VOLUME 59, ISSUE 2/2018

Milling is one of the most important cutting procedure in the wood industry. It allows planing, profiling and shaping of workpiece surfaces with a high chip-removal rate. This is possible because of a fast rotary cutting motion of the tool, the possibility to place many cutting edges on the tool circumference and a fast linear feeding motion of the workpiece or the tool. Due to these different kinds of motions (rotary and linear) the resulting effective motion during the cutting process follows a prolonged cycloid. Periodic waves are formed on the workpiece surface due to this cycloid motion. These surface patterns, called cutter-marks, may be visible on the machined surface after cutting and mainly influence the workpiece quality. Further surface machining steps are required, like sanding or slicing to meet the required standards of surface quality and roughness. Therefore, extra efforts and costs are incurred, as well as additional production steps and time, in order to finish shaping the workpiece. This is why researchers have been looking for possibilities to lower or avoid these cutter-marks for some time. Part 1 of this publication describes and analyses the geometry of cutter-marks and magnitudes of disturbance. In part 2 general, mechanical and mechatronic approaches and alternative procedures will be introduced, discussed, compared and presented then in the paper. Especially mechatronic approaches using modern hardware can improve this situation by basically adjusting the cycloid motion track when the cutting edge approaches the work piece. In this way, the effective motion of the cutting edge is changed to a nearly linear motion by means of piezo-electric actuators or magnetic bearings. First successful set-up and experiments will be shown.

The shrinkage and swelling of the raw material wood is signifi cantly improved by further processing to homogenized wooden products. These wooden based panels are characterized by their dimensional stability in the plane. Due to a multilayer orthogonal bonding of individual layers solid wood panels with homogenized shrinkage and swelling properties can be produced. Currently a reduction of the shrinkage and swelling properties can only be achieved by the use of adhesives. Within the scope of this work, the deformation behaviour due to change of moisture of an adhesive- and metal-free structural plane-like element is investigated practically and theoretically. The examined element consists of profi led single beams with an orthogonal wooden screw connection and is well known on the market under the product name “holzius solid wood element”.

Wood based products are processed using mainly synthetic adhesives. With ongoing discussions and tightened limits concerning formaldehyde emission values adhesives based on natural materials like proteins are under investigation again. Such adhesives were already tested; however, they suffer from low solid content, long pressing times and poor water resistance. Within a project at Institut für Holztechnologie Dresden (IHD) one main aspect, the solid content was improved by controlling the molar masses of wheat protein fractions. Using Osborne fractions, Gliadin and Glutenin, the solid content could not be increased and the mechanical val-ues were comparable to the native protein. With molar mass reduction by enzymatic hydrolysis the solid content could be increased; however, the reactivity decreased and the mechanical values were lower as compared to the native protein or Osborne fractions, respectively.

Within the context of research work on recycling of UF bonded fibreboards, the release of ammonia from MDF containing different amounts of recycled fibres retrieved from waste UF bonded fibreboards was evaluated. It became obvious that using recycled fibres in high amounts (67 % and 100 %) for new UF bonded MDF leads to a significant increase in the release of ammonia, whereby MDF made from 100 % recycled fibres showed the highest ammonia release value. Moreover, it seems that increasing the pressing time also fosters the release of ammonia from fibreboards containing recycled fibres in high amounts.

Users can provide a valuable source of knowledge for the development of innovative, user-friendly products using appropriate methods. The methodical analysis of the user requirements is exemplarily explained using the example of nursing chair for immobile persons. Both the product idea itself as well as the functional and design characteristics of the nursing chair have been the result of the involvement of the users in the development process. The developer acts as a translator of the statements and actions of the users in a constructive, functional and aesthetic design of the finished product.

The naturally blue-green staining of wood caused by Chlorociboria aeruginascens enjoys great popularity in the hand craft sector. In the first part of this work, different media and cultivation techniques for cultivation of the fungi C. aeruginascens were investigated concerning the biomass production for pigment extraction and to produce inoculum for controlled mycological wood staining. Mycological wood staining by C. aeruginascens is now the focus of the second part of this work presented here. Therefore different wood species were tested for their suitability as substrate. In order to accelerate staining of wood samples, classical cultivation methods were successfully combined and a reactor prototype was specially developed for the mycological wood staining (part 2) with C. aeruginascens based on the results obtained.