How to deal with moisture in the substrate?

Using Netega two-component plywood: How to deal with moisture in the substrate? How much adhesive is applied? How to keep healthy?

Substrate and glue preparation:

Wood moisture treatment: moisture content 8-12%. The moisture content error of adjacent wood on the same panel shall not be greater than +/- 1%, and the deviation of moisture content of wood on the same panel shall not be greater than +/- 2%. Usually the production of furniture for export to North America, wood moisture content control in the range of 8-10% is more appropriate.

Reason: The particularity of wood (anisotropy) the contraction/expansion rate in different directions is different, and the stress generated is different.

Wood surface treatment: wood gluing surface should be smooth, smooth, no oil, no bending; Two adjacent sides of wood at right angles; The processing error of wood gluing surface is not more than 0.5mm; Keep wood veneer fresh.

Reason: active groups on wood surface; Oil/resin seeping from inside the wood; Wood under the action of external stress, pressure uniformity.

Mixing of glue and curing agent: the mixing ratio of glue and curing agent is 100:15 (weight ratio). Any change in the ratio of glue and curing agent will affect the bonding effect. Please keep in touch with the glue supplier. The glue and curing agent must be fully mixed. Usually electric stirring 1/2 minutes, manual stirring 2 minutes, the mixed adhesive should be used within its active period. The active period of the glue is usually 45-60 minutes (when the working ambient temperature is 25 ºC and the relative humidity is 50-65%). When the operating ambient temperature is higher than 35ºC and the relative humidity is low, the activity period of the glue will be greatly shortened.

Reason: the amount of curing agent should ensure sufficient and uniform crosslinking; Glue should not cure before use.

Glue coating amount: The glue coating of the wood gluing surface should be uniform, and the glue coating amount is usually 160-200 grams/square meter. Usually, when the glue extruded from the glue seam is continuous small beads under the right pressure, the coating amount is appropriate. The glue coating method is usually manual coating and machine roll coating. According to different climatic conditions, adjust the amount of glue coating, when the temperature is high and the air humidity is low, the amount of coating should be appropriately increased.

The aging time of the glued surface (usually refers to the time between the gluing of the wood and the completion of the pressure) : usually not more than 10 minutes. Wood with strong water absorption (usually softwood) should be aged as quickly as possible, generally 4-6 minutes; Wood with weak water absorption (such as hardwood, oily wood) should have its aging time extended accordingly, generally 6-10 minutes; When the operating ambient temperature is higher than 35ºC and the relative humidity is low, the aging time should be shortened accordingly.

Reasons: volatilization of water, absorption of wood; The spread of glue, the penetration of wood. The glued surface should be maintained with sufficient pressure and sufficient time, and the pressure should be maintained evenly, the fixture should be 8-11 inches apart, no more than 2-3 inches from the edge of the plate, and the recommended board width should not exceed 3 inches.

Pressure: Cork 5-8 kg/cm2; Hardwood 8-12 kg/cm2.

Time: 45 minutes, when the ambient temperature is greater than 30ºC; 60 minutes, the working environment temperature is 25-30ºC; 90 minutes, the operating temperature is 15-25ºC; 150 minutes when the ambient temperature is 10-15ºC.

Reasons: the penetration of the glue to the wood, the stress of the wood, full contact; The curing degree of glue, high-density wood needs longer pressure time, and wood with ring holes needs longer pressure time. The wood glue with low moisture content curing speed is faster, the high humidity environment needs a longer pressure time, the low temperature conditions need a longer pressure time, the opening and closing time of the glue needs a longer pressure, the extruded glue should be uniform small particles along the edge of the plate, and the narrow wood strip should be placed in the middle of the plate to achieve uniform pressure.

Health: In most cases, the health time after pressure relief should not be less than 24 hours; If the temperature of the working environment is high and the air humidity is low, and the assembly is processed in the drying room, the health time can be shortened accordingly.

Cause: insufficient health may cause defects, interface height difference; Glue seam sinking (obvious glue line); Lack of strength to resist the influence of external forces, end cracking, the glued sheet should be placed at least 24 hours before surface treatment, smooth surface, need to be placed longer, hot pressing and high frequency bonding sheet can be faster for the next step of processing.