Robert L Youngs is a professor with the Department of Wood Science and Forest Products, Virginia Polytechnic Institute and State University, Blacksburg, USA.
An analysis of trends in wood and fibre-based forest products research, with a focus on work undertaken in the United States.
Forest products research is aimed at strengthening the economic base that gives forests their most direct economic value, i.e. at making it possible to derive productive benefits from the forest resource by effective, economical and environmentally sound utilization, processing and marketing of a diverse resource. In the long term, the forest will be protected and maintained to the degree that legislators and economic and policy decision-makers are convinced that it constitutes a positive economic asset. Unless research can contribute to this, it will not be effective.
Forest products research must be dynamic to respond to the changing demands on and the capabilities of forestry and forest industry. The timber resource from which products are made is very different from what it was even a few decades ago, as plantations and reforested areas are more and more looked to for wood supply.
The technology of forest products manufacturing is changing as the computer becomes an integral part of the mill for product evaluations, process control, analysis, inventory and communication. Quality standards and consumer expectations for forest products are becoming more rigorous.
Forest products research today moves in a world quite different from that of 100, 50 or even 20 years ago. The researcher is likely to spend more time at a computer than at a microscope or a testing machine. The researcher is also likely to be in closer contact with forest managers and forest industry, as well as with colleagues in related fields of engineering and science. Modern communications make that possible. Development in forest management, wood-use requirements, environmental awareness and the engineering and related sciences make it necessary.
Forest products research in the United States is carried out in both the public and the private sectors, with an increasing degree of cooperation between them. Public sector institutions spend from US$60 million to $70 million per year on such research. The focus is on the solid wood and composite sectors, especially in the universities, but this includes substantial research that is basic to any industrial use of wood. Although it is not possible to make precise comparisons between the investment in research at the state universities and that in the federal research institutions because of differences in the way budgets are reported, universities probably account for about 60 percent of the public sector total, with much of the funding appropriated at the federal level being specifically designated for university research.
About 40 universities in the United States conduct at least some research in forest products. This involves at least part of the time of about 200 faculty members and a somewhat greater number of support staff and graduate students. Capabilities cover the full range of wood and paper science and technology, with emphasis on wood processing.
Much of the federal research in forest products is conducted by the Forest Service of the United States Department of Agriculture (USDA). This is concentrated at the Forest Products Laboratory in Madison, Wisconsin, with additional research at several of the regional forest experiment stations. Active in this research are about 120 scientists and a larger number of support personnel.
Among the forest industries, the pulp and paper sector is the big spender for research and development, estimated to cost about $1 000 million per year compared with perhaps $60 million to $70 million in the solid wood industry. The distinction between research and development is not clear, but the development portion is possibly an order of magnitude greater than the research portion.
Characteristic of research in recent years is an increasing amount of cooperation and collaboration among industry, universities and federal research organizations. Consortia such as those focusing on big-based pulping at Madison and centres such as those focusing on pallets and marketing research at Virginia Polytechnic Institute or on international trade at the University of Washington provide a point of reference for such cooperation. As a result of this interaction substantial amounts of federal funding, in addition to that allocated specifically for university research, are used to support cooperative research at universities. Likewise, a substantial amount of industrial research is done cooperatively with both university and federal laboratories.
These are days of tight budgets and high expectations for research on the part of both the research establishment itself, the forest industry and others using the results. It is becoming increasingly critical that research be relevant to real needs and applicable in meeting them. Following are some of the trends in forest products research as it moves ahead to meet such objectives as well as examples of specific results and applications.
A major research and technology trend is related to improving process control for more uniform products with characteristics that can be specified precisely. Research being done in laboratories and in cooperation with the forest products industry is aimed at finding ways to build into the production system recent developments in electronics, non-destructive testing, tomography (single plane scanning), ultrasonics, etc. A recent addition to this trend is the introduction of knowledge-based expert systems in which the experience and knowledge of recognized experts in various mill operations is put into a computer program that can be called up as needed to deal with operation and production problems (Youngs, 1990). Notable in this area is research at Texas A&M University.
Other major thrusts of research and technological development aim at energy conservation and environmental pollution control. Blended with these are research and development to provide flexible processes that can be modified to meet different customer needs, often by producing small lots to order rather than large lots to inventory.
Research in the Nordic countries reflects increasing awareness of the need for both the price and quality competitiveness of wood products. Many wood products now move directly from producer to end-user, but the final cost of the product in use is what determines its acceptability in the market. This has led to a research emphasis on efficient ways to develop whole systems of furniture, cabinets, window frames etc., often as prefabricated, pre-finished, ready-to-use units. These accompany a change in the industry's structure from one of companies operating independently to produce entire products to one of large numbers of specialized companies making components for assembly into such systems (Birkeland, 1992).
Sawmills and sawnwood
Technology for moving logs through the headrig and the sawnwood through the mill is a subject of research and development that may offer new opportunities to improve productivity and process control. Since the 1970s, the softwood sawmills in the northwestern United States have faced a serious resource and profitability problem. Mills that had been designed to use large old-growth timber found it necessary to substitute an increasing amount of smaller second-growth logs which required more handling, sawing and labour per unit of production. The question was how this could be speeded up and made more efficient without sacrificing quality and volume of production by poor sawing decisions. Out of research on sawmill operations came the Best Opening Face (BOF) concept that was readily adapted to automated scanning and computerized decision-making. BOF is based on pioneering research at the Forest Products Laboratory, Madison, in which it was observed that the orientation of a log as it passes the headsaw for its first cut ("opening face") is a key to the yield of sawnwood in sawing that log. As a result of this finding, equipment makers developed scanners and computer facilities, operations experts developed ways to integrate them into efficient processes after which the systems were brought together and a new era in softwood sawnwood manufacturing was begun.
Research is continuing to develop technology for detecting defects and discontinuities in wood (see Photo 1). The principles have been developed and their application can soon be expected to have a major impact on production of both hardwood and softwood sawnwood when they are fast enough for on-line use in a mill at today's high operating speeds. This technology will make it possible to have flexible sawnwood grading schemes as desired by consumers or by manufacturers of speciality products. This is now envisioned primarily as a grading process.
PHOTO 1 - Image analyser for on-line detection of defects
However, automated processing to cut out or patch up defects to meet predetermined product standards would be the next step. Research such as that being undertaken at Virginia Polytechnic Institute, Michigan State University and the University of West Virginia could make this possible. Rapidly growing international trade in sawnwood will present unique opportunities for the kind of grading and sorting offered by this approach.
Wood for structural use
Research on automated processes for stress-rating structural sawnwood in the 1950s and 1960s led to the production, standardization and commercial use of stress-rating machines (see Photo 2). These machines are now used in many parts of the world as acceptable, rapid means of assigning structural grades to sawnwood. Stress-rating machines are usually more accurate in assessing stiffness and strength than are the visual grading systems commonly used. Extension of the concept to panel materials is beginning. Considerable research, particularly at Washington State University, has recently focused on applying non-destructive testing concepts to decay detection and in-place evaluation of wood structures (Ross and Pellerin, 1991).
A more precise assessment of the capabilities of structural wood allows designers to use the material more efficiently and economically (Photo 3). Reliability-based design, which makes use of knowledge of the variation in material properties and applies this on a statistical basis to determine the likelihood of failure under given conditions, is becoming the norm for most structural material. Not so for wood: structural design in wood is still based largely on traditional approaches. However, researchers in timber engineering at the Forest Products Laboratory in Madison and at several universities are developing methods to work the concept into the design of wood structures in ways that will take advantage of the substantial structural efficiency of this material. Risk analysis and criteria for fire-safe design are especially important applications.
Another key element in the structural use of wood is the connection between the individual members that make up an integrated structure. Wood structures frequently fail at the joints rather than within the wood itself. Research is needed on joints using nails, bolts, screws and specialized timber connectors that greatly improve the reliability of timber structures from pallets to light-frame buildings to heavy timber construction (Winistorfer, 1992). Significant research in this field is now being done at Virginia Polytechnic Institute and at the Forest Products Laboratory, Madison.
PHOTO 2 - Automatic stress-rating of sawnwood
PHOTO 3 - A truss frame unit being raised into place
Broadening the resource base
It has been recognized for many years that underutilized or lesser-known species that grow in many of the same regions as the preferred commercial species can offer opportunities to alleviate overcutting of preferred species and to extend the resource base while improving sustainability of the forest's use for its many benefits. Researchers have gathered information on many of these underutilized species, noting that the machinability, drying, finishing, gluing and shrinkage characteristics of many of these species may be much more important than their strength. Compilations of such information arc available and marketing efforts are beginning to introduce them to the trade (Supin, 1992; Youngs and Wang, 1992).
The structural wood industry and residential construction have traditionally gone hand-in-hand. However, attention is now shifting to the non-residential building market. In order to develop products for this market, engineers and architects are combining the results of several research areas to adapt materials for efficient and economical use of a broader resource base than that formerly drawn on to produce large structural timbers (see Photo 4). Examples are roof trusses using laminated members and prefabricated I-joists with laminated veneer lumber (LVL) flanges and webs of hardboard (see Photo 5), oriented strandboard or plywood (Moody and Collet, 1992).
The focus in manufacturing is shifting more to underutilized hardwoods and small-sized softwoods which are in abundant supply. This change is driven in part by the reduced profitability of conventional structural wood commodities such as dimension sawnwood and panel products. In the United States, yellow poplar (Liriodendrorn tulipifera) is beginning to be graded and used for structural applications, including glued laminated timber and other structural forms.
PHOTO 4 - A glued, laminated red oat bridge
PHOTO 5 - Prefabricated I-joists with laminated veneer lumber (LVL) flanges
PHOTO 6 A prefabricated house made from six-year-old plantation eucalyptus
In Brazil, where environmental issues are being raised in the face of deforestation, primarily for agriculture, research efforts are under way to improve the use of plantation-grown eucalyptus. It is estimated that 30 to 40 percent of the wood used in Brazil today comes from planted forests (De Freitas, 1992). This means small-sized logs and high processing speeds. Research is focused on overcoming the technical factors that stand in the way of economical, high-quality production under such conditions. As an example of the results of such research at the Instituto de Pesquisas Tecnológicas in São Paulo, six-year-old eucalyptus can be used in housing (Photo 6), in furniture (Photo 7) and in structural forms (De Freitas, 1992).
Composite materials and glued products
The concept (and application) of systems of products as well as the individual components that make them up warrants special attention from research. In their many different forms, composite products are particularly adapted to this concept because of their flexibility in design and processing. Such products include floor, roof, wall and foundation systems or entire house systems, using wood-based composite materials, perhaps combined with solid wood, structural paper or non-wood materials.
There is growing interest in products that combine wood with glass fibres, polyester fibres or other non-wood materials because of the opportunities they offer to enhance the unique properties of wood in specific ways for special applications. Wood-based boards bonded with cement or gypsum are beginning to be applied for their structural strength and fire resistance. Negative properties such as dimensional instability and susceptibility to degradation can be improved by modifying the chemical structure of the wood's cell wall (Rowell, 1992). Research in this area is being undertaken at the University of Idaho, Washington State University and the Forest Products Laboratory, Madison.
Research done in the 1960s and 1970s concerning the use of plywood adhesives on the very absorbent wood of southern pine in the United States led to the establishment of the southern pine plywood industry and substantially broadened the resource base for softwood plywood. More recent research in the United States and in Canada has provided a solid base for the board industry using strands or flakes to make structural panels and thereby replacing plywood in many of its structural uses. Research continues on processing improvements for board manufacturing; an example is the concept of steam injection pressing which is beginning to be used to improve production efficiency by substantially reducing pressing time.
Research on composites is also turning to the opportunities offered by recycled wood-based resources. Millions of tonnes of wood fibre in timber thinnings, industrial residues, demolition waste, used pallets and paper mill sludges could provide raw material for productive applications instead of straining waste disposal facilities, as at present. Examples of value-added composite materials made from recycled waste include wood-non-wood composites, dry-formed wood fibre products, wet-formed moulded structural products and composites fabricated with inorganic binders of gypsum, Portland cement and magnesia cement (Hamilton and Laufenberg, 1992; Wegner, Youngquist and Rowell, 1992).
Pulp and paper
The pulp and paper industry is more a product of research than is the case for much of the solid or composite wood industry. Early research, inspired by a rapidly increasing demand for paper and a dwindling supply of rags (the principal raw material at the time), led to the soda, sulphite and groundwood processes for making pulp from wood. The latter is still the major process used to make pulp for newsprint. More recent research has devised chemical and thermal treatments to improve pulping efficiency and yield while maintaining high-quality paper characteristics.
The discovery of the press-drying concept of papermaking, aimed at improving fibre bonding and paper strength, has permitted the production of strong kraft paper from short-fibre hardwoods. Further development of mechanical pulping and its variations could increase yields of paper produced in this way from 50 to 55 percent to 85 to 95 percent (Lange, 1992).
An exciting new prospect has come from research on the lignin metabolism of white rot fungi. Studies of the chemistry and mechanism of removal of lignin by Phanerochaete chrysosporium and some other white rots show the potential of biopulping as an alternative to pulping chemicals. This is being considered for use in biomechanical pulping (BMP) (Kirk, Burgess and Koning, 1992) (Photo 8). Such research is part of the programme of the big-based pulping consortium at Madison, mentioned earlier.
Recent research has led to a reduction in environmental impacts by replacing chlorine in the bleaching process and by substantially reducing harmful effluents from pulp and paper-processing. Other research has provided bases for reducing energy and improving process control for product uniformity. Computer-assisted processing, as a means of applying modern concepts of process control and scheduling, is the objective of research and application in the industry.
PHOTO 7 - A cabinet made from six-year-old plantation eucalyptus
PHOTO 8 (A) - The normal wood structure of aspen (Populus sp.);
PHOTO 8 (B) - Structure modified by three-week treatment with Phanerochaete chrysosporium
PHOTO 9 - Removing "stickers" from recycled paper
Major research efforts are now being focused on the recycling of paper as a means of both extending the raw material supply and reducing the need for landfills. This has already resulted in substantial increases in the use of recycled furnish in the paper industry. The United States industry is approaching its goal of attaining 40 percent recycled furnish by 1995; the European industry has already exceeded this level (AFPA, 1992). Current research is aimed at such areas as deinking recycled material, improving the bonding of recycled fibres, increasing strength properties of recycled paper and board, using waste paper in composite products and removing adhesive contaminants, or "stickles" (Photo 9). Research also involves blending recycled newsprint with other pulps such as that of kenaf, a hibiscus plant widely cultivated for its fibre, to restore the strength lost through fibre breakage during recycling.
Marketing research has established its credibility as an effective tool to help manufacturers identify and meet consumer needs. These are sometimes specific requirements and at other times impressions or perceptions of the market. Both of these appear in the rapidly expanding home-centre market, for example, which is becoming the primary distribution channel for both contractors and do-it-yourself homeowners, especially those involved in the repair and remodelling of homes. Combined with research in process engineering, this is leading to a more effective use of short sawnwood and new types of composites (Sinclair, 1992). Research at Virginia Polytechnic Institute and by the United States Forest Service is especially notable in this regard.
The concept of marketing is beginning to be applied at the product development stage and new analytical methods are being tested by researchers and applied in the industry. An example is determinant attribute analysis, which cart be used to identify the product characteristics that are most important in affecting purchase decisions (Moody and Collet, 1992).
The field of forest products is dynamic and rapidly changing. Research is adapting to the needs of this situation and is acting to provide a base both for conserving the resource and for economic and social development. As a result of communication through electronic media, journals, contacts with colleagues and international organizations, the differences to be found in various pan's of the world are more in the scope, scale, financial support and specific application of forest products research rather than in the research itself.
This article has emphasized the use of wood as timber or fibre, notwithstanding the fact that most of the wood harvested in the world is used for fuel. Likewise, we are aware that non-wood forest products - medicinals, fruits, extracts, fodder and many others - are at least as important as wood in many regions and are growing in importance in all regions. The field of forest products research is expanding to accommodate these broader concerns but still has far to go in this regard. Nonetheless, the scope and trends mentioned in this article are a reflection of the broader concept of the resource.
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