การลดข้อบกพร่องของผลิตภัณฑ์และการปรับปรุงประสิทธิผลโดยรวมของเครื่องจักรในกระบวนการผลิตขวดพลาสติก

Abstract

The prime objective of this independent research is to study the Product defect reduction and improvement of overall equipment effectiveness in plastic bottle manufacturing process. By focusing on the production of 600 cc round PET plastic bottles, starting from a detailed study of product information on the production process. There are 2 types of machines used in the production process which are in follows: Automatic bottle blowing machine which has an overall equipment effectiveness (OEE) of 55.82%, Labeling machine which has an overall equipment effectiveness (OEE) of 42.34%. The low overall machinery efficiency of both concerned machines are caused by too long period of time in order to set up the machine, small stoppage due to lot change, malfunction issues during production and improper work order management from the occurrence of various wastages that cause the overall equipment effectiveness (OEE) to be low incurred expenses from wasted time which caused the loss of expenses in the field of electricity cost for 4,143.6 baht and labor cost for 8,466 baht within 3 months (December 2020 -February 2021). Yet the production of defective workpieces, both clamp neck and loose labels (January 2020 -February 2021) accountable to 23,169.4 baht, thus improving by rehabilitating machinery has been taking placed such as the preventive maintenance, maintenance plan revision and improvement and self-maintenance method. By using quality tools of inspection sheet and fish bone diagrams in order to help in troubleshooting. As a result of the troubleshooting, it turning out that the automatic bottle blowing machine’s overall equipment effectiveness (OEE) had increased from 55.82% to be 88.16% and labeling machine’s overall equipment effectiveness (OEE) had increased from 42.34%. to be 65.06% For detailed information on defects that occur in the blow molding process with the automatic bottle blowing machine, it was found that there were 1.37% of the defective parts of in type of NG shape (January 2020 - February 2021) and the quantity was more than the company standard which is 0.5%, resulting in the loss of expenses from defective parts around 23,169.4 baht. Therefore, to find the cause of the problem from quality tools such as Fish bone diagram and find a solution by using 2k factorial experimental design technique and Response surface technic by Box-Behnken Design method in order to determine the optimum conditions for the adjustment of parameters used in the blow molding process. The troubleshooting by adjusting the machine condition according to the best specifications of each factor analyzed as a result, the quantity of shaping defects has been solved than the target set by the factory of 0.5%. During the same period in July, from 1.49% reduced to 0.24%. In August, from 3.51% reduced to 0.29% and in September from 2.80% reduced to 0.28%. In addition, the incurred hidden costs were reduced in the 3 months following the improvement (July 2021 -September 2021) as a result of various improvements, including costs incurred from the Automatic bottle blowing machine’s electricity bill from the original minimum total cost of 3,348.30 baht, had reduced to not less than 1,607.76 baht, labor cost had reduced from 5,487 baht, reduced to 1,473.60 baht. Defective workpieces that occurred from 23,169.40 baht, reduced to 684.50 baht. The cost incurred from the Labeling machine’s electricity bill from the original minimum total cost of 795.30 baht, had reduced to not less than 75.75 baht, labor cost from 5,958.00 baht, reduced to 552.00 baht, defective workpieces that occurred from 5.10 baht, reduced to 0.90 baht which is in accordance to the objectives set by the researcher.