Drilling and Associated Technologies

Abstract

Drilling operations are perhaps the most popular machining process being undertaken today, with their origins being traced back to cutting tool developments in North America in the 19^th century. In 1864 toward the latter part of the American Civil War, Steven Morse (i.e. later to design the significant ‘Morse taper’ – for accurate location of the ‘sleeved drills’ into their mating machine tool spindles) founded the Morse Twist Drill and Machine Company in the ‘North’. Morse then proceeded to develop probably the most important cutting tool advance to date, namely, the ubiquitous twist drill. In Fig. 42, several of today’s twist drills are illustrated along with just a small range of ‘solid’ contemporary designs. Morse’s originally-designed twist drill has changed very little over the last 150 years – since its conception. In comparison to the somewhat cruder-designed contemporary drills of that time, Morse stated: ‘The common drill scrapes metal to be drilled, while mine cuts the metal and discharges the chips and borings without clogging’. Morse’s statement was at best, to some extent optimistic, whereas the ‘cold reality’ tells a different story, as a drill’s performance is influenced by a considerable number of factors, most of which are listed in Fig. 43.