Ergonomic design and evaluation of pliers

In the present study, bent-handled needle-nose pliers, designed from an ergonomic perspective as an improvement over the conventional plier were investigated.

A convenience sample of fourteen volunteer male university students aged between (20 and 24 years old) participated in the study.

Three angles to the jaws of plier (0°, 10° and 20°) were provided in the redesigned pliers to reduce ulnar deviation of wrist. Other two angles (0° and 5°) of jaws with respect to the vertical plane. From this, (3 × 2) six redesigned pliers were investigated. Dependent variables were discomfort--scored on 10~cm Visual Analogue Scale (VAS) and difference in systolic and dysystolic blood pressure (BP).

The results of ANOVA showed that the main and interaction effects of the angle to prevent ulnar deviation of wrist and angle to prevent extension of wrist were highly significant (i.e., p< 0.001) on discomfort score. Effect of angle to prevent ulnar deviation of wrist was only found significant on difference in systolic blood pressure. Of the redesigned pliers, the pliers with 10° angle of handle from jaw to prevent ulnar deviation, and 5° angle of handle to prevent extension of wrist was found to give the minimum level of discomfort score.

Hence it is concluded that bent handle pliers up to certain angles may reduce discomfort, and after that discomfort will increases drastically. These finding will be very significant for the designers to use one more angle as per the requirement of the comfortable use of pliers. Many ergonomically redesigned pliers are available. However none was found be considering angle to give extension of the wrist based on scientific findings.