The Effects Of Cemented Carbide Binder Composition On Tool Wear Encountered In Surfacing Green Lumber

Abdel E. Bayoumi, John S. Stewart, John A. Bailey

Abstract


This paper is a summary of work carried out over the past ten years on the wear of cemented carbides during cutting of green wood (Appalachian oak). Experimental evidence is presented showing that tool wear occurs through the preferential removal of the binder through chemical attack by extractives (tannic acid) in the wood followed by mechanical removal of tungsten carbide grains. This occurs when the remaining bond strength between the grains and the binder is no longer sufficient to withstand the action of the shear forces arising from relative motion between the cutting tool, work-piece, and chip. A theoretical model of the wear process based on this evidence is given. Experimental results are presented showing the wear of various cemented carbides under both laboratory (simulated) and actual (field) cutting conditions. The improvement in performance associated with the modification of the composition of the binder predicted from the analysis and measured through (simulated) wear tests agreed well with actual (field) test data. Specifically, a fivefold increase in tool life was obtained through substitution of a chromium/cobalt binder for a standard 6% cobalt binder.

Keywords


Tool wear;green wood;cemented carbides

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