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Ghana Journal of Forestry

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Machining characteristics of khaya senegalensis and anogeisus leiocarpus

Francis Wilson Owusu, Joshua Ayarkwa

Abstract


Khaya senegalensis (Kuntunkuri) and Anogeisus leiocarpus (Kane) have been found to be in abundance in the Savannah Zone of Ghana where other Ghanaian primary species are scarcely available. In contribution to the promotion of these species, the turning, shaping, boring and sanding properties were studied. The results have shown that Khaya has a better turning, shaping, boring and sanding properties than Kane. Spindle and feed speeds were found to have significant effect on the two wood species at P ≤ 0.05. The higher the spindle speed, the better the turning and shaping qualities of the species. Spindle speeds of 2,800 rpm and 6,000 rpm used for turning and shaping tests respectively, generated Grade I quality samples for Khaya and Kane. Spindle speeds of 900 rpm and 1,400 rpm combined effectively with feed speeds of 0.9mm/mim, 1.5mm/min, 2.4mm/min and 3.9mm/min to produce Grade I bored holes in the two species while combinations of 2.4mm/min, 3.9mm/min and 300 rpm; 1.5mm/min, 2.4mm/min, 3.9mm/min and 600 rpm and 0.9mm/min, 1.5mm/min and 2,200 rpm achieved Grade I of bored holes for the species. The amount off-size in the bored boles was higher in Khaya than in Kane and the off-size increased with increasing spindle speed. The average variation from size of bored holes in Khaya and Kane with the six spindle speeds (300, 600, 900, 1,400, 2,200 and 2,900 rpm) was 0.3567 mm and 0.3233 mm respectively. Grit sizes of 40 and 60 sanded off any chipped/torn grain defects that were observed on Khaya while grit 40 eliminated the same effect on Kane. The relative freedom from fuzzing in Kane was higher than in Khaya when grits 100, 120 and 150 were used but the relative resistance to scratching with the same grits was evaluated to be higher in Khaya than in Kane. Therefore for effective preparation of the wood species for the application of finishes, grit sizes higher than 150 are recommended. The good machining qualities of Khaya coupled with its aesthetic Mahogany-like colour make it recommendable to the furniture industry while Kane is recommended to the construction industry where quality is not of prime importance. The species should therefore be grown in plantations establishment, especially in the savannah zone where they are reported to grow well to support the proposed industry.




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