Choice of tool

Deep hole drillingDeep hole drilling systemsWhen we talk about deep holes, we mean a high ratiobetween hole depth and hole diameter. The term “deepholes” originally referred to hole depths of over 5 × thediameter. Today, deep-hole drilling is a collective namefor methods for the machining of both short and deepholes.Deep-hole drilling is the preferred method for drillinghole depths of more than 10 × the diameter, but becauseof the method’s high metal-removing capacity and precision,it is also competitive for small holes down to 2 ×the diameter.The Single Tube System – STSThe first choice for high productivityThe single Tube System is based on external cutting fluidsupply and internal chip transport. As a rule, the drill head isscrewed onto the drill tube. The cutting fluid is supplied via thespace beween the drill tube and the drilled hole. The cuttingfluid is then removed along with the chips through the drilltube. The velocity of the cutting fluid is so high that chiptransport takes place through the tube without disturbances.During drilling, it is important that the chips be brokenand that they can be transported away without jammingand affecting the drilled surface. In deep-hole drilling,cutting fluid supply and chip transport have been providedfor by the development of three different systemsthat permit trouble-free machining of hole depths ofmore than 100 × the diameter.The three systems are called: the Single Tube System(STS),the Ejector system (two-tube system) and the Gundrilling system.Since chip evacuation is internal, no chipflute is required in theshank, so its cross-section can be made completely round,which provides much higher rigidity than in the gundrillsystem. The productivity for the STS drilling is up to 5 timeshigher than for Gun drilling.The Single Tube System, STSChuckWorkpieceSteady restSealInlet forcutting fluidDrill tubesupportCoolant sealChip box•••••••••• •••DrillheadDrillbushingPressureheadDrill tubeDrill slidePreferred application1. High productivity2. Long workpiece3. Large diameters4. Difficult chipbreaking5. Stainless steel6. Low carbon steel7. Heat exchangers8. Uneven materials9. Long production runs10. Special machines for mass production