The first step in making plastic mold is to extrude plastic sheet material, which is to make continuous plastic sheet material through the "plastic sheet material production line". Its general form is: equipment - crystallization and dry mixing system - a single or multiple extrusion machine - net changer - - T melt pump head - three-roll calender device - cutting edge device - traction device - the loading device - curl winding device. The thickness of the plastic sheet is 0.25mm- 2. Between 5mm, the width is about 300mm-1400mm. Thermo - forming, thermo - forming is the production process of plastic cup made from plastic sheet. Hot forming is a special process in plastic processing. It is characterized by heating the sheet material to a high elastic state, and then sticking the sheet material to the surface of the mould through compressed air pressure and die pre-stretching device, cooling, shaping and cutting. Because of the molding die usually need air pressure is positive pressure (0.4-0.8 MP), so this kind of cup process known as positive pressure hot forming, in the positive pressure moulding mold used in the production process is called "positive pressure plastic thermoforming mould".