Relief valve holes


  • To create a straight hole meeting high tolerance and surface demands.
  • To reduce the machining time while maintaining a reliable process.


The process strategy with a solid carbide step drill and step reamer reduces the processing time and produces a straight hole with tight tolerances and an excellent surface finish. 


Due to the C7 coating, tool life is increased considerably.


Machining process


Step 1: SC step drill

Step 1: Solid carbide step drill

Drawing no. 252742/999997, N = 2580 rpm, Fn = 0.22 mm/rev.



Step 2: Step reamer

Drawing no. 212850/999999, N = 2546 rpm, Fn = 0.35 mm/rev.


Step 3: HSS tap


Step 3: HSS tap

Drawing no. EN1270096