End Mills
C26
How to determine cutting conditions of end mills
1 (vc) (n)(1) Cutting speed (vc) and revolution number (n)vc 1
Cutting speed (vc) can be generally determined by tool material
grade and the kind of work material. Tool material grade is usually
selected within the range given in Table 1.
1vcTable 1 Cutting speed by material grade
2 (v f) 1 (fz)(2) Feed speed (v f) and feed per tooth (fz) v
f1fz2 8020 50Working efficiency is determined by the table speed (v
f), but the feed per tooth should be fixed first of all in setting
cutting conditions. Other conditions should be determined
considering dimension of a tool (mill diameter and flute length),
number of flutes, work ability of work material to be used,
machining precision, and capacity of a machine to be used. Table 2
serves as a guide for the short flute length type end mills. In the
case of regular flute length type, select the value about 80% the
feed per tooth of the short flute length type. As for the long
flute length type, select the value less than that of the regular
flute length type. In the case of the roughing end mill, select the
value larger than the short flute length type by 20 to 50%, though
they may vary more or less depending on the mill diameter.
21 Per-tooth feed rate for short flutes
HSS-Co
Coated HSS
ESMP/M HSS
Carbide
Coated Carbide
Cermet
vc=1530m/min
(n) Dc When work material has excellent workability, when there
is little depth of cut, or when sufficient cutting fluid can be
used, select rather high cutting speed. When work ability of work
material is unknown, it is safe to try nearly the lowest cutting
speed at first, and then increase the speed gradually. The
revolution number (n) is calculated by the following formula using
cutting speed and flute length of the tool to be used. When cutting
work is performed by using only a ball end cutting part of a ball
end mill, however, select a tool with the substantial flute length
equal to the maximum diameter of the portion to be cut. In
calculation, set Dc to a smaller value according to the cutting
condition.
n (min-1)1000vc Dc
Dc Mill diameter, mm
3.14 Ratio of circumference of a circle to its diameter
(3.14)
Dc
Dc
Tool Dia.
6
12
20
22-Flutes
44-Flutes
0.02 0.04
0.04 0.08
0.08 0.12
0.01 0.03
0.03 0.06
0.06 0.10
1
v f fz z n (mm/min)z Number of flutes
n min-1 Revolution, min. -1
3 (apae)(3) Depth of cut (apae)apae DcDc 21 Depth of cut (ap ae)
is basically determined by the size of machining allowance.General
end mills usually have the upper limit of cut area of around DcDc
inheavy-duty cutting. Therefore, if large machining allowance is
assumed, it is recommended to adopt an end mill with a large mill
diameter. Besides, care must be taken for products designed for
finishing and cutting small grooves, for example, Epoch21 series
and long flute length series, so as not to be cut excessively.
4Q(4) Chip removal volume
20 45
20 60
30 60
40 80
50 100
Q cm3/minap ae v f1000Q cm3/min Chip removal volumeap Cutting
depthae Cutting widthv f 1 /min Feed rate per minute of table
n min-1 Revolution, min-1
vc m/min Cutting speed, m/min.
v f /min Feed speed, mm/min.
fz1 /t Feed/tooth, mm/tooth
