In the 1960s, with the development of battery manufacturing technology, there appeared battery electric tools without power cord using nickel cadmium battery as power supply. But at that time, because of the high price, the development was slow. By the middle and late 1970s, due to the lower battery price and shorter charging time, this kind of electric tool was widely used in Europe, America and Japan. At first, the electric tools were made of cast iron, then aluminum alloy. In the 1960s, thermoplastic engineering plastics were applied to electric tools, and the double insulation of electric tools was realized to ensure the safety of electric tools. Due to the development of electronic technology, electronic speed regulating electric tools also appeared in the 1960s. This kind of electric tool uses thyristor and other components to form an electronic circuit, and adjusts the rotating speed by the different depth of the switch button to be pressed in, so that the electric tool can select different rotating speed according to the different objects to be processed (such as different materials, drilling diameter, etc.)
