Polycarbonate seats began failing after only a few months of use in simulation theaters from SimEx-Iwerks, Burbank, Calif., (simexiwerks.com). Multidirectional motion puts extreme stress on seat components and wall panels as thrill seekers lift off for a voyage to Mars, experience undersea adventures, and race volcanic eruptions alongside fleeing dinosaurs. Audiences experience pitching, swaying, rolling, and surging motion with the action on the screen. Industrial designers/plastics consultants Gidman Design Assoc., Toronto, helped SimEx find a more robust seat material. The replacement had to have high-impact and flex-crack resistance. Also important was resistance to scratches, fading, and typical wear and tear seen during daily operation. Gidman president Claude Gidman says the firm considered numerous materials including various acrylic/PVC (polyvinyl chloride) blends and ABS (acrylonitrile butadiene styrene). ABS had good adherence and bonding properties but proved no match for another thermoplastic from Kleerdex Inc., Bloomsburg, Pa. (kydex.com), under high-impact tests and chemical exposure.
Gidman says Kydex 100 thermoplastic sheets met all design specs. The material frequently serves in aircraft and mass-transportation applications, has reliable color integrity, and resists scuffs. "It's also lightweight relative to its resilience and durability. This is especially important in moving theater cabins that hold up to 40 seats and must withstand high g-forces in every direction," says Gidman.
SimEx makes the simulator seats and components at its Mississauga, Ont. manufacturing facility. The thermoplastic components are vacuum formed instead of injection molded. Vacuum forming evacuates the sealed air space between the heated plastic and the mold. This gives crisp detail on sculpted seat features and eliminates seams and corners that can trap dirt and pose cleaning problems. Vacuum forming also reduces tooling costs and gives SimEx the option of short production runs.
Kydex sheets exhibit outstanding vacuum-forming properties including extreme hot-tear strength and the ability to maintain uniform wall thickness, says Gidman. The material also sports good physical properties including a 6.6 kpsi (42 MPa) tensile strength, Notched Izod impact resistance of 18 ft-lb/in. (9,538 J/m), flexural strength of 9.1 kpsi (63 MP/a), and a 356-kpsi (2,450 MPa) modulus of elasticity.
It also has good fire ratings, and unlike other plastics, resists lipids present in body fats and gamma radiation, making it particularly suitable for a wide range of medical equipment components and enclosures.
Jean M. Hoffman