Milling Troubleshooting Chart

Flank wear Crater wear Built-up edge
Chipping Depth-of-cut notching Thermal cracking

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

Put the numbers to work

Your feeds and speeds are only as good as the cutter running them. These solid carbide end mills are ground to hold those numbers under load.

General Purpose End Mills → Roughing / Turbo Mills Hot Mills

New to speeds and feeds? Read the full breakdown in TechTalk.