Rotary blade mill can produce smoother finishes due to the larger radius on the inserts. They are equipped with round inserts which are secured in interchangeable cartridges and which are free to rotate as they cut. The insert rotates on a bearing attached on the cartridge. The rotation of the inserts alters chip formation on the rake face by increasing the effective inclination angle. The insert rotation is caused by the action of the cutting force and chip flow over the insert face. The contact edge length between the chip and the tool changes during cutting, leading to reduced wear distributed evenly around the periphery of the insert, and ultimately to increase tool life.