All together now
Various joining methods are being developed to help manufacturers of composite products save weight, time and cost.
If a company can reduce the time and materials used to stick multiple composite components together, it will reduce total production time and cost. So all users of composite structures – manufacturers of aircraft, wind turbine blades, motorsport technology and, increasingly, mainstream automotive equipment – are eager to perfect the bonding process. But relying purely on adhesives is not easy.
“Because we are always chasing weight and cost, bonding parts together is an efficient way of doing that and it could lead to lower-weight structures,” said John Cornforth, head of airframe and special product technologies at GKN Aerospace. “In both metals and composites, we often make individual piece parts, drill holes in them, and then we countersink them, remove the burrs and fasten them together. If you bond it in one hit, it is likely to be a cheaper process.”
But aerospace is a naturally conservative industry and the adoption of adhesive-only joining techniques is slow.
Some aerospace components today, including critical parts, are bonded with adhesives only, such as stiffeners onto panels on winglets. The intent to do more of this is there, but the industry is still nervous about bonding for highly loaded parts. The field where the industry needs a shove, Cornforth suggested, is to design these processes into a manufacturing standard; how to co-cure and marry two components quickly that meet all the regulations. “If you want to design a part for co-cured structures, then those kinds of methods are not in the textbooks,” Cornforth said. “We would like to get to more generic methods that allow you to size a joint that is sufficiently reliable.”
July 20, 2015
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