Ultrasonic Inspection of Wooden Pallet Parts Using Time of Flight
Wooden pallets exceed furniture and other solid wood products as the largest single use of sawn hardwood logs in the USA. Most wooden pallets are constructed from two types of pallet parts (Figure 1): (1) stringers—the structural center members that support the pallet load and (2) deckboards—the top and bottom facing members that provide dimensional stability and product placement. There are many variants of this basic design, but most pallets contain solid wood components that are produced from lumber or from the center cant material of logs. Cant material has a high percentage of defect area and is generally not highly valuable for other solid wood products. Therefore, the pallet manufacturing industry must make use of low-quality raw materials and yet produce a product that remains in service for many trips.