How to Achieve Precision in Deep Hole Drilling

Achieving high precision in deep hole drilling is a complex process that requires attentions to multiple factors, from the machine tool to the cutting parameters. The key aspects of precision include: hole diameter tolerance, straightness, surface finish, and roundness.

Here are the critical elements for success:
1. Machine Tool Rigidity and Stability
   - High Static and Dynamic Rigidity
   - Precise Guideways
   - Stable, High-Pressure Coolant System
   - Accurate Spindle
2. Tooling: Drill Bits and Boring Heads
   - Gun Drills, BTA (Boring and Trepanning Association) and STS (Single Tube System).

   - Tool Geometry and Coating:
      * Cutting Edge Geometry
      * Wear-Resistant Coatings
      * Precision Guide Pads
3. Workpiece Preparation and Setup
   - Stable and Secure Fixturing
   - Starting Spot / Pilot Hole
   - Workpiece Support
4. Cutting Parameters and Process Control
   - Optimized Feeds and Speeds (Cutting Data):
   - Speed (SFM / m/min), Feed Rate (IPR / mm/rev), Consistent, High-Pressure Coolant, Pecking Cycle (Optional)
5. In-Process and Post-Process Monitoring
   - Tool Life Management, Monitoring Coolant Pressure.

Post-Process Inspection:
   - Air Gauging: The fastest and most accurate method for measuring internal diameter and roundness in deep holes.
   - CMM (Coordinate Measuring Machine): Used to check hole straightness, location, and geometric profile.
   - Surface Roughness Tester: A profilometer with a long-stylus arm is used to measure the surface finish (Ra, Rz) along the depth of the hole.