There are two types of impact mechanism of impact electric drill: dog tooth type and ball type. The ball impact electric drill is composed of moving disc, fixed disc, steel ball, etc. The moving disc is connected with the main shaft through threads and is equipped with 12 steel balls; The fixed disc is fixed on the casing with four steel balls by pins. Under the action of thrust, 12 steel balls roll along the four steel balls, making the cemented carbide bit produce rotary impact motion, and can drill holes on brittle materials such as bricks, blocks, and concrete.