Everyone knows a truth. The application of a product type is different. For example, the end mill for stainless steel is different from other milling cutters according to its characteristics. So what are the characteristics of end mill for stainless steel?
For milling stainless steel, except for end mills, some end mills and hard alloys as milling cutter materials, other types of milling cutters are made of high-speed steel, especially tungsten-molybdenum series and high-vanadium high-speed steel, which have good results The durability can be 1 to 2 times higher than W18Cr4V. Cemented carbide grades suitable for making stainless steel milling cutters are YG8, YW2, 813, 798, YS2T, Y. When milling stainless steel, the cutting edge must be sharp and able to withstand impact, and the chip pocket must be large. Large helix angle milling cutters (cylindrical milling cutters, end milling cutters) can be used, the helix angle b is increased from 20° to 45° (gn=5°), the tool durability can be increased by more than 2 times, because the work of the milling cutter at this time The rake angle g0e is increased from 11° to more than 27°, and the milling is brisk. However, the value of b should not be too large, especially for end mills with b≤35°, so as not to weaken the teeth.
Using wave-edge end mills to process stainless steel pipes or thin-walled parts, cutting is brisk, vibration is small, chips are fragile, and the workpiece is not deformed. High-speed milling with cemented carbide end mills and stainless steel with indexable end mills can achieve good results.
Milling 1Cr18Ni9Ti with silver chip end mill, its geometric parameters are gf=5°, gp=15°, af=15°, ap=5°kr=55°, k′r=35°, g01=-30°, bg=0.4mm, re=6mm, when Vc=50～90m/min, Vf=630～750mm/min, a'p=2～6mm and the feed per tooth reaches 0.4～0.8mm, the milling force will decrease 10% to 15%, the milling power is reduced by 44%, and the efficiency is greatly improved. The principle is to grind a negative chamfer on the main cutting edge, and artificially generate a built-up edge during milling, so that it can replace the cutting edge for cutting. The rake angle gb of the built-up edge can reach 20~302, due to the main deflection angle As a result, the built-up edge is subjected to a thrust parallel to the cutting edge generated on a rake face and becomes secondary chips flowing out, thereby taking away the cutting heat and reducing the cutting temperature.
When milling stainless steel, down milling should be used as much as possible. The asymmetric down milling method can ensure that the cutting edge is smoothly cut away from the metal, and the chip bonding contact area is small, and it is easy to be thrown off under the action of high-speed centrifugal force, so as to prevent the chip from impacting the rake face when the cutter tooth re-cuts into the workpiece The phenomenon of spalling and chipping improves the durability of the tool.
The spray cooling method has the most significant effect, which can increase the durability of the milling cutter by more than one time; if the general 10% emulsion is used for cooling, it should be ensured that the cutting fluid flow rate is fully cooled. When the carbide milling cutter mills stainless steel, take Vc=70～150m/min and Vf=37.5～150mm/min. At the same time, make appropriate adjustments according to the alloy grades and workpiece materials.
