Auto Suppliers Quietly Making Interiors Less Noisy

OTTAWA – Suppliers to auto manufacturers are adopting innovative technology to help brands reduce interior noise in their vehicles.

Luxembourg-based automotive interiors supplier International Automotive Components, for instance, is expanding its operations to produce lightweight, injection-molded inner-dash insulation that enhances interior acoustical performance.

The company announced July 12 its Prestice 2 production facility in Prestice in the western Czech Republic is producing these insulations for two premium European OEMs the supplier declined to name.

Traditionally, these acoustic parts are made in a vacuum-forming process where a thermoplastic-based heavy layer sheet is molded in a tool under vacuum.

“This process in itself has limitations,” an IAC representative tells WardsAuto.” The thickness of the part is nearly uniform and detailed and precise part geometry is difficult to reproduce.”

IAC injection instead molds a particular compound and is able to create parts that are thicker and heavier where more insulation is needed and thinner in the other areas. “By doing this IAC can optimise the acoustic performance and at the same time reduce the weight of the component,” the spokesman says.

Also improving acoustic properties is the exact and reliable material distribution offered by the melding process so a component can be designed and produced to perfectly fit the dashboard. “This is a customer benefit resulting in augmented freedom of design within the entire dashboard module,” the spokesman says. It also offers a nearly 40% weight reduction compared to a conventional vacuum-formed product, he claims.

The spokesman notes this insulation complements IAC’s other lightweight acoustical insulation products, including innovative sprayed-polyurethane-dash inner technology. This offers weight reductions of about 20% coupled with acoustic performance superior to that of traditional technologies.

For the past few years, PUR sprayed-dash inner insulation has been in production at IAC in Spartanburg, SC, and IAC Straubing in Germany, where it debuted on the new Maserati Levante luxury SUV.

The 193,750-sq.-ft. (18,000-sq.-m) Prestice 2 facility is expected to reach full capacity by 2018 with the addition of a future major door-trim program. While IAC declines to disclose the specifics of the investment, it says it noted it has spent “several million dollars for the Prestice greenfield site.”

Lightweighting to Migrate to Volume Models

This follows the September 2015 launch of new facilities at Halewood and Elmdon near Birmingham, U.K., the start of operations for IAC Itatiaia in Brazil and a growing footprint in China: It opened its 16^th location in China last October – a new manufacturing facility in Tianjin.

Looking ahead, the company expects injection-molded acoustic insulation with its other proprietary lightweight substitution processes to become increasingly popular with OEMs and expand from the premium segment to include volume models.

For instance, the company also offers IAC HybridFleece Molding, which combines into one step the pressing of a thermoplastic mixed-fiber fleece from a natural fiber, glass or recycled-carbon fiber with a molding of stiffening ribs and clips.

IAC is not the only company innovating in the field of vehicle interior acoustics. Autoneum, a Switzerland-based developer of acoustic- and thermal-management solutions for vehicles, manufactures products ranging from carpet systems, underbody shields, inner dashes, engine encapsulations and engine covers, to heat shields, wheelhouse outer liners and dampeners, which can protect against vehicle noise.

The company’s Hybrid-Acoustics technology, for example, uses cotton fibers to create dash and floor insulation up to 50% lighter than conventional insulations made of heavy-layer foam and reduces noise within the interior of a vehicle. The technology also enables the thickness and density of the components “to be defined accurately to within a centimeter without any additional materials or layers,” Autoneum says.

“Sound can be reduced by absorption, isolation and dampening,” says Maurizio Mantovani, Autoneum’s head of research and technology tells WardsAuto. “Our Hybrid-Acoustics products block noise and prevent it from seeping through from the engine bay to the passenger compartment.

“Without noise reduction, a comfortable car journey can simply be impossible for driver, passenger, or even bystanders alike,” he says.

But many experts say overall design best reduces interior noise. Exa, a U.S.-based developer of engineering software that allows OEMs and vehicle engineers to see and hear the source of noise before prototype vehicles are built, so the design can be tweaked to eliminate the source of noise.

“Low-weight options and better vehicle designs are key to reducing noise. Ideally, the cheapest way to cut down on noise is by changing the exterior shape when you’re designing a vehicle,” explains Siva Senthooran, technical director of wind noise applications at Exa. “We help OEMs do this through our noise-simulation technology,” he says.

Looking Outside to Reduce Noise Inside

Exa’s PowerACOUSTICS technology, for example, allows engineers to simulate and visualize sources of noise caused by the flow of air outside a vehicle. It accurately can predict pressure fluctuation and identify noise sources, which helps engineers design for better airflow around a vehicle, and thus less noise.

When paired with Exa’s PowerFLOW technology, which simulates wind noise, undercarriage noise, gap/seal noise, mirror, whistle and tonal noise, sunroof and window buffeting, pass-by/community noise, and cooling-fan noise, Exa can help OEMs save money and time before a vehicle is even built, Senthooran says.

He emphasizes that when a company does not use predictive simulation technology before the engineering process is done, many of the parts and materials cannot be changed. This means if there is a noise problem it can become difficult to fix, which leads to employing expensive countermeasures.

Jud Knittel, a senior engineering consultant at Head Acoustics, a German supplier and consultancy that produces systems for recording, analyzing and playback of vibrations and sounds so OEMs can work toward improving their vehicles’ acoustic performance, says these simulations and recording technologies are important because today’s consumers expect high-quality interior-vehicle sound.

“When I first started in the vehicle-acoustics industry over 30 years ago, nobody paid much attention to noise except for sounds that shouldn’t be there,” Knittel says. “Over the last couple decades, demand for noiseless interiors has increased and is all but expected now.

“Luckily, the automotive industry has developed into the most efficient industry when it comes to managing noise.”

– with Mandy Kovacs