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● CNC-350 How to resolve machine vibration while cutting long keyway (210mm)


About vibration at the bottom while cutting long keyway (210mm) , our reply as below:

In the beginning we would like to inform you that 210mm long keyway is belong to a difficult slotting job , So you need to

try the best cutting conditions

  1. Please understand that long keyway slotting , You need to have super rigidity slotting bar , Usually the slotting bar diameter L/D <= 3 -5  , Use  good material slotting bar material , the L/D can be 4 , So your case which L (Slotting bar out length 210+40=250mm) , The Diameter of slotting bar should be 60-65mm
  2. Each cut (cutter width) as possible as small to let the cutting smoothly , You can test , 8mm, 10mm , 12mm .
  3. Each slotting feed rate test from  0.03mm  , If 0.03mm OK. then test 0.04 , then test 0.05mm , Work-piece material hard and keyway long the feed should be smaller to let the cutting from top to bottom smoothly.
  4. The cutter (Insert) bottom rake angle suggest 5 – 8 degree and with a little arc to let cutting chip formed as roll type  ,  Because long keyway cutting , You need thinking how to let the cutting from top to bottom always smoothly , You need let the cutting chip formed as rolled shape per 20mm then break then formed next rolled chip.(Cutting chip shape good , Slotting processing will be good)
  5. Let the slotting bar out bottom position more , Maybe let slotting bar out 25mm  
  6. Try higher slotting speed with 0.03mm feed rate. (Slotting linear speed 15-20M/Min. , So you can try 31, 39, 44 SPM , Stroke length 250mm)
  7. Because long keyway slotting , The cutter will be hot while cutting to bottom position , So you need let the cutting oil feed to cutter during cutter at bottom position ,  Good cutting lubricating may be able to improve the slotting vibrating .


In our experience , normal length keyway (Less 150mm long keyway) , the Slotting process is easy , Over 150mm keyway , operator  need to try slotting conditions ,  You can try to cutting 100mm keyway , If slotting is no problem , It mean machine is no problem ,  If you test 100mm long keyway, The CNC-350 can’t cut keyway well , It just mean machine have problem. 

In our experience , the long length keyway cutting is always challenge for slotting processing , Operator need try and get the know how knowledge .


  1. Improve Slotting bar rigidity (D>=60mm)
  2. Improve the cutting rake bottom angle to let the cutting chip shape as good rolled shape
  3. Add enough cutting oil during slotting at bottom
  4. Try faster slotting speed with 0.03mm feed rate
  5.  Use smaller cutter (8mm or 10mm) several cuts