Polymer Processing ■Injection Molding(注射成型 ■ Compression Molding(压塑成型) ■Transfer Molding(传递模塑法) o b Blow Molding(吹塑成型) ■ Extrusion(挤压) Thermoforming(热力塑型) Casting(铸造) ■Rotational Molding(转动成型) Shanghai Jiao Tong University 6
Shanghai Jiao Tong University 6 Polymer Processing n Injection Molding(注射成型） n Compression Molding（压塑成型） n Transfer Molding（传递模塑法） n Blow Molding （吹塑成型） n Extrusion（挤压） n Thermoforming（热力塑型） n Casting（铸造） n Rotational Molding（转动成型）
Injection Molding In the injection molding process,thermoplastic polymer granules are fed via a hopper into a heated barrel.A screw or ram forces the molten polymer into a mold cavity.Pressure is maintained until the part has hardened and then the part is ejected out of the mold. Cavities Hopper to Part feed polymer pellets Screw and ram w 日 Hydraulic Heaters for cylinder for melting mold clamp and opening Stationary half of mold Movable half of mold Shanghai Jiao Tong University 7
Shanghai Jiao Tong University 7 Injection Molding In the injection molding process, thermoplastic polymer granules are fed via a hopper into a heated barrel. A screw or ram forces the molten polymer into a mold cavity. Pressure is maintained until the part has hardened and then the part is ejected out of the mold
Injection Molding Injection Molding-products 城钱听 Pulley with Aluminum insert Water pump housing Valve cover Intake Manifold Shanghai Jiao Tong University 8
Shanghai Jiao Tong University 8 Injection Molding n Injection Molding-products
Injection Molding -Analysis Thermoplastics shrink during solidification. Cavity must be larger than part size. DC=Dp+DpS+DpS2 Dc:dimension of cavity [mm] Ds:dimension of part [mm] S:shrinkage value [mm/mm] DpS accounts for shrinkage Shanghai Jiao Tong University 9
Shanghai Jiao Tong University 9 Injection Molding - Analysis Thermoplastics shrink during solidification. Cavity must be larger than part size. Dc=Dp+DpS+DpS 2 Dc: dimension of cavity [mm] Ds: dimension of part [mm] S: shrinkage value [mm/mm] DpS 2 : accounts for shrinkage
Injection Molding Shrinkage of typical thermoplastics Plastic Shrinkage,mm/mm (in./in.) ABS 0.006 Nylon-6.6 0.020 Polycarbonate 0.007 Polyethylene 0.025 Polystyrene 0.004 PVC 0.005 Shanghai Jiao Tong University 10
Shanghai Jiao Tong University 10 Injection Molding n Shrinkage of typical thermoplastics