Ergonomic evaluation of cashew nut shelling machine

Abstract

This paper presents the ergonomic evaluation of a manually operated village-level cashew nut shelling machine. A manually operated cashew nut cracking machine was evaluated. Fifty subjects took part in the study, with physiological, postural, and subjective measurements being taken. Comfort Questionnaire for cashew nut cracking machine (CQC) was also evaluated. Using the machine resulted in postural discomfort. The perception of the subjects as per the efficiency of the machine was neutral; 50% accepted that the machine is efficient, while the other 50% were unsatisfied. Following a participatory ergonomic process and using appropriate anthropometric measurements, an improved, adjustable prototype was developed. The lever arm was designed based on 5th percentile of the subjects; blades were welded into the cracking lid to reduce the amount of impact force used for cracking, so as to reduce crushing of the nuts. Also the ergonomic seat and worktable allow posture change from sitting to standing. Other features include; feeding tray, foot rest. The work surface height is made to be 100 mm below the elbow height. i.e. 1200 mm. The length of the work table (work space) was designed to accommodate 95th percentile of the Bicromial breadth of the subjects. The foot and the knee room was 150 mm. The cracking machine is bolted to the worktable, so that it can be easily disassembled. The study demonstrated how ergonomics can play an important role in reducing drudgery and improving user satisfaction and acceptability in technology development and transfer in developing country.