Yrjö Nuutinen

Forwarding of Whole Trees After Manual and Mechanized Felling Bunching in Pre-Commercial Thinnings

Abstract This paper examines the forwarding productivity of energy wood thinnings. The objectives of the study were to: compare the forwarding productivity following either manual or mechanized felling of whole trees and create productivity models for forwarding. The time consumption of the work phases in forwarding, following manual and mechanized cutting, was formulated by applying a regression analysis, in which the independent variables were cutting removal (m3/ha) and forwarding distance (m). The final calculation unit for time consumption in each of the work elements was second (s) per solid cubic meter (m3). Time studies were carried out using two Timberjack 810B forwarders. According to these results, forwarding productivity following mechanized energy wood cutting was significantly higher compared to productivity after manual cutting. Mechanized cutting by the harvester enables the felling and bunching of whole trees into large grapple loads close to the side of the strip road, which clearly improves the output of forwarding thereby helping to reduce costs. When the forwarding distance was 250 m, accumulation of energy wood was 60 m3/ha, and load size was 6 m3, the forwarding productivity following mechanized cutting was 11.9 m3/E0h and 7.1 m3/E0h after manual cutting.

Productivity of whole-tree bundler in energy wood and pulpwood harvesting from early thinnings

Abstract First thinnings have been neglected to great extent in Finland because of high harvesting costs. The whole-tree bundler (Fixteri) was developed in order to rationalize the integrated harvesting of small-diameter energy wood and pulpwood and to reduce transportation costs through load compaction. The operation of the whole-tree bundler is composed of cutting and compaction processes. In the present study, the productivity level and the performance characteristics of the second version of the whole-tree bundler (Fixteri II) in integrated energy wood and pulpwood harvesting from first thinnings were defined on the basis of a time study. When the mean volume of removed whole trees averaged 20 dm3 at the stand, the productivity of Fixteri II per effective working (E0 excluding delays) hour was 3.4 m3/(E0) and with an average removal of 75 dm3, it was 6.1 m3/(E0). When compared with the first prototype of the whole-tree bundler (Fixteri I), the productivity of Fixteri II was 38–77% higher, depending on the stand density and mean tree volume of the removal. The higher performance level of Fixteri II stemmed mainly from the increase in multi-tree cutting and from the introduction of grapple feeding of the bunches. Furthermore, the better hydraulic capacity of the base machine enabled a higher level of simultaneous working processes.

Productivity and work processes of small-tree bundler Fixteri FX15a in energy wood harvesting from early pine dominated thinnings

First thinnings are often neglected in Europe due to high harvesting costs. The studied small-tree bundler (Fixteri FX15a) was developed in order to rationalize the integrated harvesting of small-diameter energy wood and pulpwood in thinning operations, and to reduce transportation costs through load compaction. For the time-and-motion study, three stand types were chosen, all dominated by Scots pine (Pinus sylvestris). Two were dense, small dimension stands. The third stand was a “normal” first thinning stand. The machine fells and accumulates small-trees, which are fed into the bundling unit, where crosscutting, compaction, winding, scaling, and output of bundles of approximately 0.6 m3 solid is performed in an automated process. The productivity in the dense stand with rich undergrowth was 9.7 m3/PMh (productive machine hour), with an average tree volume of 27 dm3 and 3216 trees felled per hectare. In the dense stand with no undergrowth, a productivity of 11.9 m3/PMh was reached. The average tree volume here was 44 dm3, and 2019 trees per hectare were harvested. In the normal first thinning stand with no undergrowth, the felled trees averaged 84 dm3, 1266 trees per hectare were felled, and a productivity of 13.8 m3/PMh was registered. When compared with the previous version, the Fixteri II, the productivity of Fixteri FX15a was 2.1–2.3 times higher, depending on the density and size of the removal. Several factors may explain the increased productivity, but one of the most prominent is an improved technical potential for multi-tree handling.

Quality and productivity in comminution of small-diameter tree bundles

ABSTRACT Bundling small-diameter trees from thinnings has become a viable technology with the development of the Fixteri harvester-bundler. Several studies have measured the productivity of the machine, however, bundling also influences the whole supply chain. A study was conducted to investigate the quality of chips and productivity of five different conventional chippers and one grinder when comminuting bundles produced of small-diameter trees. The productivity based on dry mass was on average 44.8 tonne per effective working hour (E0 H−1), and varied considerably between the machines; 1:2.3 being the observed relation between lowest and highest performance of machines. Productivity when comminuting bundles was 1.5–3.2 times higher than normally found in the literature for unbundled (loose) material. The quality of the produced fuel chips varied between machines in dry weight share of particle sizes <3.15 mm from around 5 to 35%. The average size of the chips varied between 5 and 20 mm. The study indicated that productivity and quality of fuel chips are dependent on machine type and the raw material processed. Further investigations should examine different machine systems in designed experiments where e.g. several assortments and operational environments are included.

Hakkuukoneen syöttörullien vaikutus rungon prosessoinnin nopeuteen, polttoaineenkulutukseen sekä tukkipuuvaurioihin

Seloste artikkelista: Operational efficiency and damage to sawlogs by feed rollers of the harvester head / Yrjo Nuutinen ... [et al.] - Julkaisussa: Silva Fennica 44 (2010) : 1, s. 121-139.