Peripheral System for Novel Foaming Technique
High Foaming Pressure during Injection Molding without Machine Upgrade
Kunststoff-Institut Lüdenscheid, Germany, and Linde AG, Munich, Germany, developed a new process of physical foaming. The process combines the easy handling of chemical foaming processes to the high foaming pressure applied with physical foaming. ProTec Polymer Processing GmbH is currently developing a peripheral system that will allow for easy integration of the physical foaming process into existing injection molding plants.
Within the new process, the dried pellets are first loaded with CO2 in a pressure vessel, and then fed to the injection molding machine. External CO2 loading has been tested before on various types of plastics, showing that they remain reproducibly foamable over several hours. Pellet preparation and feeding is done completely automatically, applying the peripheral solution by ProTec, consisting of dryer, autoclave and conveying unit. While this unit is able to feed a number of machines at the same time, manufacturing is efficient with small, as well as large charges. The integrated unit is operated via a network-compatible PLC controller.
Applying the process of foam injection molding, users will benefit from various advantages in terms of process technology. Thanks to lower viscosities and, thus, to improved flow properties, lower pressures are required for mold filling. Even with thin walls, good foaming results can be achieved, along with considerable material savings incurred. It may be sufficient to use an injection molding machine with a lower clamping force or a less rigid mold, while the process remains the same as before. At the same time, dimensional stability is enhanced, as compared to conventional injection molding, thanks to the fact that foaming reduces anisotropic material shrinkage.
In case high surface qualities are required, a gas-counter pressure process can be applied, for example.
Lightweight Solution for Numerous Branches
The new foaming solution may be especially suitable for automotive manufacturers, who wish to reduce consumption of resources and emissions by applying lightweight components, or for those who aim at stepping up the ranges of electric vehicles. In addition to weight saving, they benefit from improved thermal insulation and noise reduction as a result of the parts’ cellular structure.
The new technique is suitable for other branches, too, that wish to reduce their material consumption, such as electrical, electronics, and furniture industry, or for producers of household appliances and leisure goods. Test series have shown that part weights can be reduced by up to 60 %.