Special cutting-edge geometry ensures a high surface quality

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Furthermore, the material indicates a greater ductility than normal steel. The cutting-edge geometry of the end mill was designed in such a way that it balances the toughness of the material which in turn supports chip formation. The end mill also has an unequal helix angle: “The opposite edges respectively have an angle of 39 or 41̊. While milling pockets, the tool thus operates considerably more quietly than a same-angular tool. The chip removal also improves as e result,” explains Hamel.

Greater smoothness leads to minimal wear

While the present end mills for processing stainless steel by strong vibrations lead to clear signs of wear and tear, the X-Top distinguishes itself on the basis of its greater smoothness due to minimal wear. This is reflected, for instance, in the roughing operation on the material 1.4571(X6CrNiMoTi 17 12 2), which Wexo carried out against two competitors' end mills. An 18 mm cut depth, a 4.8 mm sidestep roughing, a 75 m/min cutting speed and a 0.08 mm feed per tooth were specified. “A competitor's end mill broke after about half the processing due to very high cutting pressure,” Hamel explains. “In the second experiment, it led to cutting-edge chipping after about 40 minutes. The X-Top end mill showed no signs of wear after this time period.” The lower vibrations not only enhance the service life of the tool but also the productivity and process reliability.

Adapted to feed rate, speed, depth of cut

Stainless steel is also difficult to machine because the basic stability of the material is clearly increased as a result of the heat produced in processing. Above all, while milling austenitic stainless steel and duplex stainless steel it leads to increased notch wear and cutting-edge chipping. In order to avoid this, the cutting-edge geometry of X-Top end mills was designed in such a manner that they counteract this effect.

Macros substantially accelerate CNC programming

In addition to geometry, the new end mills were adapted to cutting parameters such as rotation speed, feed rate, service and depth of cut especially for stainless steel so that a particularly high finish quality is attained. For instance, the end mill attains a Ra value of 0.39 μm during a finishing process on the material 1.4571 with a 12 mm diameter, a 75 m/min cutting speed, 0.06 mm tooth feed, 12 mm cut depth and 0.5 mm operational reach. Both the competitors' tools cut significantly poorly with a Ra value of 1.97 or 2.12 μm. With a Wexo end mill, an almost burr-free work piece edge can be produced during this processing. “Even here the geometry is once again significant in addition to the sharpness of the cutting edges,” says Hamel.

Suitable for cast iron, super alloys, non-ferrous materials

Based on the optimum cutting-edge geometry, the end mill is also suitable for cast iron, non-ferrous material and super alloys such as Titan, Inconel or Hastelloy and guarantees a high process reliability even with high metal removal rates. It is available in diameters from 3 to 20 mm with various flanging radii.

This article is written by Iris Gehard. It first appeared in our sister publication MM-Maschinenmarkt.

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