Glass and mirrors are drilled from both sides to reduce the edges from chipping. This is especially noticeable where holes are drilled into mirrors.
Hole sizes vary from 6mm to 75mm. Larger holes and irregular cut outs are made by a water-jet cutter.
A multi-spindle machine is a screw machine that is made in a way that it can cut materials into small pieces in a simultaneous manner through the use of a number of tools. This machine possesses multiple spindles which are found on a drum that rotates in a horizontal manner.
A drill head is defined as the cutting tool at the end of a drill string used to remove material and create pilot boreholes. Most drill heads are equipped with a nozzle capable of jetting high-pressure water to facilitate the drilling process