Psychophysical factors in wood routing tasks

Musculoskeletal disorders (MSD) and disorders causing neurological and vascular epidemiology are most common with hand tools particularly with power tools. These work related MSD due to power hand tools are developed mainly due to awkward upper limb posture under extreme loads or vibration stresses. In previous researches, tool handle design have been identified to affect the ergonomics of the tool usage. In the present study, physiological and psychophysical factors for existing router tool were evaluated. Five subjects (age: μ = 24.4 years, σ = 0.89 years) volunteered for the data collection of the subjective discomfort score, EMG activities of fourteen muscles and vibration levels at the palm during wood routing task. Results showed that Left wrist and palm were rated for highest discomfort. ECRB and Biceps Brachii were found to be actively involved muscles in this task. Vibrations levels at the palm were found to be 2.51 m/s². Results urged the redesign of the tool handles in terms of relieving the wrist and palm discomfort and also using means for vibration isolation.