Milling cutting insert

An insert for use in a peripheral rotary milling cutter having a cylindrical holder and at least one replaceable, peripherally disposed cutting insert, the cutting insert being formed with at least one cutting edge defined between a cutting rake surface and a relief flank surface of the insert wherein the relief flank surface comprises a first portion defined between said cutting edge and an intermediate portion of said relief flank surface and a second portion defined between said intermediate portion and a base of the insert, said first portion presenting a first relief flank angle, said second portion presenting a second relief flank angle, said first relief flank angle being significantly greater than said second relief flank angle, said intermediate portion bridging said first and second portions and being directed transversely with respect to said first and second portions and defining an angle, external to said insert, with respect to said first portion which is less than 180.degree..