Carbide Tipped Cutting Tools - Drills, Reamers, Cutters, End Mills & Counterbores Single Points

CARBIDE TIPPED PROBLEM SOLVING GUIDE

DRILLING
PROBLEMS

REAMING
PROBLEMS

MILLING
PROBLEMS

AVOID
PROBLEMS
BY CAREFUL
ORIGINAL
SET-UP

MACHINE CONDITION
TOOL CONDITION

FEEDS & SPEEDS
COOLANT

Tool holder in good condition & secure part holding fixture.

Use cutting tool recommended for material being machined.
Avoid excessive tool overhang.

Start with feeds & speeds recommended for material being machined.

Where used, coolant flow must be adequate to avoid intermittent quenching and to flush chips promptly, avoiding the recutting of hardened chips.

DRILLING PROBLEMS	POSSIBLE CAUSES	POSSIBLE SOLUTIONS
1. CHIPPED CUTTING EDGE
	Excessive feed	Reduce feed.
	Excessive lip relief	Reduce lip relief to provide smaller chisel angle.
	Vibration	Frequently a worn drill bushing replace.
	Thermal cracking carbide	Maintain adequate coolant flow at all times to avoid thermal shocking carbide.
2. SHORT TOOL LIFE
	Drill dwelling	Maintain adequate feed at all times.
	Only one lip cutting	Regrind with equal lip heights and chisel in center.
3. DRILL WALKS OR DRIFTS
	Unequal lip heights	Regrind with equal lip heights and chisel in center.
	Worn drill bushing	Replace drill bushing.
4. OVERSIZE HOLES
	Unequal lip heights	Regrind with equal lip heights and chisel in center.
	Excessive lip relief	Reduce lip relief to provide smaller chisel angle.
	Worn drill bushing	Replace drill bushing.
5. ROUGH FINISH
	Dull cutting edge	Regrind with fine grit diamond wheel.
	Inadequate coolant	Review type of coolant and maintain adequate flow.
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REAMING PROBLEMS	POSSIBLE CAUSES	POSSIBLE SOLUTIONS
1. POOR FINISH
	Unequal chamfers	Regrind reamer with equal chamfer angle.
	Incorrect margins	Regrind reamer with narrow margins for reaming lower tensile materials.
	Excessive spindle runout	Increase reamer back taper (will lose size faster).
	Chatter	Reduce speed and increase feed rate.
		Use power feed unless material is hard.
		Use right or left spiral fluted reamer.
		Grind secondary lead angle immediately back of 45º chamfer.
2. OVERSIZE HOLE - TAPERED HOLE - BELL MOUTH HOLE - POOR FINISH
	Misalignment	Use bushing -- .0002"/.0003" over reamer diameter.
		If hole location varies, use floating reamer holder.
		Increase reamer back taper (will lose size faster).
	Insufficient cutting action	Specify reamer with positive radial rake to reduce cutting pressure -- may produce slightly larger diameter holes.
3. EXCESSIVE TOOL WEAR
	Insufficient stock for removal	Decrease previous operation drill size to allow more material for removal by reamer - leave about 3% of hole diameter for cast iron and more stock for non-ferrous materials.
	Excessive reaming pressure	Increase feed rate.
		Reduce stock to be removed by increasing previous operation drill size -- leave about 3% of hole diameter.
	Misalignment	See problem #2 above.
4. CROOKED HOLES
	Not drilled straight	Correct previous drilling operation -- reamer will follow the drilled hole.
		Increase reamer attack angle (chamfer) to 120º/180º included angle.
5. TOOL BREAKAGE
	Excessive reaming pressure	Reduce stock to be removed -- see problem #3 above.
	Misalignment	See problem #2 above.

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MILLING PROBLEMS	POSSIBLE CAUSE	POSSIBLE SOLUTION
1. ROUGH FINISH
	Dull cutting edge	Resharpen to original tool geometry.
	Wrong feeds & speeds	Increase speed -- also try reduced feed.
2. EXCESSIVE CUTTING EDGE WEAR
	Wrong feeds & speeds	Increase feed (should always be over .001" per tooth) -- especially when machining ductile or free machining materials. -- Also try reduced speed
	Rough cutting edge	Lightly hone cutting edge with fine grit diamond hone.
	Insufficient coolant	Increase coolant flow -- review type of coolant.
3. CHIPPED CUTTING EDGE
	Poor chip removal --	Use tool with larger flute space -- larger diameter or fewer flutes.
	Recutting work hardened chips	Increase coolant flow.
	Vibration	Increase rigidity of set-up, especially worn tool holders.
	Incorrect carbide grade	Change to tougher carbide grade.
4. CHATTER MARKS
	Insufficient machine horsepower	Use tool with fewer flutes as correct speeds & feeds must be maintained.
	Vibration	Consider climb milling.
		Use larger diameter cutter.
		Resharpen tool with more clearance.
5. GLAZED FINISH
	Feed too light	Increase feed.
	Dull cutting edge	Resharpen tool to original geometry.
	Insufficient clearance	Resharpen tool with more clearance.
6. POOR TOOL LIFE
	Excessive cratering	Increase speed or decrease feed.
		Change to harder grade of carbide.
	Milling abrasive material	Decrease speed and increase feed.
		Increase coolant flow.
		Climb milling better than conventional milling.
	Milling surface scale	Conventional milling better than climb milling.
	Milling hard material	Reduce speed -- rigidity very important.
	Insufficient chip room	Use larger diameter tool.
	Delayed resharpening	Prompt resharpening to original geometry will increase total tool life.
	Thermal cracked carbide	Increase coolant flow at all times.
		Climb milling is cooler than conventional milling.
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