Application of Ultrasound Nondestructive Evaluation to Grading Pallet Parts

Abstract

Building high quality pallets makes pallets easier to repair and increases their longevity. To obtain the high quality parts necessary to build durable pallets requires grading and sorting by an automated inspection system. Ultrasonic sensing was selected for this application because (1) it is relatively inexpensive, (2) it can penetrate and characterize internal features of wooden specimens, and (3) its effectiveness has been demonstrated for certain features of wood. This study has sought: (1) to determine the ultrasonic parameters that are most sensitive to pallet part defects and (2) to specify what aspects of ultrasonic response signals best characterize defect size and location. Time of flight measurements appear reliable for delineating knots from clear wood. Also, preliminary indications are that peak amplitude may be sensitive to areas with splits/checks/shake. Results from this work and subsequent studies will be applied to the development of an industrial prototype that automatically detects defects and grades parts according to established visual grading rules.

Citation

Schmoldt, Daniel L.; Duke, John C., Jr.; Morrone, Michael; Jennings, Chris M. 1994. Application of Ultrasound Nondestructive Evaluation to Grading Pallet Parts. Proceedings, 9th International Symposium on Nondestructive Testing of Wood. 183-190.