On the Potential of Manufacturing Multi-Material Components with Micro/Nanocellular Structures via the Hybrid Process of Electromagnetic Forming Injection Foaming

Multi-material design with a combination of solid and foam structures offers a promising avenue for reducing component weight while enhancing their functionalities. However, the complexity of multi-stage manufacturing processes poses significant challenges to adopting such approaches. To address these challenges, this paper introduces an innovative concept known as Electromagnetic Forming Injection Foaming (EFIF), which integrates injection molding, forming, and foaming processes into a single hybrid process. This process begins with a simultaneous filling-forming phase, followed by supercritical fluid (SCF) assisted foaming controlled by electromagnetic forming. Through a series of experimental and analytical studies, this work investigates the feasibility and effectiveness of EFIF. First, the impact of pressure drop rate and pressure drop on cell size and density is examined through a specialized experimental setup enabling performing injection, forming, and foaming processes in a single operation. The potential influence of electromagnetic forming on foam injection molding is explored through experiments focusing on the effects of a polymer layer between sheet metal blank and the electromagnetic coils. Additionally, an analytical study evaluates the EFIF process by calculating expected pressure drop rates under different processing conditions and their influence on cell nucleation rates. The results showed the possibility of achieving pressure drop rates up to 1.5×105 bar/sec, resulting in nucleation rates up to 1.77×109 nuclei/cm3sec. Overall, this paper highlights the potential of EFIF to merge existing technologies into a scalable solution for manufacturing multi-material components with micro- to nanocellular polymer foams.