How a Changing Landscape in Energy Policy is Conducive for UV/EB Cured Products in the Automotive Industry
By Mary Ellen Rosenberger, founder/managing partner
BaySpring Solutions, LLC
Figure 1: 2015 Model Year Ford F-150 – Aluminum weight savings estimated at 32 lbs. hood/fenders; 114 lbs. cargo box; 118 lbs. doors/tailgate (inner & outer); 92 lbs. control arms/steering knuckles; 190 lbs. cab/passenger compartment with other fuel saving components delivering approximately 700 lbs. and an estimated 20 percent improvement in fuel economy.
Figure 2: The new BMW i3 structure is redesigned from the frame up utilizing a 90 percent carbon fiber frame (Life Module) and honeycomb PC/PBT A Pillar and Side deformation components, delivering a lightweight vehicle that meets all safety, quality and fuel economy demands.
Figure 3: Areas for UV/EB coating growth include automotive polycarbonate as glass replacement parts and interior/exterior parts utilizing PVD and IMC methods.
Figure 4: Thermoplastic 3D Printing – 50th anniversary Shelby Cobra – on display at the 2015 North American International Auto Show. Courtesy of the Department of Energy – Oak Ridge National Laboratory and Cincinnati Inc.
Setting the stage for industry change: US energy policy
Automotive companies are going through one of the most significant change in priorities in history. US energy policy outlined by the Department of Energy (DOE) in conjunction with the Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) have defined targets that support initiatives to reduce the effects of climate change as outlined by the US DOEs strategic plan 2014-2018.1
- Reduction in Greenhouse Gas emissions by 17 percent by 2020 (2005 baseline)
- Reduction in carbon pollution by 3 billion metric tons by 2030
- Halve US oil imports by 2020 utilizing advanced sustainable transportation technologies
- Advanced lightweight materials
- Improved aerodynamics
- Engine and powertrain improved efficiencies for both light-duty vehicles and heavy trucks
As a result, the EPA has established a set of standards aimed at reducing the emission levels on an average automotive passenger and light truck vehicle fleet by 163 g of CO2 per mile, which is the equivalent of 54.5 mpg by 2025 Model Year (MY) for cars and light-duty trucks. Achievement of the goal will rely on the use of lightweight materials to reduce vehicle mass to deliver fuel economy savings with measureable environmental benefits.
Industry estimates indicate that a 10 percent reduction in vehicle mass improves fuel economy by 6 to 8 percent. Automakers likely will rely on a multi-material approach to achieve that goal with the focus on advanced high strength steel (AHSS), aluminum, magnesium and carbon fiber composites each reducing vehicle weight by an estimated 20-50 percent versus current steel vehicle construction. With weight reduction in mind, the use of lightweight materials likely will grow across all transportation sectors with the automotive industry increasing content from 30 to 70 percent by the year 2030.2
Lightweight material vehicle construction will require the laser focus of automotive development centers with the support of university researchers, industry groups and government agencies to find the technical solutions, while at the same time maintain vehicle performance and occupant safety. Any idea offered in the final analysis needs to deliver a robust manufacturing process, to maintain a competitive total cost structure and to meet the quality requirements that savvy consumers expect. Game-changing goals such as fuel economy targets leave large gaps in applicable technology that the world of material science now must invent. New approaches will be required, from how to incorporate lightweight substrates into standard manufacturing schemes to delivering high quality, first time through (FTT) vehicle production. Likewise, industry material specialists have the challenge of modifying coatings utilized in todays vehicle construction into products that are compatible with new body and part designs. Nothing is off the table – including new and innovative substrates, treatments, paint materials and assembly processes that deliver a completely restructured fuel efficient vehicle. Radiation curing as a technology has a great opportunity to provide solutions for lightweight vehicles.
Lightweighting of vehicles – Where are we today?
Lightweighting the vehicle is indeed one of the primary approaches underway to deliver on the reduced mpg targets. One of the most promising approaches that automotive product development teams are employing is replacing portions of the standard steel structure with a combination of lightweight aluminum, advanced high strength steel (AHSS) and magnesium materials. Lightweight metal schemes are capable of following standard body shop, paint shop and final assembly process flow without significant modifications. Minimizing assembly change is an important advantage to OEMs and Tier 1 suppliers who already have invested millions of dollars in capital equipment, process control methods and employee training to achieve the latest lean manufacturing processes.
Additional lightweighting programs involve utilization of AHSS and aluminum with minor amounts of magnesium, Carbon Fiber Reinforced Plastic (CFRP), Glass Fiber Reinforced Plastic (GFRP), other plastics and rubber components to deliver lower weight structural components that also allow utilization of smaller engines, further enhancing fuel economy performance. Current state substrate choices, joining/sealing techniques and materials likely will hamper development without innovative solutions to reduce material cost, manufacturing footprint and cycle time. Radiation curing solutions are an interesting fit to solve some of the outstanding issues of the these projects through revamped composite manufacturing, a pathway to temperature sensitive and precoated substrates, new multi-substrate joining techniques and high speed processing, all while maintaining vehicle product performance.
A bold example of a lightweight metallic strategy is Fords 2015 MY F-1503 (Figure 1) that has shed 700 pounds primarily because of the use of an all-aluminum body. In this case, assembly flow and current paint products are maintained.
Key material alterations to support aluminum intensive vehicle construction is adjustment of the BIW pretreatment chemicals by utilizing a dual chemical treatment that includes trication phosphate – zinc, nickel, magnesium for steel components and a zirconium oxide treatment for aluminum components, in addition to alternative bonding techniques to replace body welds. Fords experience with aluminum intensive vehicles, including those for Land Rover and Jaguar, have replaced traditional welds with boron steel rivets coated with corrosion inhibiting materials plus adhesive bonding for improved structural strength and corrosion protection of multi-substrate joints.4
Other developments in the near term include the MMLV (Multi Material Lightweight Vehicle) Project (DE-EE0005574), an endeavor sponsored by the DOE in conjunction with Ford Motor Company and Magna International, which demonstrates the lightweight potential of a 5-passenger sedan, high volume assembly (250,000 vehicles/year) while utilizing currently available materials that maintain vehicle performance and occupant safety. Life Cycle Analysis (LCA) results of the MMLV project using the 2013 MY Ford Fusion as its baseline shows a 23.5 percent vehicle mass reduction achieved through the use of a multi-material substrate strategy. The re-design primarily includes AHSS and aluminum (5000/6000 Series) with minor amounts of magnesium, Carbon Fiber Reinforced Plastic (CFRP), Glass Fiber Reinforced Plastic (GFRP), other plastics and rubber components delivering a calculated 34 mpg versus the current vehicle value of 28 mpg. Furthermore, LCA calculations show that of the mpg savings, 42 percent are because of reduced mass and 58 percent are because of the ability to downsize the engine. In this case, a 1.6 liter four-cylinder gasoline turbocharged direct injection engine is replaced with a 1.0 liter three-cylinder gasoline turbocharged direct injection. In the final analysis, Global Warming Potential (GWP) and Total Primary Energy (TPE) are reduced by 16 percent respectively.5
Although a remarkable demonstration of the current capability to produce a high volume vehicle in a somewhat standard assembly process with existing industrial products, the MMLV project also outlines areas for improvement. Current state MMLV substrate choices, joining/sealing techniques and materials likely will hamper development without innovative solutions to reduce material cost, manufacturing footprint and cycle time. Again, radiation cure provides solutions for some of the outstanding issues of the MMLV project, through revamped composite manufacturing, a pathway to temperature sensitive and precoated substrates, new multi-substrate joining techniques and high speed processing, all while maintaining vehicle product performance.
There are many other examples of the use of lightweight materials in new vehicle designs. Automotive suppliers and other industries are participating in research programs to support the discovery of novel new lightweight products.
Will the current substrate solutions alone meet the industrys energy goals outlined by the DOEs directive? Likely not, therefore, further work is underway in the nontraditional automotive supply markets to improve upon the energy savings achieved in the first phase of the automotive industrys lightweight transformation.
Lightweighting vehicles: Next steps with plastics and polymer composites
Major contributions to vehicle lightweighting are being made by the plastics and polymer composites market. Substrate alternatives are being offered to the automotive industry to replace traditional steel and glass with lightweight multi-substrate options. Recently, the American Chemistry Council published a Technology Roadmap6 that offers a strategic pathway for the use of plastics and polymer composites to provide further vehicle weight reduction. Selection of the optimal plastic or polymeric material is the joint effort of the OEMs and the suppliers. Their goal is to define a standard package of material properties that are suited for specific automotive parts application (body panels, engine mounts, instrument panels, cross-car beams etc.) that then are matched to the engineering performance requirements of the targeted vehicle application.
BMWs new i3 is an example of polymeric composites driving innovation with the use of CFRP as a dramatic solution to lightweighting. Carbon fiber delivers 50 percent in weight reduction over traditional steel materials and 30 percent in weight reduction over aluminum. The company is working to make this chosen lightweighting path affordable and manufacturing capable. The i3s vehicle structure is designed from the ground up beginning with the use of CRFP in the frame of the vehicle, dubbed the Life Module. The vehicle A Pillar and Side deformation elements are made from a honeycomb PC/PBT structure7. The newly designed i3 provides all of the attributes of fuel economy, quality and safety characteristics (Figure 2).
To accommodate the increased use of plastics and polymer composites for future models, assembly processes must be modified, as is the case for aluminum construction. Among them is the need for new adhesives and sealants to bond multi-substrate body structures, new pretreatment processes that accommodate mixed substrate vehicles and surface treatments for novel new substrates to enhance coating adhesion. Paint shops likely will lower temperature curing processes for such coatings as Electrocoat (200 °C/30-40 minutes) to protect multi-substrate body assemblies from the effects of high heat exposure and varied coefficients of linear thermal expansion.
DOEs MMLV project demonstrated an Alternative Corrosion Strategy (ACS) that eliminates the Phosphate/Ecoat process in a standard assembly paint shop by precoating the BIW and CIW materials prior to assembly, giving greater flexibility for substrate choices. Significant reduction in ferrous metal parts calls for a new corrosion strategy. Testing of the MMLV vehicles prepared with the ACS versus the standard paint shop approach of Pretreatment/Ecoat application demonstrates that both manufacturing schemes deliver capable corrosion protection, paving the way for alternative pretreated metal and plastic strategies.8
An estimated 30 percent reduction in paint shop footprint can be achieved by eliminating the Phosphate/Ecoat process, delivering capital investment savings and daily expenses associated with labor, material, water and energy. Paint shop facility savings are achieved through reduction in building space, conveyor systems, air-handling equipment, ovens, paint/chemical delivery systems, multi-stage dip tanks, heat exchangers, cooling towers and waste treatment facilities making this approach impossible to ignore.
Multi-material lightweight vehicles will rely on new treatment methods, coating materials, joining techniques and supporting equipment to be successfully implemented in production. New products are needed to meet the demands without compromising vehicle durability, safety, appearance or overall quality. Lightweight vehicle designs will drive advanced lean manufacturing concepts as defined by reduced carbon footprint, zero waste, improved energy savings, faster line speeds and multi-product manufacturing flexibility to achieve a competitive cost structure.
Lightweighting: Advantages of a UV/EB cured product approach
UV/EB products are in a unique position to lead the next generation of automotive manufacturing by providing coatings, adhesives and processes that change how we think of next generation vehicle design. Low temperature, high speed cure UV/EB products have a place in future automotive products as they provide performance, surface appearance, scratch resistance and strength while supporting the tenets of lean manufacturing with improved cycle time, small manufacturing footprint and reduced energy costs.
Material, process and facility developments in the UV/EB area are poised to play a bigger role in the future of lightweight vehicles. R&D resources should be targeted on the key sticking points not yet resolved in the challenge to produce a lightweight vehicle. UV coatings for exterior trim components, such as vehicle forward lighting lenses and reflectors, have cornered 80 percent of the market through proven solutions that deliver the cost structure, manufacturing cycle time and performance characteristics the industry demands. Physical vapor deposition (PVD) utilizing UV primers, color coats and clear coats will expand on exterior and interior trim parts delivering design and function. As an example, UV-cured topcoats used on the interior trim of the Audi A6 allroad quattro in what the company describes as “No compromises: A UV cured topcoat makes heavily used components in Piano Black extremely scratch resistant” will expand due to design and function.9 Soft Touch UV-cured coatings offer another dimension in the future of interior products for consoles, dashboards and other interior components. IMC (in-mold color) for solid durable color and graphics are gaining favor as lightweight trim solutions and are currently commercial in the European automotive market using UV-cured clear coats that add improved scratch and mar to trim components.
Adhesive requirements for lightweight vehicles will increase dramatically, in part, to support new substrate body construction, interior/exterior trim applications, vehicle NVH properties and galvanic corrosion protection, as well as protection for electronic components. UV-cured products currently in the market will advance in use and new developments will complement new vehicle design and function for metals, plastics and composites.
Vehicle design is changing rapidly with precoated products under study in both the commercial truck and automotive vehicle space. BIW and CIW designs utilizing the Alternative Corrosion Strategy show how precoated substrates can save tremendous assembly investment cost by reducing the current paint shop footprint through the elimination of the standard Phosphate/Ecoat process. Vehicle exteriors are capable of being fitted with precoated body panels and can all but eliminate the automotive paint shop in existence today. UV/EB cured coil coated products commercially used on aluminum and steel offer superior process and performance characteristics and make sense in a mixed substrate vehicle design.
Glazing techniques for lightweight polycarbonate will take center stage as automotive research centers gear up to find technical solutions to replace glass, as it adds significant weight to the vehicle. Glass components used in windshields, rear window, side windows and roof transparencies will be replaced with lightweight alternative substrates (Figure 3). UV-cured glazing techniques have been developed and should be further refined to support this growing market.
Additive manufacturing – revolutionizing the industry
Additive Manufacturing (AM) is penetrating automotive product development to aid in the rapid development of new vehicle designs. Stereolithography (SLA), the most widely used AM technology, converts digital data into a three-dimensional solid object by curing layers of liquid resin with a UV laser. After many years of development, this 3D printing method is now advancing rapidly due to photo-curable composite resins, UV light sources and equipment that deliver speed, part size and cost reduction, further accelerating the industrial feasibility for this process.
A sign that Additive Manufacturing is growing by leaps and bounds is evidenced by the partnership between DOE – Oak Ridge National Laboratory (ORNL) and Cincinnati Incorporated that is delivering huge results10. Utilizing a process called Big Area Additive Manufacturing (BAAM), this innovative approach is expected to improve 3D process speed by 500 to 1,000 times –compared with todays industrial additive machines – and increase part dimension to a whopping 20 feet x 8 feet x 6 feet. Using a precision thermoplastic extrusion process, ORNL and Cincinnati Inc. have created a working replica of the Shelby Cobra to celebrate the 50th anniversary of this iconic vehicle. Recently presented at the North American International Auto Show (NAIAS) 2015 (Figure 4), Shelby Cobras 1,400-pound weight is made up of 500 pounds of printed thermoplastic composite parts whose makeup is 20 percent carbon fiber/ABS thermoplastic material that required 24 hours of print time.
Future efforts in this arena are expected to focus on improved product characteristics with advanced high performance resin systems. UV/EB products have the potential to further advance BAAM with photo-curable or EB-curable composite resins, as well as radiation-curable coatings, adhesives and other materials that can be used to enable environmentally friendly rapid production of automotive body and interior parts. BAAM will continue to take manufacturing to the next level.
Whats next for automotive UV/EB cured products?
In summary, UV/EB coatings, resins and adhesives can offer solutions to the automotive industry during these challenging times by delivering multi-material lightweight vehicle performance through low-temperature cure capability, enhanced vehicle durability and unique design capabilities. Manufacturing schemes with UV/EB products have the potential to improve energy consumption, increase line speed and reduce manufacturing physical and environmental footprints. Additive Manufacturing – led by SLA developments and BAAM – will continue to change manufacturing protocol at automotive OEMs. Vehicle development timelines can be reduced greatly due to prototype development in a fraction of the time previously required, resulting in significant cost savings. Future developments in Additive Manufacturing have the possibility of revolutionizing manufacturing through design innovation, manufacturing speed and reduced product time to market.
Seismic industry changes due to the advancement of strategic energy goals, although challenging, are driving innovation and unparalleled new product introduction. UV/EB products are in a position to offer novel solutions to the transportation industry today and in the future. Automotive research and development centers around the globe are taking notice of what aerospace, electronics, medical and many other industrial centers around the globe already know – radiation-curable products offer solutions to the most challenging problems in a sustainable way.
- US Department of Energy Strategic Plan 2014-2018
- McKinsey & Company; Advanced Industries; “Lightweight, heavy impact: How carbon fiber and other lightweight materials will develop across the industries and specifically automotive,” 2012
- Ramsey, Mike; “Fords Trade-In: Truck to Use Aluminum in Place of Steel”; Wall Street Journal; July 26, 2012
- Truett R.; “A Riveting Tale: How will Ford build the aluminum F150”; Automotive News: April 28, 2014
- Skszek T., Zaluzec M., Conklin J., Wagner D., “MMLV: Project Overview”; SAE Technical Paper, 2015-01-0407
- American Chemistry Council – Plastics Division; Plastics and Polymer Composites Technology Roadmap for Automotive Markets, March 2014
- 2015 Plastics in Automotive Conference; Munro & Associates, Inc. “Tomorrows Cart Today – BMW i3,” January 2015
- Smith K. and Zhang, Y., “MMLV: Corrosion Design and Testing.” SAE Technical Paper 2015-01-0410
- Source: Audi AG, Fourtitude, In Detail: Audi A6 allroad Quattro, March 26, 2012
- Oak Ridge National Laboratory, Oak Ridge, TN; Morgan McCorkle; “3D printed Shelby Cobra highlights ORNL R&D at the Detroit Auto Show”