K 2013: UV-curable LSR allows new overmolding combinations
By Karen Laird | August 13, 2013
Momentive Performance Materials GmbH is showcasing a totally new approach to hard-soft combinations at this year’s K international trade fair. The company is presenting its newly developed UV-curing LSR, producing an injection-molded multi-component design object in a fully automated process in cooperation with Engel (Hall 15, stands B42, C58) injection molding machines, using a mold supplied by the Austrian liquid injection molding specialist Elmet (Hall 12, E49-7).
Traditionally, multi-component designs utilizing silicone rubbers were limited to the combination of heat stable resins such as PA or PBT due to the molding temperatures that were required to vulcanize the silicone. Now, as the company is demonstrating at its stand (Hall 8, G45), UV LSR can be combined with more affordable, lower melting point resins, such as PP or PMMA, to produce multi-material molded products with hard-soft characteristics. Engel and Elmet previewd the technology at Plastec West 2013, produced by PlasticsToday’s parent company, UBM Canon.
Specialized pumping, feeding equipment for specialized LSR
Mounted on a standard Engel e-mac 170/50 equipped with a viper 6 robot, the Elmet mold is designed to cure the LSR by UV light transmission through the pre-molded PP part, enabling the cold curing process in short cycle time. Another innovation is Elmet’s newly developed, dedicated pumping and feeding equipment optimized for UV-curing LSR.
MPM’s UV-curing LSR offers ‘significant potential processing and manufacturing benefits’ says the company, including reduced cycle times, especially for articles with high wall thickness like cable accessories or high voltage insulators and improved sustainability, as the process requires lower temperatures and hence less energy than traditional silicone processing. Moreover, MPM points out that, significant cost saving are achievable, not only because more affordable resins can be opted for, but also because less floor space is utilized for equipment and operation costs can be reduced
Until MPM introduced UV-curing silicone rubbers, heat had always been a limiting factor for designers and manufacturers when selecting material for substrates and inserts to combine with silicone.
This new technology will allow designers to combine silicones with temperature-sensitive electronics or incorporate temperature-sensitive ingredients into the silicone that normally would not resist conventional molding temperatures.