Threaded hole: Which hole for which thread?

Welche Bohrung für welches Gewinde?

For the tapped hole (core drilling), the pilot hole diameter (see GSR catalogue) must be selected first. Then the hole depth must be determined. It is decisive for the selection of the corresponding twist drills. It is advisable to select the shortest possible type of twist drill. Here is an overview of the DIN standards for twist drills and their hole depths in relation to the nominal diameter (D):

  • DIN 1897 extra short 3 x D
  • DIN 338 short 5 x D
  • DIN 340 long 10 x D

Please select the appropriate cutting speed for the material of the workpiece in order to keep tool wear as low as possible while maintaining an economical working speed. But what is the cutting speed? It is given in meters/ per minute (m/min) and describes the speed at which the cutting edge of the drill moves in the workpiece. The diameter of the drill and the speed of the machine are the parameters of the cutting speed. The following formula applies:

cutting speed m / min = diameter mm x rotational speed 1/min x pi x 1m/1000mm

Examples of cutting speed (m/min) by material group and drill type:


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