CompositesWorld
Issue link: https://cw.epubxp.com/i/882089
NEWS 37 CompositesWorld.com Fraunhofer ICT molding processes. Technicians test the control system as Roch demonstrates how injection unit barrels can be swapped out in modular fashion, to accommodate different polymers and chopped fiber lengths: "We have a special screw for molding the phenolic thermoset granules." A robot eventually will be inte- grated into the machine for material and preform handling and mold loading/unloading, he says, adding that ICT has a total of six twin-screw extruders on site, as well as six injection molding machines, in support of its polymer processing research. A nearby machine is used to make parts that incorporate local continuous reinforcement — that is, continuous carbon or glass fiber rovings or tape wound around load introduction points that are subsequently encapsulated by long fiber-reinforced thermoplastic resin, a concept that Fraunhofer calls Tailored LFT. Roch shows a demonstrator automotive part with visible fiber filaments wound around metallic inserts as anchor points. "Right now, the tapes or fibers are being wound by hand, but we will soon have a robot for winding." He points out that the minimal use of continuous fibers, only in the areas of highest load, with the rest of the part made with commodity thermo- plastic, provides homogeneous stress distribution in the part and significantly higher breaking strength compared to a plastic part without the continuous fiber reinforcement. Roch next shows a work area containing a prototype consoli- dation station currently in use by a Ph.D candidate who is devel- oping a new methodology for rapidly heat-welding thermo- plastic tape blanks together. Termed radiation-induced vacuum consolidation (RVC), the method's details are currently proprie- tary, yet Roch points out that the method could meet a big need. "ermoplastic tape laying is a great technology, especially with the RELAY machine approach, but the consolidation and debulking of the material has always been a roadblock. We're hopeful that these experiments will be an enabler for cost-effi- cient tape processing." Passing through the hall, he points out a new injection molding machine for making small parts, including sample plaques for polymer testing and small plastic clips used for tagging live birds. A large Engel Austria (Schwertberg, Austria) duo 700 pico combi M injection molding machine is next, usable for standard injection molding, for direct long-fiber thermoplastic (D-LFT) molding or foam injection molding of LFT granules using the MuCell microcellular foam process from Trexel Inc. (Wilmington, MA, US). e 700-ton machine has two injection units, back to back, which enables co-molding, says Roch, and the inner mold part of a stackmold, mounted on a rotary table, can be turned 180° to allow injection from both sides. He points out that the glass fiber rovings are fed into the machine from above, and the glass fiber package creel: "With this direct LFT technology," he notes, "you become your own custom compounder, using longer fiber lengths than are avail- able from compounders, and you can save to 20 to 30% of the cost of pre-made pellets." One of the machine's injection units is used to make the long fiber-reinforced, in-mold foamed sandwich parts explained by Roch at the beginning of the tour; he points out where the foaming agent enters the barrel, either In-mold foaming for cored sandwich panels A number of ICT's injection molding machines are used to make long-fiber-rein- forced, in-mold foamed sandwich parts like that shown here, using a thermo- plastic in-mold foaming technology combined with a controlled mold-opening technique. The result is a part with a foamed core between solid faceskins, made in a single shot. Source | Fraunhofer ICT Well equipped for testing and prototyping ICT's massive Dieffenbacher 3,600-ton compression press occupies a separate laboratory building on the ICT campus, and was formerly paired with a process machine that fed semi-finished SMC material. That SMC line has since been removed and replaced with a RELAY machine and injection molding barrel (see photo, p. 38). Source | Fraunhofer ICT