Technical Guidance Troubleshooting for Drilling, Drilling Edition
■ Troubleshooting for Drilling Failure
Cause
Basic Remedies
Countermeasure Examples
· Use higher cutting speeds
· Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog
· Inappropriate cutting conditions
Excessive Wear on Rake Face
· Increase feed rate
· Reduce pressure if using internal coolant · 1.5MPa or less (external coolant supply can be used at hole depths (L/D) of 2 or less) · Use coolant with more lubricity · Use JIS A1 grade No.1 or its equivalent · Reduce feed rate at entry point · f =.0031 to .0047” · Pre-machining of flat surface for entry · Drill flat base with Flat MultiDrill · Change cutting conditions to reduce resistance · Increase v c to decrease f (reduce thrust) · Improve clamp strength of work material · Increase size of chisel width · Use a chisel with a width of .004 to .008” · Increase amount of honing on cutting edge · Increase the width of the thinning area at the centre by 1.5 times
· Unsuitable coolant
Chisel Point Breakage
· Off-center starts
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· Equipment, part materials, etc. lack rigidity · Cutting edge is too weak · Inappropriate cutting conditions · Unsuitable coolant
· Decrease the cutting speed
· Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Use JIS A1 grade No.1 or its equivalent
Breakage on Peripheral Cutting Edge
· Reduce feed rate
· Use coolant with more lubricity
· Equipment, part materials, etc. lack rigidity · Improve clamp strength of work material · Cutting edge is too weak · Increase amount of honing on cutting edge · Increase the width of the outer cutting edge by 1.5 times · Reduce the front relief angle · Reduce the front relief angle by 2 to 3° · Entry from peripheral cutting edge · Increase margin width (W margin specification) · Increase the margin width by 2 to 3 times
· Reduce feed rate · Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Increase amount of honing on cutting edge · Increase the width of the outer cutting edge by 1.5 times · Reduce the front relief angle · Reduce the front relief angle by 2 to 3°
· Interrupted through cutting
· Inappropriate cutting conditions · Decrease the cutting speed
· Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Use JIS A1 grade No.1 or its equivalent
Margin Wear
· Use coolant with more lubricity
· Unsuitable coolant
· Use more coolant · If using external coolant, switch to internal coolant · Remaining margin wear · Schedule for earlier regrind and ensure back taper · If margin damage occurs, regrind to 1mm or less
· Increase amount of back taper
· Make back taper 0.5/100
· Improper tool design
· Reduce margin width
· Reduce the margin width to around 2/3
· Use the optimal cutting conditions and tools · Refer to recommended cutting conditions listed in the Cutting Tools Catalog · Use more coolant · If using external coolant, switch to internal coolant
Drill Breakage
· Chip blockage
· Holding clamp too weak · Equipment, part materials, etc. lack rigidity
· If the collet chuck is damaged, replace it · Change the collet holder to the next size up
· Use strong holding clamp
· Improve clamp strength of part material · Reduce feed rate at entry point
· f =.0031 to .0047”
Oversized Holes
· Off-centre starts
· Decrease the cutting speed
· Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog
· Pre-machining added for entry in planar surfaces · Planar machining with endmill · Use the optimal drill type for the hole depth · Refer to the Cutting Tools Catalog · Improve overall drill rigidity · Large web, small groove width
· Drill bit lacks rigidity
· Improve drill mounting precision · Improve drill retention rigidity · Improve clamp strength of part material
· If the collet chuck is damaged, replace it · Change the collet holder to the next size up
· Drill bit has runout
· Equipment, part materials, etc. lack rigidity · Inappropriate cutting conditions · Unsuitable coolant · Off-centre starts · Drill is not mounted properly · Equipment, part materials, etc. lack rigidity · Inappropriate cutting conditions
· Increase the cutting speed
· Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Refer to the lower limit of the recommended cutting conditions listed in the Cutting Tools Catalog
Poor Surface Roughness
· Reduce feed rate
· Use coolant with more lubricity
· Use JIS A1 grade No.1 or its equivalent
· Increase feed rate
· Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog · If the collet chuck is damaged, replace it · Change the collet holder to the next size up
Holes are not straight
· Improve drill mounting precision · Improve drill retention rigidity · Improve clamp strength of part material · Select a double margin tool
· Refer to the Cutting Tools Catalog
· Increase cutting speeds
· Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog
Chips clog
· Increase feed rate
· Poor chip evacuation · Increase volume if using internal coolant
· Increase feed rate
· Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog
Long Stringy Chips · Inappropriate cutting conditions
· Increase cutting speeds · Refer to the upper limit of the recommended cutting conditions listed in the Cutting Tools Catalog · Strong cooling effect · Reduce pressure if using internal coolant · The pressure should be 0.5 MPa or less if using internal coolant · Dull cutting edge · Reduce amount of edge honing · Reduce the width to around 2/3
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