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DRILLING PROBLEMS: CAUSES AND SOLUTIONS
Broken or Twisted Tangs
(a) Possible Cause
Bad fit between the drill sleeve and the shank of the drill.
Solution
(i)
Use only sleeves which are in good condition (avoid
worn or damaged sleeves).
(ii) Ensure the drill shank and sleeve are thoroughly clean.
Note:
The tang is not intended to transmit the drive - it is only used for
ejection. The Morse Taper is self-holding and relies on a good fit in
the sleeve to transmit the drive.
Drill Web Split
(a) Possible Cause
The feed is too great.
Solution
Use the correct feed for the drill size material - see page 14.
(b) Possible Cause
Insufficient lip clearance behind the cutting edge.
Solution
Check that the lip clearance is as per information on page 24/
25.
(c) Possible Cause
Excessive web thinning.
Solution
The web thickness should not be less than 10% of the drill
diameter.
(d) Possible Cause
Using a hard object to seat the drill in the sleeve.
Solution
Use soft material e.g. copper or wood, to seat the drill.
Worn outer Corners
(a) Possible Cause
The peripheral speed is too high for the material being drilled.
Solution
Use the recommended speed - see page 11.
