Sandvik Coromant Heat resistant super alloys - Manual (Page 87)

85
Effect of feed per tooth, f
z
As with round carbide inserts the chip thickness varies and depends upon the entering
angle. With low a
p
/iC ratios the feed can be increased in order to raise the chip thickness
to the desired level.
Selecting the correct h
ex
value when milling with ceramic inserts is critical. Always modify
the feed depending upon the entering angle, max chip thickness (h
ex
).
Top slice/flank wear Even flank wear
Ceramic cutter, Insert grade CC6060,
z
n
4, D
3
63 mm, v
c
1000 m/min, a
e
32 mm,
f
z
0.12 mm/tooth, a
p
1.5 mm, Material: Waspalloy
Ceramic cutter, Insert grade CC6060,
z
n
4, D
3
63 mm, v
c
1000 m/min, a
e
32 mm,
f
z
0.1 mm/tooth, a
p
1.5 mm, Material: Waspalloy
Result – feed/tooth too high resulting in
excessive heat and top slice. Result – feed/tooth correct for application
giving an even wear pattern.
Effect of a
p
/entering angle
Selecting the correct cutting depth/entering angle when face milling in HRSA materials has
an effect on the tool life and productivity. When milling with ceramic inserts the entering
angle is critical due to poor notch resistance, performance is best with depth of cut a
p
between 1.5 to 2.5 mm (
k
r
= 40 to 50º).
Ceramic versus carbide comparison – milling in Inconel 718
Maintain constant engagement where possible – soft entry into cut.
Application
Coolant
Insert
Cutting speed, v
c
(m/min)
Diameter, D
3
(mm)
Spindle speed, n (r/min)
Feed rate, f
z
(mm/tooth)
Number of teeth, z
n
Depth of cut, a
p
(mm)
Radial immersion, a
e
(mm)
Metal removal rate, Q (cm 3 /min)
Tool life, (min)
Total material removed, Q
t
(cm 3 )
Conventional/up milling
Dry
RNGN 120700E 6060
1000
63
5052
0.1
4
1.5
35
106
3
318 Climb/down milling
Wet
R300-1240E-MM 2040
30
63
152
0.3
6
2
35
19
25
477
Ceramic Carbide