Triboelectric charging of dust particles during hand-held circular sawing of wood and wood-based materials

Can Surface Coating of Circular Saw Blades Potentially Reduce Dust Formation?

“…This is likely caused by the higher rotational speed of the saw blade 24 teeth (8000 rpm vs. 3200 rpm for the blade 60 teeth), which was chosen to ensure uniform feed per tooth for cutting of the grooves. This is supported by findings demonstrating that sawdust of equal particle size is obtained when beech wood planks are cut in longitudinal direction at uniform rotation speed (800 rpm) using blades of 24 and 60 teeth, respectively [21].…”

“…According to the wisdom words “the dose makes the poison” by the medieval doctor, alchemist, and natural philosopher Theophrastus Bombast von Hohenheim (Paracelsus, 1493–1541), quantitative considerations are important to assess the health risk of wood dust released during wood processing. At a slow manual feed rate of about 1 m min −1 as in the work of Myna et al [ 21 ], cutting of a 120 mm long groove (depth 20 mm, 7 s) into beech wood planks releases a wood volume of approximately 7.2 cm 3 in the form of a voluminous dust cloud with particles precipitating within different periods of time. In the presented work, the released amount of wood dust volume was 4.5 times higher (33 g), due to the larger cutting length (800 mm) and time (8 s).…”

“…This is most critical for high-speed wood processing. It has recently been shown that processing of wood and wood-based materials by circular sawing can lead to both positive particle charging, as with solid beech and spruce wood, and negative particle charging, as shown with MDF and particleboards [ 21 ]. Since the charge is locally trapped on the (large) surface of the non-conducting wood dust particles, strong repulsive forces can occur resulting in strong expansion of respective clouds and low sedimentation due to the absence of aggregation.…”

“…In the process of circular sawing, shear forces are supposed to play a considerable role in particle charging next to the primary cutting forces, creating new surfaces by shear tensile and compression failure of wood [ 4 , 21 ]. Shear forces also occur during so-called secondary particle fragmentation, which is the repeated impact of already detached particles on the cutting edge [ 2 ].…”

“…In the aforementioned research [ 21 ], it has been shown that circular sawing can generate both positively and negatively charged particles, depending on the material processed. These results confirm that the chemical composition of the friction partners play an important role regarding polarity and extent of charging as it is known from triboelectric series of materials abundant in literature [ 32 ].…”