Friday, March 23, 2007

Machining hardened forged steel

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You might think I'm a lil :twisted: because I didn't turn on the coolant. Well, this is a CBN (BNX20) insert that can't handle thermal shock very well (cracking) so it's better to run it dry since it's pretty much impossible to ensure a perfect coolant flow (there's always some swarf building up and blocking the coolant). It was also recommended to run it without coolant due to the interrupted cut.

This part is an actuator of a clutch (Tractech - now Eaton) with a Brinell Hardness of 160-200. Diameter of about 190 mm.
Insert: Sumitomo Electric CNMA120408
Cutting speed/feed rate (interrupted cut): 100 m/min / 0.08
Cutting speed/feed rate (non interrupted): 110-130 m/min 0.1

Tricone Bit