waterjet is actually a “controlled erosion process” and you are dealing with a fluid tool, as opposed to a rigid metal cutting tool, things work completely differently.
DRILLING HOLES BY CONVENTION
Most mechanical cutters will go through materials with a cutting action and a spiral cutter that actually lifts the chips, grit, debris, or whatever you want to call it, from the hole as you go through the material. With EDM the electrode will burn away the material by arcing and the debris is washed out by flooding with a liquid. In drilling glass, you may use a diamond bit, and the glass will be pulverized or ground away and you use low volume water or other liquid to carry the grit away. This is a pretty straight forward process in these instances.