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.