Researchers carried out 172 trials involving 67 operators, in order to predict chipper productivity.
The chipping operations were studies in Italy across 114 locations. The raw material that was processed represented a wide array of tree species grown in Italy and included different assortments of tops and branches, un-merchantable trees and whole trees from thinning operations. The main factors investigated to determine the productivity were the power of the machines, the average size of the raw materials and operator skills. The result showed that productivity between chippers was highly variable, ranging from 1 to 91.04 green tonnes per hour. Many factors complicate studies such as these, including the raw material type, the machine characteristics and the operator proficiency.
The results showed that that tree species have only a minor effect on chipping productivity, but clearly showed the important influence of piece size. The piece size is determined by which part of the tree the raw material originates from (e.g. stems vs. branches or whole trees). The large differences in chipping productivity were partly explained by the differences in raw material. The operator effect also accounted for a significant part of the variability. There were no differences between operator groups with regard to their overall experience. Operators performed well if they had been professionally trained.
The title of the research was “Assessing chipper productivity and operator effects in forest biomass operations”. The article appeared in Silva Fennica, vol. 49(5). The authors were B Mola-Yudego, G Picchi, D Röser and R Spinelli. Source: http://www.silvafennica.fi/pdf/article1342.pdf