Читать книгу Plastics Process Analysis, Instrumentation, and Control - Группа авторов - Страница 28

Injection molding is a well-established replication process for the cost-effective manufacture of polymer-based components (37). The process has different applications in the medical, automotive and aerospace fields among others. To expand the use of polymers to meet growing consumer demand for increased functionality, advanced injection molding processes have been developed that modify the polymer to create microcellular structures.

Using the creation of microcellular materials, additional functionality can be gained through polymer component weight and processing energy reduction. Microcellular injection molding shows a high potential for creating green manufacturing platforms (37).

The process conditions as well as nano/micro-fillers such as nanoclay and core-shell rubber have a strong influence on cell density and cell size, hence, the final material properties of the molded parts (38). The addition of nano/micro-fillers at optimum loading levels can generally facilitate the formation of microcellular plastics with higher cell density and smaller cell size, leading to superior mechanical properties.

The integration of a solid plastic surface with a microcellular plastic core via the co-injection molding technique has been investigated to achieve Class A surfaces and improved material performance. An improved mathematical model has been developed to simulate the cell growth behavior in the microcellular injection molding process (38).

The significant developments that have been achieved in different aspects of microcellular injection molding have been reviewed (37). The aspects covered include core-back, gas counter pressure, variable thermal tool molding and other advanced technologies. Also, the resulting characteristics of creating microcellular injection molding components through both plasticizing and nucleating agents were presented. In addition, the review highlights the potential areas for research exploitation, in particular, acoustic and thermal applications, nanocellular injection molding of parts and developments relating to more accurate simulations (37).