SIMULATED GRADING OF LOGS WITH AN X-RAY LOG SCANNER - GRADING ACCURACY COMPARED WITH MANUAL GRADING

Today sawmills have started to use automatic methods for log grading. The methods used are either optical or gamma-ray scanners. However, th e signals from these scanners are too coarse for accurate log grading and for good control of the sawing process at the single log level. Th e objective of the present study was to determine the grading accuracy of a log-scanner with two industrial X-ray sources. The grading accur acy was compared with the accuracy of manual grading. The results show ed that the manual grading of logs and boards is difficult. The accura cy of manual grading was low and the automatic grading systems were mo re reliable than manual ones. Possibilities fur improving the automati c grading systems are discussed.