Centering and pilot drilling with hard metal and high-speed steel
When applying solid carbide drills for drilling depths 8xD to 12xD we recommend centring or the production of a pilot hole with a depth of 1xD to 2xD. With drilling depths larger than 12xD a pilot hole with a depth of 1xD to 2xD is imperative.
High Speed Steel
Centering with drill lengths to DIN 340
When using long series drills (DIN340) in HSS/HSCO, we recommend spot drilling with a spotting diameter of 0.5 to 0.7xD ( D = drill diameter). HSS NC spotting drills are optimally suited for this process. Detailed information regarding NC spotting drills can be found in the NC spot drilling section.
Pilot drilling with drill lengths to DIN 1869
When applying extra length HSS/HSCO drills to DIN 1869 we recommend the production of a pilot hole with a depth of 1xD to 2xD.
Stub drills DIN 1897 are optimally suited.