This twist drill bits are only suitable for normal holes. If you need to process deep hole drills, please check the website, we have deep hole internal cold drilling 1.Designed for drilling abrasive materials when drilling accuracy must be maintained 2.Can be used in high temperature drilling applications 3.Used on materials such as cast iron, non-ferrous alloys, high silicon aluminum, copper, plastics, bronze, hard rubber, plexiglass, and other similar materials 4.Solid carbide tools offer long tool life and faster cutting speeds than other substrates, but are more brittle 5.Must be used with a rigid tool-holding systems.