Wood composites such as particleboard and fiberboard are a popular choice for carcase backs, drawer bottoms and concealed panels. Made from blends of wood particles and synthetic adhesive bonded together under intense heat and pressure, composite boards are as strong and as durable as most solid woods and generally less expensive. They are also more dimensionally stable.
Particleboard was first developed in the 1930s as a way of recycling wood flakes, chips and sawdust dismissed as sawmill waste. Today, many mills focus mainly on particleboard production, processing softwood and medium-density hardwoods into composite particles with machines called drum flakers, chip- pers and hammer mills.
Particleboard is manufactured by two methods: extrusion and mat-forming. In the less common extrusion process, wood particles and adhesives are forced together through a small, thin opening to form panels. The grain orientation of the particles is perpendicular to the faces of the panels. With mat-forming, the particles and adhesives are squeezed into a mat in a press. With this method, the grain of the fibers is parallel to the panel faces.
Mat-formed particleboard comes in three configurations (right). Single-layer particleboard features wood particles of uniform size and shape. Multi-layer particleboard has coarser shavings at the core of the panel and finer ones on the outside surfaces. Graded-density particleboard is similar to multi - layer particleboard, but with a more gradual change from coarse to fine particles. Standard particleboard sheets are 4 by 8 feet, although 5-by-10 panels are available; thicknesses range from XA to 2 inches.