Sandvik Coromant Silent tools - application guide - Manual (Page 73)

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4. Boring
Single-edge boring
Productive boring
Step boring
Productive boring
Involves two cutting edges and is employed for roughing operations
of holes, with tolerance IT9 or larger, where metal removal rate is
the first priority. Feed rate is obtained by multiplying the feed by the
number of inserts. (f
n
=f
z
x ZEFF)
Step boring
When adding a shim under one of the slides, the insert will only
take the inner half of the desired radial cut, and the result is a step-
boring tool. Select this method if you want to take a larger radial
cut than one insert can take, but remember to reduce the axial feed
to what is normal for a tool with only one cutting edge.
If the two inserts are set to take the same radial depth of cut, the
outer one will always take the largest cutting force, due to higher
speed and more chip removal. By doing this right, vibration can
easily be avoided and a smooth surface is guaranteed. This set-up
will produce a stepped shoulder if it is not going through the work-
piece.
The feed rate and the produced surface finish is the same as if only
one insert is used (f
n
=f
z
). Produced hole tolerance is IT9 or larger.
Single-edge boring
Single-edge boring is the best option when:
• You need to reduce cutting forces due to a low power machine
• You have problems with vibration
• Close tolerances, accurate roundness or good surface finish is
required
Produced hole tolerance is IT9 or larger.