A new approach for the characterization of machinability—application to steels for plastic injection molds

An economical analysis of the plastic injection market highlights the necessity to increase productivity. Mold steel influences the total cost of an injected part more through its capability to be worked than through its own price. Among the mold manufacturing operations, rough and finish machining are two of the most expensive, depending strongly upon the mold steel machinability. A new method has been developed to compare the machinability of three 300 HB mold steels during rough milling. Based on a half-fractional design of experiments, a new model is proposed which takes into account material variation, as well as cutting parameter interactions. The application of this approach has shown the interest of a new redesigned grade presenting high surface properties, which could be as machinable as a high sulfur content grade which presents limited surface finishing capabilities.