Lean Value Stream-based Research And Improvement Of Wheel Company S-wheel Rim Assembly Line

Toyota Production System (TPS) has been recognized as the world’s most successfulmanagement mode in automobile manufacturing industry. And lean production, whichoriginated from TPS, is becoming more and more popular in many countries throughoutthe world. As a continuously developing wheel manufacturer enjoying a good reputation indomestic industry, the Wheel Company S also keeps its pace with the times to seekopportunities for making improvements and adopts the advanced method of LeanProduction to solve problems which restricts its development.From the perspective of lean value stream, this paper is aimed to improve A3-typewheel rim assembly line of Wheel Company S by combing some theories and methods ofindustry, such as lean thinking, lean production management experience, lean value streamtool (Value Stream Mapping, VSM) and industrial engineering. It is expected to work outsolutions to existing problems, including the insufficient rim capacity, mass uncontrolledinventory of working-in-process and finished goods, unbalanced workload in differentworkstations, long delivery lead time and high welding defect rate.Firstly, the whole process beginning from raw material procurement to rim goodsdelivered to customer was selected as the research object. Analysis of the production linebasic investigation and balancing was carried out and the first description of material andinformation flow before making improvement—the current-state value stream map wasdrawn out. In order to seek opportunities for making improvements in the future, rootcauses leading to existing waste were analyzed based on detailed current-state VSM.Secondly, according to results of the current-state VSM and actual conditions of theproduction line, the second feasible and ideal future-state value stream map was createdfrom view of the theories and methods of lean value stream and lean production, whichwas very important and useful to display opportunities for improvement identified in thecurrent-state value stream map, and to achieve a higher level performance of proposedgoals. Thirdly, in accordance with results of the ideal future-state VSM, animprovement project, mainly created in terms of the rim production process and layout,specific processing technology and on-site management, was implemented to achievefuture-state goals. After all of the improvement measures were put into practice, thevariation of value flow was followed up continuously. As a result, the third improved-statevalue stream map was achieved and analysis of evaluation and comparative wasperformed.By implementing lean improvements, the situation of A3-type wheel rim assemblyline in Wheel Company S has greatly improved, summarized as follows: Changing pushproduction mode into pull production mode; Increasing capacity from less than34unitperday to50unit perday; Reducing working-in-process inventory from133unit to64unit;Rising up production line balancing rate from69%to93%; Shortening total cycle timefrom174min to117.2min; Decreasing production lead time from7.6day to2.3day;Increasing cycle efficiency from5.09%to11.42%; Improving the first pass rate of weldingparts from54.06%to93.5%.