Milling Troubleshooting Chart

• CHATTER (LINES OR GROOVES AT REGULAR INTERVALS IN MACHINED SURFACE)
• POOR SURFACE FINISH - ROUGHNESS
• POOR SURFACE FINISH - FLATNESS
• POOR SURFACE FINISH - WAVINESS
• PART BURRING
• WORKPIECE BREAKOUT
• POOR INSERT LIFE:
  

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