You may maximise the use of your drill bits by adopting the following drilling recommendations. The next time you have to drill, keep the following advice in mind.

  • Make sure the workpiece is securely held and supported. Should it bend or move, it could cause the drill to break
  • Use a good socket and thoroughly clean both the socket and the taper shank of the drill. Do not use steel objects to seat the drill
  • Straight shank drill chucks must be able to hold the drill securely
  • Keep the drill sharp. Do not allow it to become blunt as it will require extra grinding to get it sharp again
  • Direct an adequate supply of the recommended coolant to the point of the drill
  • Do not allow chips to clog the drill flutes
  • When re-sharpening, take care to achieve the correct point geometry and do not overheat the drill when grinding
  • Use core drills for enlarging existing holes – 2 flute drills are not designed for this purpose
  • Use the correct drill to suit the application

Common Drilling Challenges and Solutions

Broken or Twisted Tangs

Possible Cause Solution
Bad fit between the drill sleeve and the shank of the drill Use only sleeves which are in good condition (avoid worn or damaged sleeves)

Ensure the drill shank and sleeve are thoroughly clean

Drill Web Split

Possible Cause Solution
The feed is too great Use the correct feed for the drill size material
Insufficient lip clearance behind the cutting edge Check that the lip clearance is as per the guided information
Excessive web thinning The web thickness should not be less than 10% of the drill diameter
Using a hard object to seat the drill in the sleeve Use soft material like copper or wood to seat the drill

 

Chipped or Broken Lips

Possible Cause Solution
This is usually caused by excessive lip clearance angles behind the cutting edge Check that the lip clearance is as per the guided information

 

Broken Outer Corners

Possible Cause Solution
Drilling thin material particularly when not properly supported Use a sheet metal drill and clamp the workpiece securely
Using a 2 flute drill to enlarge the diameter of an existing hole Only core drills should be used for this purpose

Oversized and Out of Round Holes 

Possible Cause Solution
Unequal point angles This usually results when hand grinding the point. Use a point grinding fixture or machine
Unequal cutting edge length (lip height) When re-grinding ensure that the same amount of material is removed from both flanks
Loose spindle or worn drill sleeve Use equipment which is in good condition
The workpiece moves Secure the workpiece with a clamp

Cracks in Cutting Edges

Possible Cause Solution
The point is overheated and cooled too quickly when re-sharpening Use coolant when grinding or grind in stages, quenching frequently in soluble oil

Worn Outer Corners

Possible Cause Solution
The peripheral speed is too high for the material being drilled Use the recommended speed when drilling

Drill Rubbing and Not Cutting

Possible Cause Solution
Check that the lip clearance is as per the guided information

Drill Breaks at Flute Runout

Possible Cause Solution
The workpiece moves during drilling Securely clamp the workpiece
The flutes are clogged with swarf Clear the flutes by frequently withdrawing the drill, or use a drill more suited to the material
Using the wrong type of drill Like any other job, select the right drill bit for the job

 

Contact us for help if you ever have questions concerning your drilling application.