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VOLUME 49, ISSUE 2/2008

Importance of cutting processes for the wood material technology Part 1: Classification of cutting processes

Language: German
Pages: 5 - 8
Authors: Volker Thole

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On the production of wood-based materials the selection of the cutting process depends on the raw materials to be cut and the required particle dimensions as well as on the requested particle profiles. Thus specific plant concepts of the cutting process of waste and residual wood or round timber coming directly from the wood are practical. The usual simple classification into a direct and indirect cutting does not come up anymore to the actual process variants applied in the industry of wood based materials. Due to technological purposes the cutting conditions respecting the process description have to be considered. The size reduction technique of the production of laminated wood parts for the manufacture of Engineered-Wood-Products (EWP) is a focal point. Therefore the production process and the properties of the EWP from uniform particle strips are described in the second part of the report.

Fabrication and properties of large-sized panels made of compressed spruce and fir wood Part 1: Fabrication of boards

Language: German
Pages: 9 - 13
Authors: Frédéric J. Beaud, Peter Niemz, Hermann Blumer, Hans-Peter Wüthrich, Simon Wüthrich

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Panels of spruce and fir wood with a size of 1 m ·3 m and a thickness of 10 cm were industrially compressed using pressure and heat to a panel thickness of 5 cm. The compression under industrial conditions was unproblematic. A raw density profile, analogue to the one found in particle panels with higher density in the surface zones, is formed perpendicular to the panel plane. In the electron microscope the compression is particularly visible in spring wood areas. Caused by transverse contraction and thermal stress the adhesive joints were partially damaged.

Investigation on surface properties of wooden window profiles processed by ultrasound smoothing

Language: German
Pages: 15 - 19
Authors: Christoph Raatz

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Investigations had been shown that ultrasound smoothing is usable for production of wooden window frames. The surface properties had been tested in mean of utilisation requirements. The test results shown comparable properties in both ultrasound and traditional sanded profile surfaces. There are economical advances by removal of working steps such as sanding and manipulating by hand. An important condition for realise in practise is the developing of a mechanical smoothing device for wooden window profiles.

Melamine resin based thermosetting WPC – Processing and Properties

Language: German
Pages: 20 - 26
Authors: Uwe Müller, Juliane Braun, Andreas Haider, Huong Lan Nguyen, Michael Roth, Andreas Endesfelder, Ulf Panzer

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This paper shows advantages of properties and specifics of processing of cross linked thermosetting WPC (HIPE.WOOD) based on a new generation of extrudable melamine resins. Due to their modified structure these melamine resins have a thermoplastic processing window, enabling the extrusion of their mixtures with wood fibres on commercial WPC extrusion lines with subsequent cross linking. In contrast to the extrusion of thermoplastic WPC, the die had to be modified. The temperature profile was adjusted to the melamine resin. The extrudable melamine resins combine the outstanding product performance of thermosets with the advantages of extrusion known from thermoplastics in a unique way, in particular the realisation of complex and even hollow profiles. Resin modification as well as additivation and optimisation of the wood-resin mixtures now allow the control of the extrusion behaviour, cross linking kinetics and final product performance.

Rollface – Thermo smoothing of profiles on MDF parts

Language: German
Pages: 27 - 30
Authors: Klaus Föste

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Thermo smoothing is a procedure for the non-cutting processing of wood and wood-based materials, in particular for the fine processing of profiles. It uses a combination of heat and pressure to plasticise the lignin, to press and fix the base material those fibres that stick out of the surface. As the result, the surface is smoothed and compressed. A special application area of smoothing is roller smoothing which is mainly used on profiled furniture edges to be coated with liquid paint, powder coating or plastic film. Based on various developments of the Institut für Holztechnologie Dresden (IHD), the tool manufacturer AKE Knebel GmbH & Co. KG (AKE) developed a smoothing unit either integrated into a format processing machinery or into a separate feed unit. This roller smoothing unit allows to smooth profiled edges at a velocity up to 40 m/min.

Process control by process data management

Language: German
Pages: 31 - 36
Authors: Edith Martha Zikulnig-Rusch, Görg Zander, Rudolph W. Kessler, Günter Wuzella, Andreas Kandelbauer

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The present contribution illustrates the potential of automated real-time analysis of industrial processes based on process data. The production of hardboards according to the wet process is used as an example. The machine parameters were recorded during production by using a commercial process data management software package. Post-treatment of data is performed using multivariate statistical methods in order to generate a model of the industrial process. It is shown that chemical and morphological information on halffinished parts and final products is available when more than 500 process data are continuously monitored and evaluated. The data can be used for the quality management of hardboards.

Wear resistant coatings for wood surfaces based on UV nano-composite systems Part 1: Scratch resistant nano-composite coatings without corundum

Language: German
Pages: 37 - 42
Authors: Helmut Bauch, Rico Emmler, Reiner Mehnert, Roman Flyunt

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To maintain future markets for the German timber converting industry highest quality is a key prerequisite. In this context scratch and abrasion resistant coatings will play a decisive role. As result of a common development project, IOM Leipzig and IHD Dresden have developed nearly solvent- free, scratch and abrasion resistant coatings for wood surfaces which have been modified with hard nano-particles. In addition micro-scaled alumina particles can be added to the nano-composite coating. Part 1 of this paper describes the preparation and performance of nano-composite coatings. Using a in-situ organophilation of silica nano-particles in UV curable acrylate systems, wood coatings can be generated which show superior mechanical properties. In comparison to reference coatings, abrasion and scratch resistance, micro hardness, flexibility, impact and mar-resistance improved considerably. Part 2 is published in the following issue and deals with corundum containing nano-composite coatings.

Portable X-ray flash tubes for localising damages in wood

Language: English
Pages: 43 - 48
Authors: Andreas Hasenstab, Kurt Osterloh, Uwe Ewert

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Inspecting wood for damages must be accomplishable with appropriate tools on site since the specimens such as living trees, girders within buildings etc. cannot being transported into a laboratory. This is practicably feasible with mobile, even portable X-ray flash tubes (weight less than 8 kg) and systems for digital radiography capable for non-stationary use. It is essential to apply digital image processing to detect flaw indicators properly. Here, the results of radiographic inspections are being presented achieved with X-ray flash generators, a digital radiography system based on semiconductor technology and an automatically operating digital image processing program. The selection of specimens includes a sample of pine tree and another one of a deciduous tree taken from trees afflicted with certain damages. The sample of a fresh implemented construction element was furnished with artificial structures. A damaged oak beam was dismantled from the belfry of the Church of Our Lady in the town of Luther, Wittenberg. The samples shown here demonstrate how internal damages within wood can be detected with the aid of portable instrumentation.

Graphical comparison of radial profiles of highfrequency and X-ray-density scanning from smoothed wood surfaces

Language: German
Pages: 49 - 51
Authors: Frank Rinn, Andreas Kraft

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Radial wood density profiles contain information on wood quality and allow to reconstruct variances in local stand and climatic growth conditions. Because the correspondingly required X-ray analysis of thin wood slices is quite expensive a new high-frequency method should be tested by comparison of measured profiles.

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