Complex Composites Simplify Design

Put on your materials-specifier hat and try to solve these design problems.

  1. Recommend an elastomer material to replace the complex, precious-metal-plated springs that can complete a circuit in an electronic device, provide shock protection and, under compression, hold the batteries in place.
  2. Select an elastomer that has good acoustical absorption and noise barrier properties, is economical enough to use in price-sensitive transportation applications, is easy to die cut and install, and resists oil and grease.
In both cases, the solution rests not in a single material but in several materials fused into one, multi-layered component—a multi-function elastomer composite. Made up of layers of films, fabrics or substrates sandwiched around polyurethane foam, elastomer composites can solve a wide array of complex, interdependent design problems and meet seemingly disparate design goals.

Now...the answers
For the electronics application in the first problem, a 1/8-inch-thick sheet of compression-set resistant microcellular urethane foam layered with 2-mil stannous-coated copper sheet provides an unexpectedly simple alternative to battery springs. E-A-R's fine-celled ISOLOSS® LXtra™ material is easily die-cut into a foam pad that provides the resilience to hold the battery in place and push the copper facing against the conducting contact. And because LXtra foam resists compression set, that resilience is virtually permanent.

In the second scenario, E-A-R applications engineers would recommend a relatively simple, cost-effective foam-barrier-foam composite to meet the vehicle application's numerous needs. The composite comprises one-inch-thick TUFCOTE® polyether acoustical foam faced with durable and protective aluminized polyester film, a one-pound-per-square-foot flexible urethane barrier and a 1/4-inch-thick decoupling foam layer backed with pressure-sensitive adhesive (PSA).

This decoupled barrier absorber both blocks and absorbs sound, and the protective facing enables its use in harsh environments. The composite is, in fact, a staple in the noise-control treatment packages installed in numerous heavy-duty trucks, buses and construction vehicles on the highways today.

Producing high-quality products
Traditional manufacturing methods for multi-layered foam composites are labor- and time-intensive and often result in materials with intrinsic variations in quality, consistency and bond strengths. E-A-R, however, combines advanced materials and processing technology to produce foam and solid elastomers in a single layer and chemically fuse them to other materials in a single pass through the manufacturing line. E-A-R recently made further advancements with this thin-sheet casting process when the company completed construction of a new advanced-technology foam-making line, called FM3, at its Newark, Del., plant.

E-A-R's process casts liquid formulations such as urethanes in continuous lengths to desired thicknesses, directly onto or between facing and backing materials. During curing, the cast foam fuses chemically with the other materials, forming a soft, flexible, adhesive-free bond.

The thin-sheet method also allows E-A-R to carefully control the processing and thereby engineer selected properties into the foam, such as density, porosity, acoustical absorption, tensile strength, load-bearing characteristics, resilience and permeability.

Precision performance
E-A-R's proprietary ISOLOSS LXtra and FLXtra™ foams, produced by thin-sheet casting, offer excellent properties for composites, including durability, resistance to compression set, fine cell structure and energy-absorption. Casting LXtra foam on fiberboard, for instance, provides long-lasting, cushioning shoe insoles. Or, facing both sides of LXtra foam with PSA creates a self-adhering isolation-pad material that facilitates installation of tiny fans and motors in electronics.

E-A-R can sandwich LXtra foam with fabric and the company's self-conforming CONFOR® ergonomic foam, for use in a wide variety of low-profile cushioning applications, such as mass transit seating, sporting goods or footwear. The flexographic printing industry layers FLXtra foam with 10 mil PET, to make a set-resistant, cushioning backing for high-volume printing plates.

E-A-R's TUFCOTE foam and barrier composites are also cast on the FM3 line, combining polyether foams with non-lead loaded urethane barrier sheets, with damping materials, and with a wide range of films, facings, fabrics and adhesives. The resulting single-unit composites are easy to cut and install.

TUFCOTE foam-and-barrier and foam-barrier-foam combinations both absorb and block sound, compounding the noise control capabilities of each element. Polyester film laminated to acoustical foam helps the foam withstand exposure to dirt and grease. Adding fiber reinforcement to the polyester also helps protect against rips.

Materials partner
Today's design complexities—ranging from downsized, space-critical devices to demandingly short product life cycles—have design engineers seeking ways to do more with less. And technology-savvy markets want smaller, lighter, more powerful and more durable goods.

To meet these challenges, product teams are turning to integrated materials suppliers, like E-A-R Specialty Composites, to collaborate early in the development stage and bring applications experience and materials expertise to the table. Often, elastomer composites can streamline the problem-solving process by meeting multiple goals with a single component.

General Applications

  • Medical/Electronics
  • Footwear/Flexographic Printing
  • Gaskets/Seals
  • Noise Control
  • Specialty Seating/Cushioning

    Process

  • FM3 Processing Line

    For More Information

  • Article: "Complex Composites Simplify Design"
  • Article: "Thin Sheet Casting Process Means More Choices"
  • FM3 Response Form

    ISOLOSS, LXtra, FLxtra, CONFOR and TUFCOTE are trademarks licensed to Aearo Company

  • Back to FM3 Overview