The main reason why stainless steel is difficult to process is that stainless steel has poor thermal conductivity. When heated, the chips easily form built-up edges at the tip of the blade, which is the main reason for blade damage. In addition, due to the large cutting force and high cutting temperature during processing, it brings some difficulties to processing, and it is often difficult to achieve satisfactory results when cutting.
We learned from a 40-year-old master that there are some tips for stainless steel processing. Let's share the problem of stainless steel being difficult to cut today!
Picture
Tips for stainless steel cutting
Generally, high-speed steel cutting knives are used to cut bars below φ40mm, which can achieve better cutting results. When processing workpieces above φ40mm, due to the low cutting speed of stainless steel processing, carbide cutting knives can be used to improve efficiency.
1. The blade inclination angle of the tool must be 0°, and it can be ground on a tool grinder if conditions permit. This is the most important point. Because when stainless steel is cut, the friction between the chips and the groove wall is serious. If the chips cannot be rolled out vertically, chip squeezing will occur, and in severe cases, the knife will be hit. When the blade inclination angle is large, even if chip splitting measures are adopted, the effect is not ideal.
2. The radius of the arc of the tool tip should not be too large. If it is too large, the secondary back angle of the tool is easy to wear. This may be because the chip thickness at the arc is thinned, which is easy to produce work hardening and aggravate the wear of the side of the tool.
3. The tool wear should be sharpened in time. The sharpening standard of the stainless steel cutting knife should not only be determined according to the main back, but also pay special attention to the wear degree of the secondary back. If the secondary back is worn too much, the friction between the tool and the groove side will increase, resulting in a narrower groove width, making it difficult to discharge chips, and accelerating tool wear.
4. The surface roughness of the front of the tool should be reduced as much as possible. A low surface roughness value can reduce bonding wear, reduce cutting force, and cut lightly. Practice has proved that the tool life is significantly improved after grinding the front of the tool than that of the unground tool.
5. The negative chamfer of about 0.2mm is ground on the cutting edge to reduce the chipping phenomenon during grinding and obtain better cutting edge quality. The lower part of the knife body adopts a fish belly shape to increase rigidity. The secondary back angle of the tool is ground with a grinding wheel outer circle, which has good rigidity and an actual back angle of about 2°~3°.
The tool material for processing stainless steel is generally selected from YG alloys that are not easy to produce bonding wear with it. I chose YG8 with better strength. The tool width is selected according to the diameter of the bar material, and the cutting speed is about 60m/min.
This tool can meet the needs of general processing. The bar material of φ40~φ80MM can be cut off at one time without the need to drive the knife left and right. During processing, it should be noted that the stainless steel chips are very sharp. If the chips are too long, the feed should be retreated to break the chips to avoid danger. When retreating, the tool should not stay on the surface of the workpiece to reduce work hardening. When cutting solid workpieces, in order to avoid the tool from breaking, you can leave about 1~2mm when cutting to the center and break it by hand.
6. For this kind of stainless steel cutting, under normal circumstances, wet cutting has a tool life several times longer than dry cutting. I mainly look at the speed and the cutter. If the speed is high without adding water, the chips from the cutter will turn red immediately, and I will know how many jobs can be processed!
