Plywood is one of the strongest materials used in manufacturing of furniture and interiors for any housing or commercial project. Being the strongest and the most versatile material, plywood surely needs to be of high quality. The strength of the plywood is a result of individual grain layers (veneers) stacked together and bonded with glue under high pressure during the manufacturing process. This makes the plywood stronger than wood.
The use of plywood is very popular in construction, interior designs, furniture-making and even in the shipbuilding industry. The key factors which make it suitable are its moisture resistance, pests’ resistance (termites, borers, etc.), strength and durability. Also, working with plywood makes the process fast and easy.
Selecting logs and conditioning: The complete plywood-making process begins with log selection. Both hardwood and softwood are carefully identified and segregated; the main objective here is to find logs that would produce veneer with high quality physical attributes and attractive aesthetics. Once the suitable logs are selected, they are made to go through a conditioning process to assure that good quality veneer is manufactured during the peeling process. This process involves spraying the logs with water (among other properties, this is done to ensure even moisture distribution across the cross-section of wood).
Cutting and Debarking of the log: The next step is to measure the conditioned logs for cross-cutting. Once the logs have been cut to an appropriate length, the bark will then be removed using a debarking machine. The debarking process also aims to improve the cross-section roundness of the log.
Peeling and clipping of the wood: Using a lathe machine, the logs are then peeled into thin veneers. The veneers produced come in the form of continuous sheets or can be immediately clipped into a preset width and length if they are being produced for some specific order.
Drying the Veneers: The veneers produced by the peeling process are mostly wet or full of moistness, and they need to be dried off immediately. Drying is very significant for improving the bonding between the veneers. It is done by pressing them into roller dryers at a controlled speed. These dryers then produce heat using steam boilers that are ignited by barks, discarded plywood, sawdust, and other wooden waste.
Composing the Plywood: After properly drying off and trimming the veneers, they are then composed into final sheets. At this stage, they are also separated as the face, core or back plywood. The face is a surface that is to see in front. The back is the part that remains unused or hidden meanwhile, core refers to the center layer. The plywood is now checked in terms of thickness, timber grain orientation, wood species, and the quality of the ply.
Bonding using adhesives: Once the sheets are properly composed, they are then bonded with the use of glues and strong adhesives. If the plywood is a general or normal use type, then urea-formaldehyde resins are typically used. Whereas in Marine plywood, we use melamine or phenol-based adhesives. To make sure that the adhesive is evenly spread across the layers of veneer. The thickness of the final plywood product will be determined by the number of wooden sheet glued together.
Pressing of the Product: The plywoods are then pressed in a cold press at a particular temperature and a controlled hydraulic pressure. This helps the plywood with bonding, it also helps to flatten the plywood.
Quality check: After the pressing process, the plywood is ready for quality control. Samples are randomly picked and tested for mechanical strength and bonding strength. A visual check is also performed by experts.
Smoothing out the Product: Once the plywood passes quality control, it is then sanded to make sure that the plywood has a smooth surface and thickness uniform throughout the surface.
The plywood manufacturing process is quite interesting. Now that you know how plywood is made, it’s time to know about how ply damages happen and how they can be prevented.
Non-Uniform Thickness: A plywood is a bunch of wooden sheets glued together to form a thick sheet of ply. The thickness of the sheets glued together plays a significant role here. If sheets of non-uniform thickness are glued together, there’s a high probability of sheet being uneven from some part. Hence, it results in breaking of the sheet from the thinner part. Non-uniform thickness develops a fracture zone in the plywood leading to breaks in the ply.
Quantity of Veneers: Plywood needs only a particular amount of sheets to be glued together according to its use. High quantity of veneers, than needed, when glued together creates a greater probability of sheets glued unevenly in hot press. It creates uneven plywood thickness. Putting pressure on the uneven and the thinner part creates a chance of breaking the sheet from that particular point.
Tilted Pressing Plate: The plywood needs to be pressed at a proper and particular angle. If not pressed at an appropriate angle, again the tilted pressing can cause uneven plywood thickness which can cause damage to the ply.
Non-Regulated Temperatures: The temperature at which the plywood is pressed and glued is also important. Pressing the sheets at non-regulated temperatures while compression develops variations in the thickness of the plywood. Thus, hampering the quality of the ply.
We, at Chitwan Ply, are careful and cautious of these causes and the factors damaging the quality of plywood. Our highly experienced team of quality control engineers regularly monitors several such parameters to ensure that we produce best quality plywood. We understand the reasons affecting the plywood quality and take due precautionary measures to deliver the highest quality product to our happy customers.