University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Martin Herbert Jachs
(2009):
Zerspanungseigenschaften von Teak (Tectona Grandis Lf.) am Beispiel Hobeln sowie die Beobachtung der Farbveränderung nach dem Bearbeitungsschritt.
Master / Diploma Thesis - Institut für Holzforschung (IHF),
BOKU-Universität für Bodenkultur,
pp 88 Seiten.
UB BOKU
obvsg
- Abstract:
- Teak wood gained from 60 year old plantations in Costa Rica was investigated with respect to tool wearing and colour changes after milling. Investigations were carried out with teak wood with a moisture content of 8 % (+/- 2 %) to study the cutting performance of two different carbide reserving plate knives. In addition, changes in colour were analysed after the planing process. For the planing process, a 4-side planer was used and tool wearing was measured by means of a perthometer as well as with a 3D incident light microscope. The knives differed in terms of carbide grit size and bonder content levels. The results show that smaller grit sizes and lower bonder content levels lead to a 32.6 % increase in the cutting performance. The roughness tests further show that the knife with the lower grit size is 4-times sharper before the planing process. In the final cutting performance phase, both knives show the same roughness figures. Indoor discoloration was observed over a period of 208 days. One series of tests was carried out after sunlight irradiation behind window glass and the other series after storage without light irradiation. A distinction was drawn between subjective and objective colour qualification The subjective qualification shows that the colour of processed teak changes to greenish-orange immediately after the processing, but gets darker and more homogenous after a period of 14 days. Furthermore, checked surfaces can be observed at the beginning of the processing phase. These discolorations get less visible, but are still visible and discernible at the end of the processing and observation phase. Objective qualification was accomplished with a photometer by using the Lab-colour system. The results show that colour changes were most visible within the first 16 days after the processing and that the colour difference ∆E* increases 3.5-times after sun irradiation. However, after storage without light irradiation the ∆E* colour difference increases only 2.7-times. Therefore the colour change after sunlight irradiation was 60 % higher than after storage without light irradiation.
- Beurteilende(r): Müller Ulrich
- 1.Mitwirkender: Hansmann Christian