Investigation of Sawmill Management and Technology on Waste Reduction at Selected Sawmills in Moratuwa

Abstract

The demand for sawn timber and wood-based products is rising steadily with newdevelopments in the country apart from the growing domestic consumption. Therefore it isimperative to strike a balance between the increasing demand and the optimum utilisation ofthe available forest resources.

Thus the key objective of this study was to investigate the effects of sawmilling managementand technological parameters on loss in conversion from logs to sawn timber. A sample oftwenty one sawmills was selected out of 206 registered private sawmills in Moratuwaaccording to the sampling percentages determined from an initial survey. Based on the resultsmean percentage loss in conversion of private sawmills in Moratuwa was 56.9%. Significantdifferences were observed in loss in conversion values of both Teak and Mahogany speciesbetween the three categories of sawmills (frame sawmill, band sawmill and circular sawmill)as well as within the sawmills of the same category. Highest wastage was recorded in thecircular saw which was 64.4%. Percentage loss in conversion values were relatively low inframe saw and band saw which were 54.3% and 46.0% respectively. The results proved thatthe percentage loss in conversion varied between Teak and Mahogany species whereMahogany sawn in circular saw showed the highest percentage loss in conversion andMahogany sawn using the horizontal band saw showed the lowest percentage loss inconversion. The study further revealed that the loss in conversion values of private bandsawmills did not significantly vary with the State Timber Corporation band sawmills inKaldemulla.

The reasons for variation in loss in conversion values can be attributed to sawyer’sexperience, the state of saw doctoring (saw sharpening and maintenance), cutting pattern,availability of log alignment equipments and saw guards and feed speed. It was observed thathigh wastage was caused by using thick tungsten carbide tipped blades used in circularsawmills. In contrast lowest loss in conversion was showed in band sawmills with thinflexible cutting blades. Through and through sawing method was found to be the only sawingmethod employed by all the selected sawmills. However it was identified that this methodcannot be recommended for all logs especially for defective logs. As a mix of sizes isproduced from a log in these sawmills cant sawing can be suggested as an efficient sawingmethod.