Technical Guidance Chip Control and Countermeasures, Turning Edition
■ Type of Chip Generation Flowing Shearing
■ Type of Chip Control
Depth of cut
A
B
C
D
E
Tearing
Cracking
Large
Classification of chip shapes
Work Material
Work Material
Work Material
Work Material
Small
Continuous chips with good surface finish General cutting of steel and light alloy
Chip is sheared and separated by the shear angle Steel, stainless steel (low speed)
Chips appear to be torn from the surface Steel, cast iron (very low speed, very small feed rate)
Chips crack before reaching the cutting point Cutting of general cast iron and carbon
NC lathe (for automation) General-purpose lathe (for safety)
H H S S J
H S S S to J H
N
Good: C type, D type
Large Large Small Large
Deformation of work material Rake angle Depth of cut Cutting speed
Small Small Large Small
A type: Twines around the tool or workpiece, damaging the machined surface and affecting safety B type: Causes problems in the automatic chip conveyor and chipping occurs easily E type: Causes spraying of chips and poor surface finish due to chattering, along with chipping, large cutting force and high temperatures {
Poor
■ Factor of Improvement of Chip Control (1) Increase feed rate ( f )
.1575
t 1
t 2
f 2
f 1
.0787
f: : When f 2 > f 1, t 2 > t 1
When the feed rate increases, the chip thickness (t) increases and chip control improves.
.0039
.0079
.0118
.0157
0197
Feed Rate f (IPR)
(2) Decrease side cutting edge ( : )
θ 2 :
θ 1 :
45°
t 1
t 2
f
f
: When : 2 < : 1 , t 2 > t 1
15°
Even if the feed rate is the same, a smaller side cutting edge angle makes chips thicker and chip control improves.
.0079
.0098
.0118
.01378
Feed Rate f (IPR)
(3) Reduce nose radius (RE)
t 2
t 1
.0630
RE2
RE1
Corner Small radius
Corner Large radius
f
f
RE : When RE2 < RE1, t 2 > t 1
.0315
Even if the feed rate is the same, a smaller nose radius makes chips thicker and chip control improves. * Cutting force increases proportionately to the length of the contact surface. Therefore, a larger nose radius increases back force which induces chattering. A smaller nose radius produces a rougher surface finish at the same feed rate.
.0157
.0197
.0394
.0591
.0787
Depth of Cut a p (inch)
N39
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