Case Studies on the Body Postures and Technical Design of Small Angle Grinders

Abstract

Our case studies refer to small angle grinders. Work tasks, physical stresses during use, and stresses on the hand-arm system are discussed. For this purpose, a survey was administered to 42 work persons from four different industries. Angle grinders were the most important hand tools for the respondents. They used angle grinders for eight activities (from flexing to polishing). In addition, 17 detailed video analyses of the work processes with 5 different angle grinder makes were carried out in selected workshops. The survey results on working postures in the last week as well as within the last year indicated mainly bent and twisted trunk postures, squatting and kneeling at work. To that extent, these results correspond with the OWAS studies by Ellegast R, et al. The video studies pointed out the very frequent twisted or bent hand-arm postures. The (ergonomically recommended) alignment of tool axis and hand-arm axis is not possible when using angle grinders. Nevertheless, the vast majority of our test subjects are satisfied with the dimensions and characteristics of small angle grinders. The analysis results are transferred into a list of ergonomic requirements for product designers.