Variation of Basic Density and Brinell Hardness Within Mature Finnish <i>Betula Pendula</i> and <i>B. Pubescens</i> Stems
Keywords:Basic density, Brinell hardness, <i>Betula pendula</i>, <i>Betula pubescens</i>, furnishing, parquet, veneer, plywood
AbstractThe objective of this study was to analyze the variation in basic density between different horizontal and vertical locations within mature Finnish Betula pendula and B. pubescens stems. In addition, the dependence of Brinell hardness in radial direction, which is of importance especially for the parquetry, veneer, and plywood industries, on the basic density was investigated. Furthermore, the sources of error in the Brinell hardness test according to EN 1534 were analyzed. Both basic density and Brinell hardness were measured from small, defect-free specimens. The average basic density of B. pendula and B. pubescens were 512 kg/m3 and 478 kg/m3, respectively. Concerning both birch species, wood material near the pith was clearly less dense than near the surface of the stem. The average Brinell hardness of B. pendula specimens was 23.4 MPa, and that of B. pubescens specimens was 20.5 MPa. Brinell hardness was found to be positively correlated with basic density. Therefore, the assumption that Brinell hardness varies within a birch stem similarly to basic density is confirmed. The test method according to the EN 1534 standard was found to be precise enough but unnecessarily laborious for hardness tests. Finally, an alternative method is suggested for determining Brinell hardness on an industrial scale.
Bhat, K. M. 1980. Variation in structure and selected properties of Finnish birch wood. I. Interrelationships of some structural features, basic density and shrinkage. Silva Fenn.14:384-396.nDunham, R. A., A. D. Cameron, and J. A. Petty. 1999. The effect of growth rate on the strength properties of sawn beams of silver birch (Betula pendula Roth). Scand. J. For. Res.14:18-26.nEN 1534: 2000 E. Wood and parquet flooring—Determination of resistance to indentation (Brinell)—Test method. European Standard CEN 2000. 10 pp.nGertjejansen, R., and D. Hedquist. 1982. Influence of paper birch on the properties of aspen waferboard: a mill trial. Forest Prod. J.32(11/12):33-34.nHakkila, P. 1966. Investigations on the basic density of Finnish pine, spruce and birch wood. Comm. Inst. For. Fenn.61(5):1-98.nHakkila, P. 1979. Wood density survey and dry weight tables for pine, spruce and birch stems in Finland. Comm. Inst. For. Fenn.96(3):1-59.nJalava, M. 1945. Strength properties of Finnish pine, spruce, birch and aspen. Comm. Inst. For. Fenn.33(3): 1-66. (In Finnish with English summary).nKollman, F. F. P. and W. A. Côté. 1968. Principles of wood science and technology. Volume 1. Solid wood. Springer Verlag. Berlin - Heidelberg - New York. 592 pp.nKontinen, P., and C. Nyman. 1977. Hardness of woodbased panel products and their coating and overlays. Paper and Timber 9/1977 (In Finnish with English summary).nKučera, B. 1984. Bjørkevirkets mekaniske, teknologiske og fysiske egenskaper. Norges landbruksvitenskapelige forskningsråd, Slutrapport nr. 500. 21 p. (In Norwegian).nKúdela, J. 1998. Analysis of wood hardness. Pages 199-203 in S. Kurjatko, and J. Kúdela, eds., Proc. Seminar on Wood Structure and Properties '98. Arbora Publishers. Zvolen, Slovakia.nKujala, V. 1946. Some recent research data on birches. Comm. Inst. For. Fenn.34(1):1-36. (In Finnish with English summary).nLassila, I. 1926. The mechanico-technical properties of wood. Their study and its objects. Reprinted from Acta For. Fenn. 186 pp. (In Finnish with English summary).nLutz, J. F. 1977. Wood veneer: Log selection, cutting, and drying. USDA, Tech. Bull. No. 1577. 137 pp.nMöller, K., and L. Otranen. 1999. Heat treatment of timber. Publications of the Institute of Environmental Technology. Nr. 4. Mikkeli 1999. 115 pp. (In Finnish).nNiemz, P., and T. Stübi. 2000. Investigations of hardness measurements on wood based materials using a new universal measurement system. Pages 51-61 in S. E. Stanzl, and A. Reiterer eds. Proc. of the Int. Symposium on Wood Machining, Properties of Wood and Wood Composites Related to Wood Machining. Vienna, Austria, 220.127.116.110.nPagano, K., and R. Gertjejansen. 1989. The effect of mixing high and low density hardwoods on bond development in waferboard. Forest Prod. J.39(2):45-48.nSchwab, E. 1990. Die Härte von Laubhölzern für die Parkettherstellung. Holz Roh-Werkst48(2):47-51. (In German).nSiimes, F. E., and O. Liiri. 1952. Investigations of the strength properties of wood I. Tests on small clear specimens of Finnish pine (Pinus sylvestris). Technical Research Centre of Finland VTT, Report 103. 88 p. (In Finnish with English summary).nTamminen, Z. 1970. Moisture content, density, and other properties of wood and bark. III Birch. Rapp. Instn. Virkeslärä Skoghögsk.63: 1-99. (In Swedish with English summary).nVelling, P. 1979. Wood density in two Betula pendula Roth progeny trials. Folia For.416:1-24. (In Finnish with English summary).nVerkasalo, E. 1998. Raudus- ja hieskoivun laatu puuaineen tiheyden perusteella arvioituna. [Quality of European silver and white birch evaluated on the basis of wood density]. In P. Niemistö, and T. Väärä. eds. Rauduskoivu tänään-ja tulevaisuudessa, Tutkimuspäivä Tampereella 12.3.1997. Finnish Forest Research Institute. Research notes668: 127-140. (In Finnish).nWagenführ, R., and C. Schreiber. 1989. Holzatlas. 3. Auflage. VEB Fachbuchverlag Leipzig. 720 pp.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.