What distinguishes the hot pressing method from the cold pressing method of wood board glue pressing process and how do the wood boards differ as a result of these methods?
Woodworking slabs usually have five layers, with glue on the second and fourth layers, and a three-layer framework attached to the core board.
Hot Pressing And Cold Pressing Of Wood Board
Plywood
Particleboard
MDF
Hot pressing and cold pressing are two popular techniques employed in the woodworking sector to adhere wood boards together and form composite wood products like plywood, particleboard, and MDF. Below is a comparison between hot pressing and cold pressing in the manufacturing procedure:
Wood Board Hot-pressed:
High production efficiency and excellent product gluing quality are the benefits. The hot pressing technique is primarily utilized in the production of wooden panels domestically and internationally.
For example, the pressure used in the production of bakelite board with urea-formaldehyde resin ranges from 0.6 to 1.2 MPa, the temperature during hot pressing is between 100 and 120 degrees Celsius, and the thickness and structure of the slab dictate how long the hot pressing process takes. The study found that the hot pressing time for the covering material part of the single plate in the slab is 50 to 60 seconds for every 1 mm of plate thickness, and the core plate requires 1 minute for every 6 mm of plate thickness. The plate thickness is generally 19 mm, and the time is 7 to 11 minutes.
During the production of phenolic resin bakelite boards, a higher hot pressing temperature and unit pressure are utilized compared to urea-formaldehyde resin glue. A duration of 11 minutes. Using various adhesives results in varying levels of formaldehyde emissions, indicating different environmental impacts.
Reducing the temperature of hot pressing eliminates the internal stress within the slab, enhances the flatness of the sheet, lowers pressure, lowers the rate of slab compression, limits deformation of the sheet following hot pressing, and lessens warpage and irregularities on the sheet surface. The drying phase is necessary to get the moisture level of the wood down to the required level. Typically, the wick's moisture content ranges from 8% to 12%, with northern air drying at 6% to 12%, and the southern air humidity is high, not exceeding 15%.
Process Of Cold Pressing Wood Board:
Low internal stress, little deformation, and less wood compression loss are advantages of the finished product; the long production cycle is a disadvantage.
When wood is cold-pressed and bonded together, the pliability of the wood and the flow of the adhesive are limited, necessitating a slightly increased unit pressure. For cold-pressing with urea-formaldehyde resin, the pressure per unit is 1.2 MPa, and the bonding period lasts for 6-8 hours. The slabs are pressed cold in layers, with a backing plate required at specific intervals to ensure even pressure and a flat slab surface.
Hot pressing and cold pressing are two distinct techniques utilized in the woodworking sector to join wooden boards and form composite wood products. Hot pressing utilizes heat and pressure to activate adhesive and form a fast, strong bond, whereas cold pressing solely relies on pressure to bond wood layers together gradually. Every method comes with its own benefits and is selected depending on the particular needs of the wooden item being produced.
