Production improvement for reducing the number of dented cans in a pet food manufacturing plant: a case study

Abstract

This research aimed to improve the production process of a can unloading machine during the can conveying stage in order to reduce defective products, particularly dented cans, in a case study of a pet food manufacturing plant. The problem was initially investigated using a check sheet to collect preliminary data over a two-week period in June 2025. The study focused on the can conveying process, which involved a total of nine can unloading machines. The data on the occurrence of dented cans from all machines were then prioritized using a Pareto chart. The results indicated that Unloader No. 3 had the highest frequency of dented cans, accounting for 499 defective cans out of a total of 1,471 dented cans, or 29%. Therefore, the researchers conducted a root cause analysis based on the 4M framework (Man, Machine, Material, and Method) using a fishbone diagram. The PDCA (Plan-Do-Check-Act) cycle was then applied to identify and implement improvement measures to reduce the occurrence of dented cans on Unloader No. 3. The results showed that the number of dented cans produced by Unloader No. 3 decreased from an average of 2,158 cans per month to 1,270 cans per month. This represented an average reduction of 41.14% in dented cans per month. In addition, the average reduction in damage costs was 8,880 Thai baht per machine per month, equivalent to approximately 106,656 Thai baht per machine per year. The improvement effectively reduced both the number of defective products and the associated average monthly damage costs of Unloader No. 3, which was selected as the improvement case. The proposed improvement approach can also be applied to other can unloading machines or production equipment to further enhance production efficiency.