Cutting insert and cutting tool equipped with the same

A circular double-sided cutting insert including a top surface, a bottom surface, a lateral surface, and a cutting edge, and mounted to a cutting tool, wherein

• a plurality of clearance surfaces and a plurality of fastening surfaces are located on the lateral surface,
• among the plurality of fastening surfaces, a fastening surface, which is brought into contact with the cutting tool when the cutting insert is mounted on the cutting tool, forms an acute angle with respect to the top surface or the bottom surface acting as a rake surface,
• the plurality of fastening surfaces are formed in even number which is 6 or more,
• half of the fastening surfaces are first fastening surfaces each of which forms an acute angle with respect to the top surface, and each of the first fastening surfaces is increased in width as being closer toward the top surface, and
• the other half of the fastening surfaces are second fastening surfaces each of which forms an acute angle with respect to the bottom surface, and each of the second fastening surfaces is increased in width as being closer toward the bottom surface, and
• the cutting edge includes a minor cutting edge and a major cutting edge connected to the minor cutting edge, and the major cutting edge is extended from one end of the minor cutting edge and is inclined downward to be closer toward a transverse central axis of the cutting insert as being farther away from the one end of the minor cutting edge,
• wherein the first fastening surfaces and the second fastening surfaces alternate with one other, and each of the first fastening surfaces is disposed directly adjacent to each of the second fastening surfaces with no other fastening surface disposed therebetween,
• wherein a minor cutting edge clearance surface is provided below the minor cutting edge, and the fastening surface is located directly below the minor cutting edge clearance surface,
• wherein the minor cutting edge clearance surface maintains a constant width as it extends from the top surface toward the bottom surface, and the minor cutting edge clearance surface forms a right angle with respect to the transverse central axis of the cutting insert.