An interesting process that creates a very useful hole in metals is friction drilling or flow drilling. Rather than using a fluted drill bit to cut a hole, friction drilling uses a conical bit coated made of a high heat-resistant material from the ceramic family to form the hole.
In this process the bit is pressed into the target body as it rotates and the friction created heats the material to soften it. The tool then pushes into the material forming a hole without any material being removed. This gives the hole significantly more depth and wall thickness than a hole that is made with a cutting type drill. The formed hole can then have a screw thread cut with a tap and the section and depth of the hole will provide good mechanical characteristics for subsequent fastening without the ned for an additional component such as a bushing.