Impact of flail chain characteristics on productivity, costs, bark content and fuel use when processing short-rotation Eucalyptus globulus trees to produce woodchips

Infield chipping harvest systems are widely used in Australia and overseas to produce woodchips for pulp production from short-rotation plantations because they can produce uniform woodchips at low cost with high productivity from small trees. Flail chains are used in these systems to remove leaves, small branches and bark prior to chipping because these components are undesirable in paper products. Flail chains wear during use and lose links, requiring chains to be replaced. A range of flail chains is available but the most recent studies comparing flail chain performance were conducted over 30 years ago. The aim of the present study was to address this knowledge gap by comparing the performance of five flail chain types currently in use in terms of their impact on flail productivity, fuel use, woodchip bark content, chain wear and chain replacement costs. The study was conducted on a Husky Precision 2300-4 flail operating in 13-year-old Eucalyptus globulus plantations in southwest Western Australia producing export woodchips. No significant differences were found between the studied flail chains in terms of woodchip bark content, flail productivity or flail fuel use. In all cases, bark content met company standards (<0.5%). Significant differences were found between the studied flail chains in terms of their wear, link losses and replacement costs. Chain replacement costs as a proportion of total flail costs were found to be considerably lower (<1% to 4%) than those reported in previous studies (>20%).