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  • 51.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sandberg, Dick
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Preparation of wood with pulsed UV-laser ablation for characterisation of the wood structure2007In: Proceedings of Third International Symposium on Wood Machining, Presses polytechniques et universitaires romandes , 2007, p. 191-194Conference paper (Refereed)
    Abstract [en]

    In contrast to mechanical techniques involving cutting with a knife, cutting with a microtome or grinding, pulsed UV-laser ablation is an irradiation technique where a so-called Excimer laser is used, and the process is adiabatic, which means that no or a very little chemical change occurs in the material being processed. Cross sections of samples of Scots pine and Norway spruce which had been exposed outdoors have been prepared with the help of an Excimer laser (wavelength 248 nm) for study in a microscope. UV-laser ablation has been found to be a suitable method of preparation for wood when it is desired to obtain thin sections with little influence on the material, and particularly when dealing with brittle materials, e.g. archaeological wood, biologically-attacked wood or, as in this case, wood which has been exposed outdoors.

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  • 52.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sandberg, Dick
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    The Concept of Value Activation II.: The PrimWood Method for improved properties of hardwood products.2005In: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, p. 53-59Conference paper (Refereed)
    Abstract [en]

    The name Value activation refers to the basic understanding of wood, where at present there are properties that are not fully exploited, but with help of a new sawing pattern could be fully utilized. The basic idea lies at an industrial level producing radial sawn timber with good profitability and with lesser and mostly a controllable moisture movement. In short it implies an activation of values of timber that has not been exploited in ordinary industrial production to date.

    This paper gives one example how the basic ideas in the concept of Value activation can be implemented in the industry. A new manufacturing system, the PrimWood Method, producing radial sawn timber, well adjusted to the conditions of the Swedish hardwood sawmill industry is presented. The manufacturing system generates knot and defect-free hardwood products with vertical annual rings.

    Utilizing the proposed manufacturing system in the Swedish hardwood sawmill industry imply an increased focus on hardwood in consumer products, which gain both forestry, sawmill industry and the wood manufacturing industry.

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  • 53.
    Johansson, Jimmy
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sandberg, Dick
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Volymutbyte vid tillverkning av kvistfria snickeriämnen och skivor med stående årsringar2005Report (Other academic)
    Abstract [en]

    This report describes a new production concept for manufacturing of high quality boards, components and panels from softwoods and hardwoods. The concept, named the PrimWood Method generates knot-free boards, components and panels with vertical annual rings. The cross sections of the boards are either rectangular or triangular, called Triangle and Rectangle. These two products are further processed to components and panels.

    The PrimWood Method increases the quality of the wood, compared to wood processed with traditional methods (harder surface, increased shape stability, freedom from cracks, easier and faster processing, less waste and a more even finishing). The wood is also given new aesthetical characteristics (e.g. even texture, knot-free surfaces and decorative finger-joints). The PrimWood Method also improves the raw material utilization, with resulting positive environmental effects, since a renewable resource is utilized more efficiently.

    The volume yield when manufacturing different products from the PrimWood Method has in this report been studied, both theoretical and experimental during industrial conditions. For pine (Pinus sylvéstris L.) the volume exchange in different processing stages may be summarized as follows:

    Sawing, from log to dried wood             56 %

    Knot-free boards from Rectangle           75 %

    Knot-free panels from Rectangle (Panel) 52 %

    Knot-free boards from Triangle (Rhomb) 73 %

    Knot-free panels from Triangle (Prism)   53 %

    The volume yield for boards and panels are determined from incoming volume sawn and dried Rectangle and Triangle. The quality and the geometrical form of the raw material are crucial for the obtained volume yield from the manufacturing process. The volume yields described above are to be seen as guiding values, when processing pine from Sweden.

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  • 54.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sandberg, Dick
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Gustafsson, Åsa
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Design of form stable and visually crack free edge-glued oak panels.2005In: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, p. 167-171Conference paper (Refereed)
    Abstract [en]

    Edge-glued panels are a very appreciated material, for instance used in cabinet doors or worktops in the kitchen. The surrounding climate for these products is often severe, due to large seasonal variation of the relative humidity in the indoor air. Therefore problems regarding crack formation and form stability often occurs. This paper studies how annual ring orientation of lamellas, lamella width, initial different moisture content in the panels and single lamellas with deviating moisture content are affecting form stability and crack formation of edge-glued oak panels (Quercus robur).

    In the study 47 test samples with different characteristics were tested in varying climate during 182 days. The relative humidity was changed approximately every 14 days in the interval 18 to 88 % and temperature 20˚C. The panels were measured each 7 days regarding form stability factors. The crack formation was measured at the beginning and the end of the test.

    The evaluation of the results show that the annual ring orientation of the lamellas will be a significant factor regarding the form stability factors width changes and cupping of the panels and also regarding the crack formation. The lamella width is important as a significant factor regarding the surface evenness. Moisture content (initial level) will affect both the form stability and the crack formation. The effect of this factor is dependent on the relation to the climate of the surroundings.

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  • 55.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Sandberg, Dick
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Gustafsson, Åsa
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Secondary interior wood products for manufacturing in Swedish hardwood sawmills2005In: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, p. 162-166Conference paper (Refereed)
    Abstract [en]

    The Swedish hardwood sawmill industry is today in a situation where the sawn hardwood exhibit a wide variation in quality characteristics, while the customers places strict demands. To create a profitable return for all their products the hardwood sawmill industry therefore must find new markets where other quality characteristics are valuable.

    In this study the requirements regarding logistic service and product quality characteristics for secondary wood products used as for instance indoor panelling and mouldings are identified and described. The industrial setting for the study is the Swedish retail and house building industry. The purpose of the study was to study the possibilities to increase the use of hardwoods in these products.

    The study follows a case study methodology. The studied companies consisted of in total nine companies in the southern part of Sweden. Six house-building companies were studied and three retail companies.

    A total of 15 different requirements regarding logistic service and product quality characteristics were identified. The product quality characteristics were related mainly to the aesthetic appearance of the products and to the stability of the product in service. The important logistical service requirements were related to the location and time of delivery and customer-specified orders.

    The results show that adjustment to customer requirements means that a supplier of hardwood products must adjust its organization towards a stronger customer focus. In order to do this a fundamental problem for Swedish hardwood sawmills is the current lack of an accepted quality sorting system for hardwood. It is also important for sawmills to control and adjust their production processes in order to gain increased flexibility and delivery precision.

    With the results from this study a test collection of mouldings and indoor panelling has been developed by a Swedish hardwood sawmill and is now tested by one of the retail companies within the study.

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  • 56.
    Johansson, Jimmy
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Schauerte, Tobias
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Lindblad, Fredrik
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Balancing the production flow in prefabrication of wooden houses2018In: Tools for sustainability, Forest Products Society, 2018Conference paper (Refereed)
    Abstract [en]

    The industrialization of wooden house building processes from traditional on-site production to off-site prefabrication is challenging, concerning the possibility of effective handling of numerous product variants, where each house is more or less unique. To obtain high productivity in the production, a well-balanced flow with minimization of waste is of great importance. In Sweden, many off-site house producers are in the starting phases of introducing advanced automation technologies in their production processes and the need for a more detailed process control therefore increases. In previous studies, the installation of windows has been identified as a demanding step in the prefabrication process, since it often creates a bottleneck i.e. the most overloaded part of process (Slack et al., 2016) and thus negatively affects the cycle-time and a balanced production flow.This study aims to understand, how the effectiveness of windows installations could be improved. By using a multiple case-study methodology, processes of several companies are compared and discussed. Further, suggestions for improvements are made for one case company. The results show that a replacement of the windows installation could (a) shorten the cycle-time of one wall by more than 10 %, (b) reduce the queueing time for the entire wall assembly process by more than 48 % and consequently (c) help to create a more balanced production flow.

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    Balancing the production flow in prefabrication of wooden houses
  • 57.
    Johansson, Jimmy
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Söderström, Ove
    Sandberg, Dick
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Capillarity in hardwood: An important factor for hardwood market expansion2007In: The Beauty of Hardwood: Proceedings of third Conference on Hardwood Research and utilisation in Europe, University of West Hungary, Sopron , 2007Conference paper (Refereed)
    Abstract [en]

    The Swedish hardwood sawmills are today experiencing problems of finding profitable markets for products containing for instance knots and red or brown heartwood. By using hardwood outdoors, it would be possible to expand the market of hardwood with new products that may set other requirements on the wood than the present use. In Sweden today, hardwood is normally used in furniture, joinery, floors and kitchens where esthetical requirements are dominant. When considering outdoor use, technical requirements such as durability become more important and especially the capillary characteristics of the wood are of interest. The capillarity determines the ability of the material to absorb and desorb moisture, characteristics that affect the resistance of degrading. 

    In this paper, the capillary characteristics were modelled and studied by exposing the cross section of wood to a free water surface. The study compares two Swedish hardwood species, aspen and oak with pine, a softwood species that is common in Sweden and often used outdoors.

    The results show that the capillary transport mechanism is affected by the microstructure of the wood and the natural ability of the material to close the transport paths in the structure with for instance extractives, tyloses and closed pits. Based on these factors, a characteristic capillary mean radius is introduced to describe the longitudinal capillary water absorption in the studied wood species.

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  • 58.
    Johansson, Jimmy
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Woxblom, Lotta
    Sveriges lantbruksuniversitet.
    Prerequisites for the Realization of the Transnational Communication Platform WoodApps.2013In: Proceeding of ISCHP2013 - International Scientific Conference on Hardwood Processing, October 7-9, Florence, Italy., 2013Conference paper (Other academic)
  • 59. Karlsson, Reine
    et al.
    Palm, Johan
    Woxblom, Lotta
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Konkurrenskraftig kundanpassad affärsutveckling för lövträ: metodik för samordnad affärs- och teknikutveckling inom leverantörskedjan för björkämnen2011Report (Other academic)
  • 60. Karlsson, Reine
    et al.
    Paulsson, Markus
    Backman, Mikael
    Anna-Karin, Djupenström
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Explicit climate investments as a tool for societal advancement2009Conference paper (Refereed)
  • 61.
    Lindblad, Fredrik
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Schauerte, Tobias
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Identifying market mobility barriers for wooden single-family house producers to enter the multifamily segment2018In: Social Influences, Forest Products Society, 2018Conference paper (Refereed)
    Abstract [en]

    In the past decades, the housing shortage in Sweden accumulated to a level that led to acute problems for many people combined with continuously rising housing prices. The market for single-family houses, where wood dominates with 85 – 90 % of market share, is highly competitive with many companies offering relatively similar products or services. To serve the demand on that market, only 38 % of the existing companies were needed. One way to tackle the existing housing shortage, and to develop new business opportunities, could be to get more companies from the single-family house industry to produce multi-family houses. Current competence in prefabricated house production could be utilised, yet, other areas could act as barriers for these companies. The aim of this study is to identify potential market mobility barriers for Swedish companies currently producing wooden single-family houses to develop towards the construction of multi-family houses. This will be conducted by initial interviews with decision makers in those companies, combined with a survey-study covering companies within the industry. The results show that the main market mobility barriers are related to the strong market presence of traditional building materials, lack of knowledge by the market of wood as a suitable building material and the importance of governmental guidance and actions.

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    Identifying market mobility barriers for wooden single-family house producers to enter the multi–family segment.
  • 62.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Bending and Creep Deformation of a Wood-Based Lightweight Panel: An Experimental Study2019In: Wood and Fiber Science, ISSN 0735-6161, Vol. 51, no 1, p. 16-25Article in journal (Refereed)
    Abstract [en]

    When wood is exposed to long-term loading, creep deformation can occur because of its viscoelastic characteristic. The aim of this study was to increase the understanding and knowledge of creep deformation of a wood-based lightweight sandwich-type panel and to see if this type of panel has similar properties for creep as solid wood has. This was done by means of a study based on experiments. The panel studied consisted of two face sheets of beech wood and a core of pinewood struts cross-glued to the face sheets. A solid beech panel was used as a reference. In all, there were 27 samples for the test. The densities of the lightweight panel varied from 165 to 297 kg/m(3), compared with the density of the solid panel of 705 kg/m(3). The study consisted of two parts: a bending test and a creep test. The bending test was used to determine the maximum failure load for the panel. For the creep test, 30% of the original failure load was used. When the results from the bending tests were ranked for load capacity in relation to density, the results for the lightweight panel varied from 9.0 to 18.0 m(4)/s(2), compared with the value of the reference panel at 27.3 m(4)/s(2). This measured how effective the panel was in withstanding bending loads in relation to their density. However, this was not to say that the panel with the highest value also took the highest load in absolute terms. If the creep deformation is instead ranked in relation to density, the results for the lightweight panel varied from 10.4 to 33.7 kg/m, compared with the value of the reference panel at 45.5 kg/m. As with the bending test, these values rank how effective the panel was in resisting creep deformation in relation to density.

  • 63.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Sandberg, Dick
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Shape stability of modified engineering wood product (EWP) subjected to moisture variation2011In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 6, no 3, p. 132-139Article in journal (Refereed)
  • 64.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    A new light-weight panel for interior joinery and furniture2013In: Proceeding of 9th Meeting of the Northern European Network for Wood Science and Engineering -WSE 11-12 September 2013, Hannover, Germany / [ed] Brischke, Christan & Meyer, Linda, Hannover: Leibnitz Universität Hannover , 2013, p. 184-189Conference paper (Refereed)
    Abstract [en]

    Light-weight materials based on wood for interior fittings and furniture have been of interest for at least the last fifty years, mainly for cost-reducing reasons. Today, the increasing care of the environment and the growing interest in the concept of a sustainable society provide further impulses for the development of light-weight materials. A common consequence of the reduction in weight of such materials is deterioration in the mechanical properties, e.g. strength, stiffness and shape stability, compared to those of solid wood. New solutions for e.g. connections and mountings are also needed. Today, new panel materials are required where the disadvantages of conventional light-weight materials are less prominent and with aesthetic and tactile properties close to those of natural wood.

    In this paper, a new type of light-weight panel is presented. The panel is cross-laminated in three layers and consists throughout of solid wood. The weight reduction is a consequence of the hollow middle-layer construction. The intention of the construction is to make it possible to mix species in the panel, e.g. a high-quality and high-density wood on the surface and a low-quality wood with low weight in the core, and thus to optimize the properties of the panel for a specific purpose and to keep costs down at the same time. In this first study, however, the whole panel is made of Scots pine.

    Bending tests show that the glue-line between the outer layers and the core is critical for the mechanical performance of the panel and this has to be developed further.

    This study shows that this light-weight panel can be used as a single component or in a system with other components for interior fittings and furniture. The current design of this light-weight panel has some deficiencies but, in addition to its low weight, it has the potential to provide the mechanical, aesthetic and tactile properties asked for.

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  • 65.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Luleå University of Technology .
    Densified and thermally modified wood as outer layers in light-weight panels for furniture and joinery2014In: Final Cost Action FP0904 Conference : “Recent Advances in the Field of TH and THM Wood Treatment”: May 19-21, 2014, Skellefteå, Sweden : book of abstracts, Luleå: Luleå tekniska universitet, 2014, p. 79-80Conference paper (Refereed)
  • 66.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Densified and thermally modified wood in light-weight panels2014In: Presented at the 2014 Forest Products Society International Convention Program, Quebec City, Canada, August 10-13, 2014, 2014Conference paper (Refereed)
  • 67.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Sandberg, Dick
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Increased use of hardwood through light-weight constructions2013In: Proceeding of ISCHP2013 - International Scientific Conference on Hardwood Processing, October 7-9, Florence, Italy. / [ed] Berti, S. et al., Florence: CNR IVALSA , 2013, p. 291-296Conference paper (Refereed)
    Abstract [en]

    The use of high density hardwood species for furniture and interior purposes can be limited because the weight. Keeping the weight low is important both from a user perspective and for logistic reasons in the manufacturing and distribution process. This work describes the construction and mechanical characteristics of a new type of light-weight panel in wood. The panel is a sandwich construction in three layers with hardwood as the surface layers. The surface layers are made of 6 mm thick solid beech and the core consists of solid pine wood in thicknesses of 24 or 96 mm cross-laminated to the surfaces. The total panel density was then 373 and 294 kg/m3 given a beech surface layer with a density of 725 kg/m3. The presented light-weight panel resulted in a 50-60 % decrease in the use of wood compared to a traditional edge-glued panel. Tests of the mechanical properties showed a bending stiffness in the longitudinal direction (of the core) of 2.9 kNm2 for a 36 mm thick panel and 221 kNm2 for a 108 mm thick panel. In the transverse direction, the corresponding values were 11 kNm2 and 88 kNm2. The overall results indicate that the light-weight panel presented shows promising technical and environmental properties and can thereby contribute to an increased use of hardwood species.

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  • 68.
    Nilsson, Jonaz
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Ormarsson, Sigurdur
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Moisture-related distortion and damage of lightweight wood panels: experimental and numerical study2017In: Journal of the Indian Academy of Wood Science, ISSN 0972-172X, Vol. 14, no 2, p. 99-109Article in journal (Refereed)
    Abstract [en]

    This study was conducted to increase the knowledge of moisture-related distortion and damage in the field of wood-based lightweight panels. By increasing the possibilities of predicting moisture-related distortion and damage, the possibilities of using lightweight wood materials could increase. The study was performed through experiments and modelling work on a wooden panel product with numerous struts and two thin outer-face sheets of beech-wood glued tightly onto the struts, as well as reference panels of solid wood. During the testing period the results showed the density of the studied lightweight panels to vary from 170 to 290 kg/m3. These panels shrunk and swelled less than the solid wood panels and reacted faster to changes of surrounding humidity and temperature. Moisture related distortions such as twist and bow were not inferior compared to the solid wood panels. Shrinkage or swelling produced moisture related stresses. This may mean that the panel will have a risk of serious damage in the form of cracks or glue release between the outer face sheet and the struts when it is exposed to intense drying. The experimental tests also followed how various damages arose in the panels. Until the damage occurred, the deformation results showed a strong agreement between the experimental and the model findings. Better knowledge of how this type of panel reacts to climate variations is important for the further design and development of this type of product.

  • 69.
    Nilsson, Josefin A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Characteristics of un-barked small-dimensioned birch for furniture and interior applications2015In: Proceedings of the XXVIIth International Conference Research for Furniture Industry, September 2015, Turkey, Gazi University , 2015, p. 175-181Conference paper (Other academic)
    Abstract [en]

    Many interior and furniture applications today use the natural aspects of wooden materials as a sales advantage. Defects such as knots, colour variations and rough surfaces are called rustic, natural or vintage and will be considered as an appreciated feature by the consumers. This approach changes the traditional view of wood quality for technical uses, and also the industrial processing of the material. As a consequence, more variables of the material than before must be handled in the production. A specific challenge in the furniture industry is to treat the raw materials under this view with as small volume losses as possible. One way of decreasing losses could be achieved by fewer processing steps. The present study aims at exploring the possibility to relate the dimensions of the trees already in the forest in relation to specific furniture components, and furthermore to leave the bark on for creating specific aesthetical characteristics to the end product. In Nordic countries, birch wood has gained interest in furniture and interior applications due to its unique aesthetic qualities. In today’s forestry industry, the small-dimensioned material from harvesting operations of birch forests is normally used by the pulp industry or as fire-wood. For the interior and furniture industries these fractions may be a new source of raw material supply. However, a proper utilization of the material requires a better knowledge of its properties. The potential of using un-barked material in round form also sets special requirements in the process. The present study presents results from initial testing concerning the behaviour of the bark in round wood pieces. For the experiments, round specimens of downy birch (Betula pubescens Ehrh.) measuring 450 mm in length and with varying diameters from 30 to 80 mm at the top were used. The green wood was dried with and without bark as to study the drying velocity in relation to dimensions. The bark was studied in respect of changes in bonding to the wood and its characteristics. The preliminary results are promising for using the material in interior and furniture applications. However, there are still some shortcomings to be addressed in the future, such as the impact of the bark in the drying process as well as the bark bonding.

  • 70.
    Nilsson, Josefin A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Customer requirements on solid wood material: A birch roundwood case-study2016In: Proceedings of the 12th meeting of the Northern European Network for Wood Science and Engineering (WSE): Wood Science and engineering - a key factor on the transition to Bioeconomy / [ed] Bruno Andersons and Arnis Kokorevics, Latvian State Institute of Wood Chemistry , 2016, p. 22-28Conference paper (Other academic)
    Abstract [en]

    Today a majority of the pre-commercial thinning (PCT) cut birch stems in Sweden are retained on the site for biodegradation, since their market value is lower than the cost of harvesting. Some stems are removed as firewood. The uses of the PCT material can be difficult to find, and the costly PCT is carried out in expectation of greater returns later in the forest rotation. There is a growing body of literature that recognises the possibility of using low value wooden material for furniture and interior purposes. While some research has been carried out on character-marked wood, there have been few investigations on utilization of small-dimensioned roundwood. However, proper utilisation of this material requires appropriate matching of the material attributes with the end-user’s expectations on furniture or joinery products. The aim of this work is to understand challenges and possibilities for the utilization of small-dimensioned roundwood birch in furniture and joinery products. The study synthesizes literature on customers’ demands on hardwood and important material properties. A case-study approach was used to evaluate how a bench, made out of small-dimensioned roundwood birch, can meet the requirements from customers and manufacturing industries. The results demonstrate that opportunities exist within the customer segment appealed by naturalistic furniture design. Proposals are made for future research needed for successful use of small-dimensioned roundwood birch for furniture applications.

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    J.NilssonWSE2016
  • 71.
    Nilsson, Josefin A.
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Adamopoulos, Stergios
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Potential of utilizing small-dimensioned roundwood birch2016In: The 70th Forest Products Society annual convention - new horizons for the forest products industry, June 27-29, 2016, Portland, Madison: Forest Products Society, 2016Conference paper (Other academic)
    Abstract [en]

    In Nordic countries, birch wood has gained interest in furniture and interior applications due to its very unique aesthetic qualities. A significant share (33%) of the small-dimensioned (diameter at breast-height smaller than 9 cm) standing tree volumes in the Swedish productive forest land consists of silver and downy birch (Betula pendula and Betula pubescens). In today’s forest industry, the small-dimensioned material from pre-commercial thinning operations of birch and Norway spruce mixed forests is normally left in the forest if not used as fire-wood. For the furniture industries these fractions may be a new source of raw materials’ supply. However, a proper utilization of this material requires a better knowledge of its properties. This paper presents a review on the utilization aspects of solid wood from small-dimensioned timber as well as some useful concepts for successful material selection in product design. Therefore, based on customer requirement concepts, it is analyzed which wood material properties are important for furniture or joinery applications from hardwoods and how small-dimensioned roundwood birch could meet the requirements. Proposals are made for future research needed to fully explore the potential of using small-dimensioned roundwood birch for furniture applications.

  • 72. Palm, Johan
    et al.
    Karlsson, Reine
    Woxblom, Lotta
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lönsamt lövträ: Affärsutveckling för lövträrelaterad tillverkningsindustri 2007-20102011Report (Other academic)
  • 73.
    Paulrud, Susanne
    et al.
    Research Institutes of Sweden (RISE).
    Gustavsson, Lennart
    Research Institutes of Sweden (RISE).
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Tekniska och ekonomiska förutsättningar för oljeersättning i industrin med pyrolysolja2017Other (Other academic)
  • 74.
    Popovic, Djordje
    et al.
    Jönköping university.
    Schauerte, Tobias
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Prefabrication of single-family timber houses: problem areas and wastes2017In: Proceedings of the 25th Annual Conference of the International Group for Lean Construction (IGLC) / [ed] Walsh, K., Sacks, R., Brilakis, I., Heraklion, Greece: International Group for Lean Construction (IGLC) , 2017, Vol. 2, p. 837-844Conference paper (Refereed)
    Abstract [en]

    Industrialization of house building has shifted the activities traditionally done at building site to the off-site assembly. The design, manufacturing processes and on-site assembly in industrialized house building are defined and documented to form a process platform, but these must be evaluated and improved to constantly develop better and more efficient practice. Lean production and philosophy are still not well understood concepts at the shop floor and wasteful activities that decrease production efficiency are often overseen. Current waste categorizations and descriptions seem not to be addressing problem areas and occurrence of waste in prefabrication of single family timber houses. The research aim is to define problem areas that occur during the prefabrication of wall modules, associate them to eight types of waste and identify key problem areas for possible development and improvement. The study was based on secondary data from five case studies that primarily focused on identifying and proposing possibilities for development of productivity. Four problem areas were identified and the future improvement efforts for the prefabrication of single family houses can be placed on developing the processes of the assembly system problem area. The possible future study can aim at quantifying these problem areas.

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  • 75.
    Salim, Roaa
    et al.
    Jönköping University.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Automation decisions in investment projects: a study in the Swedish wood products industry2018In: Proceedings of the 8th Swedish Production Symposium (SPS 2018) / [ed] Mauro Onori, Lihui Wang, Xi Vincent Wang & Wei Ji, Elsevier, 2018, p. 255-262Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to study which aspects are considered when automation decisions are being made in the wood products industry. The aspects were identified in several decision areas of manufacturing. The data collection was based on participation in meetings of an ongoing investment project. The findings demonstrate that in the first phases of an investment project, where the project idea is evaluated, the most critical aspect for decision makers is economic benefits. This paper will provide further insights on the underlying reasoning for decisions on automation of manufacturing in investment projects in the wood products industry.

  • 76.
    Salim, Roaa
    et al.
    Jönköping University.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    The influence of raw material on the wood product manufacturing2016In: 49th CIRP Conference on Manufacturing Systems, CIRP-CMS 2016; Commundo Tagungs Hotel Stuttgart, Germany, 25 May 2016 through 27 May 2016 / [ed] Bauernhansl T.,Westkamper E, Stuttgart: Elsevier, 2016, no 57, p. 764-768Conference paper (Refereed)
    Abstract [en]

    This paper focuses on the later part of the wood processing chain in wood industry: the wood product manufacturing. Wood product manufacturers are facing many challenges e.g. due to the high variability of the raw material. Waste and rework are prevalent, resulting in high manufacturing costs. Each processing step in the manufacturing affects material utilization and cost efficiency. The proportion of the material cost and waste in most wood products are high. The challenge for wood product manufacturers is to make profit and remain competitive when on one side they need to execute the processes at the lowest cost and within shortest time and on the other side deal with a highly variable raw material. Therefore, wood product manufacturers need to consider their manufacturing process with emphasizes on the raw material consumed. The purpose of this paper is to examine the direct –and indirect influences of the material on the wood product manufacturing process in terms of productivity and efficiency. The direct influences aims at examining the impact of consuming raw material with different properties on the manufacturing process, while the indirect influences examine process-related aspects affecting the material's influence on the manufacturing process. This paper is based on a case study at a Swedish interior wood product manufacturer. The first phase of the study compares between two wooden panels with different material properties. Results show that solid, knotty raw material with higher moisture content results in lower efficiency than finger-jointed, knot free material with lower moisture content. The second phase of the study examines the indirect influences and shows that material handling is one of the key process-related aspects that need to be considered.

  • 77.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Azoulay, Michel
    Baudin, Anders
    Blom, Åsa
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Carlsson, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Eliasson, Lars
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Bengt
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Daniel
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Jonaz
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nordvall, Hans-Olof
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Utvändiga träfasader: Inverkan av materialval, konstruktion och ytbehandling på beständigheten hos fasader av gran och tall2011Report (Other academic)
    Abstract [en]

    The external façade must give expression to a building through both design and colour, and it must also protect the insulating layers in the wall from external influences. These functions can be fulfilled by almost all materials. If wood is to be competitive in this context, the wood material, the façade design and the surface treatment system must be chosen and interact in such a way that the façade is given a long life with little need for maintenance. A wooden façade will then in a broad sense be both economically and aesthetically attractive for the user.

    This study illustrates the state of knowledge regarding the outdoor use of pine (Pinus sylvestris L.) and spruce (Picea abies L. Karst.) facings above ground. Specifically, it deals with the use of wooden facings with regard to the choice of material, façade design, surface treatment and recycling. The market demands wooden facing systems, and the requirements emphasized by the actors on the market, e.g. the builders, real estate administrators, architects, designers, frame suppliers, contractors and representatives for the single-family timber housing industry can be summed up as follows:

    • There must be a specified life-time and given time intervals for maintenance of the wooden facings. (Shall be similar to those of competitive materials)
    • The supplier of the facing system should shoulder the long-term responsibility for its maintenance.
    • Flexibility, the supplier shall be able to replace or renovate the facings when necessary.
    • Building requirements, the wooden facing materials must be able to interact with other, specially fire-classified, materials.
    • The facing system shall have an attractive appearance.

    The primary market for the new facing systems should be multi-family houses but not necessarily multi-family houses of wood. The focus shall lie in the flexibility of the facing system in architectural expression, and in relation to other materials and systems. New building is important, but the million program, renovation and additions (ROT) and greater energy efficiency are also important spheres.

    The Swedish market is small (currently ca. 70 000 m3 wood for façades), but it should nevertheless be given priority before the Nordic countries, and thereafter Switzerland, Austria and Germany. The literature describes more or less well-founded recommendations for prolonging the life of wooden facing materials and extending their maintenance intervals, although some of the recommendations are directly conflicting.

    Many details relating to materials choice, façade design and surface treatment are important for the durability of wooden facings. It is difficult to separate the most important factors, but without taking into consideration aspects such as costs, availability and other factors of a practical nature, the following key factors can be identified as important for an environmentally correct and durable façade of pinewood or spruce:

    Choice of material

    • The wood shall have a high proportion of heartwood, preferably exclusively heartwood
    • The wood shall have vertical annual rings.

    Handling from forest to the façade

    • The wood shall be handled so that it does not suffer mechanical damage or microbial attack, or become wet or soiled, i.e. a rapid and correct handling with good packaging.

    Design

    • The façade shall start at least 30 cm above the ground level.
    • The façade shall be ventilated so that moisture can rapidly dry out. Ventilation of the space behind the facing is an easy way of achieving this.
    • Water run-off – no horizontal surfaces.
    • Flexibility –both in the construction and in the architectural design. There is a demand for facing systems which can be simply “hung onto” existing buildings.

    Surface treatment

    • Sealed end-grain sections – sealing of the end-grain surface to prevent moisture absorption into the wood is decisive for the life-time of the wood material. Nailing can open up new end-grain surfaces and should thus be carried out carefully and only after due consideration.
    • Rounded edges – increase the covering ability of paint and reduce the risk of mechanical damage to the facing boards.
    • Choice of surface treatment – vital for the performance of the facings. The wooden facings shall be delivered as part of the complete maintenance package.

    Nowadays there are many types of surface treatment where nano-technology is used to create an added value in a surface compared with what the more traditional products can offer. Nano-based surface-treatment products are already on the market, and they are said to make the surfaces dirt- and water-repellent, to prevent the growth of algae, fungi and moss, to improve UV- and temperature-resistance and colour permanence, to improve scratch- and abrasion-resistance, and to have anti-graffiti qualities etc. However, most of these products are new and for some of them there are still question marks with regard to their long-term performance and technical life-time, as well as their serviceability and thereto related economy seen from a life-cycle perspective for the product or system for which the surface treatment constitutes only a part.

    A cost analysis carried out as a part of the study makes the assessment that the new nano-technology-based surface-treatment systems could lead at most to a reduction of 15 %. in maintenance costs. The assumption is then that the façade needs to be cleaned every fifth or seventh year when a traditional painting system is used.

    According to the Swedish Standard, recovered wood from a wooden façade is defined as tree fuel and is generally designated recycled wood or, when the material is in a disintegrated form, as recycled chips,

    There is a major problem in recovering energy from recycled wood when a part of the material has been treated in some way, e.g. impregnated with a wood-protection agent or surface-treated, or when it contains other design components of e.g. plastic or metal. Recycled chips are a very good fuel for energy recovery provided the plant has adequate flue-gas cleaning and the ash is handled in a correct manner. Contaminated ash constitutes a problem, since it is classified as dangerous waste and cannot therefore be returned to the forest. If the content of heavy metals is not too high, the ash can be used as a covering and filling material. Otherwise, the ash must be deposited as landfill. A better sorting of household waste and an overhaul of the regulations would mean that the cleaned recycled wood could be burned in conventional biofuel boilers and that the contaminated portion could be burned separately.

     

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  • 78.
    Sandberg, Dick
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Blomqvist, Lars
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Material- och produktionsparametrars betydelse för formstabiliteten hos skiktlimmade fanerprodukter2007Report (Other academic)
    Abstract [en]

    This report describes a number of investigations carried out to illustrate the importance of various material and production parameters for the shape stability of laminated veneer products. The moulded products are manufactured from veneers which are shaped by being glued together under pressure, the veneers being oriented in various directions in relation to each other to achieve greater strength and a better shape stability than that of solid wood.

    The laminated veneer shells have been manufactured under industrial conditions, where a number of parameters have been varied in order to assess the influence of these parameters on the shape stability. The tests differed from normal production conditions only in that all the veneers were conditioned to a defined moisture content before the tests were carried out. The change in shape of the shells has been determined immediately after pressing, after a certain period of storage in the production premises and/or after the shells have been conditioned in a climate chamber at low and high relative atmospheric humidities.

    Factors studied were:

    • wood species, i.e. peeled veneers of beech and birch;
    • variations of an adhesive system based on urea-formaldehyde, i.e. various moisture ratios in the adhesive, various types of hardener (liquid or powder) and the addition of a filler;
    • the influence of different moisture content in the individual veneers to be pressed to a laminate;
    • the influence of how the veneers are fed through the adhesive spreader (in a roller application of the adhesive) and of an uneven application of the adhesive on the veneer before pressing;
    • the influence of different fibre orientations in the individual veneers in a laminate; and
    • the influence of exposure of the product to a varying relative atmospheric humidity.

    The conclusions which could be drawn regarding the influence of different parameters on the shape stability were:

    • Beech is a more “mobile” wood species than birch and showed overall a poorer shape stability than birch.
    • The variations in properties of the adhesive systems studied had little practical importance for the shape stability of the product.
    • Differences in moisture content between the veneers glued together into a product had serious consequences for the shape stability of the final product.
      • If veneers with different moisture ratios were placed asymmetrically in the structure, (in this study the moisture content was 14 %-units higher) the shape stability was worse, i.e. a greater spring-back and a greater twist.
      • A slight difference in moisture content (3 %-units) in the surface veneers did not greatly influence the shape stability.
      • To achieve a good shape stability in the laminate, the veneers should be well conditioned, so that as small a moisture gradient as possible arises in the laminated structure.
      • The magnitude of the spring-back, but not the twist, immediately after lamination was influenced by how the veneers were fed through the roller spreader and by the evenness of application of adhesive to the veneer sheet. These factors did not however have a decisive influence on the shape stability of the products.
      • The fibre orientation in the individual veneers was decisive for the deformation and shape stability of the products studied.
        • A grain deviation of only a few degrees could under certain conditions lead to deformations and a deterioration in shape stability so severe that the final product was useless.
        • A grain deviation in the longitudinal veneer resulted in twist, while a deviation in the cross veneer resulted in cupping in the products studied (Study 6). The spring-back was influenced to a small extent by a grain deviation in the veneers.
        • Gluing veneer sheets with a grain deviation so that the fibre orientation was in the opposite direction for veneers on each side of the symmetry line (in the thickness direction of the structure), so called cross-gluing, gave the absolutely worst conditions for obtaining a shape-stable product. Conversely, having the grain deviation in the same direction on each side of the symmetry line reduced the tendency to twist.
        • The shape of the laminated veneer products depended on the moisture content of the veneers of which the product was made, i.e. the product shape followed the variations in the temperature and in particular the relative atmospheric humidity of the surroundings. Variations in moisture content (which in practice are very difficult to prevent) can release stresses built into the product, and this can lead to deformations. This can occur even if the product during production is assessed to be free from stresses. The magnitude of the deformations which follow from the variations in the climate surrounding the product depend on the design/structure of the product, the level and duration of the prevailing climate, and the various material and process parameters, e.g. those mentioned above, which can influence the shape stability.

    The results of this investigation show clearly that material and process parameters can have a great influence on the shape stability of laminated veneer products. The fibre orientation in the individual veneers and differences in moisture content between the veneers which result in moisture gradients in the final product have in this study been identified as the most important parameters influencing the deformation and shape stability of these products.

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  • 79.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    A New Method for Bending Solid Wood: High Frequency Heating of Beech2005In: Hardwood research and utilisation in Europe / [ed] Bejo, L., Sopron: University of West Hungary , 2005, p. 156-161Conference paper (Refereed)
    Abstract [en]

    In their natural state, most hardwoods cannot be bent to an appreciably small radius of curvature. This is due to either fracturing or retaining elastic properties sufficient to cause spring back to approximately their original shape on removal of the bending force. But some species when subjected to heat in the presence of moisture (usually by steaming or boiling) become semi-plastic and their compressibility is very increased.

    By holding the bended material to shape after bending, and subsequently drying and cooling it, the wood tends to become rigid and “set” almost exactly to the curved shape imposed on it by bending. The rate of production when using traditional methods for solid wood bending is considerably slow and there is request from the industry to reducing the processing time and thereby reducing the production costs.

    A new method for solid wood bending is presented in this paper. The method is based on high frequency technique for heating, plasticizing and drying the wood to be bent in one step. One of the purposes to use high frequency heating was to decrease the time of the bending process. In practise this means reducing the time to bend and dry a straight piece of solid wood from a moisture content of about 25 % to 6 – 8 % from about 24 hours to about 10 minutes. This gives high demands on controlling the moisture content, temperature and the strain fields that occur in the wood during bending.

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  • 80.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Die PrimWood-Methode: Teil 1: Eigenschaften und Herstellung von Holz mit stehenden Jahrringen2007In: Holztechnologie, ISSN 0018-3881, Vol. 48, no 4, p. 5-9p. 5-9Article in journal (Refereed)
    Abstract [en]

    Old traditions and modern measurements show that radial sawn wood is subject to smaller moisture movements in the plane of the surface and has a harder surface and better shape-stability than timber sawn by conventional sawing techniques such as square sawing and through-and-through sawing. The advantages are greater if the juvenile wood is removed. Timber with radial faces and where the juvenile wood has been removed is said to have vertical annual rings, and such timber is particularly valuable for products such as floors, furniture, panels and exterior carpentry. The special properties of the timber are then utilised in the best possible manner.

    The PrimWood method is a new production concept for the manufacture of high quality wood components and boards of massive wood from both softwood and hardwood. The concept leads to a knot-free material with vertical annual rings.

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  • 81.
    Sandberg, Dick
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Die PrimWood-Methode: Teli 2: Das neue Produktionskonzept für die Herstellung von astfreien und formstabilen Holzkomponenten mit stehenden Jahresringen2007In: Holztechnologie, ISSN 0018-3881, Vol. 48, no 5, p. 11-15p. 11-15Article in journal (Refereed)
    Abstract [en]

    The PrimWood Method is a new production concept for manufacturing of high quality boards, components and panels from softwoods and hardwoods. The method generates knot-free boards, components and panels with vertical annual rings.

    The PrimWood Method increases the quality of the wood, compared to wood processed with traditional methods (harder surface, increased shape stability, freedom from cracks, easier and faster processing, less waste and a more even finishing). The wood is also given new aesthetical characteristics (e.g. even texture, knot-free surfaces and decorative finger-joints). The PrimWood Method also improves the raw material utilization, with resulting positive environmental effects, since a renewable resource is utilized more efficiently.

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  • 82.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    New production system for the manufacture of high-quality wood with vertical annual rings2004Report (Other academic)
    Abstract [en]

    The PrimWood method is a production system for sawing hardwood and softwood timber, and for further processing and refining the dried wood into knot-free boards, components and panels with vertical annual rings.

    This article presents an idea for a technical realisation of the PrimWood method. The method has in the first place been adapted to the sawing of quantities which correspond to the available volume of hardwood existing in Sweden, but the system is also well suited for softwood.

    The basis of the production system is that the log is sawn according to the star-sawing pattern in a vertical band saw with a carriage. The carriage is fitted with equipment for rotating and changing the position of the log or log parts in the vertical or horizontal directions in order to make it possible to saw pieces of wood with either a rectangular or a triangular cross-section.

    After it has been dried by conventional methods, the sawn wood is further processed by cross cutting, jointing, planing and gluing into knot-free components with vertical annual rings.

    The system seems to be well adapted to the conditions which apply in the small-scale processing of hardwood and softwood, and high-quality products can be produced with a high volume yield.

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  • 83.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    New products and production systems for improved competivness within the mechanical hardwood industry2005In: Creation of Industrial Competitiveness: CIC 2001-2004 / [ed] Pehrsson, A. & Al-Najjar, B., Växjö: Växjö University , 2005, p. 75-92Chapter in book (Other academic)
    Abstract [en]

    This research project focuses on the identification and development of profitable products of Swedish hardwood that can make the Swedish mechanical hardwood industry become more competitive.

    The starting point is that the structure of the Swedish mechanical hardwood industry is characterised by a small scale and the fact that it is located primarily in southern Sweden. The development of new production systems for the products identified within the project has been judged to be essential if the results are to become industrially applicable.

    The general question propounded is how the degree of refinement and the profitability in the Swedish mechanical hardwood industry can be improved through the development of products and production systems.

    In the description below of this field of research, a number of ideas for products and production systems are also presented. These constitute the basis for the ongoing work of finding solutions to the problem of increasing the profitability of the Swedish mechanical hardwood industry.

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  • 84.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Simulation of the yield of knot-free components from Scots pine (Pinus sylvestris L.): A comparative study of star-sawing and square-sawing2006In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 1, no 3-4, p. 8p. 108-115Article in journal (Refereed)
    Abstract [en]

    The production of knot-free wood is important since the market demands wood without knots for reasons of both appearance and material properties. This work describes a simulation of the removal of knots from star-sawn timber and square-sawn. The efficiency of the two methods is compared in terms of the length of the knot-free components obtained and the volume yield.

    The simulation is based on data for trees and logs taken from The Swedish Stem Bank. These data are then used to simulate the sawmill process in a computer program called the Virtual Sawmill. Data related to the boards obtained are then used in a MATLAB model simulating the cross-cutting of knots.

    Simulated star sawing of logs with a top diameter exceeding 230 mm gave a mean knot-free component length of 417 ±321 mm, while the mean length of knot-free components for simulated square sawing of the same logs was 298 ±122 mm. The volume yield of knot-free components from the two sawing patterns was 91 % for star sawing and 87 % for square sawing. For timber with cross-section dimensions of 38 x 75 mm2, the mean length and yield of knot-free components from simulated star sawing were 451 ±349 mm and 90 % respectively. In simulated square sawing, the corresponding values were 263 ±197 mm and 82 % respectively. This shows that star sawing has a potential for the production of knot-free timber.

  • 85.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    The Concept of Value Activation I: Wood properties with different annual ring orientations in hardwood2005In: Hardwood research and utilisation in Europe: new challanges / [ed] Bejo, L., Sopron: University of West Hungary , 2005, p. 47-52Conference paper (Refereed)
    Abstract [en]

    The concept of value activation is focused on the basic understanding of wood, and the fact that there are properties that are not fully exploited in conventional wood manufacturing systems to date. The strategy is to activate these inherent properties by a better understanding of the fundamental behaviour of wood, combined with new applied process technology and the development of the required manufacturing systems.

    The value activation program has so far shown that there are great possibilities of utilizing the properties of wood in a better way than our conventional wood production concept can achieve. New wood products with desirable properties can be developed. Most of these products are expected to give greater added value to the wood.

    Within the Value activation program the following properties, which were judge to be the most important ones for future wood products were chosen:

    -          Aesthetic and tactile factors

    -          Controlled moisture movements

    -          Accuracy in size and geometry

    -          No check and splits

    -          Strength and hardness

    These properties are all strongly influenced by the annual ring orientation in the cross section of the sawn timber. This paper describes the influence of the annual ring orientation on these properties and how they can be improved by using a new sawing pattern on hardwood.

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  • 86.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Neubauer, Peter
    KTH.
    Simulation of the yield of knot free boards from Scots pine (Pinus sylvestris L): a comparative study between square-sawing and star-sawing.2005Report (Other academic)
    Abstract [en]

    This work describes a simulation of the removal of knots from square-sawn wood and from wood sawn with the star-sawing pattern. The efficiency of the two methods is compared according to the length of the received boards and the volume exchange. The production of wood free from knots is important since the market demands wood without knots for reasons of both appearance and material properties.

    The simulation is done with data for trees and logs taken from The Swedish Stem Bank. The data is then used to simulate the sawmill process in a computer program called the Virtual Sawmill. Data related to the received boards are then used in a MATLAB model simulating the cross cutting of knots.

    The simulation gave a mean knot-free board length of 263 ±100 mm and a spillage of 15.9 % when logs with a top diameter of 100-370 mm are square sawn. Star sawing simulated for logs with a top diameter exceeding 230 mm gave a mean knot-free board length of 417 ±321 mm, while the mean length of knot-free boards was 298 ±122 mm for square sawing when simulating sawing of the same logs. Under these conditions the volume losses for cross cutting is 9 % for star sawing and 13 % for square sawing. This shows that star sawing has a potential for the production of knot-free wood.

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  • 87.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Ormarsson, Sigurdur
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Johansson, Jimmy
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Improved Manufacturing Process for Bent and Laminated Wood Products of Beech: FE-modelling2005In: Hardwood research and utilisation in Europe / [ed] Bejo, L., Sopron, 2005, p. 151-155Conference paper (Refereed)
    Abstract [en]

    To make the development process for new laminated wood products more effective, there is need for a simulation tool based on a model of the wood material. With help from this tool the risk of fractures in the veneers, cracking in the wood or in the glue line will be estimated.

    Wood is a complex hygroscopic material that is highly anisotropic, non-homogeneous, and strongly dependent on the loading rate. Most importantly, it is very sensitive for changes in temperature and moisture content. The material stiffness in the transversal directions is very low for wood and it is highly affected by changes in environmental conditions. During a manufacturing procedure of veneered products for curved furniture panels, the veneers are exposed to large membrane and bending deformations and high pressure in the radial fibre direction. When hot-press forming is used, the products are also exposed to high temperature on their surface. These hard conditions often result in large viscoelastic and elasto-plastic strains that have strong influence on the final quality of the product (spring-back, stiffness, distortion etc).

    To be able to improve the manufacturing process the key issue is to understand the material behaviour during these severe conditions. The main scientific challenge is to establish a new thermal and moisture related elasto-plastic material model for non-linear and strongly orthotropic wood material behaviour. Based on this work a FE-model for analysing the whole forming procedure of the bended and laminated wood products is presented.

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  • 88.
    Schauerte, Tobias
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Gustafsson, Åsa
    Linnaeus University, School of Business and Economics, Department of Management Accounting and Logistics.
    From Customer Values to Production Requirements: Improving the Quality of Wooden Housing2013In: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 9, no 4, p. 780-787Article in journal (Refereed)
    Abstract [en]

    The industry of wooden single-family houses in Sweden faces several challenges; both with regards to production but also with regards to the market conditions. In order to avoid uncontrolled price increases of wooden single-family houses, an act regulating the cash contribution when purchasing a house has been introduced. This has led to an increased focus of the house price as well as on the individual producers to control its processes and thereby its costs. The purpose of this paper is to give an overview of existing research related to product and production developments related to the industry, identifying research gaps, and suggest research activities. This research has been carried out as a literature study focusing on these concepts. It concludes that existing research is fragmented and that the linkage between the consumer and the product is neglected as well as the holistic approach is missing in development activities. The authors propose that in order to study how the industry could come closer to their consumer markets and the aligned requirements as well as to facilitate product development, the Means-End Chain approach may be of use and that the approach could further be linked to Quality Function Deployment.

  • 89.
    Schauerte, Tobias
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Lindblad, Fredrik
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Wooden multi-family houses in Sweden: issues related to public procurement and quality2014In: Forest Products Society and World Conference on Timber Engineering joint proceedings, 2014Conference paper (Refereed)
  • 90.
    Schauerte, Tobias
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Lindblad, Fredrik
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Industry structure and risk positions for wooden single-family house firms in Sweden: evaluating their potential to enter the multi-family house segment2014In: Forest Products Society and World Conference on Timber Engineering joint proceedings, Forest Products Society, 2014Conference paper (Refereed)
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    Schauerte et al. 2014a
  • 91.
    Scheepers, Gerhard
    et al.
    RISE .
    Nilsson, Jonaz
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Mätning av ytspänningar i torkat gran med NIR2017Report (Other academic)
    Abstract [en]

    In sawmilling, a lot of timber properties are measured online in the sorting and grading of dried timber. This may include moisture content, shape, and a host of other parameters. An important wood property that cannot be measured online is drying stresses, although it is an important parameter for many customers. Since the destructive test methods for stress determination are time consuming, no high frequency routine measurement of the internal stresses is done. In literature, there are a few examples of near infrareds (NIR) capability to detect surface stresses along the fiber direction. There is also an example of stress measurements across the grain on a Japanese wood specie during drying, however, these measurements were always done on a tangential surface. It is unknown whether NIR prediction models can predict surface tension and stress measurements across the grain of dried Norway spruce with varying characteristics, i.e. material from different logs, heart- or sapwood, different year ring orientations, etc. If the technique cannot handle the variation in material properties, such as occurs in a sawmill environment, this means that a simple NIR measurement would not be sufficient to predict the surface tension in industry. This study investigated whether surface stresses in mechanically loaded as well as dried spruce samples with varying material properties can be predicted by NIR models. The measurement data from some mechanically loaded samples showed a correlation between the predicted and actual stress values, but many other samples showed no correlation. Moreover, the data for a single sample could show a good correlation, but the prediction could be at an incorrect stress level. As for the dried samples, NIR models were good at separating the conditioned and nonconditioned samples, but had no predictive power concerning the stress level. The models used to predict the stress level in mechanically loaded samples, were also used to predict the stress in the dried samples, but there was no correlation between the measured strain and the predicted stress level. Therefore, it is concluded that there are no clear indication that NIR measurements can be used in an industrial application for predicting the surface stress level of dried Norway spruce boards.

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    fulltext
  • 92.
    Scheepers, Gerhard
    et al.
    RISE Research Institutes of Sweden.
    Wiberg, Pär
    Alent Dynamic.
    Johansson, Jimmy
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    A method to estimate wood surface moisture content during drying2017In: MADERAS: Ciencia y Tecnología, ISSN 0717-3644, E-ISSN 0718-221X, Vol. 19, no 2, p. 133-140Article in journal (Refereed)
    Abstract [en]

    A method to estimate the surface moisture content below the fibre saturation point that is a function of the surface temperature, wet- and dry bulb temperatures, equilibrium moisture content, and fibre saturation point was evaluated. The method is based on the premise that the surface temperature is solely influenced by the surface moisture content and the climate that the surface is exposed to. The prediction model contends that the surface moisture content is equal to the fibre saturation point when the surface temperature is equal to the wet bulb temperature, and equal to the equilibrium moisture content when the surface temperature is equal to the dry bulb temperature, with a linear interpolation between those two points. The model thus predicts that the average moisture content of a thin piece of veneer can be predicted with fairly good accuracy. Also, when drying boards in a fast changing climate, e.g. fan reversals in industrial kilns, the surface temperature and surface moisture content should change as abruptly as the climate does. Additionally, the surface moisture content should correlate to the known drying phases, with a consistently high surface moisture content during the capillary phase when the wet line is close to the surface, and a quickly decreasing surface moisture content when the wet line moves into the wood during the transition to the diffusion phase. The prediction model was tested in these three scenarios and the results suggest that the basic premise is reasonable, and that the method is useful for surface moisture content estimation.

  • 93. Woxblom, Lotta
    et al.
    Karlsson, Reine
    Palm, Johan
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lönsamt lövträ: affärsutveckliing för lövträrelaterad tillverkningsindustri 2007-20102011Report (Other academic)
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