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Copy Mills • M270 ™ Series
Additional Application Advice • M270 Ball Nose
Selecting the Correct Insert and Cutting Conditions for Your Application
1. Insert Style: Considerations for Selecting the Correct Insert
BR Geometry
BF Geometry
Best Choices for Insert and Grade Selection


First choice
Alternate choice
Grade
Roughing Operation
TN7535 TN2510
 
TN2505


Finishing Operation
Low RPM Machine  
Flat Areas or Face Milling (≤10° inclination)  


Hard Machining
Unstable and/or Long Overhangs  
HSM or 5-Axis Machining (smaller ap/ae values)  
2. Calculating effective diameter and resulting surface speed
It is important to consider the effective
diameter (Deff) when using light depths
of cut in order to properly calculate RPM
values. Use the following formula when
machining fl at surfaces or inclinations
of 10° or less to fi nd the Deff value,
and then use this for RPM calculations
as opposed to using the overall insert
diameter (D1).
Deff
When machining inclinations between
11° and 55°, further modifi cation of vc
is required. Apply factor “k” from the
given formula to calculate the correct
vc (vceff). This corrected value is then
used to calculate the proper RPM for
the tool.
Ap1
α
D eff D eff
D 1 D 1
k =
-(D1-2Ap1) 2
2
1
sin [ α + arcCos (1-(2 (Ap1/D1))) ]
v c eff = v c X k
Starting Values for Semi-Finishing in Common Material Types (L/D ratio <3 x D1)
M270 is usually applied for semi-fi nishing and fi nishing operations; Ap1/ae conditions depend on the operation. As a general rule: Ap1/ae )0,05D.
Tool Diameter
max rec.
(mm)
Material
Ø12
max rec.
fz
(mm)
(mm/
tooth) Ap1 ae
Ø16
max rec.
fz
(mm)
(mm/
tooth) Ap1 ae
Ø20
max rec.
fz
(mm)
(mm/
tooth) Ap1 ae
Ø25
max rec.
fz
(mm)
(mm/
tooth) Ap1 ae
Ø32
max rec.
fz
(mm)
(mm/
tooth) Ap1 ae
fz
(mm/
tooth)
Ap1 ae Soft Steel <250 HB 0,7 0,7 0,2 0,8 0,8 0,2 1,1 1,1 0,27 1,3 1,3 0,27 1,7 1,7 0,3 2,1 2,1 0,3
High-Strength Steel
33–44 HRC 0,5 0,5 0,15 0,6 0,6 0,2 0,8 0,8 0,25 1 1 0,25 1,3 1,3 0,25 1,6 1,6 0,25
Hardened Steel
44–55 HRC 0,3 0,3 0,15 0,4 0,4 0,2 0,5 0,5 0,22 0,7 0,7 0,22 0,8 0,8 0,25 1,1 1,1 0,25
1 1 0,2 1,2 1,2 0,25 1,6 1,6 0,25 2 2 0,25 2,5 2,5 0,3 3,2 3,2 0,3
0,7 0,7 0,2 0,8 0,8 0,25 1,1 1,1 0,25 1,3 1,3 0,25 1,7 1,7 0,3 2,1 2,1 0,3
Grey Cast Iron GG25…
Nodular Cast Iron
GGG60…
widia.com
M117
Ø10