Sandvik Coromant Threading - Manual (Page 44)

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2. Applications – Thread milling
External threading with milling tools.
All thread milling inserts are designed for internal threads, however
CoroMill 327 and CoroMill 328 inserts can also be used for external
threading. Consider the size of insert nose radius for the two operations,
as a larger nose radius needs to be chosen for the external thread (internal
- pitch/8, external - pitch/4).
Thread root sizes differ slightly for internal and external threads. In the ex-
ample below, a 2 mm (.078 inch) pitch insert, nose radius 0.25 mm (.0098
inch) fi ts a 2 mm (.078 inch) pitch internal thread, root 0.25 mm (.0098
inch). The corresponding external thread has a larger root, 0.50 mm (.019
inch) and therefore a 4 mm (.157 inch) pitch insert with larger nose radius
should be chosen to fi t this thread.
For external thread milling recommendations see
chapter 5, Technical reference (page 112).
P = Pitch
Internal thread
Pitch 2 mm
Height 1.08 mm
Root 0.25 mm
Insert 327R12-22 200MM-TH
Pitch 2
Max depth of cut 1.08 mm
Nose radius 0.25 mm
External thread
Pitch 2 mm
Height 1.08 mm
Root 0.50 mm
Insert 327R12-22 400MM-TH
Pitch 4
Max depth of cut 2.17 mm
Nose radius 0.50 mm