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Deep hole drilling was first developed for the manufacturing of firearms, hence the name gundrilling. Originally a time-consuming and expensive process, technological advances have made it a highly efficient manufacturing process utilized in all metal cutting industries, including automotive, aircraft, aerospace, construction, medical, tool and die, petro chemical, hydraulics, pneumatics and more. Gundrilling is an ideal solution for most deep hole and high precision drilling projects. This operation produces accurate, repeatable holes with excellent surface finishes.
Gundrills hold location to precise tolerances, are sized to exact specifications, produce burr-free holes  and can be formed to produce specific shapes in blind holes and bottom forming with a minimum of machine adaptation. These systems can be easily integrated with CNC machining centers, lathes and milling machines for a relatively small investment, making it affordable for large or small shops with production requirements varying from one piece to hundreds of thousands.
The Gundrill's Function
Gundrilling is a metal removal process involving a drilling machine, a high pressure coolant system and a high quality drill with a single or double flute along the shank. In operation, the drill is positioned and held in the spindle nose, then guided into the workpiece through a prestarted hole or guide bushing to prevent vibration and ensure accuracy. The drill tip's cutting edges produce thin curled chips that are carried back along the shank by the high pressure coolant and deposited in the chip box. The off-center design of the cutting edges creates pressure within the bore, which is carried by pads behind the drill tip. The coolant that flushes out the chips also lubricates these pads, which burnish the surface and develop the fine finish for which gundrilling is known.
The Gundrilling Machine
Designed to provide optimum conditions for gundrill operation, the gundrilling machine's high pressure pump delivers lubricant to the rear of the drill. The drill can be driven by the spindle or be held stationary if the workpiece is rotated. During drilling, the workpiece can be advanced or the drill can advance. The gundrill is supported by anti-whip devices along the shank and at the rear of the chip box. The chip box contains chip deflectors and a front end bushing, which guides the drill into the workpiece. The chip box also contains escaping chips and lubricant, which are separated and filtered.
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