2010 Full-Line Drill Catalog - Desanto

General InformationCoolant pressure and volumesThe illustrated optimum, good and minimum requiredcoolant volume apply only to spiral-fluted Ratio drills typeRT 100. In contrast to the pressure, which is a feature ofthe machine tool; the cooling system fitted to it and alsothe possibility of leakage, volume does not depend on themachine (fig. 1). The pressure figures given are thereforerecommendations which serve only as guidelines.Ratio drills type RT 80 with central coolant duct are subjectto different standards (fig. 2). The diagrams shown are forRatio drills in their most important application, machiningof steel.But they are also guidelines for the machining of other materials,primarily because the highest coolant pressures areconstantly required for the machining of steel. The effectsof cooling using straight-fluted Ratio drills type RT 150 isparticularly sensitive and is clearly demonstrated in theexamples for particular workpiece materials. For example,the loss in tool life through low pressures when machininggrey cast iron is considerably higher than when machiningAlSi alloys. But this is only the case when the AlSi alloy isshort-chipping! The absolute necessary minimum pressureor good pressure should, when machining cast iron, begenerally a little higher than for AlSi machining (figures 3and 4 ).The recommended values are to be used only for drillingdepths of up to approx. 5 x D. Deeper holes should be producedwith tools having internal coolant ducts, as for exampleRT 150 GN, otherwise the production of deeper holes(depending on the material) becomes uneconomical.Required coolant pressures Required coolant volumesoptimum pressureoptimum volumegood pressuregood volumeminimum pressureminimum volumeTechnicalfig. 1:Required coolant pressures and volumes for RT 100 Ratio drills withinternal spiral coolant ducts.fig. 2:Required coolant pressures and volumes for RT 80 Ratio drills with centralinternal coolant duct.coolant pressure p [bar]coolant volume V [l/min]coolant pressure p [bar]coolant pressure p [bar]coolant volume V [l/min]coolant pressure p [bar]coolant volume V [l/min]tool diameter d [mm]tool diameter d [mm]coolant volume V [l/min]292tool diameter d [mm]fig. 3:Required coolant pressures and volumes for straight-fluted Ratio drilltype 150 GG when machining cast iron.tool diameter d [mm]fig. 4:Required coolant pressures and volumes for straight-fluted Ratio drilltype 150 GG when machining AlSi7.