Engineered wood industry: saving money by using less
Faced with recent dramatic increases in the cost of raw materials, manufacturers of engineered wood products are looking at ways to use raw materials - industrial timber and adhesives - more efficiently. There are a range of new and optimised production processes that can significantly reduce the amount of timber, glue and additives used by makers of engineered wood panels. One of the main ways of using wood chips and fibers more efficiently is to have a production control system that tracks the various stages in the production chain. The latest systems do much more than simply control production; they lead to greater cost transparency, reduced resource consumption, greater plant availability and, ultimately, significantly reduced costs.
Production control systems of this type generally comprise a basic module, a business module, a quality module and a maintenance module. The basic module captures and analyses the usual sorts of production data. The business module delivers cost transparency by classifying products and product consignments according to characteristics such as production costs, raw material consumption and reject rates and is thus the main driver of raw materials savings.
The quality module provides online forecasts of key board properties such as transverse tensile strength, flexural strength, thickness swelling rates and delamination strength. This yields raw material savings in excess of 2.5% without sacrificing quality. The maintenance module organises and optimizes the maintenance of all plant subassemblies, thereby reducing maintenance costs and increasing overall plant availability. Investments in these kinds of technologies pay for themselves very quickly. The upward trend in the cost of resin (glue) for MDF production is likely to continue over the medium term.
Consequently, MDF manufacturers are looking for new processes to reduce resin use. The most common MDF production process is blowline blending, where resin is blended with wood fiber and then dried to produce mats. Blowline blending has the advantage of mixing the resin very homogeneously. The down side is that the exposure of the resin to high temperatures in the drier reduces the final strength of the resin, meaning that more resin has to be used to achieve the desired strength.
This problem is remedied by an innovative new drying process in which the resin is applied to the pre-dried wood fibers as an ultra-fine mist. This process uses up to 50 percent less resin than blowline blending because most of the thermally intensive drying takes place prior to resin blending. The process’s combination of mechanical dispersal, increased fiber surface area in the air flow and more effective resin distribution produces defect-free board surfaces while greatly reducing costs. The mats produced using this method still require some additional drying in order to eliminate the excess moisture introduced with the resin. The subsequent processing of the mats into actual boards is also very energy intensive. Consequently, it is now common for the by-products of board production to be used to generate much of the energy needed for this process.
The energy takes the form of thermal oil for the presses, process steam for the refiners and flue-gas for the driers. The fuels used to generate this energy include the bark and waste fibers that are generated when the plant is started up, sanding dust, excess material, and scrap wood that is not suitable for board production. The integrated energy plants found in modern fiberboard manufacturing facilities are over 90 percent efficient - an achievement the automotive sector can only marvel at.
Everything the market has to offer in the way of solutions for the resource- and energy-efficient production of engineered wood will be on show at LIGNA HANNOVER, the world’s biggest trade fair for the forestry and wood industries, which runs from 18 to 22 May 2008 in Hannover, Germany. The engineered wood displays range from technology for the production of wood veneers, veneer plywood, chipboard and fiberboard, to systems for processing waste wood and industrial timber into wood chips and fibers. They also feature solutions for board gluing, pressing, drying and finishing and the overall process control systems.