Quality increase analysis of sawn lumber

In today's sawmills, logs are processed into lumber without knowledge about interior defects or about the potential grade and yield of lumber. In some mills an experienced individual, the sawyer, determines the sawing pattern on the basis of log-size and log-surface characteristics. In other mills, optical scanners generate size and shape information which is processed by a computer to determine the cutting pattern that will maximize lumber recovery and, in some cases set the machinery to process the logs. Most headrig process control system involve the use of Best Opening Face (BOF) sawing technology. These systems do not have the capability of maximizing lumber grade. Recent advances in scanning technology make the scanning of logs for internal defects technically possible, and high speed production logscanners may soon be developed. Past research has shown that knowledge of defect locations can be used to increase the grade of lumber sawn from logs. Several studies have investigated repeated computer sawing of logs into various configurations. These studies have concentrated on the algorithms and computer procedures for simulated sawing and on the potential advantage of altering sawing methods based on hypothetical defect locations. The initial rotational position of the log on the carriage was reported to be very important to lumber value yield. An extensive study by the USDA Forest Service Forest Products Laboratory also showed that the rotational position for the first sawline was very important to the value of sawn lumber.