Machining properties of fast-growing tree in Japan —Cutting force in orthogonal cutting—

Abstract

In order to clarify the machining properties of fast-growing trees in Japan, the cutting force were measured during the orthogonal cuttings of the heartwood and sapwood of sugi (Cryptomeria japonica) and five fast-growing tree species, namely koyozan (Cunninghamia lanceolata), sendan (Melia azedarach), two species of eucalyptus (Eucalyptus maidenii and robusta), and yurinoki (Liriodendron tulipifera). The cutting angles and depth of cut were 22°, 32°, 42°, 52°, and 62° and 0.5, 1.0, 1.5, and 2.0 mm, respectively. The quarter-sawn surface was finished by cutting along the grain, whereas the flat-sawn surface was finished by cutting across the grain. When cutting was done along the grain, the parallel cutting force increased with increasing cutting angle and/or depth of cut for all species tested. The parallel cutting force increased with the basic density of the specimen. The cutting forces of yurinoki, koyozan, and sendan, whose basic densities were close to that of sugi, were similar to that of sugi. The normal cutting force increased with increasing depth of cut and/or basic density, however the relationship with the cutting angle was unclear. When cutting was done across the grain, the parallel cutting force increased with increasing cutting angle and/or the depth of cut, but the relationship with the basic density was unclear. The normal cutting force increased with increasing depth of cut, but no dependence on the cutting angle or basic density was observed. No difference was found in the cutting force between the heartwood and sapwood regardless of the species or cutting direction. The difference in the cutting force between the species became smaller with decreasing cutting angle and depth of cut. Thus, we found that fast-growing trees could be cut with a small cutting force by setting a small cutting angle and depth of cut, even if their basic densities were high.