BTA stands for Boring and Trepanning Association, and is also sometimes referred to as STS (single tube system) drilling, as it uses one single drill tube for the BTA tool, compared to other processes such as ejector drilling, which use two.
BTA drilling is a deep hole drilling method which was created by the Boring and Trepanning Association in the 1940's.
BTA drilling is a deep hole drilling process that uses a specialized drilling tool on a long drill tube to produce deep holes in metal, from holes with a diameter of 20 mm [0.80 in] and larger, up to depth-to-diameter ratios of 400:1. BTA drilling is the most effective method of drilling deep holes, as it is a cleaner, more reliable and capable process than conventional twist drills, and can achieve larger diameters and higher feed rates than the alternative gundrilling.