CompositesWorld
Issue link: https://cw.epubxp.com/i/632301
FEBRUARY 2016 48 CompositesWorld PLANT TOUR efcient tooling utilization and an overall reduction in energy use. IRIS is the subject of two separate patents for Spirit. A large composite, upper wing cover demonstrator has been made at Prestwick (see Fig. 2, above). Watson was able to show CW representative sections of this cover, and what stood out boldly was the overall fnished quality of the part. In particular, the stif- ening ribs and associated features were very accurately placed, consistently within aerospace geometric standards over the entire part area. Watson also showed a typical photomicrograph of a sectioned spar fange corner (see Fig. 3). Te quality of the feature is clear, and fber wrinkles and other defects that are commonly seen in similar prepreg parts are absent. Clearly, if such quality can be consistently demonstrated in full production, Spirit has taken a big step forward with the IRIS process and its smart approach to tooling. another important feature of IRIS is that cure is not controlled by the direct measurement of temperature by thermocouples, as is the aerospace norm. Instead, strategically placed calorimeters are distributed across the tool surface, located at higher density in critical areas of the part geometry. IRIS, therefore, ensures a more uniform and efcient cure across the entire part. Te IRIS process represents a considerable deviation from the norm in aerospace composites manufacture. Te cure cycle is usually rigidly controlled, with long, slow ramp-up and cool-down rates, based on the lowest temperature, slowest thermocouple. Tis means that thicker areas of the part are adequately cured, and that thin, large areas of parts are cured more than is necessary. IRIS, however, enables zoned tool heating, to put the heat exactly where it's needed. Tese features of IRIS have enabled Spirit to accrue signifcant cost savings in terms of turnaround time, more Preforming for structural complexity This preforming station at Spirit's Prestwick facility features multi-zone infrared heating, which ensures temperature uniformity for thermoforming of geometri- cally complex composite preforms. FIG. 1 Controlled and monitored infusion An important feature of Spirit's proprietary vacuum resin infusion process, which is called the Intelligent Resin Infusion System (IRIS), is shown in this laminate stackup — a resin fow media (white mesh layer) that helps distribute the matrix resin. IRIS also monitors cure progress by means of calorimeters and zoned heating, which helps speed cycle time. FIG. 2 Complex structures in one shot This composite wing cover demonstrator, with fully integrated stifeners, is manufactured in a single cure cycle, using IRIS. FIG. 3 Reducing wrongs at radii This representative sectioned and polished spar fange corner shows that Spirit AeroSystems' IRIS delivers excellent ply linearity and minimizes voids and other defects, such as wrinkling.