A Method to quickly identify the quality of tapping   There are a lot of silk brands on the market, because of the different materials used, the price of the same specification is also a lot different, so that buyers like to see flowers in a fog, I do not know which good to buy, the following teach you a few simple methods:     Purchase (due to no detection equipment, except for no slot tap) can be simple detection (M6 as an example) : 1; See tap groove front thread shovel grinding (chamfering) is uniform, cutting groove knife edge is fast mouth, good positive 7 word, bad inverted 7 word or U shape (out of tap will cause two cutting, easy to fracture and affect the precision of thread); 2; Detection of heat treatment: wire tapping to the air parabola (5 meters or so) flat fall is broken, broken indicates that the brittleness is large; 3; Knock off the tap, see its fracture is diagonal long, the molecular particles in the fracture (metallographic structure 10.5#) fine junction, indicating that the heat treatment and material is good, flat or oblique short, molecular particles (metallographic structure) thick is not good. For the quality of tapping mainly depends on its original material, heat treatment, groove type, accuracy, equipment, speed and be processed material, hardness, the quality of the operation staff and so on, more related! When selecting taps, special attention should be paid to the original material, heat treatment and groove type of taps. It is recommended to choose different types of taps for different processing holes. In appearance: 1. Have black, yellow, burn marks 2. Whether the front edge Angle is straight, whether there is negative edge or step 3. Whether the mark is clear and in accordance with relevant regulations