In the labor-intensive production of plywood, a veneer ribbon of wood is clipped into 4 × 8-ft sheets and passed through a dryer. The sheets are inspected and sorted according to grade and then inserted into a press, layered, and combined with glue, pressure, and steam heat to make a plywood panel. The sheets pass along a conveyor belt at a rate of 1/s, and the task of looking for knots, holes, dirt, gouges, and other defects is challenging for workers. In addition, smoke and dust raise health concerns.
Ventek (Eugene, OR, USA; www.ventek-inc.com) has developed a machine-vision-based inspection system, the GSC2000, that scans the sheets and calculates a grade with an accuracy rate of 95% or higher. The GSC2000 features a Basler (Ahrensburg, Germany; www.baslerweb.com) L301KC color camera and a Matrox Imaging (Dorval, QC, Canada; www.matrox.com/imaging) Meteor-II/Camera Link frame grabber in a 3-GHz Xeon PC (with hyperthreading technology). Ventek's True Color Lighting illuminates the inspection area. Image capture, processing, and measurements are all performed by Matrox MIL version 7.
The system relies on Ventek's Neural Network Classifier software, which must be trained with images of defects. The sheets are assigned a grade or rejected; lower-grade sheets can be used as the central layer of the plywood. More than 40 GSC2000 systems have been sold to major plywood producers, including Boise Cascade, Georgia-Pacific, Martco Plywood, and Weyerhaeuser.
