Support-Pads

Problem Description BTA drilling machines face unique wear challenges that standard gun drilling machines don’t. The coolant and chips flow through the center of the drill tube, so internal abrasion is constant. I’ve cut open BTA drill tubes that had worn through 2 mm of wall thickness over 2,000 hours of operation — hidden damage that would eventually cause a catastrophic tube failure. The support pads on BTA cutting heads also wear in ways that affect bore quality. Worn pads allow the head to chatter, producing a bore with spiral marks that fail surface finish requirements. ...

BTA tooling has more components than gun drilling tooling. The cutting head, drill tubes, guide pads, and driver system all need to work together for successful drilling. Here is what I have learned about each component after years of BTA drilling on production jobs. BTA Cutting Head Types BTA cutting heads come in several configurations. The right head type depends on the diameter range and material. Head Type Diameter Range Cutting Edges Best For Standard single-tube 18 - 200 mm 2 - 4 General purpose steel and cast iron Multi-edge roughing 50 - 300 mm 4 - 6 High-feed roughing in mild materials Indexable insert head 20 - 150 mm 2 - 4 Quick insert changes, production runs Brazed carbide head 12 - 40 mm 2 Small diameters, hard materials Stepped head 30 - 150 mm 2-step design Reducing thrust on low-power machines I run standard single-tube heads for most jobs in the 20-100 mm range. The indexable insert version is my go-to for production runs because I can change inserts at the machine without pulling the tool from the spindle. On one aerospace job in 15-5 PH stainless, the indexable head saved 15 minutes per insert change compared to a brazed head. ...