EFFECT OF CHEMICAL TREATMENT ON GREEN MACHINABILITY OF IRON POWDER

Abstract

Inter-particle cold-state welding amongst the powder-particles determines strength attained by the green compact. The contacting surfaces also decide inter-particle sliding behaviour under consolidation pressure to govern compressibility of the powder. Rough surface of the powder enhances inter-particle cold-welding abilities but simultaneously suppresses compressibility of the powder. This study deals with conditioning of Fe powder particles with H2SO4 in order to roughen their surfaces. Variations in roughness of the powder have been obtained by varying concentrations of H2SO4 and duration of the acid treatment. The study attempts to co-relate roughness of the powder with its compressibility with green strength and machinability of the compact. Green machining is performed on the green compacts in order to enhance the machining performances associated with Powder Metallurgy components. Green machining has been proved to lower the cutting forces and tool wear. Although there may be certain problems arising from the use of green machining like larger exit edge breakout has to be addressed. It has also not so widely used and even it is, it is used with addition of additives. This work aims to check the green machinability of powders of different surface properties, best machining parameters for obtaining better machining performance.