Two-component Injection Molding of Polymers: Simulation and Experiment
Avraam Isayev, Chengtao Li, Dongjae Lee, Russ Warley
The University of Akron
USA

Keywords: co-injection molding, transfer molding, plastics, rubbers

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Two-component molding process is a technology for manufacturing products with skin/core polymer structure used in automotive, aerospace, and household applications. Typically, in this processing, two different polymers are injected or transferred into a mold sequentially and/or simultaneously. For the performance characteristics and quality of molded products, it is very important to avoid a breakthrough and to obtain a uniform encapsulated structure. Presently, only a few papers have been published on the subject matter and science-based technology for optimized process setup is not available. In an attempt to solve this problem, a process model and simulation were developed based on the Hele-Shaw approximation along with interface treatment. Two-dimensional simulations and experimental studies of the flow-rate controlled simultaneous co-injection molding of thermoplastics into a center-gated disk cavity were carried out. The effects of rheological properties and processing conditions on the material distribution, penetration behavior and breakthrough phenomena were investigated. In addition, simulation and experimental studies of the pressure-controlled sequential sandwich transfer molding of two rubber compounds under isothermal conditions were conducted. The penetration and encapsulation behaviors, and the interface development were significantly affected by the rheological properties of both components and the processing conditions. These experimental findings were in good agreement with the present predictions.