Spark plug "one shot"

UM DANDIA - Injection bore common rail


CFS PCD step drill



Reduction of machining time by using fewer tools than the 3 tools that were used pminiously. The hole is made in solid material (no precasting). This makes it a great challenge for a one shot solution, since the large amount of chips often results in a surface finish worse than the Rz 6.3 required.

Kyocera Unimerco tool solution:

CFS PCD step drill on solid carbide tool body with sandwich drill point. Adjustable UM Dandia™ toolholder to ensure optimum runout. Tool no.: 210800/000005



By implementing a CFS tool, the hole is succesfully machined with a one shot solution, achieving a surface finish of Rz 1. This is possible because the CFS feature ensures that the chips do not get in contact with the hole surface.


The machining time is dramatically reduced. Using 1 tool instead of 3 eliminates 2 tool changes, 2x4 positionings, as well as 2x4 counterboring and reaming processes.



› 1 tool replacing 3 tools
› 33.8 seconds saved per cylinder head (478 hours/year)


  • 10,000 rpm
  • 3,000 mm/min. feed rate
  • Tool life 150,000 holes
  • Tool costs = 0.06 euro/cylinder head



  • Grob twinspindle machining centre
  • 40 bar internal coolant
  • 10% emulsion
  • Material : ALSi9Mg


CFS PCD step drill
n = 10.000 Rpm
f = 3.000 mm/min