Pallet part and cant evaluation for grading and processing using high-speed ultrasound

Abstract

This paper presented the results of several years of testing the use of ultrasound to find structural defects in pallet parts and pallet cants used to produce pallet parts. To determine the magnitude of unsound defects, we inspected full length cants from seven saw mills from Virginia and West Virginia. Split, wane, shake, holes, decay, unsound knots, bark pocket, and mechanical defects were all considered as unsound defects. Regardless of mill and species, split accounted for the highest percentage of defect volume per cant. Decay: bark pockets, shake, and holes also contributed significantly to the total defect volume. The scanning results of deckboards, stringers and cants showed that ultrasound can be used effectively to locate, identify, and quantify the various pallet parts defects. Significant losses of ultrasound signals/energies were observed through these defects. Other ultrasound parameters, such as time of flight, pulse length can be used for characterizing defects. Reconstructed two-dimensional images were able to show the exact position and surface area of the defects. Defects can be classified/distinguished using classifying tools like multi-layer perceptron, probabilistic neural network, and k-nearest neighbor. Results demonstrated that real-time, online inspection and classification of defects in wooden pallet parts are possible by ultrasound scanning. Results also showed that pallet cants can be graded by unsound wood content and that processing full length cants to cut-to-size cants can be optimized with the knowledge of defect size and location provided by the ultrasound scanning.

Citation

Kabir, M. Firoz; Araman, Philip A.; Schafer, Mark. 2003. Pallet part and cant evaluation for grading and processing using high-speed ultrasound. Proceedings, ScanTech 2003, The Tenth International Conference on Scanning Technology and Process Optimization in the Wood Industry. 133-138.