PLYWOOD AND APPLICATIONS
For the last so many years, the use of the plywood and other manufactured boards has, in varying degrees have replaced the use of solid timber in the making of furniture, fittings, paneling and many forms of constructional work. Plywood is generally made of three or more sheets of veneer glued together, with the grain of successive plys laid cross-wise. Since the strength of timber lies along the grain, when plys of veneer are bonded in opposing grain direction, strength is distributed to both length and breadth of the piece. The plywood can be obtained in much larger sizes without shrinkage and warping in comparison to plain wood. The molded plywood boats, television and radio cabinets can be formed from plywood. The plywood can withstand easily against humid condition. Plywood is lighter in weight and stronger across the grain than even the toughest hardwoods. Screws and nails can be driven close to the edge of plywood without any danger of splitting. High class surface finish can be are easily obtained on plywood.
The development of moisture and heat-resistant adhesives have contributed to the use of laminated members for heavy truss construction, to the gluing together of narrow boards to make wider ones, and to the making of finger joints by which short lengths are joined to make longer pieces. Plywood is used for many forms of construction, including sheathing, interior finish, sub flooring, under-roofing, paneling, flooring, cabinets, furniture, shelving, partitions, ceilings, containers such as baskets, boxes, crates, trunks into boats, toys, tables, woodenware and repair work in garages and basements. The factors influencing the selection of timber involve the quality of timber in terms of its durability, workability, weight, hardness, cohesiveness, elasticity, type of texture, type of grains, resistance to fire, resistance to various stresses, ability to retain shape, suitability for polishing and painting. Copied from Basic of Manufacturing Processes and Workshop Technology by Rajender Singh.