Stainless steel boring processing what need to pay attention to?

1, tool material selection

Due to the processing of stainless steel parts when the cutting force, high cutting temperature, tool materials should try to choose high strength, good thermal conductivity YW or YG cemented carbide. YT14 and YT15 carbide blades can also be used for finishing. Batch processing the material parts, ceramic cutting tools can be used, because this kind of material is the main characteristic of the great toughness, work hardening is serious, the chip of cutting the material in the form of unit chip, will make the tool produces vibration, easy to cause the blade to produce micro collapse phenomenon, so choosing ceramic tool cutting such material parts should consider above all is the micro toughness.

At present, Sialon is a good choice, especially α/βSialon material, because of its excellent resistance to high temperature deformation and diffusion wear performance, and successfully applied to cutting nickel base alloy, its life is far more than al2o3-based ceramics. In addition, SiC whisker reinforced ceramics are also an effective tool material for cutting stainless steel or nickel-based alloys.

For the processing of such material quenching parts, you can use CBN (cubic boron nitride) blade, CBN hardness is second only to diamond, the hardness can reach 7000 ~ 8000HV, so the wear resistance is very high, compared with diamond, CBN outstanding advantage is much higher than diamond heat resistance, up to 1200℃, can withstand high cutting temperature. In addition, its chemical inertia is very large, and iron group metal in 1200 ~ 1300℃ also does not have chemical action, so it is very suitable for processing stainless steel materials. Its tool life is carbide or ceramic tool dozens of times.

2, tool geometric parameters

The tool geometric parameters play an important role in its cutting performance. In order to make the cutting light and smooth, the carbide tool should use a larger rake Angle to improve the tool life. In general rough machining, the front Angle is 10° ~ 20°, and the semi-finishing Angle is 15° ~ 20°; When finishing, take 20° ~ 30°. The selection of the main deflection Angle is based on 30° ~ 45° when the process system is good rigidity; If the rigidity of the process system is poor, take 60 ~ 75°, when the ratio of the length and diameter of the workpiece is more than 10 times, take 90°.

When boring stainless steel material with ceramic cutter, in most cases, ceramic cutter adopts negative rake Angle for cutting. The front Angle should be -5° ~ -12°. This is beneficial to strengthen the blade and give full play to the advantages of ceramic cutting tools with high compressive strength. The size of the back Angle directly affects the tool wear, also has an impact on the blade strength, generally choose 5° ~ 12°. The change of the main deflection Angle will affect the change of the radial and axial cutting forces as well as the cutting width and cutting thickness. Because the vibration of the process system is very unfavorable to the ceramic tool, the selection of the main deflection Angle is conducive to reducing the vibration, generally 30° ~ 75°. When CBN is used as the tool material, the tool geometric parameters are 0° ~ 10° front Angle, 12° ~ 20° rear Angle, 45° ~ 90° main Angle.

3. The roughness value of the front blade surface should be small when grinding

In order to avoid the phenomenon of chip sticking to the knife, the front and back of the tool should be carefully grinded to ensure that there is a small roughness value, so as to reduce the chip flow resistance and avoid chip sticking to the knife.

4, keep the edge of the knife sharp

The cutting edge of the tool should be kept sharp in order to reduce work hardening, and the feed and the back draft should not be too small to prevent cutting tools in the hardened layer, affecting the service life of the tool.

5. Pay attention to the grinding of the chip breaker

Because the stainless steel chip has the characteristics of strong and tough, the cutting tool front chip groove repair and grinding should be appropriate, so as to make the cutting process interrupt chip, chip tolerance, chip discharge convenient.

6, select the cutting dosage

According to the characteristics of stainless steel materials, processing should choose low speed and large feed for cutting.

When using ceramic tool for boring, the reasonable choice of cutting dosage is one of the keys to give full play to the performance of ceramic tool. When the ceramic tool is continuously cutting, the cutting amount can be selected according to the relationship between wear durability and cutting amount. Discontinuous cutting should be determined according to the law of tool damage reasonable cutting amount. Due to the superior heat resistance and wear resistance of ceramic knives, the influence of cutting amount on tool wear life is less than that of carbide knives.

In general, when ceramic cutting tools are used, the feed rate is most sensitive to the damage of the tool. Therefore, according to the nature of the workpiece material, in the machine tool power, process system stiffness and blade strength permit under the premise of boring stainless steel parts, as far as possible to choose a high cutting speed, a larger back tool amount and relatively small feed.

7, choose the right cutting fluid

Because the stainless steel has the characteristics of susceptible to bonding and poor heat dissipation, so choose in boring cutting liquid phase bonding and thermal resistance good as important, if choose high chlorine cutting fluid, and has good lubrication and cooling, cleaning and antirust function does not contain mineral oil, do not contain the aqueous solution of salts, such as H1L - 2 synthetic cutting fluid.

The use of the above process method, can reduce the stainless steel processing difficulties, greatly improve the stainless steel in drilling, reaming, boring tool life, reduce the operation of grinding, tool frequency, not only can enhance the production efficiency and hole processing quality, can also reduce labor intensity and production cost.

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