Spiral fluted, with 6 guide chamfers and internal cooling channels. New generation of high performance deep hole drills in the HPC range. With 135° point angle and special h7 cutting edge tolerance for optimum generation of a deep hole. High roundness and alignment accuracy of the deep hole.
Maximum drilling depth:
Flute length (see table) less 1.5×nominal ⌀.
For process reliability when using the 16×D deep-hole drill, an initial centre drilling with No. 121068– 121130 or 4×D pilot drilling operation with pilot drill No.122606 is necessary. For deep holes greater than 20×D, a 6×D pilot hole with pilot drill No. 122606 is absolutely essential.
The generation of a pilot hole improves the process reliability. See also pages 112/113.