Automatic cutting table round knife, tungsten steel knife, high-speed steel knife, etc., are vulnerable parts on the machine, and the price is not cheap, so the correct use and maintenance of common sense, starting workers must know, round knife is easy to break several problems are summarized as follows. First, the quality of grinding knife depends on the production materials and equipment, grinding process specification and the technical level of the operator. The higher the quality of sharpening, the longer the service life of the cutter and the better the cutting quality. 2、 The cutting edge and body of A4 paper cutter are made by high temperature welding. The cutting edge is made of high hardness chromium tungsten manganese steel and the body is made of low carbon steel. The durability of the tool is directly proportional to the hardness of the steel used for the blade. The hardness of the blade with high quality can reach hr55 after quenching ~ 60。