Plywood QC Inspection Checklist : Part 9 Hot pressing temperature
Hot pressing temperature is determined according to the performance of plywood, type of glue, and production efficiency of hot press. During hot pressing, the thermal energy has enhanced the plasticity of the fiber and created conditions for the integration of different bonds. The thermal energy will cause the moisture in raw veneer plywood to vaporize. Temporary heating will expedite the solidification of hot set resin for decreased friction and increased fluidity. The hot pressing temperature usually refers to the temperature of hot pressing plates, but what plays function in actual use is the temperature inside the raw plywood.
Thickness losses in plywood panels during hotpressing are well known but recent trends toward gluing at higher veneer moisture content (MC) and press temperature result in losses much greater than previously expected. These losses can be minimized by reducingpressure at press closure or during the press cycle.Panels wetted immediately after hot-pressing recovered 1percent of thickness, regardless of veneer and pressing conditions.
Prepressing significantly affected panel thickness .