On the Wear of Carbide Tools in Machining Cast Iron Roll : The Relation between Microstructure and Tool Wear

Abstract

Carbide tools for machining rolls are apt to be fractured at the cutting edge. Therefore, the carbide grades of WC-Co having low contents of TiC, TaC, Co, low transversal rupture strength and high hardness are generally used. Predominant cause of the tool wear when cutting of rolls of high hardness is considered to be falling off of carbide particles which slowed out of the tools by the hard particles exclosed to the bottom side of the chips and those to the surface machined. Therefore, the relation between the mean free path of Co-phase and grain size in microstructures of carbide tool and the tool wear is investigated, additionally including that with carbon steels and cement-mortar as materials cut. The following are found. The shorter the length of mean free path is the case of the predominant cause of wear that is the abrasion type as in the machining of rolls, and the larger the mean grain size is in the case of that of the attrition type as in the machining of carbon steel, the longer tool life is obtained respectively. And the adaptability of carbide tools for the machining of rolls can be examined simply by the machining of cement-mortar.