Section N Technical Guide

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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