in the construction industry for cutting reinforcement bars (rebar), protruding bolts or anything that needs quick removal or trimming. Most handymen would recognise an angle grinder and the discs they use. Use To use the grinding wheel it must first be clamped to the grinding machine. The wheel type (e.g. cup or plain wheel below) fit freely on their supporting arbors, the necessary clamping force to transfer the rotary motion being applied to the wheels side by identically sized flanges (metal discs). The paper blotter shown in the images is intended to distribute this clamping force evenly across the wheels surface. Dressing Grinding wheels are self-sharpening to a small degree; for optimal use they may be dressed and trued by the use of wheel or grinding dressers. Dressing the wheel refers to removing the current layer of abrasive, so that a fresh and sharp surface is exposed to the work surface. Trueing the wheel makes the grinding surface parallel to the grinding table or other reference plane, so that the entire grinding wheel is even and produces an accurate surface. Testing for grinding tools Grinding wheels and grinding tools are used extensively in industry and manual trades for treating surfaces and for separating and cutting objects and have to withstand massive mechanical stress. Mostly centrifugal forces can cause a break, but also flexural and shear forces. Since a break or failure of the grinding tool can present a severe hazard to people and machinery due to the high levels of energy released, high standards are placed on the mechanical and breaking strength of grinding tools in the European safety standards. The Institute for Occupational Safety and Health of the German Social Accident Insurance conducts tests based on the "Rules of Procedure for Testing and Certification carried out by the Testing and Certification Bodies in DGUV Test". See also Diamond tool Diamond grinding cup wheel Sharpening stone References Grinding and lapping Metalworking tools