Temperature effects on fines generation during wood flaking

The amount of fines produced by flaking green logs Into strands for oriented Strandboard depends on a combination of temperature and the knife sharpness angle. In winter, a larger knife angle reduces the fines significantly. Two conditions are necessary for this phenomenon to occur: the fines must be created by (at least) two different processes, and the two processes must have different temperature dependencies. During flaking, a piece of wood is removed from a log through a combination of splitting and cutting. Results from two full-scale facilities suggest that the splitting component is temperature-dependent because lignin softens with increasing tem-perature. Laboratory results indicate that the cutting action is insensitive to temperature. These data provide a working hypothesis for the practice of reducing flaker fines by adjusting the knife sharpness angle in response to log temperature. A similar approach should also apply to reducing fines from chipping wood for pulping, although the significance would be smaller given that far fewer fines are generated during chipping than in flaking.