Förbättrat råvaruutnyttjande vid kvalitets-sortering av timmer : utvärdering av analysprogrammet Stockholmen för automatiserad timmersortering i dimensions- och kvalitetsklasser hos BARO WOOD AB

Abstract: The aim of this thesis was to analyse BARO WOOD AB:s timber measuring and quality sorting and to evaluate the analyse program Stockholmen. The purpose was to get a better understanding for the quality sorting made at BARO WOOD AB today, analyse differences in center board quality from logs with a good quality and logs with a bad quality, suggest new sorting criterias developed from analyses made with Stockholmen and to evaluate the program Stockholmen. All analyses are based on data gathered in a test sawing made at BARO WOOD AB in June and July 2002. The test sawing was made on four different diameter classes and every diameter class consisted out of A or M-grade logs, with a better quality, and B-grade logs with a lesser quality. The logs where sorted out with BARO WOOD AB:s existing quality criterias. The test sawing was carried out so that the centre board yield from each log could be related to the geometry of every individual log. The sawn wood were graded according to the "green book" (the Swedish standard) and to BARO WOOD AB:s rules for grading of sawn wood to specific products. The comparison between the amount of approved centre boards for the better A and M-logs and the B-logs indicated that quality sorting for the A and M classes was functioning satisfying. All the better log classes had a higher amount of approved center boards. It was in the log classes with a lesser quality that an improvement of the quality sorting could be made by sorting more of these logs to the better A and M-classes. By analysing the data from the test sawing with the analyse program Stockholmen it was possible to find relations between the logs with an approved centre board quality and the sorting criterias that influences the quality sorting. The sorting criterias that affected the quality sorting was VMR 1/99 quality, log type and bumpiness. A suggestion to new sorting criterias for every diameter class was worked out with Stockholmen. The new sorting criterias increased the share of approved logs but it also decreased the total amount of sorted out logs. An adjustment must be made between the higher share of approved logs and the lesser amount of sorted out logs to be able to decide if a change in sorting criteria gives an increased value. The evaluation of Stockholmen has shown that the program is a very good tool and complement to a quality sorting system. With Stockholmen analyses can be made to get an easy overview of log criteria such as taper, bumpiness and VMR 1/99 quality for a specific batch, try different sorting criteria to see what the outcome would be and to see what a change in sorting criteria would give in outcome over time.