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● CNC-350 About relief angle for cutting insert (workpiece material 4140,HBN280)


About hard steel cutting for CNC-350, Hereby our engineer reply it as below:

  1. The material hardness from HBN200 (HRC20) to HBN250 is belong to hard material ,Hardness >HBN270 (HRC27)belong to very hard material ,Your material hardness HBN280 (HRC29) is belong to very hard material.
  2. For very hard material slotting , First the slotting tool hardness must over HRC68 or HRC69
  3. The bottom relief angle should be small about 3 degree to 5 degree and grinding with an arc to let cutting chip forming smoothly as roll type.
  4. According for your workpiece , We suggest cutting speed suggest higher a little (High 1 step 44 SPM) match smaller feed rate 0.03mm.
  5. Slotting bar rigidity you use is OK.

You can try to use Rev slotting tool insert which hardness can be HRC72 and discuss Rev to match suitable bottom Relief angle (our idea is about 3-5 degree).


(Please refer to above REV. insert link; and I also attached one page to show you about 3~5 degree on bottom relief angle.) We suggest you directly contact with REV. reseller in Australia about your cutter requirement.


If the cutting insert can cut into material well , You will see the cutting chip like a roll type , You can check the cutting chip shape , Bad cutting the cutting chip will like broken shape , If the cutting chip can be like roll type , It mean the cutting tool and cutting condition is correct.