[Ergonomic evaluation and effectiveness analysis of improvement measures in the assembly position of an automotive parts production company].

Objective: To evaluate the improvement effect of ergonomics in the assembly position of an automotive parts production company. Methods: From February to December 2023, the assembly positions and 8 operators of an automobile brake parts production company were selected as the research objects. The Swedish Ergonomic Hazard Identification Method and rapid upper limb assessment (RULA) were used to identify and evaluate the adverse ergonomic factors of work-related musculoskeletal disorders (WMSDs) in different parts of the body before and after the improvement. Through field investigation, observation and personnel interviews, three ergonomic problems were identified that need to be solved, namely, the height of the assembly table did not match the height of the operator, the storage space for small accessories was not set reasonably, and empty boxes were difficult to be placed. Technical improvements were made by designing an adjustable height assembly table, improving the layout of the workbench, and designing a mechanical pedal automation device. Statistical analysis was performed by t-test and paired rank sum test to evaluate the effectiveness of ergonomic improvements. Results: The operation of the assembly position could be divided into 13 actions, and the time to complete 1 cycle was (83.0±2.7) s. The Swedish Ergonomic Hazard Identification Method identified 28 adverse ergonomic factors of WMSDs in different parts before improvement, and 15 adverse ergonomic factors after improvement. Before ergonomics improvement, the RULA scores were 5 to 7 points, and the risk levels of 6 workers were Ⅳ (very high risk) and 2 workers were Ⅲ (moderate risk). After ergonomics improvement, the RULA score was 4 points, and the risk level was reduced to Ⅱ (low risk). Paired rank sum test results showed that there were statistically significant differences in upper arm, A-part (upper arm, lower arm and wrist) exertion and load, A-part muscle use, neck, total score, and risk level before and after improvement (P<0.05). Per capita productivity of assembly post was (40.1±1.4) pieces/ (person·hour) before the improvement and (44.0±1.7) pieces/ (person·hour) after the improvement, the difference was statistically significant (t=50.35, P<0.001) . Conclusion: The ergonomic improvement measures can reduce the adverse ergonomic factors in the assembly position of an automotive parts production company, reduce the risk of WMSDs, and improve the production efficiency.