WORKING ENVIRONMENT FOR SAW CUTTING .1. PARTICLE-SIZE DISTRIBUTIONS OF SAW DUST

Particle size distribution of cutting particles produced when wood (we stern hemlock, Tsuga heterophylla (Raf.) Sarg.) and manufactured board s (plywood and particleboards) were sawn with three types of circular saws were investigated by the sieving method. Masses of particles sift ed through screens were measured, and the distributions were estimated as three different typical distributions (normal distribution, log-no rmal distribution, and Rosin-Rammler distribution). We recognized that the Rosin-Rammler distribution was best to explain distributions of s awdust particles. The modes of particle sizes (D(mo)) were calculated from Rosin-Rammler distribution equation. This value was used when the effects of materials for cutting, directions of grain to sawing, toot h numbers of the saws and saw-diameters on the particle size distribut ions were evaluated. We obtained the following results: (1) D(mo) was smallest when plywood was sawn. (2) D(mo) of which western hemlock sto ck was sawn parallel to the grain, was largest, and this value was rel ated to saw diameters linearly. (3) D(mo) was related almost linearly to the product of tooth numbers and square roots of saw diameters when particleboard, plywood, or western hemlock was sawn perpendicular to the grain.