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UBC Theses and Dissertations

Friction sawing of wood Yu, Kwei Cho

Abstract

The friction sawing of wood by a high speed rotating disk has been studied. The present experiments were carried out by sawing two commonly used timbers; namely, Douglas fir and Western red cedar of different moisture Contents. A 14 inch diameter, 14 gauge steel disk with a smooth edge, driven at a rotating speed of 4,620 rpm was used for the research. A theoretical analysis of heat transmission characteristics and temperature distribution in the sawing disk is presented. Experimental results showed that the frictional forces, power consumed and cutting temperatures increased as feed speeds increased. The results also showed that the moisture content of the wood had no noticeable influence on the sawing action. A narrow kerf, straight, smooth and polished cut surfaces are some of the advantageous features of the process. At low feed speeds the calculated cutting edge temperatures were well below the ignition temperature of the wood specimen. However at high feed speeds the experimental horse power values increased and high calculated cutting edge temperatures consequently obtained. Excessive power consumption and high cutting edge temperatures were believed to be related to the difficulty of disposition of cut material with a smooth edge disk. Reasonably high feed speeds were evident in cutting plywood and veneer. For these materials clean, smooth and polished cut surfaces were evident. The method may be advantageous in the cutting of plastic sheets. When cutting thicker lumber with this method the feed speed was confined to an impractical low level and power consumed was far higher than that required for ordinary sawing. Thus, whether this method of sawing can be put into practical use or not is determined by the possibility of having an effective means to dispose of cut material. In this connection several methods of modifying the disk for more efficient cutting and waste disposal are presented.

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