Ejector Drilling: Process, Tools & Retrofit

Ejector drilling (Double-Tube System / DTS) uses a Venturi effect to create internal suction for chip evacuation, eliminating the need for a high-pressure seal at the workpiece entry. Coolant flows between the outer and inner tubes, while Venturi nozzles generate suction that pulls chips through the inner tube. This makes it the most practical deep hole drilling method for retrofitting onto standard CNC lathes and boring mills. The DTS covers diameters from 18 mm to 200 mm with depth ratios up to 100:1, offering a balance of productivity and flexibility for medium-to-large hole applications.

How Ejector Drilling Works

Ejector drilling uses two concentric tubes. High-pressure coolant flows between the outer and inner tubes to the cutting head, then passes through Venturi nozzles at the drill head. These nozzles create a pressure drop that generates suction, pulling the coolant and chips back through the inner tube. Because chip evacuation relies on this suction rather than a sealed pressure head, ejector drilling can be set up on standard lathes and machining centers with a simple chuck or fixture — no pressure-head seal at the workpiece entry, and no dedicated machine required.

Key Capabilities

Ejector Drilling Core Topics

• What is ejector drilling? — the double-tube system explained → What is Ejector Drilling
• How the process works, step by step → Ejector Drilling Process
• Parameters — speeds, feeds, and coolant → Ejector Drilling Parameters
• Tooling and drill heads → Ejector Drilling Tools
• CNC setup on standard lathes → Ejector Drilling CNC Setup
• Applications across industries → Ejector Drilling Applications
• Troubleshooting common ejector problems → Ejector Drilling Troubleshooting
• Ejector vs BTA vs gun drilling → Method Comparison

When to Choose Ejector Drilling

Choose ejector drilling when you need medium-to-large holes (18–200 mm) but do not have — or do not want to invest in — a dedicated BTA machine. Because it needs no pressure-head seal, ejector drilling retrofits onto existing CNC lathes and boring mills, making it the lowest-capital option for in-house deep hole drilling. If you need the highest precision for small diameters, gun drilling is a better fit; if you already run high-volume production of large holes, BTA drilling is faster.

Start Here

New to ejector drilling? Read what is ejector drilling first, then walk through the process overview. To compare it against the other methods, see the deep hole drilling method comparison.