Main materials, tool design, heat treatment, processing accuracy, coating quality and so on. For example, the taper cross section of the transition size is too large or no design rounded corners lead to stress concentration, the use of easy to break at the stress concentration. The cross section transition at the edge of the handle and the blade is too close to the weld, resulting in a complex stress and a stress concentration at the cross section transition, resulting in a greater stress concentration leading to the breakage of the tap in use. For example, improper heat treatment process. Taps heat treatment, if the quenching before heating without preheating, quenching overheating or over burning, not timely tempering and cleaning too early may lead to cracks in the tap. This is also the overall performance of the domestic taps as an important reason for the import tap.