Feed Force and Sawdust Geometry in Particleboard Sawing

Abstract

The measurement of cutting forces permits building of physic-mechanical cutting models for a better understanding of the phenomena observed during cutting. It also permits the design and optimization of processes, machines, tools, and wood preparation. Optimization of cutting conditions of wood-based materials can decrease the cutting forces, which directly relates to the energy consumption and surface quality. The sawdust analysis may serve for analysis of cutting kinematics and occupational health risk. The aim of the study was to estimate the correlation between the feed rate and both feed force and sawdust particle size produced during particleboard circular sawing. A saw machine type K700 was used in experiments. There were three feed rates of 12, 18, and 24 m/min executed by a horizontal pneumatic actuator fixed to the sliding side table of the saw machine. Based on the results of the experiments, a positive correlation was observed between the feed rate in a circular sawing process and feed forces and an unexpected particle size distribution depending on the feed rate.

Cutting Forces in Peripheral Up-Milling of Particleboard

“…It occurs even when the thinner end-portion of the chip (the decreasing part of IUCT visible in Figure 9 ) is not taken into consideration. A similar phenomenon was observed earlier, for the maple wood cutting [ 26 ]. A hypothesis was formulated that this happens when the tensile strength of the workpiece is exceeded, before the knife reaches the theoretical maximum chip thickness position.…”

“…High cutting speeds generate vibrations not only at the machining center [ 25 ] but also at the fixed workpiece, significantly disturbing the force measurement. For rough measurement of the feed force that is felt by an operator during PB sawing [ 26 ], these vibrations do not play an important role, since several teeth are working at the same time, and the impact frequency is too high to be felt by the operator. However, in high-frequency measurements of cutting forces, these vibrations can introduce a significant error.…”

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

“…This difference was even more pronounced for the particle fraction < 100 µm, where twice the amount of dust was produced with the blade having fewer teeth (Figure 5). Being in good agreement with a recent study [2], these findings suggest that secondary particle fragmentation in the narrow gaps between saw blade and the solid wood is here more pronounced, affording finer particles as originally produced during primary cutting. 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.…”

“…These technologies have one thing in common: they all produce particulate matter. While the latter can be relatively coarse, as in the case of circular saws, huge volumes of wood dust are released from a wide range of smaller woodworking machines [ 1 , 2 ]. This is particularly critical for commercial indoor wood processing facilities, but also undesired in the do-it-yourself sector for two main reasons.…”

“…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 ]. According to the pseudo-fluid model, heat transfer from the saw blade to the dust particles generated during secondary fragmentation is a factor to be considered as well as a reason for mechanochemical reactions to occur, entailing triboelectric charging to wood dust.…”