Abstract: [Objective] In order to lay a foundation for the optimized wood dust,the size and shape distribution of particles emitted in panel furniture manufacturing was studied to clarify their influence on the particle flowability. [Method] The particle samples were collected in the panel cutting and paint sanding processes. The area diameter, aspect ratio, roundness, solidity and bluntness of the particles were investigated by means of image analysis to characterize their size and shape distribution. The influences of size and shape distribution on the particle flowability were then analyzed.[Result] The sawdust and sanding dust were mainly composed of fine particles with diameters of less than 100 μm, which could float long and travel wide in the air. Compared to the sawdust, the size of the sanding dust was smaller and the size distribution was narrower, making them more cohesive and adhesive. In terms of macroscopic shape, the sawdust and sanding dust were both irregular particles, exhibiting small aspect ratios and great inter-particle shape variation. However, they presented highly smoothed surface in mesoscopically, and the shape irregularity decreased with the falling particle size. Compared to the sanding dust, the sawdust showed higher shape irregularity and greater inter-particle shape variation.[Conclusion] The flowability of both particles was poor, which highly correlated with their size and shape characteristics. The small size of both particles causes high cohesive and adhesive forces, which in turn lower the flowability of the particles. With respect to the particle shape, the irregular larger particles tend to interlock with each other, while the relatively regular smaller particles are often trapped in the voids formed between the larger ones. This structure restricts the flow of particles with all sizes.

Key words: image analysis, sawdust, sanding dust, size distribution, shape distribution, flowability