高分子材料加工技术专业英语 Molding Processes 17 Foaming.pptVIP

Foaming MFG 355 Foaming Overview Processes to create foams Mechanical, Chemical, Physical, Syntactic (hollow spheres) Processes to shape and solidify foams Molding, RIM, Foam-in-place, Extrusion, Casting, Expanded foam molding Rebond materials Foam product characteristics Foaming Mechanical foaming Mix air into the resin while in a liquid state Plastisols, vinyl esters, urea formaldehydes, phenolics, polyesters Foaming Mechanical foaming Mix air into the resin while in a liquid state Plastisols, vinyl esters, urea formaldehydes, phenolics, polyesters Foaming Chemical foaming Foaming agents or blowing agents Chemical reaction that forms a gas/vapor Foaming Physical foaming Gas is forced into a liquid or molten resin Pressure is released quickly Foam is created Foaming Syntactic foams Physically mix in hollow beads Beads are usually glass or plastic Wide density capability Foams Self-healing plastics Beads filled with reactive resin Initiator (catalyst) mixed into the surrounding plastic Beads crack under pressure of crack growth Self-healing foams Processes to Shape and Solidify Foams Molding RIM Foam-in-place Extrusion Casting Expanded foam molding (EPS) Rebond Foam Molding Foam Molding Molded foams Reaction Injection Molding RIM Foam-in-place Extrusion Foaming Extrusion foam line Casting Foams Casting Foams Skiving the Foamed Bun Foam Spraying Foaming agents mixed as they exit the spray nozzle Expanded Foam Molding PS is the standard material used Can be done with PP or PE as well Expanded Foam Molding EPS beads EPS Rebond Scrap from other foaming processes Ground/chopped up Molded into sheets Material Considerations for Foamed Parts Most thermoplastic and thermoset materials can foamed by one or more of the methods The most commonly foamed resins are PVC, Polyurethane, PS, PE, PP, Epoxy Phenolic, ABS, Ureaformaldehyde, Silicone, Ionomers and Cellulose Acetates Foam Applications Strength to weight ratios Thermal insulation (Celestia product) Energy absorpt