Circular solid bonded abrasive tools with a central through-hole, made from abrasives and binder resins. Angle grinders are a type of abrasive tool widely used and with a broad application range. They rotate at high speeds and can perform rough, semi-finishing, and finishing grinding, as well as notching and cutting operations on the outer and inner circles, planes, and various shapes of metal or non-metal workpieces. There are many types of angle grinders. They can be categorized by abrasive material into common abrasive wheels (such as corundum and silicon carbide) and natural abrasive superhard wheels (such as diamond and cubic boron nitride); by shape into flat wheels, bevel edge wheels, cylindrical wheels, cup wheels, and disc wheels; and by binder into ceramic wheels, resin wheels, rubber wheels, and metal wheels. The characteristic parameters of the wheels include abrasive material, viscosity, hardness, binder, shape, and size. Since wheels usually operate at high speeds, they should undergo a rotation test (to ensure the wheel will not crack at high working speeds) and a static balance test (to prevent vibration during operation) before use. After some time of operation, the wheel should be dressed to restore its grinding performance and correct geometric shape.