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Polymer Quiets EVs by Way of Structural Chassis, Suspension Applications

New PA 66 from Celanese offers carmakers “damping with structure” to improve NVH performance, remove weight, and reduce costs.

January 4, 2023

3 Min Read
Cadillac Lyriq
Celanese developed a glass-filled PA composite to provide enhanced damping/NVH without loss of mechanical properties for the Cadillac Lyriq's drive-unit mounting brackets.Image courtesy of Cadillac

Most automotive OEMs still use metal for structural chassis and suspension applications. Replacing that metal with Zytel NVH Gen 2, a newly formulated polyamide (PA) 66 from Celanese, is said to offer a host of compelling improvements. In addition to reducing weight, a switch to the Celanese material reportedly gives drivers and passengers a superior driving experience by controlling noise and vibration more effectively than metal.

Electric vehicles (EVs) pose unique challenges when it comes to isolating structure-borne noise and vibration originating from electric drive units. Without the relatively loud internal combustion engine masking them, these noises become much more noticeable in the vehicle cabin. It’s a complex issue that affects both vehicle safety and passenger comfort. Meanwhile, engineers find it difficult to point to a single part or component that is the root cause of the noise.

Damping material maintains structural properties of base polymer

To meet these challenges, the automotive electrification team at Celanese Engineered Materials developed Zytel NVH70G35HSLA2, the first entry in the Zytel NVH Gen 2 product family. This PA 66-based, 35% glass-filled polymer offers high damping, yet keeps its base polymer’s robust structural properties for parts that need sustained mechanical strength throughout their lifecycles.

“This new Zytel formulation takes a different approach to high-frequency vibration isolation by utilizing the material’s structural damping ability without sacrificing extended fatigue resistance over time,” explained Gabe Knee, Automotive Market Manager, Celanese. “We’ve created a cost-efficient, mass-saving, and tunable solution for electric drive units that mitigates NVH [noise-vibration-harshness] problems in electric vehicles, making them even quieter and more comfortable.” The material can endure high-stress conditions and provide stable characteristics under varying ambient and loading conditions.

In a recent commercial application in North America involving EV motor mounts for the Cadillac Lyriq, Zytel NVH Gen 2 maintained structural integrity while offering more than 20% direct mass savings and considerable material cost savings compared with aluminum. With these mounts, designers were able to tune, mitigate, or eliminate irritating harmonics that would otherwise be transmitted and detected by drivers and passengers in the cabin.

“With our design and prototyping capabilities,” added Knee, “we help customers identify problematic component designs that are contributing to NVH issues, then help create the solution for managing them.”

SPE-awarded technology

The NVH suspension component that is used in the Cadillac Lyriq received finalist awards in both the 2022 Automotive News PACE competition and 2022 SPE Automotive Innovation Awards. It was molded from the new Zytel NVH Gen 2 material. The vehicle has been described by automotive reviewers as “crypt quiet.”

These materials provide superior NVH performance in the temperature range of automotive applications, produce less noise vs. metal, reduce weight by 30 to 50% compared to metal parts, and reduce costs via parts integration and by eliminating aluminum and insulation needs, according to Celanese.

The company formulated a new glass-filled PA composite to provide enhanced damping/NVH without loss of mechanical properties for the Cadillac Lyriq's drive-unit mounting brackets. The material enabled structural support brackets to be tuned, along with elastomeric bushings, to provide broad vibrational filtering with 34% reduced mass and 19.5% lower cost.

Friction, wear, and noise characteristics are system dependent. Celanese has extensive experience developing tribological formulations for customers based on its POM, PBT, PA, PPS, LCP, and PP-LFRT solutions. In response to increased demand for materials with renewable content and lower environmental impact, Celanese has launched sustainable grades for existing products within its Engineered Materials portfolio — biomass balance content (ECO-B) and recycled content (ECO-R) materials.

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