How blade wear of chippers can affect fuel consumption and wood chip size distribution

This paper presents the results of a research conducted on the effect of wearing chipper knives on machine performance - in terms of productivity and fuel consumption - and particles size distribution. Blade wear causes a significant reduction of chipping productivity and a remarkable increase of fuel consumption. For the same screen type and knife wear level, productivity and fuel consumption are the same for the two species analyzed, poplar and pine. The use of a narrower screen has a similar effect, further decreasing productivity and increasing fuel consumption. Concerning chip size distribution, chips produced from logs always contain a smaller proportion of oversize particles and a higher proportion of accepts. For the same large mesh screen, poplar chips tend to be larger than pine chips and to restrain a higher proportion of oversize particles. Conversely, pine chips tend to be smaller and to contain a higher proportion of fines.