Patent ID: 6824726
Filing Date: 2004-11-30
Classification: B29C,B29K

Abstract:
A method of sandwich molding comprising the steps of:(1) joining mold portions at a part line, each mold portion defining both of a mold cavity and an unheated branched runner passage free from valves, the branched runner passage having a common section and a first and second separate section, the common section and at least one of the separate sections of the runner passage extend from the cavity to the outside of the mold portion entirely along the part line; (2) placing a first and second injection nozzle against the first and second separate sections of the branched runner passage, respectively; (3) injecting a first thermoplastic material from the first injection nozzle through the first separate section of the runner passage to partially fill the mold cavity; (4) injecting a second thermoplastic material from the second injection nozzle through the second separate portion of the runner passage to expand within the first thermoplastic material so that the second thermoplastic material is substantially wholly enveloped by the first thermoplastic material, the first and second thermoplastic materials completely filling the mold cavity; (5) allowing the first and second thermoplastic material to solidify in the mold cavity and runner passage; and (6) opening the mold portions and separating a molded part formed in the mold cavity from a runner formed in the runner passage.