Epsilon Archive for Student Projects

Abstract

The aim of this study was to provide SCA Forest Norrbotten District with material to assist in their work towards decreasing the frequency of bucking splits in their saw timber logs. SCA Forest supplies the Munksund sawmill with pine timber. Periodically the sawmill experiences problems related to bucking splits in their logs.
The purpose of this study was to find an available method to measure the occurrence of splits directly on incoming timber. The ambition was also to gain some knowledge about possible variations between different logging crews in terms of split frequency. If possible, this information could be used to investigate if certain crews produced more splits than others, and thereby making it possible to provide feedback to the logging machine operators.
The study consisted of two major parts, a literature review, and a practical sawmill study. Several methods for measuring bucking splits used in earlier studies were initially reviewed and considered for inclusion in this study. A methodology, in Swedish called “Trissmetoden” was found to be the most practically useful out of those compared. This method involved crosscutting a short section at the end of the log and then inspecting it. If splits were observed, there was a possibility to make a distinction between splits caused during bucking and splits caused by felling operations.
Top logs, middle logs, and butt logs were analyzed separately. In total, the study included 390 logs with 130 logs for each category. The results varied considerably between categories. The percentages of logs with splits were 29 % for the middle logs, 16 % for the top logs, and only 8 % for the butt logs. The average length of a split was between 5,6 and 11,0 centimeters depending on the category of log and the longest split found was 42 centimeters. Out of all the measured logs containing splits, 64 % had rather short splits, less or equivalent in length to only one crosscut section of the log.
One conclusion was that the largest problem with splits seems to occur among the middle logs since the highest percentage of splits was observed for this category.