The Combustion Mask Is Gone 

Combustion engines have long helped commercial vehicle OEMs mask road noise, wind intrusion, structural resonance and motor whine. Quieter electric and hybrid powertrains have lost that mask, pushing cab acoustics from an afterthought to a key manufacturing issue for OEMs competing on cab quality and driver experience.

Quieter powertrains don’t eliminate noise, vibration and harshness (NVH) problems—they expose them. For commercial vehicle programs, the challenge goes beyond acoustic into material engineering, according to Greg Precup, Outside Sales Converter Specialist for Saunders by R.S. Hughes. 

Where NVH Lives in the Vehicle 

“As engine noise quiets down in the vehicle, the areas where components are rubbing together, vibrating or buzzing around become clearly audible,” Precup noted. “Trim assemblies, small bonded-in pieces, interior panels and traditional fasteners can all create NVH when they allow movement between components.”

In the cab, center consoles, glove compartments, dash areas, trim assemblies and interior panels can squeak, rattle or buzz without a foam, rubber, tape, gasket or other buffer.

The same material decisions apply beyond the cabin. Door and window seals control wind intrusion and air leaks. Floor and firewall insulation manage road and powertrain sound paths, while electrified systems may need isolation materials at motor, drivetrain, battery and frame interfaces.

Sealing is another important application area. Air noise can come from panel pass-throughs, doors, windows, floors or firewall locations. Precup cites an electrical panel pass-through that creates both noise and light pollution, necessitating a gasket that blocks light and prevents part movement.

Material choice depends on gap size, contact force, surface type, durability requirements and noise source. Engineers must also account for heat, cold, humidity, salt spray, exterior exposure and long-term durability near the cab, floor, firewall, drivetrain, engine or exhaust.

Two material categories typically matter: materials that absorb vibration or create a buffer, and adhesives that hold parts in place. If either is mismatched with the environment, it can break down, leading to increased noise, reduced sealability or heat propagation. Common options include flock tape for light-duty plastic interfaces, felt tape for thicker or more durable applications, ultra-high molecular weight (UHMW) tape for demanding contact points and foams where compression and cushioning are required.

Structural damping is another major NVH use case. Lightweighting, composites and downgauged metals can make panels less rigid, allowing flutter at higher speeds. Strategically placed materials can absorb or mitigate that noise.

“Butyl patches are one approach for flutter and structural vibration,” Precup noted. “These can be cut into specific shapes and placed strategically. During the paint cure process, heat activation helps them cure and become structurally rigid, strengthening the metal so it flexes less while the vehicle is moving.”

In heavy commercial trucks, NVH can also appear in specific cab structures. In one over-the-road truck bunk bed application, the assembly rubbed against the cab frame, causing vibration and squeaking. A densified polyurethane foam placed between the materials acted as both buffer and cushion, eliminating squeak and rattle at key touch points.

The Design Cycle Problem 

Many NVH issues are identified too late. Precup notes that customers often bring in materials support during testing or prototyping, after vehicles are already on test tracks. At that point, a rattle, distraction or nuisance must be corrected within the existing design. 

Late-stage changes can drive up cost and compromise performance. Once tooling is complete, modifying plastic or metal parts can be expensive. Some parts are not designed to accept a peel-and-stick component, or there is insufficient space for a gasket. If the geometry forces a gasket to be taller than it is wide, the material may slump, reducing sealability. 

Moving NVH Decisions Upstream 

Early engagement helps avoid those problems. During design, a materials partner can review assemblies, flag potential noise, leakage, vibration or contact issues, and recommend a gasket, foam, tape, adhesive or fabricated part before bolts, molds and components are finalized.

“Early specification conversations support manufacturability,” Precup said. “Saunders by R.S. Hughes can design a part to meet the engineering specification and work with manufacturing engineers on a delivery system that makes application faster, such as arranging parts so operators can pull and place them without slowing the line.” 

Precup shared an example of a commercial vehicle customer with new design requirements. Saunders collaborated with 3M and the customer to identify films and shielding materials for the application. “3M can perform lab work to prove out materials,” he said. “That type of supplier collaboration is vital to the success of these applications.” 

NVH solutions are rarely one-size-fits-all. Testing, qualification, durability review, documentation and production realities all matter. Bringing in a materials and converting partner like R.S. Hughes early helps engineers avoid late-cycle fixes and select solutions that perform in the actual vehicle environment.