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7.1 General grinding fundamentals
If a cutting edge has become dull, material must be removed in order to reach its original
sharpness.
To do so, the respective knife is ground to the cutting edge. While doing so, if a burr is created
on the cutting edge, then the grinding process is complete and can be finished. Before creating
the final sharpness, the resulting burr must be removed as part of an additional step. This is done
with a finned brush.
As it is not only the sharp cutting edges but also the long service lives that define a blade, the
cutting edge angle is another important indicator of a blade's performance. The smaller the
cutting edge angle, the higher its theoretical service life. In practice, however, it seems that a
cutting edge angle that is too small results in the cutting edge breaking off and thus becoming
dull.
The cutting edge angle is therefore between 15° and 35°. For cutting edge angles below 15°, the
cutting edge is so unstable that it snaps with the smallest resistance. For a cutting edge angle of
more than 35°, the cutting edge angle is extremely stable, but this does reduce the service life.
The cutting edge profile is an additional criterion for the characteristics of the cutting edge.
There are three different ground surfaces:
Convex ground surfaces can mostly be found on cutter blades and hand knives. Tapered and
concave ground surfaces are predominantly found on circular knives and blades.
In essence: The profile and cutting edge angle stipulated by the manufacturer must be
maintained.
7. Operation
Tapered ground surface
Convex ground surface
Concave ground surface