High-Tolerance High-Quality Holes - up to Eight-Times Faster Than Conventional Drilling

Over the last decade, the use of gun-drilling technology on CNC lathes, turn-mill centres and machining centres is estimated to have increased some four-fold. Moreover, gun-drilling can produce a wide range of hole diameters. Indeed, the technology can be used to produce micro-holes just 0.5mm in diameter to 100mm-diameter bores — and depths up to 100-times the tool diameter. The trend away from twist drills to solidcarbide ‘specialist’ deep-hole tools has, by and large, come about as a result of the more-general availability of through-the-tool high-pressure coolant on new machines, as well as retrofitted spray mist systems on existing production equipment.

However, further key advantages offered by the gun-drill include its ability to consistently produce high-tolerance high-quality geometrically straight and round holes at far higher overall penetration rates. Indeed, such is the performance of the latest HP series of gun-drills from Chessington-based Mollart Engineering Ltd (Tel: 020 8391 2282 – www.mollart.com) that tool penetration rates can be up to eight-times greater than that achieved by a conventional drill. In addition, gun-drills are now seen as being very competitive on price compared to standard long-series or special carbide twist drills; and further benefits are generated when account is taken of higher machine utilisation and greater security of process.

Chris Barker, the director of Mollart Engineering’s tooling division, says: “In the past, gun-drilling has been pigeon-holed as a highly specialised process requiring a dedicated machine, high-volume production and very deep holes — over 10:1 length-to-diameter ratio — often in difficult materials, but this is a misconception. The gun-drilling process is now a highly viable solution for use on standard machining centres and lathes that feature through-tool coolant; it is even becoming widely used on holes of shorter depth.”