| 摘要 |
A cutting insert according to an embodiment has an upper surface, a lower surface and a side surface, and a polygonal plate shaped in which a cutting edge is formed at a ridgeline where the upper surface and the side surface intersect each other. The upper surface has a major part having a flat upper end surface, a first protrusion protruding from the major part toward a corner part of the upper surface, a second protrusion protruding from the first protrusion toward the corner part, and a pair of projections located between the second protrusion and the cutting edge. A height of an upper end of the first protrusion from the lower surface is lower than a height of the upper end surface of the major part and is higher than a height of the cutting edge. A height of an upper end of the second protrusion from the lower surface is equal to the height of the cutting edge. A height of an upper end of each of the pair of projections is lower than the height of the second protrusion. |
