EVALUATION OF THE SAWMILLING WASTAGE OF SAWMILLS IN WESTERN PROVINCE OF SRI LANKA

Abstract

The main objective of this study is to find the amount of sawmilling wastage of popularsawn timber species used in the sawmills situated in the Western Province of Sri Lanka.

Fifteen sawmills were selected out of 345 registered sawmills in the western province byusing a random sampling method. The selected sawmills represent all types of sawmillmachinery available in Sri Lanka, (Horizontal band saws, vertical band saws, circular sawsand frame saws). Twelve common timber species were also selected. One hundred andsixty five logs representing the selected twelve species were measured and sawn at theselected fifteen sawmills. For each log, length and under bark mid girth were measured tocalculate log volume. Sawn timber produced from each log was also measured and volumewas calculated. Percentage loss in conversion was calculated.

The percentage loss in conversion of sawmills in Western Province is 55.7%. Percentageloss in conversion varies with the type of sawing machine. The most wasteful machine isthe inserted tooth circular saw (percentage loss in conversion is (54.1 %). Percentage lossin conversion values are respectively lower in circular saw (53.2%), vertical band saw(47.8%), horizontal band saw (44.4%) and horizontal frame saw (42.4%).

Percentage loss in conversion of the selected 12 timber species varied; jak when sawnusing a circular saw gave the highest percentage loss in conversion (60.8%), followed byAlbizia when sawn using inserted tooth circular saw (59.2%). Mahogany when sawnusing a horizontal band saw, showed the lowest percentage loss in conversion (33.6%).Saw gauge does not significantly affect the loss in conversion.

The value of the sawmill machines is Rs.250,000/ and up. The value of the raw materialsshows wide variation: log price Rs.60 per cu.ft.(rubber) to Rs.550 per Cu.ft.(Teak). Mostsawmills cannot work throughout the year due to lack of raw materials and financialproblems. Generally workers are hired on daily paid basis and their salaries vary from Rs.150 to Rs.350 per day which depends on the timber species, machinery used and endproducts (Rs. 25 per.cu.ft. to Rs.40 per cu.ft.).

Major causes for wastage can be attributed to technological problems such as adopting athrough and through sawing method to produce the widest boards, rather than sawing toproduce a mix of sizes, use of bad sawing practices such as poor log alignment andimproper log turning, use of low gauge wide diameter saws to cut small diameter logswhich could be converted by small diameter high gauge saws, inefficient and inadequatesaw maintenance (saw doctoring) and use of out-dated machinery. Improper buckingpractices at the logging sites, log defects and inefficient sawmill management are the otherfactors which cause higher wastage.