Problems that are caused by multi-layer plate hot presses when hot pressing plywood

- Sep 04, 2019-

Hot pressed plywood is an important process for the production of plywood and also determines the quality of the plywood. However, when using the multi-layer hot press to hot-press the plywood, some problems will inevitably occur, which will inevitably affect the quality of the plywood. So today, Jianye Machinery and the majority of manufacturers discuss the use of multi-layer hot presses. Some problems and solutions will be encountered.

    First, low bonding strength or degumming

       Causes: 1. The quality of the glue is poor; 2. The amount of glue is insufficient or the glue is not uniform; 3. The aging time is too long, the glue is dry or the aging time is too short, and the glue does not form a continuous film; 4 Insufficient pressure, or too low temperature, or hot pressing time is too short; 5, the burr groove of the veneer is too deep, the quality of the rotary cutting is poor; 6, the moisture content of the veneer is too high;

       Solution: 1. Check the quality of the glue; 2. Pay attention to the moderate and uniform amount of glue; 3. Control the aging time; 4. Increase the pressure temperature or extend the hot pressing time; 5. Improve the veneer rotation. Quality; 6, control the moisture content of the veneer does not exceed the specified range;

   Second, the plywood thickness is different or exceeds the allowable tolerance range

      Causes: 1. The number of hot pressing sheets in each interval is too large; 2. The thickness of the veneer is different; 3. The inclination of the platen or the inclination of the plunger; 4. The calculation of the thickness of the plywood plate is not correct or the pressure in the hot pressing process is too large. ,Temperature is too high;

     Solution: 1. Use a one-press hot pressing process as much as possible; 2. Improve the quality of the veneer; 3. Fix the multi-layer plate hot press installation to the level; 4. Adjust the plate embryo with the thickness, adjust the pressure and temperature. ;

     Third, bubbling and partial degumming;

     Causes: 1. The moisture content of the veneer is too high or the drying is uneven; 2. The amount of glue applied is too large; 3. The depressurization speed is too fast or the hot pressing temperature is too high; 4. The degree of resin condensation is not enough; 5. The hot pressing time insufficient;

     Solution: 1. Control the moisture content of the veneer in the range of 8-12%; 2. Control the amount of glue to meet the process requirements; 3. The speed of the second stage of depressurization should be slow, and the hot pressing temperature should be appropriately reduced; Check the resin quality; 5. Prolong the hot pressing time;