Study about fiber quality TMP for MDF production
With a worldwide production of 70 million m3 in 2010 (FAO, 2010), medium-density fiberboard (MDF) is one of the most important wood-based panels in the market. In the manufacturing of MDF, wood chips are defibrated into thermo mechanical pulp (TMP), the fibers are glued with a thermoset resin, and finally are continuously hot-pressed into flat panels. With respect to panel properties, MDF is used for a variety of applications. MDF properties are influenced inter alia by the fiber quality used, whereby fiber quality is determined by the process parameters applied.
Despite the importance of fiber quality for MDF production, its evaluation is still just done on a low technical level. Almost all fiber quality control is performed by skilled personnel (haptically and visually), followed by the application of various sieving methods and optical measuring systems with obviously limited capabilities.
With the aim of overcoming the limitations of currently available measuring systems, in 2009 the Department of Wood Science and the Thünen Institute of Wood Research started to develop a software for image analysis-based fiber quality control at the joint research site in Hamburg-Lohbrügge (Germany) with participation by the industry partner KOGS (Hamburg University) andGreCon (Alfeld).
The result of these research activities was the creation of an image analysis system for the recognition of shives on the surface of MDF panels (inline fiber characterization), a software for the separation of cross-wise overlapping fibers and a technique for mechanical fibre separation. This mechanical fiber separation technique is trend-setting for automatic offline fiber characterization and is currently awaiting patent approval.
The offline fiber characterization system is currently being tested, further developed, and used for the determination of the considerable influence parameters on fiber quality and fiber quality on fibreboard properties in the context of aresearch project (Fiber-Impact), conducted by the cooperation partnersThünen Institute of Wood Research,GreCon, Glunz AG (Meppen, Germany),Andritz AG (Graz, Austria), KOGS andInstitut für Holztechnologie Dresden (IHD) (Dresden, Germany). The aim of this project is to develop a suitable measuring device for the MDF industry that can be used for
(1) internal quality control: specifying, checking, and ensuring the target fiber quality;
(2) machinery service life evaluation: infer the refiner disk state from the achieved fiber quality ;
(3) process optimization: observing the effects on fiber quality during optimization of steaming and defibration conditions to ensure that panel properties are above the minimal requirements;
(4) validate agreed performance data of defibration machinery with regard to the product guarantee: objective information about the achieved fiber composition would be advantageous for both machinery suppliers and plant owners.
First results of the development activities were presented at the IWCS 2013and at the “Arbeitskreis Faseranalytik 2013” (Work Group Fiber Analytic). A more extensive description of the developed hardware and software was published in the “Journal of the Society of Wood Science and Technology - Wood and Fiber Science” (Benthien et al. 2014).
Within a recently finished industrial trial, the developed Offline measuring device was operated in a MDF plant for the duration of three grinding disc lifetimes and successfully proved its system stability and usability in practical application.
1.2012 - 7.2014
Project funding number: 22013211
Funding program: FNR
Project status: finished