period of February-November 2020, PT. XYZ produces 15,395 units of BTP 450/456.
However, BTP 450/456 products have the highest percentage of defective products. The average percentage
of defective products is 3.06%, while the tolerance for the number of defects determined by the company is
1%. This indicates a problem in the production process. The most types of defects in the production process
of 450/456 are broken with a percentage of 41.88%. Based on Critical to Quality, the process stages that do
not meet the requirements in the drawing process can cause various types of defects, such as wrinkles, breaks,
miss-sizing, process failures, scratch and dents. The Fault Tree Analysis method is used to identify the root
cause of the type of broken defect. The root of these problems includes the absence of a guide for setting
dies, the machine being operated for a long time, operator negligence, and the incorrect position of the
plastic. The proposed improvement given are determining the optimal engine pressure, designing dies setting
guides for operators, evaluating and improving the maintenance process, analyzing new machine
requirements, supervisors giving good directions to operators, periodic work evaluations to assess operator
performance, designing visual displays as reminders for operators, and designing aids for positioning plastics
on materials.