Innovations for Lightweighting: Eaton’s “hybrid” materials replace metal

May 1, 2017

Lindsay Brooke

Eaton is developing composites with future supercharger applications in mind. Might the successor to the TVSII (shown) be a “hybrid” materials solution?

As product portfolios go, Eaton Corp.’s may be the broadest and deepest among Tier 1s supplying the mobility sectors. Materials innovation is core to the seven primary industries and at least five dozen product areas served, but you’d be forgiven if you answered “steel” to the question, “What material comes first to mind when you think of Eaton?”

The world’s dominant source of poppet valves for ICEs and a pioneer in drivelines and supercharger systems has played longer on the “heavy metal” stage than has Jimmy Page. But Eaton has quietly spent more than a decade developing what it calls “hybrid” materials technologies that blend various metals with a composite, to leverage the best properties of each. Examples include a carbon fiber-reinforced polymer (CFRP) over- molded-steel differential carrier and heavy-truck transmission gears.

“We don’t have specific targets for reducing weight but we’re definitely conscious of weight and maintain a competitive cost-to-weight ratio in our products,” explained Kelly Williams, Eaton’s Research and Technology Manager, Polymers and Nanocomposites, based in Southfield, MI. “So, when we’re looking at these “hybrid” technologies it helps balance the cost impact of lightweighting — to our customers and to theirs as well.”

With more-stringent emissions regulations, Williams’ composites-focused teams find themselves regularly challenged in respect to higher loads, torques, pressures, harsher thermal environments and relentless eternal duty cycles. She noted that the “hybrid” approach allows the engineers to do component- and system-level lightweighting “without having to go to aerospace-type processes with continuous carbon fiber and pre-preg layups. By combining the metal with the composites we can still use a high-volume/short-fiber composite solution to balance the cost,” she said.

There’s a major focus to drive component consolidation, starting with the current manufacturing process “and the ability to eliminate secondary finishing steps that we currently have in our metal applications,” Williams said.

As an example of unique parts consolidation enabled by a composite material, Williams cited a development on a differential product. The application included a metal piston that had two polymer seals, one outside diameter and one inside diameter. In a two-shot process, Williams’ team was able to mold the piston and the seals in a single piece. This significantly improved assembly and alleviated the hassle of precisely positioning the OD and ID seals during assembly.

Properties such as thermal conductivity or EMI [electro-magnetic interference] shielding are of high importance to many customers. Composites also allow more complex geometries than are possible using only metals: “That’s another way we’re able to balance the cost and weight savings” with the ‘hybrid’ solution,” she said.

Williams is asked if an Eaton super-charger housing in composite would be feasible. It’s “an area we’re actively working to investigate alternative materials,” she replied. And reinforced-composite drive-axle housings?

“I can see it becoming commercially viable as carbon-fiber prices decline and we become more adept at processing,” Williams asserted. “Right now, the limitation is less technical and more commercial; the cost of the process and materials today are preventing that from becoming a reality. But yes, it’s definitely a technical solution,” she said.