In a comparative ergonomic study, which comprised both objective and subjective assessments, 11 types of currently available screwdrivers were tested with respect to their ergonomic quality. In order to objectively record performance (maximum exertable torque) and physical strain during the use of the professional-grade screwdrivers, various test series were carried out (consisting of static torque measurements and dynamic tests of screwdriver use). Twelve male right-handed test subjects (Ss) who were between 22 and 30 years of age participated in the test series. The muscle activity of 4 muscles was recorded via surface electrodes in order to quantify objectively measurable differences in strain during the various screwdriving tests. Each of the Ss had to complete the test series with all screwdrivers under identical, controlled working conditions.
The Ss also assessed in detail the design of the handles via a specifically developed questionnaire. The handles exhibited substantial differences with respect to the 4 most important design aspects: “shape,” “dimensions,” “material,” and “surface.” Items such as working efficiency with clean and oil-covered handles as well as the general design, among others, were also part of the questionnaire. In a special block of items of the questionnaire, the Ss were asked to express also potential physical complaints with respect to intensity, duration, and occurrence in the fingers, hand, and forearm. The same was true for various detailed areas of the palm. The detailed subjective evaluation of the handles by means of approximately 30 questions offered a differentiated view of the impacts of the work situation and reflected the advantages and shortcomings of the different models' specified design characteristics. Additionally, the objective measurements showed that especially an ergonomic shape in conjunction with favorable dimensions and the proper design of the material's friction coefficient of a pressure-anthropomorphic material can contribute to the success of a product.