MELBOURNE, Australia, November 21, 2023 – In the same way a hole in a bucket will let water leak out, certain parts in a vehicle can let in air, and that can create noise in the cabin.

Chasing down these virtual and physical noise pathways is the challenge Ford’s Noise, Vibration and Harshness (NVH) team takes on, said Mark Thompson, PhD, who is the NVH engineer for Ranger and Everest.

“Customers want their Ranger to be quiet and peaceful, so they can have an easy conversation with any passenger, no matter where they’re sitting in the car,” Thompson said.

“The Articulation Index for Ranger is very good, and that means if someone talks to the driver from the back seat, they can hear each other without having to raise their voices.”

To determine how well passengers to easily talk to each other, the NVH team relies on the Articulation Index – a standard form of measurement used to determine the percentage of speech audible in a typical one-on-one conversation.

Rigorous quality right from the blueprint

Before a single prototype was built, the NVH team spent hundreds of hours conducting virtual pressure tests and sophisticated flow analyses on Ranger to ensure only the air needed for cabin ventilation made it in (around 100-plus litres per second).

“We look at this in computer-aided design (CAD) in the pre-prototype stages down to the level of each individual clip, join and rubber seal to make sure that each one is a tight seal. We also use simulation tools to look at where leaks could be and then plug them,” said Thompson.

Once the concept had been validated virtually, prototypes were put through physical pressure testing as part of Ford’s stringent quality process. To ensure the air leakage rate was within acceptable limits, the cars were pumped full of air while the doors, windows and air vents were closed to produce a positive pressure environment. Mass airflow sensors are used to measure the amount and speed of air leakage.

Continued focus on quality

Pressure testing to ensure a well-sealed cabin didn’t stop once Ranger had been approved for production.

“We continue pressure testing at our production facilities each and every day,” said. Thompson. “A random sample of vehicles, representative of all variants in the lineup, is selected as they roll off the production line and delivered to a test room in the factory where we conduct a pressure test using sophisticated airflow sensors.

“The air leakage results are shared in real-time with teams at the plant and here in Australia to ensure the Ranger meets the airtight design specifications on every vehicle that we make,” said Dr. Thompson.

Solutions for silence

The quest for a serene cabin isn't just about fitting larger seals. It’s a multi-faceted approach, rooted in quality and precision. The team employs an extensive repertoire of advanced sealing materials to form a noise-proof shield:

• Sealing goo between sheet metal panels.
• Heat-expanding baffles within the vehicle structure that expand and fill cavities as the vehicle moves through paint ovens.
• Rubber gaskets or sealed clips precisely placed on anything that attaches to an exterior panel, from the roof's antenna to the floor's wiring harness.
  

“No matter where you are on the production line in the factory there is likely something being done to help seal up the vehicle,” he concluded.

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