Thermal Drilling / Thread Forming
Thermal drilling, also called friction drilling, is unlike any other forms of drilling. Most drilling is classified as a cutting process due to the material that is taken out of the work piece. Thermal drilling, which removes zero excess material, is considered a forming process in metalworking. Likewise with the thread forming method associated with thermal drilling—the hole formed through thermal drilling is rolled rather than cut and produces no chips.
Thermal drilling, or friction drilling, is done with a conical bit which is spun at a high RPM and heated to 900 degrees Celsius. As the drill is lowered to the material, the combination of heat from friction and heat from the tooling liquifies the material and pushes it down and out creating a hole. If tapping, a new tool is used to roll threads on the interior of the hole.