Patent ID: 8342779

Claim:
A cutting insert comprising: a body comprising an upper surface comprising a corner and a first side and a second side disposed on both sides of the corner, and a lower surface corresponding to the upper surface, a cutting edge disposed along the corner and the first side; a breaker groove disposed along the corner and the first side on the upper surface and lying inside of the cutting edge; a protruded portion disposed corresponding to the corner on the upper surface and lying more inward than the breaker groove; and an inclined side surface disposed along the first side on the upper surface and lying more inward than the breaker groove, the protruded portion comprising: a breaker projection adjucent to the corner; a breaker wall face lying more inward than the breaker projection and connected with the breaker projection so as to project more upward than the breaker projection; and a breaker side face connected with the breaker wall face and formed disposed along the first side, wherein the breaker wall face has a first width on a lower end thereof and a second width on a upper end thereof, wherein the second width is smaller than the first width, and is disposed corresponding to the corner as to be passed through by a bisector of the corner when viewed from above, and inclined to have a higher position as it departs from the corner in a vertical cross section with respect to the lower surface including the bisector of the corner, the breaker side face is connected with the inclined side surface, and has a third width on a first end near the corner and a forth width on a second end near the inclined side surface, wherein the forth width is larger than the third with and in the vertical cross section with respect to the lower surface including the bisector of the corner, the height of the breaker projection with respect to a reference line passing through the lowermost point of the breaker groove and being parallel to the lower surface is not more than half of the height of the top of the breaker wall face and lower than the height of the cutting edge along the corner.