Causes:

• Workpiece deflection during drilling and springback after breakthrough
• Insufficient machine tool rigidity
• Inadequate drill material strength
• Excessive drill runout (>0.02mm)
• Poor toolholder clamping rigidity

Solutions:

1. Reduce cutting speed
2. Increase feed rate
3. Optimize coolant direction (prefer internal cooling)
4. Add chamfer at breakthrough point
5. Verify drill concentricity (TIR <0.02mm)
6. Check/optimize relief angle geometry

2 Flute Chipping/Breakage

Causes:

• Workpiece deflection and springback
• Machine tool rigidity issues
• Suboptimal drill material
• Excessive runout
• Insufficient clamping force

Solutions:

1. Use drills with larger web taper
2. Verify spindle runout (<0.02mm)
3. Pre-drill with spot drill
4. Implement rigid tooling:
   • Anti-vibration drills
   • Shrink-fit/hydraulic holders
   • Collet systems with neck relief

3 Built-Up Edge (BUE)

Causes:

• Chemical affinity between tool and workpiece materials (notable in high-carbon low-alloy steels)

Solutions:

1. Enhance coolant performance:
   • Increase lubricant content
   • Add EP additives
2. Adjust parameters:
   • ↑ Cutting speed
   • ↓ Feed rate
3. For aluminum:
   • Use polished, uncoated drills

4 Tool Breakage

Causes:

• Chip evacuation failure
• No feed reduction at breakthrough
• Overshoot in soft materials (copper/brass) due to:
  • Excessive relief angles
  • Unmodified rake angles
• Overly sharp cutting edges causing edge collapse

Solutions:

1. Implement preventive tool replacement
2. Enhance tool mounting:
   • Increase support area
   • Boost clamping force
3. Maintain machine components:
   • Spindle bearings
   • Guideways
4. Use precision holders (hydraulic type preferred)
5. Select tougher tool materials