Grain Direction In Plywood Manufacturing
When answering this question we need to look at the requirements of plywood. In nearly all cases there is a need for rigidity and strength from plywood no matter the species or its application.
Plywood is constructed from three or more thin sheets of ply, stacked, glued and compressed together under a high heat to bond. During this manufacturing process the mills will lay the grain of the ply sheets in alternating directions. In higher quality plywood like that supplied by Global Panel Products, the grain is laid running at a right angles (45 degrees) to the adjacent layer. This will give more strength to multiple axes across the panel.
The effect of laying the grain in this manner is called ‘cross-graining’ and has a few benefits including:
- Reducing the potential of the wood splitting when nailed
- Reducing expansion and shrinkage
- Improved stability
- Makes the strength consistent throughout the panel
Additionally, in order to balance the plywood, there is always an odd amount of ply sheets used.
In the furniture industry there is often a need for plywood to have less rigidity and become more flexible. In this case during the manufacturing process the grains are kept in the same direction. This then allows for the plywood to become pliable and bend to create curves.