The process of making plywood many variations, but in principle use the sequence and procedures are relatively similar. The sequence of plywood manufacture according Massijaya (2006) is as follows:
o Selection log
Logs will be used as raw material for plywood is selected from the size, shape, and condition of the defects are still allowed.
o Pretreatment on log
Early treatment is intended to facilitate the stripping process, especially for wood logs that have a high density. Some initial treatment in the logs which are warming the log (with hot water, steam, high pressure steam, electricity, forcing the water / steam entrance from the longitudinal direction). Haygreen and Bowyer (1993) and Tsoumis (1991) suggested some benefit from warming logs include increased yield of 3-5%, improving the quality of veneer (thickness more uniform, more delicate surfaces, cracks due to stripping may be reduced), reduction of processing costs , a reduction in the amount of adhesive consumption, reducing the difference in moisture content sapwood and wooden terrace, improve the color of wood, kills fungi and wood destroying insects.
Tsoumis (1991) suggests that there are three methods of stripping the veneer namely (1) Rotary cutting / pelling, (2) Slicing / slice, (3) Sawing. Pelling process of continuous manufacture of veneer sheets, while sheets of veneer slicing produce disconnected. Pelling mostly used in the manufacture of plywood ordinary type while slicing to fancy plywood. Veneer produced by rotary cutting process generates two sides of the outer side (tight side) and the inside (loose side).
Loose side part is a part that there are cracks due to stripping known denganleathe check.
This activity is conducted to select veneers after stripping process, veneer separated between damaged and that no veneer for face and core sections.
This activity is carried out with the aim of reducing the moisture content of veneer so as to avoid a blister on plywood after heat compression. Tsoumis (1991) suggested that the temperature in the drying veneer around 60-80C depending on the type of wood, moisture content initially, the thickness of the veneer.
Application of adhesive in plywood resurfacing can be done by roller coater, curtain coater, spry coater, or liquidand foam extruder (Youngquist, 1999). Adhesives which can be used in the manufacture of plywood, among others Phenol Formaldehyde (PF), Urea Formadehyde (UF), Melamine Urea Formaldehyde (MUF), Polyurethan and Isocyanat (Vick, 1999), Tsoumis (1999) suggested that the weight labur (the amount of adhesive that is prepared per unit surface area of veneer) between 100-500 g / m depending on several factors such as the type of wood, type of adhesive and the way pelabu ran.
According Tsoumis (1999) pengempaan grouped into 2 (two), namely hot press (hot press) dancold press (cold pressed). Most plywood dipruduksi using a hot press. The amount of pressure ranges between 100-250 psi depending on the density of the wood. For low density wood species (100-150 psi) .For medium density wood species (150-200) as well as for high-density wood (200-250 psi).
The amount of compression temperature depends on the type of adhesive used. UF (120C) and PF (150C). Cold pressed done when the adhesive glue used is natural or synthetic adhesive that hardens at room temperature. The amount of pressure on the cold compression berkisarantara 150-350 psi depending on the density of the wood. The use of cold compression (mechanical pressure or clamp) is difficult to obtain uniformity in the thickness of the plywood is made.