Planing and Turning Characteristics of Gmelina arborea Grown in Two Ecological Zones in Ghana

Abstract

Gmelina arborea grown in Ghana has not been promoted for its efficient use by the wood industry due to the limited technical information available and is therefore classified as a lesser-used timber species. This paper presents research findings on the planning and turning properties of Gmelina arborea cultivated in two ecological zones in Ghana. Samples of logs from six trees of the species were obtained from Daboase and Abofour in the Wet Evergreen and Dry Semi-Deciduous Forest zones of Ghana. These were crosscut into top, middle and butt sections using a chainsaw. An LT 15 Wood-Mizer bandsaw was used to saw each log into 2.6 cm-thick boards; these were then stacked for air drying. Planning and turning tests were conducted following the American Society for Testing and Materials International D1666-87-2004 method to determine the machining characteristics of the wood. The results of the study indicate that Gmelina arborea is a medium-density species and that irrespective of where it is grown, the best planing performance is obtained at a feed speed of 6 m/min using a cutting angle of 30°. The results also indicate that the turning characteristics of Gmelina arborea obtained from the two ecological zones were best at spindle speeds of 1850 rpm and 2500 rpm. At the 5% level of significance, the spindle speed and the interaction between location and spindle speed, tree section and spindle speed and location, tree section and spindle speed had a significant effect on the surface quality of the turned specimen. It is therefore found that Gmelina arborea cultivated in Ghana has good planing and turning characteristics.