Investigation on bubble morphological evolution and plastic part surface quality of microcellular injection molding process based on a multiphase-solid coupled heat transfer model. (January 2017)

• Record Type: Journal Article
• Authors: Zhang, Lei; Zhao, Guoqun; Wang, Guilong; Dong, Guiwei; Wu, Hao
• Is Part Of: International journal of heat and mass transfer. Volume 104(2017:Jan.)
• Page Start: 1246
• Page End: 1258
• Publication Date: 2017-01
• Subjects: Microcellular injection molding -- Multiphase -- Coupled heat transfer -- Bubble morphological evolution; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.09.043
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A model combining with multiphase flow (unlimited number of fluids) and implicit domain coupling algorithm is established. The bubble morphological evaluation in the flow field of RHCM/MIM process is first researched by a numerical simulation method. The phenomena of bubble bursting delay in the RHCM/MIM process are revealed, theoretically. The morphology of dendritic welding marks, pocks and pits on the surface of RHCM/MIM part is first observed. Abstract: The surface of plastic parts molded by Microcellular Injection Molding (MIM) process usually has silver marks, spiral lines, pits and other defects. Rapid Heat Cycle Molding (RHCM) technology has become an efficient technology to eliminate these defects by controlling the heat and mass transfer in the MIM mold. However, the influence of heat transfer on the evolution of multiphase composite (polymer, supercritical fluid, air) in the mold cavity is still not clarified. To understand it, a new non-isothermal transient multiphase model based on finite volume method was established, and the Implicit Domain Coupling Algorithm (IDCA) was used to synchronously calculate the temperature field of mold and cavity regions. A compound experiment of RHCM and MIM (RHCM/MIM) with mold temperature control realized by electrical heating and water cooling was performed. Based on the simulation and experiment results, the transient flow behavior of foam composite in mold cavity was analyzed. The effect of mold temperature on the deformation, bursting and collapsing process of bubbles in fountain flow field was revealed. The phenomena of bubble bursting delay in filling stage of RHCM/MIM process were discovered, and the formation mechanism of the surface defects of RHCM/MIM plastic part was also revealed.