Efficiency of different machine layouts for chain flail delimbing, debarking and chipping

Based on data collected from seven commercial harvesting operations in Western Australia, the study developed a productivity model for chain flail delimber-debarker-chippers (CFDDCs) used in blue gum (Eucalyptus globulus Labill.) plantations. The tests covered 45 h and 3395 cycles, and were conducted using time-study techniques. Despite the observational character of the study and the dampening effect of multi-tree processing, the study yielded a viable prediction model for estimating CFDDC productivity as a function of mean tree size, tree form, bark-wood bond strength (BWBS), and machine type. Productivity increased with mean tree size on a logarithmic scale, and was lower for poorly formed trees and high BWBS. Under equal conditions, a separate delimber-debarker and a chipper were 10% to 20% less productive than the integrated delimber-debarker-chipper. Productivity estimates were consistent with those reported in published case studies of CFDDCs used in planted Eucalyptus. Neither this study nor any of the previous ones could offer a reliable estimate of long-term machine utilization, which would be an ideal subject for future research.