Rotary hammer is a widely used electric tool. Rotary hammer is a kind of electric drill, which is mainly used to drill holes in concrete, floor slab, brick wall and stone. It is specialized in drilling holes on the wall, concrete and stone. There is also a multi-functional electric hammer. It can be adjusted to an appropriate position and equipped with an appropriate drill to replace ordinary electric drills and pickaxes.Because the drill bit of the electric hammer rotates and also produces rapid reciprocating motion (frequent impact) along the direction of the electric drill rod, it can quickly punch holes in brittle cement concrete, stone and other materials. The high-grade electric hammer can use the change-over switch to make the drill bit of the electric hammer in different working states, that is, only rotate without impact, only impact without rotation, both impact and rotation.