Abstract: A polygonal cutter insert is formed with a rake surface extending inwardly from a cutting edge, a breaker chip surface lying in a breaker plane, a groove between the rake and breaker surfaces and at least one longitudinal upwardly convex rib extending outwardly from the breaker chip surface and having an apex lying in a rib plane lower than the breaker plane.

Abstract: Cutting inserts are provided at their rake faces with a plurality of raised chip-forming elements in the form of longitudinal ribs which can be notched to have longitudinally-separated segments and at least some of which are parallel to one another.

Abstract: A cutting bit (1) has a bottom side (2), flanks (3) that are inclined at a positive clearance angle (.alpha.) with respect to the bottom side (2), and a top side (7). The top side (7) has cutting edges (5 and 5') which are inclined with respect to one another at an angle of inclination (.lambda.). The cutting bit is made by sintering a blank which is formed using a pressing tool (10). The pressing tool includes a mold member (11), an upper die (12), and a lower die (13). The upper die (12) has a pressure face (20) which corresponds precisely, except for an allowance for the shrinkage ratio of the sinter material, to the actual surface of the upper side of the cutting bit (1). When the upper die (12) is fully inserted into the mold (11), a free space (31) exists between the upper die (12) and the mold member (11), the free space being disposed above the delimiting line (21) of pressure face (20) of the upper die (12).