Main Article Content
Independent Study aimed to investigate the wastes that occur in the process of cart welding to determine the causes of wastes in the process of cart welding, and to study the reduction of wastes in the process of cart welding with Lean Thinking: A Case Study of D-Pattanamongkol Co., Ltd. in Rayong. The study began with the study of the process flow, the writing of process layout and Value Stream Mapping of the current state of the cart welding process to study the current state of the process. After that, the in-depth interview and video recording were conducted to employees located in the cart welding section to determine the causes of the wastes that occur in the process by the seven wastes. Then, Lean Thinking was applied to study the waste reduction in the cart welding process. Results from the study showed that there are wastes in the cart welding process (1) The over process lost from welded steel cut each time and welding accessory part can be reduced by reducing the size of the cut steel and welding accessory part. (2) The transportation lost due to the individual machines are not suitable for the flow which causes a waste of time in transit can be reduced by arranging the manufacturing layout in welding section properly for work. (3) The over process lost from the improper sequence can be reduced by a control plan for the cart welding. The results from the waste reduction in the cart welding process showed that the flow of work was improved which decreases lead time 67.34 percent and increases the number of finished welding cart per day at 28.75 percent. The performance in the cart welding process was improved at 28.89 percent and working distance was reduced 57.73 percent. This resulted in a system to produce efficiently and competitive in the market continuously because cost was decrease due to reduce and control the wastes that occur in the manufacturing process.