Gear milling cutters with internal through the tool cooling that presents either air, neat cutting oil or emulsion directly into the chip clearance space in front of the indexable carbide insert have been developed by LMT Fette.
The effect of direct feeding of air or coolant creates a significant improvement in surface quality of the flanks of a gear tooth due to smoother cutting. In the case of dry machining, pressurised air feed clears any chips from the cutting zone and improves tool life.
Further advantages of through-the-tool feed include the lowering of temperature in the tool body as well as in the drive system of the machine and particularly the thrust bearing assembly of the spindle.
LMT quotes an example of a 16 module, 20º pressure angle gear having 21 teeth, with 15º helix and 240 mm gear width made from 17 CrNiMo6 steel. Using a 300 mm cutter with eight teeth, set to 36 mm -- full depth of cut at 135 m/min, feed per tooth was also set at 0.3 mm to obtain a machining time of 73 minutes. Between eight to 10 components were produced per insert tip.
|