A process where a physical or chemical blowing agent is solved into the polymer melt, which leads to the melt foaming and expanding in the cavity.
Due to the gas expansion of the blowing agent, the injected part will have a sandwich structure with a foamed core and compact skin layers.
The gas pressure inside the part can shorten or completely substitute the holding phase of the injection process, which leads to shorter cycle times.
With this process, part properties such as lesser warpage as well as part weight reduction can be realized. With process-optimized part design, part weight reductions and material savings of up to 35% have been realized.
Chemical blowing agents are usually added to plastics as a masterbatch and decompose into blowing gases and solid by-products under heat.
For the metering and mixing of physical blowing agents, such as nitrogen or carbon dioxide, additional equipment and a special screw are required.
Injection Molding: Schematic plasticizing unit with special equipment for the introduction of physical blowing agents for foam injection molding (© Yizumi Germany GmbH)
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