This document is final report of an expertise project lead for ALPHA Company. The project focuses on the machinability characterization and comparison of various lamellar cast irons metallurgies. The comparison is performed in order to improve the casting process and the cast irons composition of brake and hub disk, to increase their machinability. The characterization of the metallurgies was made by tool life test with measurements of the cutting forces. Hardness and surface roughness measurements were performed too. Several Silicon nitride tools were tested. First an adjustment test has been performed to validate the machining parameters, and the methodology of characterization. Secondly, a reference test on Alpha’s cast iron brought reference data for the comparison of the various metallurgies to be tested. This test has improved the method of characterization. Cutting forces recording appeared as the most relevant and irrelevant measurements such as surface roughness were eliminated from the method. A test performed on a second cast iron showed that it has a lower machinability. Project succeeded to characterize and compare cast irons’ machinabilities, allowing the improvement of the composition by further tests.