PROBLEM |
CAUSES |
SOLUTIONS |
CHATTER (lines or grooves at
regular intervals) |
Lack
of rigidity |
Check
spindle & fixture rigidity |
Excessive
cutting force |
Reduce
feed rate, depth of cut or width of cut if excessive |
Use
sharp edge inserts; avoid hone or T-land |
Thin-walled
part |
Dampen
part |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR SURFACE FINISH - Roughness |
Insert
worn |
Use
more wear resistant coated grade |
Built-up
edge |
Increase
speed, use PVD coated inserts, use coolant |
High
tooth |
Correct
improper preset. Set wiper |
Wiper
insert set too high |
.0005"
to .002" above high insert |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR SURFACE FINISH - Flatness |
Deflection |
Check
for deflection of part, cutter or spindle |
Improper
spindle tilt (milling machines) |
Check
spindle tilt - .0015" per foot is recommended |
Excessive
cutting force |
Use
a more positive rake cutter |
Width
of cut too large for cutter |
Use
a larger diameter cutter |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR
SURFACE FINISH - Waviness |
Advance
per revolution greater than width of flat of insert |
Deflection |
Reduce
feed rate |
PROBLEM |
CAUSES |
SOLUTIONS |
PART BURRING |
Insert
worn |
Use
more wear resistant coated grade |
Excessive
insert edge prep |
Reduce
or avoid hone or T-land |
Improper
angle of entry or exit of cutter |
Change
position of center of cutter over part |
Improper
lead angle |
Use
larger lead angle; avoid 0° lead angle cutters |
Chip
load too great or too small |
Increase
or decrease chip load |
PROBLEM |
CAUSES |
SOLUTIONS |
WORKPIECE BREAKOUT |
Improper
geometry |
Use
larger lead angle; avoid 0° lead angle cutters |
Use
inserts with double facet corners |
Improper
angle of entry or exit of cutter |
Change
position of center of cutter over part |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Flank Wear |
Excessive
heat |
Reduce
speed. Increase chip load to carry away heat |
Use
coolant |
Incorrect
grade |
Use
a more wear resistant coated grade |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Crater Wear |
Excessive
heat |
Use
a more heat resistant coated grade (Al2O3 layer) |
Reduce
speed |
Flush
with coolant |
Excessive
cutting force |
Reduce
feed rate |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Built-up Edge |
Insufficient
cutting temperature causes chip adherence to insert |
Increase
speed |
Use
coolant to aid lubricity |
Use
sharp edge inserts |
Use
grades with high lubricity surfaces (PVD coated grades, Cermet grades,
polished carbide grades) |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Chipping |
Chatter |
Check
spindle & fixture rigidity |
Reduce
feed rate, depth of cut or width of cut if excessive |
Use
sharp edge inserts; avoid hone or T-land |
Insufficient
edge prep |
Use
hone or T-land |
Incorrect
grade |
Use
tougher grade |
Built-up
edge |
Increase
speed, use PVD coated grade, use coolant |
Excessive
cutting force |
Decrease
feed per tooth |
Re-cutting
chips |
Use
cutter with chip gullets large enough for chip clearance. |
Use
air blast or coolant to remove chips. |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Depth of Cut
Notching |
Scale
part, high work hardening materials |
Use
larger lead angle; avoid 0° lead angle cutters |
Use
more wear resistant grade |
Reduce
feed per tooth |
Reduce
speed |
Use
T-land |
Vary
depth of cut |
PROBLEM |
CAUSES |
SOLUTIONS |
POOR INSERT LIFE - Thermal Cracks |
Heat
stresses due to temperature variations |
Reduce
speed |
Use
cutter with more positive geometry |
Use
grade designed for use with coolant |
Discontinue
coolant use |