What is BTA deep-hole drilling? A plain explanation

BTA drilling is a deep-hole drilling method for larger diameters, used when a hole is far deeper than it is wide and productivity matters. It’s one of the two main deep-hole methods, alongside gundrilling.

How BTA works

In a BTA system, coolant is fed around the outside of the drill tube under pressure, and chips are evacuated back through the centre of the tube. This internal chip evacuation is the key difference — it lets BTA remove a lot of material quickly and keep long, deep holes clean and straight.

BTA vs gundrilling

The short version: gundrilling suits smaller diameters and the highest precision; BTA suits larger diameters and higher output. Gundrilling evacuates chips along an external flute with coolant fed through the tool; BTA reverses that, evacuating chips internally.

Where it’s used

BTA drilling is common in oil & gas (valve bodies, manifolds), hydraulics (large cylinders), and heavy engineering — anywhere large, deep, accurate bores are needed.

If you’re deciding between methods for a specific part, talk to our engineers or read our gundrilling vs BTA guide.