Timbre harmonic of selected hardwood species

One of the limited information about the acoustic characteristics of wood is the timbre harmony. We measure the sound harmony of selected hardwood species using a timbre harmonic model. 324 wood samples of 20 x 20 x 300 mm (R x T x L) were collected axially from 12 trees of Albizia adianthifolia, Gmelina arborea, Delonix regia and Boscia anguistifolia for the experiment. Results were subjected to descriptive statistics and analysis of variance. The timbre harmonic model prescribed a scale of 0-1, 0 being the perfect harmonic while 1 represents imperfect harmonic. G. arborea wood had the significantly lowest mean timbre harmonic of 0.078 ± 0.006, thus it had the best sound harmony. Meanwhile, A. adianthifolia wood had the highest timbre harmonic value (0.120 ± 0.008). Conclusively, this study successfully measured the timbre harmonic of sound from selected hardwood species and information provided revealed the species all performed fairly, owing to their values closer to 0.00.

Machining properties of lesser used wood species from Mozambique

The present study was aiming at measuring cutting forces for wood of lesser used species from Mozambique such as Acacia nigrescens Oliv (namuno), Pericopsis angolensis Meeweven (muanga), Pseudolachnostylis maprounaefolia Pax (ntholo) and Sterculia appendiculata K. Schum (metil). Another aim was to use an expeditious method to compare performance of the species when cut. A machinability index calculated using Digraph and Matrix Methods was used for ranking the performance of the species when cut. Two different cutting tools 20o and 30o rake angle were used. Main cutting force in 90°-90° and 90°-0°cutting directions were measured by piezoelectric gauge. The results of the experiments showed that cutting forces followed normal trends to increase with density and decrease with increasing rake angle. The ratio between wood density and cutting forces in cutting directions 90°-90° and 90°-0° were 7 s2m-4 and 17.3 s2m-4, respectively. The most difficult species to be machined was Namuno, whereas the easiest species to be machined was Metil.