Page 356 - Gear Technology Solutions

26 Three-Face Blade Technology

26.1 Three-Face vs. Two-Face

In order to utilize the full potential of 3-face ground and all-around coated
blades the cutter head slot inclination of 4.42° as it is used in the Pentac®-FH
cutter system is not sufficient. In case of 2-face ground blades, the front face
remains untouched during the re-sharpening, only pressure angle and clear-
ance side of the blade are reground. The front face of 2-face blades is parallel
to the blade shank and has a permanent coating. After re-sharpening, the
blades are ready to be built in the cutter head.

If two-face blades should be all around coated, then it is necessary to strip the
coating from the front face before re-coating. The reason is the continuous
buildup of coating layers on the front face if no stripping between coatings oc-
curs. It is possible to strip the front face coating chemically before every re-
coating, but this would involve additional cost and results in a degradation of
the carbide under the repeatedly stripped surface. In case of a desired all-
around coating, it is recommended to convert the two-face blades to three-face
blades and grind the front face of the blades also in order to remove the previ-
ous coating. This opens the possibility to achieve more optimal top rake and
side rake angles with a different front face orientation. The “package” 3-face
grinding and all-around coating can double the tool life, compared to 2-face
grinding with permanent front face coating.

Figure 1: Top rake angle as function of slot inclination (slot tilt angle)

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