Changing from gun drilling to BTA or ejector changes the fluid and chip routes as well as the tool. A diameter-based shortlist can be useful within a supplier’s range, but it does not describe the complete installation change.
Start with the conventional gun-drilling route
UNISIG’s machine overview describes fluid supply through the gun drill and external return along its groove. Entry guidance, external tool support and the chip-return enclosure are parts of that installation. The diagram below follows those functions rather than prescribing an operating pressure.
The head’s guidance inside the bore does not replace entry guidance or external support. When considering an existing machining centre, identify which functions are already available and which require additional equipment.
BTA and ejector route the return differently
The botek BTA catalogue describes external supply around the drilling tube and return through it. The ejector catalogue describes a double-tube arrangement with supply and return separated within the tube system.
These publications describe named tool and connection configurations. An ejector option offered without a pressure-head seal does not remove every guidance requirement. Likewise, an existing through-tool coolant connection does not establish that the machine has a suitable BTA return path or the relevant pressure-head interface.
Compare a complete candidate route
For each candidate, identify the selected tool range, workpiece entry condition, guidance arrangement, fluid supply and chip return. Retain any access and subsequent-operation requirements from the actual drawing. A material name and hole depth alone leave several of those decisions open.
Claims of better cycle time or precision require comparable results for the specified part and acceptance requirements. The cited architecture descriptions do not provide a universal three-process ranking, diameter crossover or accepted-output trial. Tool ranges should remain attached to their named products rather than being promoted into immutable boundaries between processes.
Convert the comparison into a proposal
Use the RFQ worksheet to describe the present route and the proposed change. Ask a supplier to identify the installation functions and inspection evidence included in its proposal. A quote for a tool head and a quote for a complete drilling route cover different work.
Continue to the BTA and ejector introductions for their respective architectures. The comparison remains open until the selected configuration and inspected deliverable are defined.
Revision note
October 8, 2026: revised the technical explanation and connected reading after source review. Original publication date and URL retained.
