Project details

Use of hand-held vibrating tools like drill machines, polishing machines etc. are very common in unorganised sectors (e.g. construction, agriculture, stone/ metal polishing etc.) where users/ operators recurrently encounter occupational vibration. Vibrational energy is transmitted from the vibrating hand-tool to human body primarily through hand-arm and affects from early fatigue to irreversible hand injuries. While research and development activities related to occupational vibration are in full swing in the developed countries, it is not promising in Indian scenario. It is evident from the literature that research regarding impact of vibration on occupational health of workers in various occupational set-ups (especially in informal sectors) has not received much attention in Indian Scenario. Hence, the present project has been planned towards design modification of the existing hand-held stone polishing machine in terms of easy maneuverability; avoidance of hand holding of weight; use of vibration dampening material etc. to reduce the negative impact of occupational vibration on physical well-being of the operators. User survey (involving 30 stone polishing workers in and around Guwahati city, India) has been carried out to identify actual sufferings of the users involved in the stone polishing occupation. Data pertaining to demographic characteristics, body parts discomforts and other occupational health related issues has collected from the users of hand-held stone-polishing tool after administering the standardized questionnaire.

Working postures have been evaluated using REBA (rapid entire body assessment) technique. Quantification (using hand-arm vibration meter) of the exposure level to vibration during use of hand-held vibrating tools (polishing machine) by the workers, has been performed for 15 workers in three different working conditions (polishing on floor, stair and vertical wall). Following analysis and interpretation of aforesaid data, it has been found that workers are exposed to high level of hand-arm vibration, adopting awkward postures, performing strenuous repetitive activities for prolong duration which ultimately imposing adverse impact on occupational health of the workers. Following user survey, quantification of exposure to vibration and brain storming, CAD model of the final concept has been developed. The new concept model of the stone polishing machine has been developed considering anthropometric and biomechanical compatibility to reduce biomechanical stress associated with hand and arm of the operators, providing the supportive mechanism to avoid sustained load holding during polishing and using dampening material like rubber coatings on the handle to reduce the vibration transmission to arm. It is expected that the modified design with better usability and aesthetic look was liked by the users. Presently, work is going on  for developing the prototype of the redesigned polishing machine and its field trials for user feed-back to validate the usefulness of project out-come.

Project by
Dr. Sougata Karmakar