The defense industry as a user of thermoplastic composites isn't dead.
This month's Modern Plastics (hard copy) says that Fiberite (now part of CYT) have been working with the Air Force on a thermoplastic composite radome.
It is online at modplas.com but the contractor is 'undisclosed' in the online file.
JD
The story is buried in a lot of plastics news - the relevant text is:-
Advance composite thermoforming is being used by an undisclosed U.S. defense contractor, to produce
aerospace radomes. The project, part of a manufacturing technology initiative from Wright-Patterson Air
Force Base, OH, involves the production of domes which house radar equipment for Air Force RC-135
reconnaissance planes.
Radomes are being thermoformed from sheets of polyetherketoneketone (PEKK), impregnated with woven
quartz fibers. PEKK will replace an oven-cured/hand-lay-up thermoset polyimide in the radome application.
Compared with the polyimide, PEKK offers greater impact resistance and reduced moisture absorption
(moisture undermines the structural integrity and dimensional stability of the polyimide, and clouds radar
transmissions).
A major advance from the composite radome project is the development of an "articulated" clamp frame,
which positions the sheet in the female section of the forming station. Sixteen pneumatically controlled
clamps have a wide range of motion, to hold the sheet and allow it to move and set properly, while avoiding
wrinkles. Because it's a continuous fiber weave, the prepreg doesn't flow or stretch like a standard
thermoforming sheet; the articulated frame compensates for this.
Overcoming the part-fixturing challenges associated with thermoforming woven, continuous fiber composite
sheet also is the focus of development efforts by Manfred Jacob Kunststofftechnik GmbH, Wilhelmsdorf,
Germany. Manfred Jacob, founder and chairman, says his list of commercial programs for thermoformed
composites includes industrial housings, automotive parts, as well as helmets and body armor.
Jacob says the critical element is the engineering that goes into the match-mold tools, developed by
computer-aided design/manufacturing (CAD/CAM) process simulation. Parts are thermoformed from woven
glass fiber sheets. Other reinforcements, such as carbon fibers, also are utilized. |
