Cutting insert and cutting tool assembly including same

A cutting tool assembly for turning a workpiece, comprising:

• a cutting insert configured to be usable for both front-turning and high feed back-turning;
• a tool holder provided at a tip thereof with an insert pocket in which the cutting insert is mounted;
• and
• a fixing member configured to fix the cutting insert to the insert pocket of the tool holder,
• wherein the cutting insert includes an upper surface, a lower surface opposite to the upper surface in a vertical direction, a plurality of side surfaces positioned between the upper surface and the lower surface, and a plurality of cutting edges formed at edges where the plurality of side surfaces meet the upper surface,
• the upper surface and the lower surface are mirror-symmetrical about a virtual reference plane positioned between the upper surface and the lower surface and perpendicular to the vertical direction,
• the upper surface has a pair of cutting corners,
• the plurality of cutting edges include a major cutting edge used for front-turning and extending from each of the pair of cutting corners and a minor cutting edge used for high feed back-turning and extending from each of the pair of cutting corners,
• a representative inclination of the minor cutting edge is greater than a representative inclination of the major cutting edge with respect to the virtual reference plane, and
• the major cutting edge has an entering angle larger than 90° with respect to the workpiece, and the minor cutting edge has an entering angle smaller than 30° with respect to the workpiece.