6 - Chipboard, oriented strand board (OSB) and structural composite lumber

Abstract

Different types of wood-based materials which are manufactured from chips and strands bonded together with adhesives are described in this chapter. The choice of wood species, the shape and size of chips and strands and the type of adhesive all influence the properties. Chipboard is composed of particles and thin slivers of wood which are made by cutting the wood feedstock with rotating knives and shearing the wood into small elements. The characteristics of chipboard are low cost, high thickness and the capability to manufacture large dimension boards. Chipboard manufactured from waste materials has extra carbon offset value making a contribution to a sustainable environment. Oriented strand board (OSB) is an engineered, composite, wood-based panel product, designed as a structural replacement for sheathing grades of plywood. OSB is characterised by its constituent strand elements which vary in size and aspect ratio and are larger than the chips from which chipboard is pressed. Since the birth of OSB, which is used mainly for structural applications, the product has expanded rapidly in the marketplace because of the lack of good quality forest resources and deforestation. Techniques such as image analysis can be used to measure strand orientation on the production line providing feedback to enhance the reliability and stability of engineered OSB. Structural composite lumber (SCL) is historically classed as re-engineered wood, developed as a substitute for high-quality wood. SCL products include laminated veneer lumber, laminated strand lumber, parallel strand lumber and oriented strand lumber. There are significant advantages in producing SCL including consistent quality and flexibility in selecting raw materials. In future, efforts will be made to reduce the cost of manufacturing SCL and adding value by improving properties.