Abrasive belt sanding plays an important role in wood processing. The abrasive grits on the belt perform similar to small cutting tools with negative rake angles. In this study, a series of single-grit scratching tests were carried out on Sugar maple workpieces to investigate the cutting characteristics of two different abrasive-grit shapes. The spherical cone grits had two kinds of included angles, and the triangular pyramid grits provided two cutting forms: one main cutting edge and two side cutting edges as well as two main cutting edges. Both scratching along and across the wood grain direction were conducted. In all cases, the material deformation and surface creation were analyzed, as well as cutting force. Several physical cutting models were established to help further understand the cutting mechanism. A new method was proposed to evaluate the energy consumption of single-grit scratching. The results showed that triangular pyramid grits with sharp cutting edges could sever wood fibers more efficiently, while spherical cone grits are prone to make material plastic deformation mainly manifested as superficial densification and pile-up. When scratching along the wood grain, the triangular pyramid grit with two main cutting edges showed the best cutting performance with better surface quality. It was also shown that the cutting force ratio of spherical cone grits was apparently less than that of triangular pyramid grits. The overall cutting power for spherical cone grits was remarkably higher than that for triangular pyramid grits for both scratching along and across the wood grain, which indicates that triangular pyramid grits have higher cutting efficiency and power utilization.
Keywords: energy consumption; grit geometry; material removal; single-grit cutting; wood sanding.