Paper tray product will be deformed during the drying process, then use the hot press machine to create high temperature 150°～25 0° and high pressure 3T-50T to restore the designed shape.  As the hot press die is vertically stressed, the plane structure is strong, the paper tray surface is smooth, inclined surface is slightly rough, then according to the product requirement design, small inclined areas will form more ribs and plane, more spherical arcs will be difficult to form smooth surface.