Large-Diameter

I use BTA drilling for holes over about 20mm that need fast cycle times. When I need to remove a lot of material quickly and the diameter is large enough to support the tool, BTA drilling is my go-to process. It is also called single tube system drilling because the coolant flows around a single drill tube rather than through a double-tube arrangement like ejector drilling. BTA drilling — named after the Boring and Trepanning Association — is a deep hole drilling process for larger diameters. It’s the method I use when the hole is over about 20mm diameter and needs to be cost-effective. The process was developed in Germany in the 1930s and has been refined continuously since then. Modern BTA drilling machines can produce holes up to 300mm diameter and 20 meters deep. ...

I choose trepanning when the core material is valuable enough to save. Trepanning is a deep hole drilling method that cuts an annular groove and leaves a solid core. I’ve recovered over $12,000 worth of core material in a single year by trepanning Inconel parts. The core can be recovered and used for another purpose. Solid drilling removes all the material as chips. Here’s when each method makes sense. Trepanning Trepanning uses a cutting head with a hollow center. The head cuts an annular groove around a central core. The core is recovered when the cut is complete. ...

I use trepanning when the core material has value. Trepanning cuts an annular groove around a solid core instead of removing all the material as chips. The core is recovered and can be used for another part. The economics make sense in specific situations, and the tooling and setup are different from solid deep hole drilling. When Trepanning Pays Off Trepanning makes the most sense for large diameters in expensive materials. The material savings drive the decision. Drilling a 200 mm hole through 500 mm of titanium solid removes about $8,000 worth of material as chips. Trepanning the same hole recovers a 180 mm diameter core that can be used for a smaller part, saving most of that value. ...