The National Plastics Exposition (NPE) recently took place March 23-27 in Orlando, Florida. Let's go behind the scenes and take a look from a plastics engineering standpoint at some of the regulatory impacts in key plastics end-uses and related technologies.

In a three-part recap, we'll look at automotive lightweighting, food labeling/packaging and green building.

Automotive lightweighting regulatory drivers

Automakers and their suppliers need to explore every possible avenue — from parts redesign and consolidation, to alternative powertrains and materials substitution — to meet the ambitious new mileage targets they have agreed to with the U.S. government.

Those regulations call for U.S. corporate average fuel economy, or CAFE, standards to climb to 54.5 miles per gallon by 2025, up from less than 30 mpg in 2010. Ford Motor Company, for one, has gone on the record saying it wants to lighten cars by 200-700 pounds in the coming years.

Faced with growing concerns about the impact that automobiles have on the environment, OEMs are embracing the use of lighter weight materials in automotive components and parts, part optimization/consolidation and the use of innovative processes. As a result, plastics and their composites as well as lighter-weight metals are increasingly being used to reduce vehicle weight.

Auto lightweighting goals are driven by:

  • Government regulations calling for step changes in fuel economy/emissions. Reducing structural weight is one of the most important ways of reducing fuel consumption. A 10 percent reduction in vehicle mass yields approximately a 6-8 percent increase in fuel economy.
  • Rising/fluctuating fuel prices
  • Growing global warming concerns
  • Hybrid, other fuel systems development — Every pound of vehicle weight saved conserves batteries and fuel, providing greater overall energy efficiency and operating range.
  • Continual addition of car features causing spiraling weight increases

The global market value for lightweight materials used in the transportation industry is expected to grow to nearly $125.3 billion in 2015, up from an estimated $95.5 billion in 2010, for a five-year compound annual growth rate (CAGR) of 5.6 percent. The consumption of these materials is projected to grow to 67.7 million tons in 2015 from its 2010 figure of 46.7 million tons.

Weight-reducing material selection is impacted by:

  • Material availability in quantities required for series volume production
  • Cost/kilogram of weight saved
  • Material weight-saving potential/vehicle produced

Material selection is also impacted by assembly methods, formability, paint technologies and corrosion protection requirements, as well as general acceptance by OEMs of performance correlations for the alternate materials.

The push for lightweighting means materials technology is increasingly being considered as part of the initial design. Researchers from MIT and GM have developed a tool for estimating secondary mass savings potential early in the vehicle design process. Using the tool early in the process — before subsystems become locked in — maximizes mass savings.

Secondary mass savings are mass reductions that may be achieved in load-bearing vehicle parts when the gross vehicle mass (GVM) is reduced. Mass decompounding is the process by which further reductions are identified via secondary mass savings that result in further reduction of GVM. Maximizing secondary mass savings (SMS) is a key tool for maximizing vehicle fuel economy, but can be difficult to achieve given the current design process.

Weight-saving technology trends center on reductions in vehicle weight that can be achieved by a combination of (1) material substitution, (2) optimization of component design and system layout, and (3) innovation in manufacturing processes. Plastics, composites and alternative metals are increasingly used to reduce vehicle weight.

Every pound of material used in a vehicle is under investigation, resulting in new materials, processes and assembly technologies. Material substitution replacing heavier iron and steel with advanced composites and other plastics, aluminum, magnesium and advanced high strength steel is essential for boosting the fuel economy of modern automobiles while maintaining safety and performance.

Material substitution is dependent on mechanical properties, cost, design and manufacturing capabilities. Carmakers are more willing to accept higher costs for high-performing material systems as reduced weight not only improves fuel efficiency but also will also extend the range or allow lower-weight batteries in hybrid electric, plug-in hybrids and electric vehicles.

Advanced plastics and plastic composites offer enormous weight reduction potential. Fiber-reinforced plastic composites are typically 25-35 percent lighter than steel parts of equal strength. Advances in low/ultra-low density sheet molding compound (SMC) are also facilitating weight reductions.

To reduce weight, some of the more dramatic new material uses will be:

  • Increased use of plastics and composites in car body panels
  • Long-fiber technology for structural parts
  • Greater use of carbon-fiber reinforced plastics (CFRP) for structural and other parts as lower cost composites are developed
  • Polycarbonate (PC) or polymethylmethacrylate, acrylic (PMMA) as glazing, including car roofs and rear ends
  • Advanced polyamides in under-the-hood applications
  • Foaming/glass bead technology to reduce plastic part density
  • Increased use of plastic-metal hybrid technology
  • More use of thinner gauge high-performance steel
  • Much higher use of aluminum and magnesium

More than half of Ford vehicles already have aluminum hoods. In another example, the Audi A4 uses aluminum for its front impact management system. GM in an industry-first used die-cast magnesium alloy (AE44) for a front engine cradle cast by Meridian Lightweight Technologies Inc. It provides a 35 percent weight savings over the previous aluminum structure.

On the component level, the weight saved from using alternative materials depends on application and design intent. For example, in a body panel designed for strength and resistance to plastic deformation, 1 kilogram (kg) of aluminum replaces 3-4 kg of steel. However, for a structural component designed for stiffness to resist deflection, 1 kg of aluminum only replaces 2 kg of steel.

In general, the weight reduction obtained by replacing steel tends to be greatest for CFRP, FRP (fiberglass-reinforced plastics) and magnesium, followed by aluminum. To illustrate, the degree of weight savings by different materials used for a car rear floor is as follows: