Ergonomic Risk Assessment and Work-Related Musculoskeletal Disorders in Seated and Standing CNC Operators

Abstract

Objective: This study is to assess the ergonomic challenges faced by CNC machine wheelchair-bound and standing posture operators, this study to identify the risk factors contributing to Work-Related Musculoskeletal Disorders (WMSDs). This research specifically determines which operators are more susceptible to WMSDs by evaluating the ergonomic compatibility of CNC machine designs for standing and wheelchair-bound operators.

Methods: Data were collected from 124 CNC machine operators, including 11 wheelchair users, through structured interviews, discomfort questionnaires, and direct observation of tasks. A discomfort mapping technique, based on Corlett & Bishop's method, was used to assess body pain and discomfort at different work intervals. Injury records were reviewed, and capture discomfort ratings from operators. Using quantitative evaluation tools, anthropometric data for standing and wheelchair-bound operators were analyzed to identify the critical ergonomic risk factors. Discomfort ratings were further analyzed using one-way ANOVA to determine the significance of various factors. The identified significant ergonomic risks were assessed using the Rapid Upper Limb Assessment (RULA) tool to evaluate physical workloads and awkward postures.

Results: The study found significant discomfort more in wheelchair-bound operators as compare to standing posture operators. The discomfort in wheelchair-bound operators due to awkward postures, repetitive tasks, and poor machine accessibility, particularly affecting the neck, shoulder, and lower back conversely standing operators reported significant discomfort, particularly in the abdomen, chest, and knees. A comparative analysis and quantitative analysis highlighted that the ergonomic design of CNC machines profiles revealed that only a few designs are ergonomically suitable for both seated and standing operators and often fails to accommodate mostly wheelchair users effectively, resulting in awkward postures and repetitive strain injuries.

Conclusion: The findings highlight the need for ergonomic interventions in CNC machine design to improve accessibility for wheelchair-bound more as compare to standing posture operators and reduce WMSD risks. Inclusive design modifications, such as adjusting machine height and improving monitoring window placement, can significantly enhance operator comfort and efficiency..