Application of Well-balanced Work Scheduling for Prevention of Work-related Musculoskeletal Disorders in an Automotive Parts Assembly Line

Well-balanced work scheduling was developed and applied for preventing work-related musculoskeletal disorders (WMSDs) in an automotive parts assembly line. In general, workers are shifted 4 or 5 times a day regularly, but there is no reasonable way to determine work order considering workers’ physical stress. To provide work order reasonably, it should be avoided to concentrate physical stress on a specific body part continuously. Therefore, a coefficient of cumulative workload of a station (CCWS) was elicited by sum of multiplying frequency of physical stress on specific body parts and relative weighted value of each body parts. For this study, customized checklists were proposed by using items from various international safety and health-related organizations according to job demand and workplace conditions. Analytic hierarchy process (AHP) was also applied to carry out to get relative weighted values of each body parts using pairwise comparison depending on tasks. Consequently, combination of work order was determined by summing each CCWS of various work stations based on severity of physical stress during a single day; and rotation cycle (i.e., days) was determined by numbers of worker. For verifying this methodology, a case study was carried out through the example of an automotive parts assembly line with 10 different kinds of assembly work stations connected by a conveyor system and participating 12 female workers. AHP was carried out by 9 experts to get relative weighted values. In this case study, a software tool of well-balanced work scheduling was developed using JAVA 2.7 for convenience and time-saving. By using this tool, the task manager(s) of the manufacturer will be able to generate work schedules very easily and quickly as well as reasonably, just by inputting the frequency of physical stress on a specific body part and relative weighted values derived by expert evaluation for each body parts. The result of this study may help workers have higher satisfaction in shifting work because they were provided well-balanced work scheduling based on their severity of physical stress, which leads to prevent WMSDs. Higher productivity is also expected because of improved workers’ satisfaction and safety.