Circular solid bonded abrasive wheels with central through-holes, made from abrasives and binder resins. Angle grinders are a type of abrasive tool widely used and with a broad application range, rotating at high speeds to perform rough, semi-fine, and fine grinding on the outer and inner circles, flats, and various profiles of metal or non-metal workpieces, as well as slotting and cutting. There are many types of angle grinders. They can be categorized by the abrasive material used, such as common abrasives (corundum and silicon carbide) wheels and natural abrasive super-hard wheels (diamond and cubic boron nitride) wheels; by shape, including flat wheels, bevel-edged wheels, cylindrical wheels, cup wheels, and disc wheels; and by binder, such as ceramic wheels, resin wheels, rubber wheels, and metal wheels. The characteristic parameters of the wheels mainly include abrasive material, viscosity, hardness, binder, shape, and size. Since wheels often operate at high speeds, they should be subjected to a rotation test (to ensure they won't crack at high working speeds) and a static balance test (to prevent vibration during operation) before use. After a period of use, the wheels should be dressed to restore their grinding performance and correct geometric shape.