Nuutti Kiljunen et Jean-François Gingras
Integration of Work Tasks and Supply Chains in Wood Harvesting -: Cost Savings or Complex Solutions?
The concept of integration is understood as a means for more cost effective solutions in the harvesting and transport of forest products. Harvesting of several assortments simultaneously or accomplishing several tasks at the same time and/or with a single machine are assumed to increase overall productivity. Integration of industrial roundwood and energy wood harvesting is an example, where a multitude of solutions based on integration have been proposed, introduced and tested. In some cases integration has given clear cost savings and simplified operations. There are, however, a large number of experiments, where integration has led to complex and expensive technological solutions, imbalance between machine elements or stages of the harvesting system and overall increase of expenses. In this paper, the concept of integration in wood harvesting in general and in thinnings, in particular, is described and discussed. A number of successful and unsuccessful integration cases are analysed. Finally, features of successful integration concepts are sketched.
Thinnings are not as common in Canada as they are in most European countries for a variety of reasons, not the least being the high treatment costs. In recent years, FERIC has proposed a host of strategies to reduce the costs of thinnings and thus increase the attractiveness of this treatment. One of these strategies is to use multi-tree handling harvester heads because the use of single-grip harvesters often results in high wood costs when harvesting small stems typical of commercial thinning treatments. Recently introduced harvester heads such as the Waratah HTH-470 HD provide multi-stem felling and processing options that can increase harvester productivity in small trees. This paper describes the early results from FERIC studies of multi-stem heads working in eastern Canada.
During FERIC studies, the ability to handle more than one stem at a time increased machine productivity by an average of 21 to 33% compared with handling stems one at a time. On average, multi-stem work cycles were longer than single-stem cycles, but the ability to process more than one stem at a time in 30 to 40% of the cycles lowered the mean harvesting time per stem. The delimbing quality and the length-measurement accuracy for sawlogs were comparable to those of conventional heads currently on the market.
This technology is thus well suited to final felling of small trees and to commercial thinning because its productivity is less affected than with conventional heads by the small tree volumes. The accumulator that keeps felled stems vertical also provides benefits, since it lets the operator control the fall of the felled stems and thus may reduce the risk of damaging residual stems.
Henrik Heräjärvi, Aki Jouhiaho, Vesa Tammiruusu et Erkki Verkasalo
In the future, the building industries will need predictable, homogeneous and cost-competitive wood products with structural safety in increasing quantity and quality. This can be provided by, e.g., breaking solid wood and reconstructing the structure in a way that the degrading influence of knots, cracks, decay and other natural irregularities in wood will be eliminated. Beams, panels or boards made by this principle are called the engineered wood products (EWP). The purpose of this study was to investigate the possibilities to utilize small-diameter Scots pine and birch timber for production of EWPs that are reconstituted of strands. The wood technological characteristics of the tree species used in these products worldwide were studied based on the literature, and the findings were compared to the characteristics of domestic woods. In addition, test specimens were manufactured from domestic raw materials of Scots pine and birch species, and tested in order to examine the differences between woods from young trees from the first commercial thinnings and top sections of mature trees from final cuttings as a raw material. According to the literature review, the average basic density and, consequently, many mechanical properties of pine and birch grown in Finland do not markedly differ from those of the numerous foreign species used for EWPs. The empirical tests indicated that beams (air-dry density ca. 620-800 kgm-3) with relatively auspicious static stiffness (ca. 6000-8500 MPa) and bending strength (ca. 32-42 MPa) could be manufactured from timber equal to or smaller than pulpwood in diameter.
Feasibility of an Adapted Tree Section Method for Integrated Harvesting of Pulpwood and Energy Wood in Early Thinning of Scots Pine
This paper deals with the feasibility of adapted tree section method using a conceptual bundle harvester for the integrated production of pulpwood and energy wood in first commercial thinning of Scots pine (Pinus sylvestris L.). The harvester would operate on the site, and it would be comprised of a base machine, an accumulating felling head, and a compacting device. Separation of pulpwood and energy wood fractions would take place at a pulp mill. In this experiment, the trees were topped and the top sections were left at the site.
The concept was evaluated from an ecological and economic point of view. Nutrient losses were significantly lower compared to whole-tree harvesting. The energy fraction increased by 150% compared to the cut-to-length method, in which stem bark represents the energy fraction.
In bundle transportation, the load-bearing capacity of standard trucks can be highly utilized. For short distance hauling by conventional forwarders, an expansion of the load space is required in order to improve the utilization of the load-bearing capacity.
Due to insufficient compaction capability when dealing with large trees, the bundling concept seems to be more appealing in harvesting energy wood from dense stands characterized by small stem size. In energy wood procurement, the bundling concept has several indirect advantages compared to the conventional forest chip production. Standard vehicles, with minor modifications, can be used for transportation. Machines involved in the operation can work independently, increasing the reliability of the system. Bundling with accurate real-time information about the daily production and inventories creates favourable conditions for efficient process control.
Kalle Kärhä, Esa Rönkkö et Seppo-Ilmari Gumse
High harvesting costs are the main problems in first thinnings. Machines with lower operating costs could be one potential solution for cost-efficient first thinnings. The research investigated the productivity of the four most widely used small harvesters, i.e. thinning harvesters, and their cutting costs. Data were also collected on the productivity relationships between working methods and the differences between operators. In the time studies involving thinning harvesters, the Nokka Profi and Timberjack 770 represented the larger, more expensive machines, while the Sampo-Rosenlew 1046X and Valtra Forest 120 represented the more compact, less expensive thinning harvesters.
The productivity per operating hour (E15 including delay times shorter than 15 minutes) of the thinning harvesters was found to be 5.6-10.3 m3/ E15 (stem size 50-100 dm3) in first thinnings and 9.1-12.7 m3/ E15 (100-150 m3) in second thinnings. The productivity figures of the individual machines were similar. The differences were mainly attributable to the operators. The time study showed that the differences between operators using the same machines were as great as 40%.
The cutting costs for the thinning harvesters were 7.5-14.2 US$/m3 (50-100 dm3) in first thinnings when using the Nokka/Timberjack machine group. The corresponding costs for the Sampo/Valtra machine group were 5.7 and 10.5 US$/m3. It would appear that thinning harvesters can be operated at the same productivity level of medium-sized harvesters in thinnings and, consequently, they can be run at cutting costs lower than those of medium-sized harvesters.
Andrew Nicholls, Leon Bren et Neil Humphreys
Falling financial margins have prompted many owners of Australian harvesting businesses to extend normal working hours. After brief trial periods, most companies have again reverted to short-term and ad hoc solutions to meet peaks in demand.
The harvesting industry is also being persuaded to operate extended hours under the guise of service-delivery and the `24-hour society', in response to customer demand. A poor understanding of human factors poses a threat to profitable harvesting, and contributes to low productivity on extended hours work regimes.
Decreased operator productivity was observed in both shifts of a shiftwork operation. Experience in other industries have noted reduced operator alertness led to increases in the risk and severity of accidents and machine damage.
Successful implementation of extended hours work regimes relies on addressing operational needs as well as recognising the human needs, managing productivity, safety, communications and maintenance.
Heikki Ovaskainen, Jori Uusitalo et Kari Väätäinen
Productivity levels between harvester operators have been noted to vary significantly, by up to 40% in similar stands. It is believed that differences originate from the operators cutting techniques, motoric skills, planning of work, experience, felling order of removable trees, decision processes at the working location, machine properties and the surrounding environment. The objective of this study is to examine and compare six harvester operators and to detect those features of working technique that improve and rationalise the work. Consequently, improving the basic working technique can raise average productivity. The harvester operators' work was examined by using the normal stopwatch study method and the operators' working technique was registered for each handled tree. Working technique observations were adjoined to stopwatch the study time units as a large matrix after data collection.
Results indicate that unnecessary stem movements in the felling phase should be avoided. The stem should be processed close to the stump so that the positioning-to-cut distance to next removable tree is short. This reduced positioning-to-cut time for the next felling. In processing, a productive operator can operate without big delays and the variations in processing times for same stem sizes are small. Furthermore, the productive operator avoids reversing when he is doing normal harvesting work.
Teijo Palander, Janne Väätäinen, Sanna Laukkanen et Jukka Malinen
This study introduces a support method to use in modeling backhauling. The method minimizes a truck's on-road driving while empty. The backhauling model is based on a commonly used timber transport allocation model. Here, this model is applied to a simulated energy-wood network. The resulting optimization provides two different delivery plans for two-way transportation: one with a constraint to minimize travel distances when empty and the other without this constraint. By applying the empty-route minimization method, the best return routes for trucks are determined beforehand with fewer alternatives then left to be solved by the backhauling model. The results prove that the method can be used to minimize empty-route driving, but further development of the empty-route minimization method is still needed before it can be used in combination with the optimization of backhauling. Therefore, the effects of empty-route minimization on the transportation distances with respect to stand and hauling alternatives are discussed. In addition, the possibility of increasing the profitability of transportation, through the use of the method to optimize energy-wood backhauling, is also discussed.
Vesa Tanttu et Matti Sirén
The aim of the study was to investigate the effects of co-operation and integration in large-scale wood energy production. The total procurement cost and yield of forest chips (small-sized trees and logging residues) delivered to the consumption plant were calculated for three harvesting strategies. In Alternative 1 individual stands were harvested. In Alternative 2 the harvesting of small-sized trees and logging residues was integrated within forest holdings. Alternative 3 included both co-operation between neighbouring forest holdings and the integration of harvesting. In integrated harvesting, small trees and logging residues were jointly chipped at intermediate storages.
The study material consisted of forest management planning information and forest maps, in digital form, for privately owned areas totaling 15000 ha, of which 3720 ha was forest. GIS data and costs models were used in constructing a production model for a power plant consuming 100000 m3 of forest chips per year.
Integration raised the harvestable small energy wood yield by 30.5% (Alternative 2) and 31.5% (Alternative 3). The corresponding values for all forest chips were 12.9% and 13.3%. The average cost of forest chips was 3.4% lower in Alternative 2 and 4.9% lower in Alternative 3 than in individual stand harvesting. The cost effects on the total production cost of small tree chips were greater than on the production cost of logging residues. Co-operation and integration broaden the raw-material base for wood energy and make the supply more even.
Close-to-nature forestry may contribute to fulfil the objective of sustainable forestry. In western Denmark conversion of even-aged monocultures of Norway spruce to more stable stands has high priority, and must be done before close-to-nature forest management systems such as selection management can be implemented. Shelterwood regeneration in medium-aged Norway spruce stands seems to be the most promising method for conversion. Time consumption and damages were studied on the different harvesting methods in the establishment of the shelterwood. The traditional cut-to-length system gave higher net income than the fuel chip harvesting systems, but changes in price relations or lower stand quality might reverse this. The damage rate of remaining trees seems to be negatively correlated with the productivity of the logging/chipping operation.
Kari Väätäinen, Lauri Sikanen et Antti Asikainen
In the next twenty years in Finland, annual cuttings on peatland forests are foreseen to increase by up to 30 % of the total cuttings. Cost effective harvesting methods on low yield peatland forests coupled with low ground bearing capacity are required. One solution to improve the feasibility of harvesting could be excavators tailored for forestry use and equipped with a harvesting head.
In the study, cost competitiveness and productivity of the excavator-based harvester were investigated. The cost analysis focused on operating hours of harvester use, shift arrangements and purchase prices for the base machine and harvesting equipment when the base machine was used partly as a harvester and an excavator. Results were compared to conventional wheeled harvesters.
If the base machine is used more than 3 working months as a harvester in addition to normal (6-8 months) excavator work, the harvesting method would be cost competitive compared to purpose-built harvesters (if 1½ and 2 shift arrangements were used). The 25 % increase of the base machine's and harvester equipments' purchasing costs did not eliminate the cost competitiveness of harvesting, when harvesting was carried out in 1 ½ shifts for at least 4 months.
It would be feasible and profitable to invest in harvesting equipment for the excavator and therefore diminish the winter lay-days of the base machine by utilizing it in logging operations. Conditions on peatland sites mean that during the winter time the use of the excavator-based harvester is ideal, when the utilisation of all logging machines is at its highest.
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