CBN Inserts(TNMG160408)

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MATERIALS RECOMMENDED FOR CUTTING WITH CBN

PCBN

If polycrystalline diamond has a major disadvantage, it is that being carbon based, it has an affinity to the free carbon found in most ferrous materials and is therefore generally unsuitable for machining steels and iron based materials. For this reason a range of products has been developed based on polycrystalline cubic boron nitride which have been demonstrated to be extremely cost effective especially with the harder ferrous materials (45-65 HR). Examples of materials that may be considered for machining with these inserts are listed below:
Hardened Steels
Martensitic and Chill Cast Iron
Hardened Bearing and Cold Work Tool Steels
Martensitic Stainless Steels
Hard Facing Alloys which are Cobalt, Nickel and Iron based
Pearlitic Grey Cast Iron

PCBN For Rough Machining

Different types of PCBN exist for the rough machining of the materials listed above which are usually selected on the basis of the required amount of stock removal.
For roughing cuts in excess of 1mm depth the PCBN is usually supplied in the form of solid ISO tips for use in a clamp type tool holder, designed for use with negative top rake geometry. It is also usual to provide a strengthened cutting edge by means of a lapped or honed 'T' land.
Where roughing cuts up to 1mm only are to be taken or when the applications require positive tool geometry, a brazable type of PCBN may be employed. In these cases the inserts are fabricated in a similar manner to diamond tips but usually with a polished 'T' land.

PCBN for Finishing

A specific form of PCBN with reduced CBN content is supplied for use on fine finishing of hard ferrous materials. This material is capable, given the correct machining parameters, of producing turned finishes equal to those of ground components. The attendant cost savings found from switching from grinding to turning are often very dramatic. Again, the inserts are fabricated in a similar manner to those in PCD.