Impact of Sycamore Maple Thermal Treatment on a Granulometric Composition of Chips Obtained due to Processing on a CNC Machining Mentre

Abstract

This article deals with a granulometric composition of chips from the milling process of native and thermal treatment maple cuttings on a 5-axial Computer numerical control (CNC) machining center SCM Tech Z5. The aim of this article was to determine the changes in the granulometric composition of chips due to the thermal treatment of wood and to assess the potential risk of the creation of harmful dust fractions. Cuttings were milled with a shank cutter with exchangeable razor blades at feed speed vf = 1 ÷ 5 m·min−1 and material removal e = 3 mm. The thermal treatment in order to modify the color of the maple wood was done with water vapour at temperatures of tI = 112.5 ± 2.5 °C for a period of τ = 5.5 h (Mode I), tII = 127.5 ± 2.5 °C for a period of τ = 6.5 h (Mode II), and tIII = 137.5 ± 2.5 °C for a period of τ = 7.5 h (Mode III). The granulometric composition of the chips was detected by sifting. A granulometric analysis of the chips provided that more than 2/3 of the produced chips are a coarse fraction consisting of flat chips with dimensions over 1 mm. Dust fractions smaller than 500 μm form isometric grains, i.e., chips having approximately the same size in all three dimensions. Inhalable dust particles, smaller than 125 μm, do not exceed a 2.5% share. The granulometric analysis of chips shows that the thermal treatment of maple wood does not create respirable fractions, and therefore, the thermal treatment of the wood does not have a negative impact on the living and working environments.

Granulometric Characterization of Wood Dust Emission from CNC Machining of Natural Wood and Medium Density Fiberboard

“…The feed rate reduction means the decrease of the nominal thickness of the particle and, thus, the particles move between finer fractions. This fact was also confirmed in the works [59,64]. The formation of dust particles can be from all open places of machines as well, especially on the premises of CNC machines as a result of maintenance, repairs, cleaning, inspection, tool change, etc.…”

Occupational Exposure to Dust Produced when Milling Thermally Modified Wood

“…Dust fraction, (i.e., particles below 125 µm) was less than 1% in the case of native beech wood samples and less than 4% in thermally modified beech wood samples. When maple wood was thermally modified at a temperature of up to 137.5 ± 2.5 • C, significant changes in granular composition of particles resulting from the process of milling using a CNC (computer numerical control) milling center were not confirmed as it is mentioned by [60]. Similar results of particle granularity using the frame saw when modifying wood with lower temperatures were observed in the case of beech and pine wood [44].…”

Quantifying the finest particles in dust fractions created during the sanding of untreated and thermally modified beech wood

“…However, in scientific publications on the dust generated during sanding thermally modified wood (oak, spruce, meranti), based on the sieve analysis performed, a lower content of particles with the smallest size was found in the dust from the wood modified at the highest temperature (220 °C) (Kučerka and Očkajová 2018;Očkajová et al 2019). The absence of the finest particles, that is less than 32 µm, was also found by Kminiak and Dzurenda (2019).…”

“…The analysis performed by Kminiak and Dzurenda (2019) showed that more than two thirds of the maple (Acer pseudoplatanus L.) wood particles produced during milling on a 5-axis CNC machining center were coarse-grained fractions, i.e., greater than 100 μm. The amount of particles with a size smaller than 125 μm did not exceed 2.5%.…”