CompositesWorld
Issue link: https://cw.epubxp.com/i/546021
AUGUST 2015 34 CompositesWorld WORK IN PROGRESS Technology for monitor- ing the molding process from within the mold cavity, a practice familiar to injection molders, is making an appearance in resin transfer molding. » In the injection molding of plastics, in-mold sensors, as part of a variety of process control packages, have been around for decades. But comparatively recently, similar technology has begun to make an incursion into composites manufacturing in resin transfer molding (RTM), one of a number of closed-molding processes that have eclipsed open molding of composites. One reason is that of all the closed molding models, RTM is most similar in format to injection molding. Te need for sensing technology is driven by customer emphasis on greater part quality and better part-to-part consistency. In response, several suppliers and at least one fabricator are developing and bringing to market new sensor technology specifcally targeted at RTM, resin infusion and other types of composites manufac- turing processes. Paul Lagonegro, application manager, Kistler Instrument Corp. (Novi, MI, US), says the processing features particular to RTM are an ideal match for the capabilities of process-control sensors. Fabricators — and their customers — are fond of RTM's ability to produce lightweight parts with short cycle times and to tight tolerances. Yet RTM usually requires the ancillary manufacture of a preform, which adds steps and requires a greater degree of automation to carry out cost-efectively. By Michael LeGault / Contributing Writer In-mold sensors: In-situ process monitoring for RTM In-mold, in-situ sensing Calloway Carbon (Santa Ana, CA, US) embeds "of the shelf" piezore- sistive pressure sensors in its polished aluminum molds. Coupled with its own proprietary software, the sensors monitor and control manufacture of structural carbon fber composite parts via RTM. Notably, part infusion will not initiate until sensors are within predefned pressure limits. Source | Calloway Carbon