Here is a neat process I saw in the current issue of MMSONLINE. Some excerpts of the article follow:
By Derek Korn
Drilling holes in thin-walled parts isn’t hugely challenging. The process might require some means of workpiece support to counteract the pressure of the drill as it begins to penetrate the material. Depending on the application, the hole may also need to be deburred or chamfered.
The Flowdrill concept uses a conical drill that contacts material with high axial (downward) pressure and rotational speed. The frictional heat the drill generates softens the material, making it malleable enough for the drill to pierce the workpiece and form a collar and bushing around the hole.
The tungsten carbide Flowdrills are available in diameters from 0.06 to 2 inches and can hold 0.0005-inch repeatability. They can be used on standard drilling machines or CNC machine tools, operating at power levels between 1.5 to3.5 kW and spindle speeds from 1,000 to 3,500 rpm.
For applications requiring a smooth joining surface or a chamfered hole, flat Flowdrill versions can be used to cut the collar that is formed on the surface of the workpiece. Fluted-tip Flowdrills are recommended for coated materials because the tip helps remove the coating at the start of the drilling operation. Fluted Flowdrills also help prevent the deformation of thin workpieces that can occur because of the drill’s downward pressure. This distortion can also be avoided by drilling a small starter hole. ===========================================================================