Nondestructive evaluation for sorting red maple logs

Existing log grading procedures in the United States make only visual assessments of log quality. These procedures do not incorporate estimates of the modulus of elasticity (MOE) of logs. It is questionable whether the visual grading procedures currently used for logs adequately assess the potential quality of structural products manufactured from them, especially those in which MOE is of primary concern. The purpose of this study was to investigate the use of stress wave NDE techniques to sort red maple logs for the potential quality of lumber obtained from them. One hundred seven red maple logs were nondestructively evaluated using longitudinal stress wave techniques and sorted into four stress-wave grades. The logs were then broken down into cants and lumber. The same procedure was used to obtain stress wave times in cants and lumber. The lumber specimens were then dried and graded using a transverse vibration technique. The results of this study show that good relationships exist between stress wave times measured in logs, cants and the lumber produced from the logs. It was found that log stress-wave grades have a positive relation-ship with the resulting lumber grades. Logs with high stress-wave grades produce high-grade lumber. These findings indicate that the longitudinal stress wave technique could be used in sawmills to sort logs/cants for the production of high MOE products.