1. Use of standard and extended length holders
2. Starting on an inclined surface
3. Worn or mis-aligned spindle (e.g. lathe, screw machine, chucker)
4. Use of low rigidity machine tools (e.g. radial drills, multi-spindle drill press etc.)
5. Poor work piece support
6. Flood coolant, low coolant pressure or low coolant volume
7. Interrupted cuts. Entry or exit surfaces that are not perpendicular to the spindle. (e.g., draft angles, parting, lines, curved or stepped surfaces, cross holes and cast or forged surfaces).
8. Material harder than expected or running tools beyond recommended speed.
9. Poor material microstructure or foreign particles: (e.g., forgings and castings that have not been normalized or annealed, poorly prepared steel flame cut parts and sand casting).
10. Poor chip control
11. Spot drilled holes with included angle less than that matching T-A ^® or cored holes.
12. Use of high wear resistant tool grades.

1. Barber pole
2. Bell mouth hole
3. Chatter
4. Chipping of blade point
5. Hole lead off
6. Hole out of position
7. Retract spiral

• Start with short holder and drill a minimum depth to the margin length.
• Spot hole with stub tool of same or greater included angle as T-A^®.
• Decrease feed a minimum of 50% until establishing full diameter.
• Use a special holder with wear pads or chrome bearing area to work with drill bushing.

1. Chatter
2. Chipping of blade point
3. Damaged or broken tools
4. Excessive margin wear
5. Hole lead off
6. Hole out of round
7. Retract spiral

• Spot face surface to provide a flat entry surface.
• Spot hole with stub tool of same or greater included angle as T-A^®
• Decrease entry feed minimum of 50% until establishing full diameter.
• Use special holder with wear pads or chrome bearing area to work with drill bushing.

1. Accelerated corner wear
2. Bell mouth hole
3. Chatter
4. Chipping of blade point
5. Damaged or broken tools
6. Excessive margin wear
7. Hole lead off
8. Oversize hole
9. Poor hole finish
10. Retract spiral

Possible Solutions:

• Align spindle and Turret or Tailstock.
• Repair spindle.
• Spot hole with stub tool of same or greater included angle as T-A^®

1. Barber hole
2. Bell mouth hole
3. Blade chipping
4. Chatter
5. Chipping of blade point
6. Damaged or broken tools
7. Hole lead off
8. hole out of postion
9. Retract spiral

• Spot hole with stub tool of same or greater included angle as T-A^®
• Reduce penetration rate to fall within the physical limits of the machine or setup (Caution:Do not reduce feed below threshold of good chip formation).
• Use special holder with wear pads or chrome bearing area to work with drill bushing.
• Use tougher tool steel grades with high wear resistant coatings.

1. Barber pole
2. Blade chipping
3. Chatter
4. Damaged or broken tools
5. Excessive margin wear
6. Hole out of round
7. Poor hole finish
8. Restract spiral

• Provide additional support for the work piece.
• Reduce penetration rate to fall within the physical limits of the machine or setup (Caution:Do not reduce feed below threshold of good chip formation).
• Use tougher tool steel grades with high wear resistant coatings.

1. Accelerated corner wear
2. Blue chips
3. Build Up Edge (BUE)
4. Chip packing
5. High flank wear
6. Oversize hole
7. Poor hole finish
8. Poor tool life
9. Power spikes - Load meter
10. Step burned on blade

• Run coolant through tool holder when drilling greater than 1x diameter.
• Increase coolant pressure and volume through the tool holder.
• Reduce penetration rate to fall within the physical limits of the machine or setup (Caution:Do not reduce feed below threshold of good chip formation).
• Add a peck cycle to help clear chips.

1. Blade chipping
2. Chatter
3. Chipping of blade point
4. Damaged or broken tools
5. Excessive margin wear
6. Hole lead off
7. Hole out of position
8. Hole out of round
9. Oversize hole
10. Poor hole finish
11. poor tool life

• Pre-mill (spot face) entry or exit surface to remove interruption.
• Spot hole with stub tool of same or greater included angle as T-A^®.
• Decrease feed as much as 50% through entry or exit interruption.
• Use short holders in low impact entry cuts.

1. Accelerated corner wear
2. Blue chips
3. Build Up Edge (BUE)
4. Damaged or broken tools
5. High flank wear
6. Poor tool life
7. Step burning on blade

• Reduce speed. If a step is worn in the blade, calculate SFM at the worn diameter. Reduce this value by 10% and apply this new value to the original tool diameter.
• Increase coolant pressure and volume
• Improve coolant condition by use of quality products and regular maintenance.
• Select a tool grade (premium, super cobalt, or carbide) or coating (TiAIN or TiCN) that is more wear and heat resistant.

1. Blade chipping
2. Build Up Edge (BUE)
3. Damaged or broken tools
4. High flank wear
5. Hole lead off
6. Notching of blade
7. Poor tool life

• Compare performance of other tools for similar wear problems, which may indicate poor micro-structure. Anneal or normalize parts to improve micro-structure for machining.
• To improve tool life in materials with poor micro-structure try carbide grades.
• For hard spots or inclusions use the tougher steel grades with high wear resistant coatings (e.g. TiAIN, TiCN).
• Reduce feeds.(Caution: Do not reduce feed below threshold of good chip formation).

1. Chip packing
2. Damaged or broken tools
3. Excessive margin wear
4. Hole lead off
5. Oversize hole
6. Poor hole finish
7. Poor tool life
8. Power spikes - Load meter

• Increase feed to recommended levels. Contact the Allied Application Engineering Group for technical recommendations.
• Increase coolant pressure and volume
• Improve coolant condition by use of quality products and regular maintenance.
• See Geometry & Grades for special purpose geometries.

1. Accelerated corner wear
2. Blade chipping
3. Chatter
4. Hole lead off
5. Notching of blade
6. Poor tool life

• Spot hole with stub tool of same or greater included angle as T-A^®.
• Reduce feeds. (Caution:Do not reduce feed below threshold of good chip formation). If possible drill from solid

1. Blade chipping
2. Damaged or broken tools

• Use tougher grade of T-A^® (i.e., from carbide to cobalt to HSS). See the Inch Wear vs. Toughness Chart or the Metric Wear vs. Toughness Chart.
• Increase rigidity of setup.