Yield maximization of rotary veneer in a mill in Kumasi (a case study)

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1998-02-14
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Abstract
The study was conducted in the Rotary Veneer milling section of Logs and Lumber Limited in Kumasi to determine the average veneer recovery factor for some tropical hardwoods. The effect of log diameter on veneer recovery for the seven species Hyedua (Guibourtia ehie), Chenchen (Antaris toxicaria), Bombax (Bombax brevicuspe), Onyina (Ceiba pentandra), Edinam (Entandrophragma angolense), Mahogany (Khaya ivorensis) and Koto (Pterygota macrocarpa) were also studied. Sixty-three (63) bolts comprising of 9 each of the species was selected randomly for the study. The mean recovery factor determined in this study for the seven species was 65.0 ±2.5% with 95% confidence. Residues in the form of peeler cores, rounding off and wet clipping losses were determined to be 10.3%, 9.7% and 15.0% respectively. An average bolt form of 0.92 was obtained. A weak correlation was observed between bolt diameter and veneer recovery for the following species: Chenchen (R2 = 2.8%), Bombax (R2 6.6%) and Edinam (R2 18.9%), Koto (R2 = 32.5%), Ceiba (R2 = 30.1%) and Hyedua (R2 = 29.8%). Except Mahogany, though R2 = 44.4%, significant (5% level) relationship was established between bolt diameter and veneer recovered. Analysis of variance performed indicated that there were significant (x = 5%) difference in the diameter classes of the species. However, the species indicated no significant difference in relation to veneer recovery. A t-test statistic conducted on the influence of two different thicknesses on recovery for Koto species revealed no significant differences between the mean recovery values.
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A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Science, 1998
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