Influencing Factors on Looseness of Chipped Material Generated during Wood Planing

It is necessary to know the looseness factor and bulk density of chipped wood generated in the mechanical wood processing to make the optimal choice of equipment for handling, transportation and storage, and also to determine the durability and quality of chipped wood as raw material. The looseness factor of chipped wood is defined as the ratio of volume of chipped wood and volume of solid wood. This paper presents the analysis of the effect of feed speed, rake angle and wood species on the looseness factor of chips generated in planing solid wood. Selected samples of chipped pine-wood, oak-wood, steamed and thermally modified beech-wood (at temperature of 212 °C) were generated in planing at four different feed speeds (vp1= 6; vp2=12; vp3=18 i vp4=24 m/min) and three rake angles (γ1 = 15°; γ2 = 20° i γ3 = 25°). The increase of feed speed only affects the reduction of the looseness factor for beech-wood and fir-wood. The impact of the rake angle during planing of researched wood species is not entirely clear. The presumed significant influence of cutting depth on the looseness factor was not established but significant influence was found of the cutting direction relative to the wood grain direction, the particles shape and their ability to fragmentation. The maximum looseness factor was obtained for chipped litewood generated during planing of fir-wood at minimum feed speed (fr=28.42) and the lowest in planing thermally modified beech-wood (fr=2.62). All obtained looseness factors were several times higher than those quoted in the literature.