A plywood consists of three parts: substrate, veneer, and edge banding.
But most people usually only care about the type of substrate and decorative technology, and few pay attention to the edge banding of plywood. It is also very important.
The role of edge banding
- Beautiful. The connection between the good edge banding strip and the finish is smooth, without any residue of offset printing. After installation, the overall appearance is good.
2. Moisture proof. If the environmental protection level of plywood is relatively high, the main function of edge banding is to prevent moisture. Nowadays, the mainstream on the market is particle board. If the edge banding is not done well, in a humid environment for a long time, plywood is prone to peeling, bulging, and even irreversible deformation such as bending.
3. Good door-opening experience. A cabinet without a handle design, if you want to open the door, you need to manually move it from the edge of the door. A good door panel has smooth edge banding and cutting, smooth transition, and no feeling of clutching hands, providing a good experience.
There are three types of edge banding processes: EVA edge banding, PUR edge banding, and laser edge banding.
EVA is an abbreviation for ethylene vinyl acetate copolymer material and a type of hot melt adhesive. The process of EVA edge banding is to apply high-temperature liquefied EVA material on the side of the plywood, and then press the edge banding strip onto the plywood through a pressure wheel mechanism. After EVA cools and solidifies, the two produce strong adhesion, and the entire process is a physical reaction.
PUR is the abbreviation for polyurethane reactive hot melt adhesive and also a type of hot melt adhesive. The edge banding process, like EVA, is also to apply high-temperature liquefied PUR material on plywood and then bond with edge banding strips. The difference is that PUR is a reactive adhesive, which contains isocyanate groups (- NCO) that continue to undergo chemical crosslinking reactions with water molecules in the environment or substrate, forming wet curing. The entire process is a chemical reaction and irreversible.
Laser edge banding distinguishes between the two hot melt adhesive edge banding technologies mentioned above, without the need for additional glue application. The edge banding strip comes with a coating, which quickly melts the functional layer of the edge banding strip through high-energy lasers. Then, the edge banding strip is pressed onto the workpiece through a pressure wheel mechanism. The curing process may be a physical or chemical reaction, depending on the material of the coating.
Discrimination method
Due to the differences in the three processes, the differences between the three are still quite obvious.
1： What you’re looking at is the glue thread
Both EVA and PUR need to be glued together, and both edge banding processes have adhesive lines. The most obvious one is EVA, as it has the highest amount of adhesive and the most obvious adhesive layer. The thinner one is PUR, while laser edge banding almost cannot see the adhesive lines, and the transition is very smooth.
2： Check if the edge of the edge seal is smooth.
This is to test the quality of edge cutting and decoration, as hot melt adhesive edge banding involves applying glue, and there must be glue overflow during the pressing process. It is necessary to remove the glue in the later stage, cut excess edge strips, and then chamfer them to make them smoother. Although laser edge banding does not require removing glue, it also requires cutting chamfers.
3： Can the edge banding be easily removed after heating.
If the plywood processing factory pays great attention to the cutting and decoration of edge banding, even EVA edge banding can achieve a good edge banding effect.
So if it cannot be distinguished from the appearance, the characteristics of the edge can be used to distinguish it. EVA is a physically cured adhesive, while PUR is a reactive adhesive. By heating with a hot air gun, the edge of EVA can be easily torn off, while PUR is not.