VOLUME 52, ISSUE 1/2011

During cutting by water-jet, there might be an intake of moisture into the structural components. This moisture leads to swelling and could cause warping of the work piece. In purewater-jet-chipping the workable materials portfolio is more or less limited to solid wood, plywood, (soft) plastics and partly suitable for structural boards (OSB) and fibrous materials. Due to the potential of water absorption during the process of material cutting, the machined structural components once again have to undergo the drying process and need to be stored. In pure-water-jet-chipping the material thickness to be cut limits the use of the technique.

For the judgement of production performance of band-saw blades, and thus of production lines, a practical, inexpensive method is presented as an alternative to the presently available laser-guided solution. To investigate the saw blade sawing capacity, twelve beech and pine logs were sawn up to 267 boards in a mill under controlled conditions. Data were taken from the logs, the band saw machine and the sawing process. Sawing of logs was carried out using three chosen log speeds. For the determination of density and moisture content, solid wood and sawdust samples were collected. Additionally, the sawdust samples were subjected to standard compression tests. The results demonstrate that (i) sawdust might show two and more times loser density in the tooth gullet than that of solid wood depending on cutting height and log feed speed, that (ii) it was possible to determine the degree of utilisation of the cutting potential using practical data, and that (iii) the usual sawing operation made use of the blade capacity of 40 % to 80 % only. Based on these findings, an increase of the sawing performance of around 20 % became possible.

Due to a thermal modification wood gets a completely darker colouration. Different modification levels make an adjustable colouration possible, so that veneers with different colourations can be produced. Thermal modified veneers have besides the dark colour the advantage, that the dimension stability is improved and the water absorption is reduced. Different investigations were carried out and have shown, that thermal modified veneers with a thickness of 0,5 mm are producible, manageable and processible. A modification with 210 °C results in a strong embrittlement of the material which handicaps the processing. Considerable reductions exist under bending loads.The production of thermally modified veneers by slicing a modified flitch is possible. But as a consequence of the oftening in water the colour of the flitch and the veneers respectively is changed. However the colour changes occurs uniform and do not have to evaluate disadvantageously. The colour differences over the thickness of the flitches have to evaluate as disadvantage. Veneers that are sliced at the eginning of a flitch are darker then the veneers that are sliced from the middle of the flitch.

Increased raw material efficiency is the need of the future, which demands the development of new low weight materials. On the other hand an image change of light weight materials is required to increase the application in the furniture production and interior works. Honeycomb sandwich constructions are the optimal solution for industrial and bulk production. However, individual and flexible processing of panels for interior uses and furniture needs additional light weight material concepts with more homogeneous structure and improved mechanical properties.

Due to their advantageous properties and the comparatively low price the paper honeycomb core is a good material for producing lightweight sandwich panels for furniture and interior applications. according to the specific field of application, different combinations of materials, construction methods and manufacturing processes are applied for the sandwich panel production. The current situation of lighweight construction in the field of furniture and interior application as well as important types of paper honeycomb cores will be presented in part 1 of this paper. Panel construction methods and manufacturing processes are shown in part 2.

The present article presents a novel laminate with a high performance surface (IPL) which was produced by process newly developed at the Impress Décor Austria GmbH. Especially notable with this product innovation is that it was achieved for the first time to manufacture an abrasion resistant laminate industrially feasible in a way that the hardness conferring material is directly deposited onto the decorative paper surface without being detrimental to the processability of the material in the hot press. Traditionally such products were manufactured by positioning an impregnated and coated so-called overlay paper as the upper top layer which functioned as a protective separation layer between the press plate and the highly abrasive corundum layer. The novel process avoids this additional production step and the laminate can be manufactured with a lower material input and higher production speed. To achieve this, a novel measuring technique had to be developed that allows the estimation of the press plate damage by the corundum at the paper surface.

The detection of glue-line delamination is important for the quality control during production (e. g. glue-laminated timber) as well as for in-situ inspections. To test possible fields for ultrasound technologies, investigations on spruce-wood with artificially generated gluing faults were carried out. For the tests, small, clear samples composed of two lamellae of 5 mm thickness each and glue-laminated beams made of 7 lamellae of 30 mm thickness each were produced. Different test devices were used to measure the running time with the transmission method. Gluing faults, in particular, became well apparent with doubleply material. As a result of variations in the running times due to the variance of wood properties, a reliable interpretation of the test results for glulam was impeded. However, the contours of the defects were also observable.

Analytical methods for the characterisation of complex relations between fibre-adhesive-interdependencies are discussed. Specific values determined with those methods shall be usable for the estimation of properties of MDF made from the analysed fibres and adhesive. The focal point is set on the influence of fibre-properties on the fibre-adhesive-interdependencies, with quasi constant adhesives, glue-process- and press-processparameters. The hypothetical relations between fibre properties and fibre-adhesive-interdependencies are presented and discussed. In addition, the method of measuring contact-angles is presented, as a potential analytical method for the characterisation of fibre-adhesive-interdependencies. There remains an extensive need for further research, like the development of methods to evaluate fibre-properties such as: fibre-porosity, fibresurface as well as the determination of adhesive-distribution, -penetration, -kinetics and -adhesion in relation to the mentioned fibre-properties.