Development of the binder system for solvent and thermal debinding in MIM process

Although the thermal debinding method is mainly used in the industrial production of MIM components, this method needs a long debinding time. To solve this problem, some of new binder systems or debinding methods have been developed and reported so far. In this study, to clarify the behavior of various binders during the debinding step, the pyrolyzed temperature and solubilities of binder resins and wax were examined. Then, some of binder systems were investigated to be suitable or not for thermal and solvent debinding from the following viewpoints. One is that the binder resins should be pyrolyzed at three temperature ranges during thermal debinding, and the other is that the above 70% of binder resins should be removed by solvent debinding. The binder system achieved above concepts was composed of polypropylene, polymethyl methacrylate, paraffin wax and stearic acid, the composition of which was 30 mass%, 40 mass%, 29 mass% and 1 mass%, respectively. From the thermogravimetric analysis, it was found that they were pyrolyzed at about 523 K, 623 K and 703 K, and almost 70% of binder resins were removed by solvent debinding with hexane.