Page 1039 - Tungaloy Catalog

Technical Reference
Drilling Tools
Troubleshooting for solid drills and brazed drills

Problem Cause Countermeasure
•Inappropriate cutting speed •Increase the cutting speed by 10 % within standard conditions if abnormal wear is around center.
•Lower cutting speed by 10 % within standard conditions if abnormal wear is on the periphery.
Relief surface
•Inappropriate cutting fluid •Check the filter.

•Use cutting fluid superior in lubricity. (Increase the dilution rate)
Abnormal wear •Inappropriate cutting speed •Lower the cutting speed by 10 %.
•Regrinding timing, insufficient reground amount
•Shorten the regrinding timing.
•Insufficient rigidity of the machine and workpiece
•Change the clamp method to one with rigidity.
Margin
•Insufficient drill rigidity
•Inappropriate cutting fluid •Use smallest possible overhang.
•Check the filter.
•Use cutting fluid superior in lubricity. (increase the dilution rate)
•Intermittent cutting when entering •Avoid interruption at entry and exit.
•Lower the feed rate by about 50 % during entering into and leaving the workpiece.
•Insufficient rigidity of the drill •Reduce the drill overhang as much as possible.
•Increase the feed at entry when the low speed feed is selected in standard cutting condition range.
•Use a bushing or a center drill.
Chisel section
•Insufficient rigidity of the machine and workpiece •Change the clamp method to one with rigidity.
(center of drill
•Inappropriate entry into •Avoid interruption at entry into the workpiece.
cutting edge)
the workpiece •Lower the feed rate by 10 % at entry.
•Lower the feed rate by 10 %.
•High workpiece hardness
Chipping and fracture cutting edge •Insufficient drill rigidity •Lower the cutting speed by 10 %.
•Check if honing has been made to the center of cutting edge.
•Inappropriate honing
•Increase the feed at entry when the low speed feed is selected in standard cutting condition range.

Peripheral
•Check the run out accuracy after drill installation. (.001 in or less)
•Inappropriate drill mounting accuracy
•Change the clamp method to one with rigidity.
•Insufficient machinery
and workpiece rigidity
•Inappropriate honing
•Check if honing has been made to the cutting edge periphery.
•Insufficient machine and workpiece rigidity •Lower the feed during entering into and leaving the workpiece.
•Change the clamp method to one with rigidity.
•Insufficient drill rigidity •Use smallest possible overhang.
Margin •Use a bushing or center drill.
•Regrinding timing and insufficient amount of reground stock. •Shorten the regrinding timing.
•Intermittent cutting when •Avoid interruption at entry and exit.
entering or exiting the cut. •Lower the feed rate by about 50 % during entering into and leaving from the workpiece.
•Tendency to cause chipping or •Check the failure mode condition before breakage and find out the wear and
develop abnormal wear chip countermeasures. Technical Reference
•Chip packing in the drill flutes •Review the cutting conditions.
Breakage •For internal coolant supply, raise the supply pressure of cutting fluid.
•Use peck feed for deep holes.
•Insufficient machine output •Review the cutting conditions.
•Use machine with high power. 14
•Insufficient rigidity of the machinery and workpiece. •Change to the clamp method with rigidity
•Inappropriate drill installation accuracy •Check the run out accuracy of drill mounting. (.001 in or less)
Insufficient hole •Chip packing in the flutes. •Review the cutting conditions.
accuracy •Raise the cutting oil supply pressure.
•Use peck-feed for deep holes.
•Inappropriate edge sharpening accuracy •Check the edge shape accuracy.
•Inappropriate cutting conditions •Increase the feed rate by 10 % within standard conditions.
Prolonged chips •Inappropriate honing •Provide the appropriate honing.
•Cutting edge with chipping or breakage •Lower the cutting speed by 10 %.

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