SCREWDRIVERS AND THEIR USE FROM A SWEDISH CONSTRUCTION-INDUSTRY PERSPECTIVE

The purpose of this paper is to focus on certain important aspects of screwdriver use in occupational work situations, with an emphasis on force exertion and screwdriver use in construction work. Hand tools are involved in many accidents and injuries in the Swedish construction industry. Traditions within the industry sometimes have a strong influence on what tools are being used and how the work is performed. Manual and pistol-grip powered screwdrivers are the most common tools and the work is often performed with highly repetitive arm elevations, sometimes in constrained postures for long periods of time. Manual screwdriving causes high loads in the forearm muscles. There has therefore been a shift to the use of battery-powered screwdrivers, which have been shown to reduce forearm muscle load considerably, while at the same time increasing production. Factors apart from the tool itself, such as working height, screw-head type and characteristics of the target material, leading to long external shoulder moment arms and high required push forces, are primarily responsible for high loads, particularly in the shoulder muscles. Push reaction forces may exceed 70% of MVC and sometimes account for more than 70% of the external shoulder torque. Fatigue develops rapidly in the shoulder muscles during short-cycled repetitive overhead screwdriving. To reduce the risk of developing injuries from screwdriving in construction work, it is necessary not only to improve screwdriver design, but also to improve posture and to select appropriate screws and material. It is also important to consider the work organization.