Hammer - a percussion machine that provides, along with the impact, rotation of the working tool. Unlike drilling, the punch does not drill (does not cut) the hole with the sharp edge of the drill, but punches the hole with a drill, like a chisel, with mechanized rotation of the drill. Therefore, sharpening a drill is more like sharpening a chisel than drill. The power of the punch is determined by the impact energy (in joules) and the power of the electric motor (in watts). To create a pulse directed towards the material being processed, a pneumatic, less often electromagnetic mechanism is used. In pneumatic mechanisms, reverse movement occurs due to rebound and suction. The design and application has a number of similarities with a drill. The first rotary hammers were developed in 1851 specifically for the mining industry. By 1932, the first electric hammer drill appeared, which was a modified electric jackhammer