Ejector Drilling Troubleshooting: Coolant Flow, Chip Jams, and Tool Wear
How Ejector Coolant Flow Works: Inner and Outer Tube Before you can troubleshoot an ejector system, you have to understand how the coolant actually moves through the tool. I spent my first year working on ejector drills thinking the coolant flow was similar to BTA – and I paid for that assumption with scrapped parts and broken tooling. Ejector drilling uses a dual-tube system. The outer tube carries the drill head, and the inner tube runs concentrically inside it. Coolant enters the system at the outer annulus – the space between the inner and outer tubes. About two-thirds of the coolant flows forward to the drill head, where it exits through the clearance gap between the drill head and the bore wall. This forward flow lubricates the cutting edges and guide pads, and it carries chips back along the flute area into the outer tube annulus. ...