Page 284 - THREADING CATALOG

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THREAD MILLING There are two milling methods that also apply to Climb Milling (Down Milling)
Climb Milling vs. Conventional Milling

thread milling: conventional milling (up milling) and
Cutter direction is the same as feed direction. Climb milling
climb milling (down milling). The difference between
is a recommended method for all milling applications.
the two methods lies in the relationship of cutter
The thickness of the chip starts from maximum and
rotational direction relative to the feeding direction.
decreases, so heat is more likely to be transferred to the
chip and not to the cutter. As a result, wear is slower
Conventional Milling (Up Milling)
Cutter rotation direction is against feed direction. The
cutter, which reduces the chance of re-cutting. In this
thickness of a chip increases as the tooth of the cutter
way the machined surface stays clean and smooth.
enters the material and reaches its maximal size when and tool life increased. Chips are removed behind the
the same tooth of the cutter exits the material. This Climb Milling
method causes heat to be generated in the cut area chip started
and a sudden heavy load on the cutter in initial contact zero thickness
of the tooth with the workpiece. As a result, wear is rotation
faster and tool life decreases significantly. Chips are
carried upward by the tooth and fall in front of the
cutter creating a flawed finish and re-cutting of chips.
Convetional Milling
chip started
zero thickness
rotation feed

When to Choose Conventional Or Climb Milling?
Climb milling in most cases is the preferred way for
machining threads due to a lower load on the cutter,
longer tool life, and better surface finish. During
conventional milling, the cutter can dig into the workpiece
feed and may cause the part to be machined out of the
tolerance. However, there are cases in which conventional
milling is the preferable way and even necessary. If the
machine does not counteract backlash, then conventional
milling is recommended. In addition, conventional milling
is preferable for machining cast iron or hardened materials
(as the cut begins under the surface of the material).

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