Ergonomic risk assessment for manual material handling tasks : a case study in a manufacturing industry in northern peninsular Malaysia / Athirah Binti Yusof

Faculty of Mechanical and Automotive Engineering Technology

Thesis (Master of Science) -- Universiti Malaysia Pahang - 2026

Includes bibliographical references

Manual material handling (MMH) remains a major ergonomic concern in the manufacturing industry, as it commonly involves repetitive exertion, forceful lifting, and non neutral working postures that increase the risk of work-related musculoskeletal disorders (WMSDs). Although manufacturing is recognised as a high risk sector, ergonomic research in Malaysia, particularly studies focusing on MMH tasks, remains limited and often relies on single assessment tools, resulting in a fragmented understanding of ergonomic risk. This study therefore aims to investigate the prevalence of musculoskeletal discomfort among manufacturing workers performing lifting and lowering tasks, evaluate significant ergonomic risk factors, and simulate and validate ergonomic risks using Digital Human Modelling (DHM) to support evidence based intervention planning. The study was conducted in a manufacturing facility located in Penang, Malaysia, involving 19 workers recruited from five Plastic Technology departments. A structured ergonomic assessment framework was applied by integrating the Initial Ergonomic Risk Assessment (ERA), Cornell Musculoskeletal Discomfort Questionnaire (CMDQ), Manual Handling Assessment Charts (MAC), and DHM-based Rapid Upper Limb Assessment (RULA). The Initial ERA identified forceful exertion as the dominant risk factor, with 90.5% of workers exceeding the minimum score requirement for advanced assessment. CMDQ findings showed that the lower back was the most affected body region (49.41%), followed by the left foot (9.32%) and right foot (8.91%). MAC analysis indicated that 42.10% of lifting tasks required action in the near future, while 57.90% required action soon, mainly due to excessive hand distance from the lower back, unfavourable vertical lift zones, trunk twisting, and poor grip conditions. DHM-based RULA analysis further confirmed critical ergonomic risks, with several tasks scoring 7 despite differences in load weight. Simulated ergonomic interventions focusing on posture optimisation successfully reduced RULA scores from 7 to 5, demonstrating meaningful risk reduction without altering load weight or task frequency. Overall, this study contributes an integrated ergonomic assessment framework that bridges observational screening and digital validation, providing practical and methodological value for improving ergonomic risk management and intervention planning in manufacturing industries.