The machinability of stainless steel is inferior to that of medium carbon steel. With the development of equipment manufacturing, stainless steel fasteners are increasingly used in various industries. The processing and manufacturing technology of stainless steel fasteners has also gradually matured. Each company must choose the right blade material for machining stainless steel according to its actual needs, and the cutting amount is expected to reach the optimal price/performance ratio.
1, the choice of tool material
Stainless steel fasteners processing tools to be a reasonable choice. According to the cutting characteristics of stainless steel fasteners, the tool material is required to have heat resistance, good wear resistance, and a small affinity with stainless steel. Nowadays, high-speed steel cutters are not used in machining stainless steel fasteners, and often carbide tools are used. In the processing of stainless steel fasteners, YG type hard alloy is often used. The toughness of YG type hard alloy is better. Larger rake angle can be used, and the cutting edge can also be sharpened to make the cutting lighter and the chips and tools are not easy to produce. Bonding, more suitable for processing stainless steel fasteners. This type of advantage of YG alloys is even more important in vibrating roughing and interrupted cutting. In addition, the thermal conductivity of YG-based alloys is nearly twice as high as that of high-speed steels and twice as high as that of YT-based alloys. Therefore, YG-type alloys are widely used in the cutting of stainless steel fasteners, especially in rough cutting tools, cutting blades, and reamers. For a long time, general grades of cemented carbide such as YG6, YG8N, and YW2 have generally been used as cutting tool materials for stainless steel fasteners, but they have not reached a smooth surface; new grades of hard alloys 813, 767, 640, and 798 are used. Cutting stainless steel fasteners such as YM051, YM10, YS2T, YD15, FK235 can obtain better results.
2, the choice of tool parameters
In addition to selecting suitable tool materials for machining stainless steel fasteners, the tool geometry parameters must be selected. Front angle (γo): The hardness and strength of stainless steel fasteners are not high, but their plasticity and toughness are good and the thermal strength is high. The cutting chips are not easily cut off. Under the premise of ensuring that the knife has sufficient strength, a larger rake angle should be selected. This not only can reduce the plastic deformation of the metal being cut, but also can reduce the cutting force and the cutting temperature, and at the same time reduce the depth of the hardened layer. The rake angle of various stainless steel fasteners is approximately 12° to 30°. For martensitic stainless steel fasteners (such as 20Cr13), the rake angle may be larger, and the austenite and austenite+ferrite Stainless steel fasteners, the rake angle should be smaller. For stainless steel fasteners that have not been quenched and tempered or have lower hardness after quenching and tempering, larger rake angles are preferred. For smaller diameter or thin-walled parts, larger rake angles are preferred.
3, the choice of cutting amount
The amount of cutting has a great influence on the work hardening, cutting force, cutting heat, etc. during the machining of stainless steel fasteners, especially the influence on the tool durability. Choosing the right amount of cutting will directly affect the cutting effect. Table 1 below shows the selection of the cutting amount when the tool material is high speed steel and the thread drilling, expansion, and reaming.