How it’s done
To make materials replacement successful, the first step involves bringing design team members and material supplier technologists together to evaluate the overall system and opportunities for improving it.
Rather than taking a silo approach, in which each component is designed in relative isolation, designers and their material suppliers together evaluate the product in terms of function, looking for areas where plastics and/or TPEs can provide equivalent performance to traditional materials along with a host of other benefits.
When replacing metal, the first consideration is often stiffness and impact at low and high temperatures, because these two properties are likely the reason metal was chosen in the first place. When replacing elastomeric materials, the considerations are durometer (hardness) and compression set.
It’s helpful to remember that on their own, plastics are not as rigid as most metals, but can nonetheless replace metals with the addition of ribs to the design or filler to the base resin without sacrificing performance levels, leading to an optimum strength-to-weight ratio.
The next opportunity for replacement lies in conductivity for heat dissipation, as in the high-brightness LED example, as well as electromagnetic shielding (EMI/RFI). Thermally and electrically conductive polymer formulations can be tailored to specific applications, making them more cost effective than metal.
Finally, the team of designers and material technologists considers aesthetics, magnetic properties, perceived quality, and density. As an example, OEMs are now turning to plastics with a metallic filler to create engine covers that improve aesthetics and perceived quality while removing paint, associated VOCs, and cost from the process.
Again, to meet the specific targets in an application, a material supplier can customize each of these categories and can also combine them according to the application’s needs.
Using this approach offers an opportunity to significantly redesign components to utilize the polymer material to the fullest. This can involve functional integration, in which two or more components in an assembly are combined. Further, this approach can include designing for productivity improvements, whether by eliminating secondary operations, reducing wall thickness for faster cycle time, or lowering scrap rates. Finally, adding functionality is also possible with metal-to-plastics redesign.
Marc Mezailles is automotive market manager Europe for PolyOne Engineered Materials.
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