A cutting insert for a tool for machining a workpiece, wherein the cutting insert comprises: - a main cutting edge which is configured rectilinear and extends between a first end and an opposite second end; - a first minor cutting edge which comprises a first rectilinear portion and a first concavely curved portion, wherein the first rectilinear portion is connected to the first end of the main cutting edge directly or via a radius or chamfer; - a second minor cutting edge which comprises a second rectilinear portion and a second concavely curved portion, wherein the second rectilinear portion is connected to the second end of the main cutting edge directly or via a radius or chamfer; and - a rake face which comprises a chip shaping geometry; wherein the main cutting edge, the first rectilinear portion and the second rectilinear portion are arranged in a common cutting plane, wherein the main cutting edge forms an acute angle (α) with the first rectilinear portion of the first minor cutting edge and the second rectilinear portion of the second minor cutting edge, respectively, wherein the rake face is recessed downwardly with respect to the cutting plane in a front area which is laterally bounded by the first rectilinear portion of the first minor cutting edge and the second rectilinear portion of the second minor cutting edge, and comprises a low point in each cross-section parallel to the main cutting edge, which low point has an equal first distance from the first rectilinear portion and the second rectilinear portion and has a maximum distance from the cutting plane compared to all other points on the rake face in the respective cross-section, wherein the chip shaping geometry is arranged at least in a rear area of the rake face, which is laterally bounded by the first concavely curved portion and the second concavely curved portion, and projects upwardly beyond the cutting plane and comprises at least two elevations so that the rake face in the rear area in a further cross-section parallel to the main cutting edge comprises two high points and an intermediate second low point which has an equal third distance from the first concavely curved portion and the second concavely curved portion, and characterized in that a rake angle varies along the main cutting edge such that the rake angle γ1 at a center of the main cutting edge, which has an equal second distance from the first end and the second end of the main cutting edge, is greater than the rake angle γ2 in the area of the first and/or second end (34, 36). - a main cutting edge which is configured rectilinear and extends between a first end and an opposite second end; - a first minor cutting edge which comprises a first rectilinear portion and a first concavely curved portion, wherein the first rectilinear portion is connected to the first end of the main cutting edge directly or via a radius or chamfer; - a second minor cutting edge which comprises a second rectilinear portion and a second concavely curved portion, wherein the second rectilinear portion is connected to the second end of the main cutting edge directly or via a radius or chamfer; and - a rake face which comprises a chip shaping geometry;