Porcupine milling cutters offer a high potential for increasing the metal removal rate in heavy machining of steel and titanium. Here, the available machine power and the maximum radial force represent important process limits. According to the current state of the art, mainly rectangular indexable inserts are used. Investigations show that the use of round inserts can significantly reduce the resulting radial force and cutting torque similar to serrated endmills. However, the design of such tools is a major challenge due to the complicated shape of cross-section of the undeformed chip. Therefore, this paper presents a new method for optimizing the position of individual indexable inserts by means of geometric material removal simulations. With the new method, the radial force can be reduced by 14%.