Lightweight parts, energy-saving processing or combining several process steps into one. It can all be summarized under one buzzword: sustainability. A technology that is highly promising is thermoplastic foam injection molding. Although in use for decades, the process offers great potential thanks to continuous development. The Institute of Polymer Injection Molding and Process Automation (IPIM) at the Johannes Kepler University (JKU) in Linz, Austria, is joining forces with ENGEL AUSTRIA and the Competence Center CHASE in Linz to leverage this potential.
Thermoplastic foam injection molding (TFIM) offered by ENGEL AUSTRIA under the name foammelt, is one of the oldest special injection molding processes. The commercialization, principally of chemical TFIM processes at first, began in the 1950s. Small amounts of baking powder were added to the melt to avoid sink marks in the part . Chemical blowing agents grew in importance and led to the first series production of foamed parts in the 1970s .
The use of supercritical fluids (mainly nitrogen and carbon dioxide) in physical TFIM process-es, such as MuCell by Trexel today permits the manufacturer of microcellular foams with pore diameters below 100 µm or cell densities of over 109 cells/cm3. This special morphology offers advantages particularly for impact applications since the fine cells act as crack arrestors . Although the foaming of polyolefins during injection molding has undergone many years of development, many questions remain open. Current developments are aimed at finding alter-natives to gas introduction, investigating the conditions in the plasticizing unit, as well as the deployment of Industry 4.0 technologies.