Assessment of the Ergonomic Quality of European Screwdrivers
Authors: Mario Penzkofer, Anna-Sophia Henke, Karsten Kluth
Abstract: In a comparative ergonomic study, the ergonomic quality of 10 various screwdriver handles from European manufacturers which exhibited decisive differences in the design aspects “shape”, “dimension”, “material” and “surface” was tested. For this purpose, a test layout was developed in order to analyze the potential advantages and disadvantages of each handle type taking into account the anatomical and physiological characteristics of the human hand-arm-shoulder system. A group of 21 male right-handed test subjects (Ss) aged between 20 and 32 years, had to carry out different static and dynamic screw driving tests. In order to reveal possible model-specific differences in muscle strain, the electromyographic activity (EA) of 4 muscles involved in the different screwing tasks was measured via surface electrodes. Each of the Ss had to complete the test series with all screwdrivers under identical, controlled working conditions.Before and after the tests, the Ss had to assess specific criteria of the handles using a specially developed questionnaire addressing aspects such as handling, design features, material, surface finish as well as color design and manufacturing quality. In a second approach, the Ss were asked to express potential physical complaints in the fingers, hand, palm and forearm with respect to intensity and occurrence. This test-procedure with an objective and subjective evaluation offered a differentiated view on the impacts of the work situation and should reflect the advantages and disadvantages of the different handle types. When analyzing the results from the determined EA data and the users’ subjective perceptions while handling the screwdrivers, a great impact of the design features “shape”, “dimension”, “material” and “surface” became quite apparent. Only those screwdrivers designed according to appropriate ergonomic criteria enable a high operational performance with lower physiological costs which have to be paid by the muscles.
Keywords: Hand-Held Tools, Electromyographic Activity, Subjective Assessments, Physiological Responses, Maximum Torque during Pronation and Supination, Hand-Arm-Shoulder System
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