... in feeding sysytem, then go into No.1 Extruder---Inject foaming agent--After filter changer, material go into N0.2 Extruder-- ... the filter immediately without stopping the machine. 3. The foaming shaping machine adopts PLC control, touch screen operation, easily ... extruding process, foam agent (such as butane gas or LPG) is injected at high pressure. 6. After extruding, foaming, cooling, shaping ...