How to choose the tool processing stainless steel

In the processing of stainless steel, the choice of tool is very important, then from the following aspects to see how to choose a tool:

The geometric parameters of the tool requirements When machining stainless steel, the geometry of the cutting part of the tool should generally be considered from the choice of front angle, back angle. When choosing the rake angle, factors such as the shape of the chip groove, the presence or absence of chamfering, and the angle of the positive and negative angles of the rake angle should be considered. Regardless of the type of tool, the larger rake angle must be used when machining stainless steel. Increasing the rake angle of the tool can reduce the resistance encountered during swarf separation and removal. The selection requirements for the relief angle are not very strict, but should not be too small. When the relief angle is too small, it can easily cause serious friction with the workpiece surface, which can degrade the surface roughness and accelerate tool wear. And due to the strong friction, the effect of work hardening on the stainless steel surface is enhanced; the back angle of the tool should not be too large, and the back angle is too large, so that the wedge angle of the tool is reduced, which reduces the strength of the cutting edge and accelerates the wear of the tool. In general, the relief angle should be larger than when processing ordinary carbon steel.

The requirement for the surface roughness of the cutting portion of the tool to increase the surface finish of the cutting portion of the tool can reduce the resistance of the chip when forming the curl and improve the durability of the tool. Compared with processing ordinary carbon steel, when machining stainless steel, the cutting amount should be appropriately reduced to reduce tool wear; at the same time, appropriate cooling lubricant should be selected so as to reduce the cutting heat and cutting force in the cutting process and prolong the service life of the tool.

Requirements for shank material When machining stainless steel, the arbor must have enough strength and rigidity to avoid chattering and deformation during cutting due to the large cutting force. This requires the use of a suitably large cross-sectional area of ​​the shank, but also the use of high-strength materials to make shank, such as the use of quenched and tempered 45 steel or 50 steel.

The requirement for the material of the cutting part of the cutting tool When machining stainless steel, the material of the cutting part of the cutting tool is required to have a high wear resistance and can maintain its cutting performance at a relatively high temperature. Currently used materials are: high-speed steel and carbide. Since high-speed steel can only maintain its cutting performance below 600°C, it is not suitable for high-speed cutting, but is only suitable for machining stainless steel at low speeds. Because cemented carbide has better heat resistance and wear resistance than high speed steel, tools made of hard alloy are more suitable for cutting stainless steel.

Cemented carbide is divided into tungsten-cobalt alloy (YG) and tungsten-cobalt-titanium alloy (YT). Tungsten-cobalt alloys have good toughness. The tool can be made with a relatively large rake angle and a relatively sharp cutting edge. In the cutting process, the chips are easily deformed, the cutting is light and the chips are not easy to stick, so in general In the case, it is appropriate to machine stainless steel with a tungsten-cobalt alloy. In particular, tungsten and cobalt alloy inserts should be used in the case of rough machining and interrupted cutting operations, which are not as hard and brittle as tungsten cobalt titanium alloys. They are not easy to sharpen and easy to chip. Tungsten, cobalt and titanium alloys have better red hardness and are more wear resistant than tungsten and cobalt alloys under high temperature conditions. However, they are brittle and are not resistant to shock and vibration. They are generally used as tools for stainless steel precision vehicles.

The choice of rake angle from the cutting heat generation and heat dissipation, said that increasing the rake angle can reduce the generation of cutting heat, the cutting temperature is not too high, but the rake angle is too large due to the reduction of the heat dissipation volume of the cutter head. Increased. Decreasing the rake angle can improve the heat dissipation conditions of the cutter head, and the cutting temperature may decrease. However, if the rake angle is too small, the cutting deformation will be severe and the heat generated by the cutting will not be easily dissipated. Practice shows that it is most appropriate to take the anterior angle go=15°~20°.

When the rough corner is selected for rough machining, the strong cutting tool requires high cutting edge strength, and the smaller relief angle should be taken; during finishing, the tool wear occurs mainly on the cutting edge area and the flank surface. Stainless steel, which is prone to work hardening, has a great influence on the surface quality and tool wear. The reasonable relief angle should be: Austenitic stainless steel (below 185HB), and the following angle is 6°~ 8 °; processing of martensitic stainless steel (above 250HB), followed by 6 ° ~ 8 ° angle; processing of martensitic stainless steel (250HB below), followed by 6 ° ~ 10 ° is appropriate.

The choice of the blade inclination angle and direction of the blade inclination, to determine the direction of debris, a reasonable choice of blade inclination ls, usually take -10 ° ~ 20 ° is appropriate. In the case of micro fine car outer circle, fine car hole, fine planing plane, should use large blade angle cutter: should take l45 ° ~ 75 °.

In order to suppress the build-up of the built-up edge and scaly and improve the surface quality, when cutting with a carbide tool, the cutting amount is slightly lower than that of turning a normal carbon steel workpiece. In particular, the cutting speed should not be too high. Generally, the cutting speed is generally recommended. Vc=60~80m/min, cutting depth ap=4~7mm, feed rate f=0.15~0.6mm/r