การลดของเสียในกระบวนการขึ้นรูปโลหะแผ่นสำหรับโครงหลังคาเหล็กรถกระบะ / ชมพูนุท เติมสายทอง = Defective reduction in metal sheet forming process for pick up metal roof / Chompunoot Termsaithong
The objective of this thesis is to reduce defective rate and total defective cost due to wrinkling and out of standarddefects, which have 71.80 % and 77.11 % defective rate respectively. This thesis applies the Six Sigma approach with the aim to reduce 50 % of defective rate. This thesis applied Six Sigma approach, which consisted of 5 phases. In the define phase, the problem, objective and scope were defined. Next, in the measure phase, attribute agreement analysis was evaluated for accuracy, precision and effectiveness of the measurement system. Then, process capability analysis was performed and possible causes of wrinkling and out of standard were brainstormed and analyzedin the cause and effect diagram, cause and effect matrix and failure mode and effects analysis (FMEA). In the analysis phase, the design of experiment was applied to test significant attribute factors affecting the defective. Next, in the improvement phase,variable factors were improved to yield the smallest proportion of defective. Finally, in control phase,confirmatory experiment was performed for 2 weeks. Moreover, the new control plan and work instruction were developed in order to control the process after improvement. The improvement result was the defective rate of wrinkling and out of standard was decreased from 71.80 % and 77.11 % to 20 % and 11 % respectively.This reduction led to the net saving of 462,135 baht from 12,798produced pieces or equivalent to 554,662 baht per year.
