This standard specifies the types and dimensions of 7/24 tapered shank end mills. This standard applies to 7/24 tapered end mills with a diameter greater than 23.6 to 95 mm.
GB/T 6117.3-1996 history
2010GB/T 6117.3-2010 End mills.Part 3:Milling cutters with 7:24 taper shanks
1996GB/T 6117.3-1996 End mills--Part 3: Milling cutters with 7/24 taper shanks