School of Ecosystem and Forest Sciences - Research Publications

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    Prediction of non-recoverable collapse in Eucalyptus globulus from near infrared scanning of radial wood samples
    Wentzel-Vietheer, M ; Washusen, R ; Downes, GM ; Harwood, C ; Ebdon, N ; Ozarska, B ; Baker, T (SPRINGER, 2013-11-01)
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    A Wood Recovery Assessment Method Comparison between Batch and Cellular Production Systems in the Furniture Industry
    Prasetyo, VE ; Belleville, B ; Ozarska, B ; Mo, JPT (AMER SOC TESTING MATERIALS, 2019-01-01)
    Enhanced wood recovery mirrors a successful wood manufacturing operation. Studies of wood recovery in secondary wood processing, however, are scarce, particularly in furniture manu-facturing. Although recovery rates are under the continuous surveillance of sophisticated tech-nology, this attempt to monitor wood recovery would be especially challenging for small- to medium-sized furniture enterprises, as the capital investment in such technology would be substantial. This would hinder the possibility for improvements in production efficiency of the furniture industry. A methodology of wood recovery assessment in the furniture industry has been developed and proposed but has not been validated with a cellular production sys-tem, a different layout process and distinctive machinery, species, and other customer require-ments. The objective of this study is to assess the wood recovery protocol individually used in batch and cellular production systems, followed by examining the wood recovery of furniture manufacturing in these distinct production systems. Two Indonesian medium-sized furniture companies that individually operate batch and cellular production systems were employed, and two methods, mass and volume, were used to assess wood recovery at each furni-ture-making station. There was a significant difference in cumulative wood recovery rates be-tween batch and cellular production systems. Based on species and product dimensions, the average individual and cumulative wood recovery rates of furniture manufacturing resulted in a significant difference at the resawing and edging station. Large-dimension product recorded higher wood recovery level than small-dimension product. The wood recovery rates at the resawing and edging, surface planing, thickness planing, and trimming stations were mostly influenced by species, the quality of sawn timber, and cutting bills. Meanwhile, wood recovery at other stations was affected by product dimension and design. The mass method was the most acceptable method according to the measurement systems analysis.
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    Furniture Production Efficiency in the Indonesian Context
    Prasetyo, V ; Belleville, B ; Ozarska, B (International Conference on Wood Science and Technology, 2018-10-16)
    Most efficiency improvement strategies implemented in furniture manufacturing are data-driven methods. Due to a lack of production systems used in most Indonesian small and medium-sized furniture companies, the evaluation of production efficiency for future improvement seems rather difficult to perform. A wide range of existing evaluation tools and the varying capabilities of the companies to adapt the methods contribute to a problematic evaluation process. Research has been undertaken with the aim to develop a generic efficiency evaluation method and to prioritise a new potential metric to assess and control efficiency in furniture manufacturing. A basic production cost analysis with standardized variables has been demonstrated as a typical method to evaluate production efficiency in multi furniture companies, followed by applying a wood recovery assessment, a Pareto analysis, an X-Y matrix, and process capability analysis. The heartwood proportion of teak (Tectona grandis) has been determined as a key potential efficiency metric to control and monitor teak sawn board quality and its utilisation. Applying process capability analysis with a setting of lower specification limits to the population of teak heartwood rates produces a model to simulate optimal teak utilisation.
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    Quality assessment of the drying process for Eucalyptus delegatensis timber using greenhouse solar drying technology
    Phonetip, K ; Ozarska, B ; Harris, G ; Belleville, B ; Brodie, G (Springer Verlag, 2019-01-24)
    The aim of this study was to investigate the process of drying Eucalyptus delegatensis in a greenhouse solar kiln. Specific objectives were to assess stress formation, moisture gradients and timber distortion, the moisture content distribution within various sections of the timber stack, and internal checking and collapse development within the boards. The maximal temperature and relative humidity (RH) during day time were set at 430C/72% RH. In the night time the temperature was at ambient condition with 90% RH. The strain measurements were undertaken before and after the samples were sliced. The timber quality at the end of drying was assessed based on Australian and New Zealand standard (AS/NZS 4787:2001). The moisture content values in the three different sections (front, middle and end) of 2400 mm long boards were compared by Analysis of Variance. The results showed that the mean compressive strain was -2 x 10-4 mm/mm in the core layers and the tensile strain was 14 x 10-4 mm/mm in the outer layers. All sample boards were within the acceptable limits for cupping, spring and bow, even though the relative humidity level did not reach the set value. However, the amount of twist in three out of twelve sample boards was above the acceptable limit. Mean moisture gradient was 0.6%. There was a significant difference in moisture content at end section compared to the front and middle sections. Internal checking, collapse and residual stress were graded as Class “C” (class A is the highest grade and D is the lowest).
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    Drying timber in a solar kiln using an intermittent drying schedule of conventional laboratory kiln
    Phonetip, K ; Brodie, G ; Ozarska, B ; Belleville, B (Taylor & Francis, 2018-10-01)
    The purpose of this study was to apply an intermittent drying schedule developed from a conventional kiln to a solar kiln. Implementing this experiment could help better understand the oscillation of the temperature inside a solar kiln and timber quality during drying progress. The theoretical recharge and discharge curves were used to predict the temperature inside the solar kiln using experimental data obtained previously using a solar kiln. The surface and internal checks were measured using ImageJ freeware, and the development of the Moisture Content (MC) profile was assessed by coring and slicing method for the Eucalyptus delegatensis boards during drying. The results showed that the recharge and dis-charge model can predict the temperature with less than 2 C error from the experimental data in the solar kiln. The total drying time to 12% MC was 87 days for the solar kiln. The drying rate was equivalent to the conventional kiln decreasing at an average rate of 0.2%per day. The surface check formation was found when the MC gradient between the core and the case of the board was greater than 42% at 9 days of drying in the solar kiln and conventional laboratory kiln. The applied drying schedule used in the solar kiln was success-ful and offered similar drying time. However, the oscillation of temperature in the intermittent drying will require further improvement to get closer conditions in a solar kiln.
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    Comparison of two dye uptake measurement methods for dyed wood veneer assessment
    Nguyen, N ; Ozarska, B ; Fergusson, M ; Vinden, P (Springer Verlag, 2018)
    Dyeing of veneer is an important value-adding process, particularly for young plantation hardwood species which often have uneven colour and “dull appearance”. An important indicator in the assessment of the performance of veneer dyeing process is the dye uptake. This study compared two different methods of measuring dye uptake of dyed veneers; by using either liquid uptake based method or spectrophotometry method. The study revealed that there was a significant difference in the percentage of dye uptake determined by the two methods, but the overall results in the correlation between the percentage of dye uptake and the dyeing parameters had a similar trend.
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    Potential of Veneer Peeled from Young Eucalypts in Laos
    Belleville, B ; REDMAN, A ; Chounlamounty, P ; Phengthajam, V ; Xiong, S ; Boupha, L ; Ozarska, B (North Carolina State University, 2018-08-23)
    In Laos and neighboring countries, opportunities exist for the production of engineered wood products such as plywood and laminated veneer lumber to supply the rapid growth of construction, furnishing, and joinery activities. The objective of the present study was to assess the potential of peeling fast-growing high-yielding pulpwood from managed eucalypt stands in Laos for veneered products. Eucalyptus pellita, Eucalyptus camaldulensis, and eucalypt clone K7 (E. camaldulensis × E. deglupta) stands were characterized based on veneer quality and recovery. The influence of log position, log geometry, and other log traits during recovery were also investigated. The selected taxa achieved green veneer recoveries that ranged between 57% and 67%. End splitting and branch-related defects were the most important grade-limiting defects that restricted veneer sheet quality to a lower grade of most sheets. However, simple timely silvicultural decisions, such as pruning, could significantly help improve the quality of veneer obtained. The obtained results could be used in the formulation of recommendations to adopt better management practices in Laos to improve the value of plantation-grown wood.
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    Minimizing environmental impacts of timber products through the production process “From Sawmill to Final Products”
    ADHIKARI, S ; Ozarska, B (Springer, 2018-07-04)
    As awareness of climate and environment issues increases and consumption habits change, new opportunities are opening up for the forest industry and wood construction to develop functional green solutions to meet consumers’ needs. Wood is a versatile raw material and the only renewable construction material. The manufacture of wood products and structures consumes little energy in comparison to similar products and structures made of other materials. Unlike other materials, most of the energy needed to manufacture wood products is derived from renewable energy sources. The global timber sector currently faces the dual challenges of meeting the growing demand of quality timber products and minimising possible adverse impacts on the environment and human health. Major sources of environmental impacts occur throughout the wood supply chain from sawmills to final products. The major objective of this paper is to explore ways to reduce the environmental impacts of timber products, from sawmills to final products. The specific objectives include the identification of major sources and mechanisms of environmental impacts from timber products, the assessment of the status of energy consumption and GHG emission in wood products during timber processing and manufacturing as well as identifying the potential ways to minimize these environmental impacts.
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    Achieving Long-Term Adhesion and Bondline Durability with difficult-to-bond Australian Hardwoods Species
    LI, S ; Belleville, B ; Gutowski, M ; Kuys, B ; Ozarska, B (Society of Wood Science and Technology, 2018-07-25)
    Australia has unique resources of native hardwoods producing a range of aesthetically and structurally attractive timbers suitable for high-strength structural applications and other products for internal and external applications. Amongst problems limiting broader hardwoods applications is their excessive susceptibility to hydrothermal movements in response to changes in the atmospheric moisture. This, in turn, produces excessive interfacial stresses between hardwood surface and glues, resulting in fast degradation of adhesion in products exposed to weathering. A range of Australian hardwood species also suffers from poor adhesion due to high bulk phenolic and surface lipophilic extractive content as well as high density. Research has been undertaken with the aim to improve the performance, durability, and designs flexibility of hardwood-based components for outdoor and indoor applications. The method relies on the application of eco-sustainable water-based formulations of functional polymer and chemical additives overcoming the impact of extractives and facilitating chemical bonding of designated connector chains to cellulose constituents. To date, results of adhesion bonding tests have demonstrated a significant increase in shear strength, wood failure, and durability compared to unmodified samples of Eucalyptus camaldulensis, Eucalyptus pilularis, and Eucalyptus regnans. The results could potentially facilitate the effective transformation of the housing and construction industry by targeting drastically increased use of hardwoods by the rapidly developing Australian prefabricated housing and construction industry.