All About Plywood

Summary

Plywood, as the name suggests, is a manufactured wood product.   No matter the type of plywood it is always made in the same way: by gluing and then pressing thin layers of wood (known as plies) together to form either flat solid sheets or curved shapes.  Just like solid wood, the wood grain in ply and veneers run at a specific angle, making the ply bendable and pliable in one direction but not the other.  Each ply is laid with their grains running at opposing angles, giving the contrasting stripe effect you see on the side of plywood boards

This technique known as cross-graining stops plywood from splitting, warping, expanding, shrinking or bending, creating a very versatile product that is more durable, stronger and cheaper to manufacture than solid wood.  Laying plies at lower angles to one another (at 45 degrees rather than 90 degrees for example) increases the strength of the final material, but also increases waste as the plies need to be cut at an angle. Most commercial plywood has each plywood going at 90 degrees to the adjacent ones.  The strength and properties of each type of plywood depend also on the number of plies (always an uneven number) type of wood and glue used as well as any finishing applied.  

Composition of plywood

Plywood is made from several thin layers of wood veneers stacked over one another. These veneers are called plies, which are firmly glued to each other so that they don’t come apart easily.

The number of plies in every plywood sheet is usually an odd number, such as 3-ply, 5-ply, 7-ply, etc.

While stacking the veneers over one another, it is ensured that the grain direction of the plies in adjacent layers is perpendicular to each other.

How plywood is made

The veneers, which are thin slices of wood are obtained from the logs. The logs are mounted on a lathe machine and are rotated about their longitudinal axis, while a cutter peels off thin layers from the log (Somewhat similar to the way we peel layers from vegetables).

Glue is applied to all the peeled slices of plies using glue spreader machines, and the plies are placed one upon the other. The stack then goes into a hot press machine, which firmly presses the veneers together and forms a strong bond between the individual plies so that they do not come apart. Thus a plywood sheet or board is made.

 Adhesives used in plywood

There are two kinds of glue used. One is UF (Urea Formaldehyde) resin, and the other one is ‘Phenol Formaldehyde’ resin. Phenolic resins are considered better than UF resins because they can form a stronger bond between the plies.

Popular uses of plywood

For making furniture like tables, chairs, wardrobes, single and double beds, kitchen cabinets, etc.

Also in some cases of wooden roofing and wooden flooring.

Apart from this, there are hundreds of other uses of plywood such as for making sports equipment (table tennis racquets and tables), musical instruments (such as a guitar) and many other things. It’s a very versatile material that is easy to work with.

Conclusion

Plywood became a more commonly used material in the US and UK during the second half the 19th century but it wasn’t until 1928 that production became standardised.  Originally considered a cheap material, plywood was mainly hidden, disguised under beautiful veneers or upholstery. Plywood has historically been used in many unexpected products, from fighter jets in the 2nd world war to stretchers and flat-pack housing.  It is now even being used as a wood turning material, bringing the story full circle.  A truly exceptional material, whose worldwide standardised production makes it extremely versatile, it is durable, easy to work with and looks beautiful once finished.

Published by avnid

I am a former business development executive. Currently I left my job and trying to peruse my career in blogging. You can except Technical Article, Cloud Technology Update, Any Breaking and Trending News.

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