Chip grain size from the process of machining steamed and unsteamed alder wood on a cnc machining center and assessment of separation results

The paper discusses the particle size of the chips formed in the process of machining unsteamed and steamed alder wood on a CNC machining center. From the granulometric analysis of the chips, it follows that the average share of the coarse fraction of the chips created from unsteamed alder wood is 66.0% and steamed alder wood is 62.9%. The representation of medium-coarse fractions of alder wood with dimensions of 1.0-0.125 μm in unsteamed wood is 29.5% and steamed by 32.7%. Dust fractions with dimensions below 125 μm in unsteamed alder wood account for 4.5% and in steamed alder wood 4.4%. Chips of non-steamed or steamed alder wood with dimensions below 32 μm were not measured, so it can be concluded that no respirable dust particles with dimensions below < 10 μm are formed. Changes in the physical and mechanical properties of steamed alder wood are manifested by a decrease in the coarse fraction above 2 mm and an increase in the fraction of chips 0.125 to 2000 μm. For the separation of chips, both unsteamed and steamed alder wood, from the transport air, fabric filters and filter fabric Finet PES 4 are suitable, the separation limit of which is smaller than the size of the smallest chips formed in the milling process: aMO = 7 m <<< amin = 32 m.