Filters
Influence of thermal modification and sanding parameters on finest particle content in pinewood dust
Change of cutting parameters and their influence on the particle size distribution when sanding thermally modified material
Quantifying the finest particles in dust fractions created during the sanding of untreated and thermally modified beech wood
This article deals with the fractionation of wood dust by sieve after sanding. Dust from untreated beechwood was compared to dust from thermally modified beechwood (at 200 °C for 3 h). The authors hypothesized that the thermal modification changes the particle size distributions of the dust sieve fractions and that all the dust sieve fractions contain the finest particles, which are suspendable in the air and are potentially respirable. To obtain dust for testing, both wood materials were sanded with P120 paper at a belt speed of 14.5 m/s and a pressure of 0.65 N/cm2. A set of sieves with aperture sizes of 25, 80, and 250 µm were used to separate the dust into sieve fractions with grain sizes less than 25 µm, 25 to 80 µm, 80 to 250 µm, and greater than 250 µm. The content of the finest particles in the fractions was measured via a laser particle sizer. Both dusts had similar particle size distributions. In addition, each investigated fraction of both dusts contained the finest particles, i.e., less than 10 µm. It follows that the laser analysis method may be necessary to correctly assess the occupational risk at a sanding.
The effect of average chip thickness on the potentially respirable dust from CNC finish milling of wood-based materials
Milling wood-based materials on CNC devices causes the creation of chips in small sizes that may escape the chip extraction zone to the surrounding environment and pollute the air. The article studied the effect of the feed rate (vf) and the width of cut (ae), transformed into kinematic average chip thickness, on the amounts of chips in respirable sizes <10.0μm created in the cutting zone from particleboards (PB) and medium-density fibreboards (MDF). The amounts of dust-sized chips are discussed and were determined by the sieving analysis. The sizes of potentially respirable chips were estimated by weighting with the laser diffraction method. The highest amounts of chips from PB were of 0.250-0.500 mm (38-41%w), but in MDF, amounts varied depending on cutting conditions. With (ae) 1 mm were in the size range of 0.125-0.250 mm (35-54%w), for (ae) 2 mm (33-35%w), and (ae) 3 mm (36-40%w) with combinations of (vf) 6-8 m·min-1. With a combination of (vf) 10 and 12 m·min-1 distribution moved to a higher size range. Chips in sizes 10.0-4.0 μm were estimated by <1%, for 4.0-2.5 μm <0.5%, in 2.5-0.1 μm <0.3%, and <0.1 μm by <0.05%. Statistically was proven (p<0.05) only in PB, with adjusted (ae) by 1 mm, increasing the value of (vf) from 6 to 12 m·min-1 and also with (vf) at 6 m·min-1, between values of (ae) 1 and 2 mm (hm of 0.025-0.035 mm), will significantly (p<0.05) lower the percentual amounts of chips in sizes 10.0-4.0 and 4.0-2.5 μm.