Spiral fluted, with 4 guide chamfers and internal cooling channels. New generation of high performance deep hole drills in the HPC range. With 135° point angle and special fg6 cutting edge tolerance for optimum generation of deep holes. High roundness and alignment accuracy of the deep hole.
Maximum drilling depth:
Flute length (see table) less 1.5×nominal ⌀.
To achieve good process reliability with 40×D and 50×D deep-hole drills it is absolutely essential to drill a 6×D pilot hole with a pilot drill No.122736 and a 20×D co-pilot hole with a co-pilot drill No. 123691.
The generation of a pilot hole improves process reliability. See also pages 120/121.