Monday, March 18th, 2013

Another Plastics First: Engine Supports for Mercedes GL

Like many plastics innovations in the transportation sector, the first plastic engine support, which is installed on the six-cylinder diesel engine used in the new Mercedes-Benz GL Class, provides considerable improvement over its metal predecessor. And like most of the other plastics breakthroughs, it will be unknown to the vehicle owners.

Compared to the previous aluminum support, the plastic part that now supports the engine (with the aid of the engine mounts) provides improved acoustical properties, better thermal insulation, and a definite weight advantage, and is able to sustain the same load.

The new Mercedes polyamide (PA/nylon) engine support (left) replaces and improves on its aluminum predecessor (right), facilitated by BASF’s Ultrasim software (center).

The new Mercedes polyamide (PA/nylon) engine support (left) replaces and improves on its aluminum predecessor (right), facilitated by BASF’s Ultrasim software (center).

The new engine support is molded from BASF’s Ultramid A3WG10 CR, a highly reinforced specialty polyamide (PA, often called nylon) that has been optimized for high mechanical loads. Various carmakers already use torque supports molded of Ultramid, but those are not subject to the permanent load of the engine’s weight while absorbing the entire engine torque.

The primary benefit of the Ultramid support over the aluminum predecessor is the improved acoustic performance. The damping behavior of the plastic lets the support contribute to a more balanced sound. In addition, the plastic conducts considerably less heat than aluminum, which helps protect and extend the service life of the natural rubber engine mounts connected to it. The weight savings — over 30 percent versus aluminum — supports better fuel efficiency, an ongoing goal throughout the automotive industry.

Mercedes Bens GL 500 4Matic

Mercedes Benz GL 500 4Matic

The plastic part has to pass numerous tests, including the repair crash replicating smaller crashes where the support must remain undamaged, and the “massive offset” head-on crash where the support must fail quickly in a way that prevents the engine entering the passenger compartment.

BASF incorporated both those tests during early development of the support with the help of its Ultrasim simulation tool, which predicts the part’s performance behavior. That made it possible to incorporate ribbing that would withstand the high loads, while still meeting the acoustic requirements, and provide the added bonus of reducing the number of prototypes required.

Currently installed plastic auto and truck components that once were considered “impossible” would make for a very long list. And many of us in the plastics industry now can easily recall when auto designers believed there would never be plastic components under the hood, let alone something as highly stressed as engine supports. Never say never.

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