Uppfattningar om tryckved bland träbearbetande företag i Sverige

Sammanfattning: The primary purpose of this study has been to investigate the Swedish timber industry's perception of compression wood. A secondary aim has been to describe particular areas within the production process where compression wood is likely to cause problems. This study has mainly been carried out as a questionnaire. In order to connect the findings to current research, additional information has also been collected by means of a literature review. The questionnaire has been intended for sawmills and wood-manufacturing companies from various production classes and owner categories, as well as from different parts of the country. In total, questionnaires were sent out to 153 sawmills and 120 woodmanufacturing companies. Seventy sawmills participated in the investigation, which represents 46% of those who received the questionnaire. Within the wood-manufacturing industry, 29 companies took part in the investigation, which represents 24% of those who received the questionnaire. The low proportion of responses among wood-manufacturing companies could be attributed to a lack of time, resulting from the fact that this category contains many small companies with few employees. The study shows that compression wood is a well-known problem, which according to the timber industry mainly causes production problems and deformation of the sawn wood. Regarding these deformations, most sawmills consider compression wood to cause bow, followed by spring and twist. Within the wood-manufacturing industry, however, most companies consider compression wood to cause twist, followed by bow and spring. Furthermore, the investigation shows that the wood-manufacturing companies accept considerably smaller deformations than the sawmills, and that the largest sawmills, those producing more than 200 000 m3 per year, accept larger deformations than the rest of the sawmills. In the investigation, a number of steps in the production process have been identified, where methods can be applied to improve the stability of the wood. Examples of such methods are curve sawing, grading of sawn products before drying, and applying a top-load on the wood while drying. According to the questionnaire, over three-quarters of the participating companies are using curve sawing. Only about half of the companies producing less than 50 000 m3 per year, however, are doing this. Furthermore, approximately fifty percent of the sawmills are grading their sawn products before drying. This number is considerably larger among companies producing more than 200 000 m3 per year. 38% of the sawmills are applying a top-load on the wood while drying. However, among companies producing less than 50 000 m3 per year, this number is considerably lower. Responses to the questionnaire, as well as literary references, indicate that actions taken in order to reduce the negative impacts of compression wood should be implemented as early as possible in the production process. The sooner this is done, the greater the possibilities are to affect the quality of the finished product.