Cutting insert

Claim 1

A disposable cutting insert having an upper and a substantially planar base face; side walls adjoining said faces; at least one cutting edge formed at an intersection of the upper face and a side wall; at least one cutting corner formed at an intersection of an adjacent pair of side walls; a chip control structure formed in said upper face extending along the cutting edge from the cutting corner for at least an effective cutting length of the cutting edge; a land surface spacing said control structure from the cutting edge; said control structure comprising first and second descending surfaces respectively extending in the direction of said cutting edge; a first chip deflector surface between said descending surfaces and merging therewith; one or more further chip deflector surfaces extending between said second descending surface and a central portion of said upper face; said land descending and deflector surfaces having, in general, a substantially downwardly directed slope with respect to the base face in the direction of the cutting edge and from the cutting corner at least over said effective cutting length said land and first descending surfaces increasing in width from said cutting corner and at least along said effective cutting length; said first descending surface sloping with respect to said land surface by an angle which decreases from said cutting corner along said effective cutting length; said chip control structure constituting a stepped cavity of which said land surface is the rim and said central portion the base such that along every radial section line directed centrally through and in the direction of said central portion no surface is directed upwardly with respect to a preceding surface whilst along every section line directed normally with respect to said cutting edge and at least over the effective cutting length at least one further deflector surface slopes upwardly with respect to or is substantially parallel to the base surface.