How to solve the problem of stainless steel thread turning

Thread is one of the common geometric features of mechanical engineering, widely used. Thread processing technology, such as based on the plastic deformation of the rolling and rolling thread, based on the cutting of turning, milling, tapping and thread sets, thread grinding, thread grinding and so on.

Different types of stainless steel due to mechanical properties and chemical composition of the different, the difficulty of CNC cutting is not the same. Some stainless steel in the cutting process, it is difficult to achieve a satisfactory surface roughness; and some stainless steel, although easy to achieve the required surface roughness, but in the cutting process is particularly vulnerable to wear and tear tool. The summary, all kinds of stainless steel is difficult to cut the main reasons are the following aspects:

1 high heat intensity and strength

Austenitic stainless steel and martensitic stainless steel its hardness and tensile strength is not high, only the equivalent of 40 steel, but the elongation, section shrinkage and impact values are relatively high, so that the process of high-speed CNC cutting is not Easy to be cut, cutting deformation of the work consumed considerable. Relatively speaking, the strength of stainless steel at high temperatures reduce less, such as the 45 steel at 500 ° when its lasting strength of 7kg / mm2, while the 1Cr18Ni9Ti at 550 ° when its lasting strength remained at 19 - 24kg / mm2. Practice has proved that the role of the same cutting temperature, stainless steel cutting harder than ordinary carbon steel, the high heat intensity is an extremely important factor.

2 strong processing hardening trend

In the process of NC high-speed turning, the metal in the cutting area is deformed due to the extrusion of the tool tip, the slip, lattice distortion, dense structure and mechanical properties of the cutting zone change with the change of hardness. Can also increase 2 - 3 times. CNC cutting after processing hardened layer depth can range from tens of microns to hundreds of microns, so the previous pass generated by the phenomenon of work hardening and hinder the next pass when cutting, and hardened layer of high hardness lead to the tool Particularly easy to wear.

3.Strong chip adhesion, low Thermal conductivity

In the NC cutting process, the cutting debris is easy to firmly adhere to or melt in the nose and knife edge, the formation of BUE, resulting in surface roughness of the workpiece surface deterioration, while increasing the cutting process vibration, speed up the tool Wear. And a large number of cutting heat can not be transmitted in time, and even the heat generated by cutting can not be transmitted to the chip as a whole, resulting in the total heat input tool than ordinary carbon steel 3 - 5 times the cutting edge at high temperatures loss of cutting performance. In the CNC cutting process, the resulting large amount of heat can not be quickly discharged, is bound to pass to the cutting tool, the cutting temperature. At the same time because of chip removal more difficult, especially the constant chip, so that cutting down the chip to produce congestion, especially in the processing hole, chip more serious congestion. In addition, the tool due to the thread section of the shape of the restrictions, coupled with their own strength is poor, easy to produce vibration in the cutting process is easy to cut the local temperature is too high due to burn or too much vibration and crack.