February supplement: Out-of-autoclave processing for aero use

We here at CW put together a supplement published with the February issue of the regular magazine that focuses on the technologies, tools and materials being used today in out-of-autoclave (OOA) processing for aerocomposites. If you're a CW subscriber you will receive the supplement in the mail, but if you're not, or if you don't want to wait for the postal service, you can find the supplement here: cw.epubxp.com/i/630867-autoclave-2016, or just click any of the images.

Although OOA processing in aerospace applications has been employed for decades in the manufacture of thermoset composite parts for unmanned spacecraft and, more recently, in the manufacture of substructures for commercial passenger aircraft, the autoclave remains the curing technology of choice for the world’s large aircraft OEMs, primarily because of its brute strength — its ability to definitively consolidate composite parts and remove the voids that can compromise struc- tural performance. Such robust consolidation, however — <1% void content — comes at a high price in terms of capital expense, operational costs and time. As composites move further into aircraft, it’s clear the autoclave cannot be the only process available to aerocomposites fabricators. Today, OOA alternatives include vacuum bag-only (VBO) prepregs, dry fiber placement, infusion processes (which rely on oven cure), resin transfer molding (RTM) and thermoplastic composites.

From a technical viewpoint the question is simple: Can OOA options be matured sufficiently to yield parts with <1% void content? The answer, based in part on the reports in this supplement, is yes, but there is a larger question: Can OOA processes match this parameter and demonstrate enough overall savings in capital expense and time to justify the process development/recertification efforts that a move to OOA will require?

We may have that answer sooner than later. As the stories in this OOA Supplement demonstrate, the activity level in OOA process development is substantial, involving structures on flying aircraft. And the composites professionals involved with each, as you’ll find, are strongly invested in making OOA not only feasible, but successful.