A new process of gas-assisted injection molding for faster cooling

摘要

Gas-assisted injection molding (GAIM) process, that can be used to provide a hollow shape in a molding, is a variant of the conventional injection molding process. GAIM has many advantages such as reduction of material, sink mark, warpage, and lower injection pressure. Thus, GAIM has been widely applied in the industry to make moldings with a hollow channel such as handles, TV frames and so on. On the other hand, GAIM has some disadvantages such as slow cooling time and flow marks. In the disadvantages, hot gas core causes slow cooling of a molding and post-warpage. To solve these problems, we devised a new GAIM process that has been called the reverse gas injection molding (RGIM). The RGIM has two special units; one is the overflow buffer, which is used for reduction of a material, and the other the air unit, which is used for faster cooling of a molding. Through experiments verifying the efficiency of the cooling in the RGIM process, it was found that the efficiency of the RGIM process was approximately 50% better than the conventional GAIM process. Also, this experimental result was confirmed in the numerical calculations and CAE simulations.