An independent evaluation of the new H215E harvesting head compared productivity and quality.
Mondi, a global pulp and paper company, and SiyaQhubeka, a South African company, set the objective of achieving debarking within a single pass for its harvesting operations to follow the standard set by the Brazilian forestry industry. A Waratah H215E head was fitted to a Kobelco SK210LC excavator carrier for the study.
The study took place on SiyaQhubeka’s plantations in compartments of Eucalyptus grandis x urophylla and aimed to compare the productivity and quality of the H215E head with that of Waratah’s H616C head. The H616C was not suitable for a single pass so the results compared the single pass of the H215E with three passes of the H616C.
Various methods of processing were tested. Single pass and multi pass treatments on both heads were compared, recording productivity, roller damage and remaining bark. Productivity increases ranged from as high as 29% in larger 0,3m³ trees to being negligible on smaller (0,05m³) trees. Stem damage on the three pass treatments was noticeable.
The single pass treatment with the H616C head left significant bark, while a single pass treatment with the H215E head resulted in stems with an average of 0,35% bark versus the H616C with a three-pass treatment resulting in 0,41% bark remaining. The design of the rollers and knives had a large impact on the quality of the timber. The H616C has two knives and three rollers, where the middle roller is much bigger than those on the H215E and adds to log damage. The debarking is done by the rollers and the more passes that are required, the more pressure is exerted on the logs by the rollers and the greater the damage. The H215E has four knives and two rollers like the heads used in Brazil. The log is held by the knives, which essentially do the debarking. The design prevents clogging of the bark and pushes the bark away from the log.
Adopting the reduced pass method showed benefits of increased production, lower costs and fibre yield optimisation through reduced log surface damage infield. These benefits could further be increased using the single pass. Source