Bonding with a thermo setting adhesive (Fig. 12A.3). it is desired to bond together two sheets of a solid material, each of thickness 0.77 cm. This is done by using a thin layer of thermosetting material, which fuses and forms a good bond at 160°C. The two plates are inserted in a press, with both platens of the press maintained at a constant temperature of 220°C. How long will the sheets have to be held in the press, if they are initially at 20°C? The solid sheets have a thermal diffusivity of 4.2 x 10^-3 cm²/s. 

Thermosetting adhesive Upper platen (heated) 2b Lower platen (heated)