Sound absorbers are a type of acoustic insulation that trap sounds, an audible form of energy that travels through the air as invisible waves. Sound absorbers are made of foams and facings and used at the source of the sound and at its receiver. If you’re wondering whether sound absorber products are right for your industrial noise control application, keep reading to find answers to these questions.
- How do sound absorbers work?
- Which types are available?
- What questions do I need to ask about the application?
- How are sound absorbers made?
Elasto Proxy fabricates sound absorbers for the mobile equipment industry and can also help you to find the noise control solutions for machine enclosures. If you need assistance, contact us.
How Sound Absorbers Work
Sound absorbers are made of open cell acoustical foams that can be combined with specialized facings. Sound energy passes through the foam’s open cells and is converted into small amounts of low-grade heat that is dissipated. The acoustical performance of a sound absorbing foam is highly predictable because the material manufacturer carefully controls the uniformity of each cell. Elasto Proxy also has an in-house laboratory where we perform testing.
Types of Sound Absorbers: Foams and Facings
Most sound absorbers are made of the following types of foams:
To meet fire safety requirements, polyimide foams may be used instead.
Acoustic foams can also have facings that tune-out specific frequencies. For example, a facing material can tune out the low-frequency rumble of a diesel engine or the high-pitched squeak of industrial machinery. The facing material can also provide a decorative, durable, or cleanable finish.
Vinyl and aluminum foils are common facing materials. Vinyl can absorb low frequencies and is easy to clean. Aluminum foil reflects radiant heat. With mobile equipment, a vinyl-faced sound absorber might be used in the cab while a foil-faced sound absorber is used in the engine bay.
Examples of sound absorbing products include:
- Un-faced polyester or polyurethane foams for maximum sound absorption
- Aluminized polyester faced foams for hostile environments that need to stay clean
- Urethane faced foams that reduce the ingress of dirt, particles, and debris
- Convoluted foams with increased surface area for enhanced sound absorption
How Sound Absorbers Are Made
Sound absorbing foams are supplied as sheets or rolls in various lengths, widths, and thicknesses. Some materials come with a facing but others do not. Using water jet cutting, Elasto Proxy converts these faced and unfaced materials to size. Because there’s no tooling to pay for or wait for, water jet cutting is ideal for prototyping. It also supports low-to-medium volume production and, compared to manual cutting, provides higher material yields with lower labors costs.
Elasto Proxy can also combine materials together to create an insulation “sandwich” with the properties you need. For example, at our manufacturing center near Montreal, Canada, we can laminate a vinyl facing to a polyurethane foam. Then, on the other side, we can apply a pressure-sensitive adhesive (PSA) with a removable liner. The finished product then has the facing on top, the liner on the bottom, and the foam in the middle. This “sandwich” stops low-frequency sounds and is easy to install and clean.
Seven Questions to Ask During Sound Absorber Selection
To choose the right sound absorber, engineers need to ask and answer a series of questions about acoustic insulation. Each application is different, but this list is a good place to start.
- What is the maximum insulation thickness that your application can support?
- Are you trying to insulate an area where there’s air flow resistance, or can air flow in and out?
- Do you need facing materials that can absorb a specific frequency or frequencies?
- Do you need facing materials for protection? If so, what are you protecting against?
- If the sound absorber must provide flame resistance, what is the flame rating you need to meet?
- Will the acoustic insulation remain stationary, or be subjected to opening, closing, and bending?
- Will you add sound absorbing materials to structural components where there’s vibration?
Four Sound Absorber Products You Can Order Now
Elasto Proxy fabricates both standard and custom sound absorbers for mobile equipment. Here are four types of standard sound absorbers that are part of the Elasto Bag, a sackful of samples that you can get if you are manufacturer in search of noise control solutions.
SH1000-54-PVTBL is a sound absorber that sandwiches a thick layer of polyether or polyurethane foam between a PVC-coated fabric facing and a removable liner with PSA adhesive. The charcoal-colored facing material contains a series of small holes for enhanced noise control. The acoustic foam is tested to ASTM specifications and meets various flammability standards.
SH-250-60-PVTM (FM-ZM) is an insulation sandwich that consists of a sound-absorbing foam bonded to a vinyl facing. The facing material contains small holes for enhanced acoustical properties and provides an attractive appearance for cabin interiors. For ease-of-insulation, SH-250-60-PVTM (FM-ZM) features a removable liner with PSA adhesive.
SH-1000-54-ZZUT consists of a sound-absorbing foam that’s heat-laminated to a urethane film or matte facing. These films and facings come in different colors and can provide resistance to moisture, dirt, and most petroleum products. For ease-of-installation, SH-1000-54-ZZUT can include a removable liner with PSA adhesive.
SH-2000-48-MEZT is a lightweight, fire-resistant melamine foam that can be combined with various facing materials and PSA liner. This open-cell foam combines high-temperature resistance with superior sound-absorbing properties. Facing materials like aluminum foil can reflect radiant heat and provide chemical resistance. This makes it a good choice for engine bays.
Custom Sound Absorbers for Industrial Noise Control
Do you need a custom sound absorption solutions for a commercial or industrial application? Elasto Proxy is ready to help and can leverage the application experience and technical expertise that we’ve gained by working with manufacturers of mobile equipment and military vehicles. We also offer value-added services such as parts marking, kitting, custom packaging, and warehousing.
To find your sound absorbing solution, contact us.