When design engineers face a specific challenge, they often turn to advanced materials, either plastics or metals.
Case in point: Design engineers turned to Amodel polyphthalamide (PPA) when they were developing a sealed version of a rivetless nut plate used in aircraft assembly. “We were in need of a thermoplastic material that has a high melting point and excellent compressive strength,” says Scott Cohen, senior project engineer for Acument Global Technologies (formerly Textron Fastening Systems). “Also of great concern was chemical resistance and moldability.” The washer in the assembly is used for load bearing as well as sealing. Amodel PPA has excellent mechanical properties over a broad temperature range.”
Veritas, a German rubber manufacturer, needed a stronger material for a middle, load-bearing, structure of a hose used in new high-performance diesel engines equipped with turbochargers for better efficiency. “Pressure, heat and aggressive media (such as oil, lubricants or fuel) are by no means the only stresses that components in the charge-air lien have to withstand,” says Veritas development engineer Peter Kahn. “Although torques have risen dramatically in recent years, engine mountings are being designed increasingly 'soft’ for comfort reasons. Other components have to tolerate this, for example the charge-air line, which must absorb up to three centimeters of inherent vibrations.”
Veritas now uses a monofilament structure of Fortron polyphenylene sulfide (PPS) to provide the strength, thermal properties and chemical resistance while also providing flexibility.
Design Creativity Grows
This section highlights other examples of how elastomers, metals and high-end plastics also solve specific functional problems. The range of materials’ capabilities to solve problems keeps expanding. Also growing is the creativity of engineers in their use of materials. A new plasma panel developed at the University of Illinois from various aluminum components creates intense light.
Meanwhile, metals’ suppliers are also busy with innovations. Chicago White Metal Casting of Bensenville, IL, says the superior mechanical qualities of magnesium can now be combined with a premium cosmetic-plated finish offering product designers a cost-effective new option. The new look is possible due to new joint material and process finishing developments that have brought quality electroplating to magnesium die casting for a wide range of new applications. According to Chicago White Metal, the new chrome-plated surface finishes for die-cast housings and components are comparable to that achievable in high-quality zinc parts and superior to that of molded plastic. Part weights are comparable to plastic.