While we’re hearing more about the benefits of composites and the many new automotive and mobility applications they enable for lightweighting, challenges still confront that industry. Dale Brosius, Chief Commercialization Officer at the Institute for Advanced Composite Manufacturing Innovation (IACMI; Knoxville, TN) told attendees at the recent SPE Thermoset TopCon in Scottsdale, AZ, that while there are a wide range of processes and applications, the thermoset industry still gets a “bad rap for slow process times” and the perception that the material is not very tolerant of damage.
|The BMW i8 has 45 parts made from carbon composites.|
One big barrier to adoption is cost. The high price of carbon fiber and the excessive level of recapitalization needed by traditional processors, along with the long processing times, make composite components expensive. “We need speed,” said Brosius, “but also how do we get the fibers in the place we need them to be? Slow robotic material transfer and iterative prototyping along with long process times continue to be barriers.”
Another key to the successful use of composites involves understanding how to design to true minimum mass, said Brosius. “What is needed is confidence in the manufacturing process and the performance of the materials used in automotive. How do you repair a composite car that’s been in a crash?”
The automotive industry focuses on lightweighting to save energy, yet it takes 130 km to recover the energy spent in producing the carbon composite material. “Carbon fiber is as energy intensive as traditional processes but also more costly,” Brosius noted. “In some applications, 75% of the cost of the composite material is in the fibers. Ninety percent of the energy expended is in the carbon fiber itself. If we could triple the amount of material going through the carbonization line, we could reduce costs.”
There’s also industry concern about recycling the material, as more companies think about the circular economy. Brosius noted that there are multiple institutes working on these challenges, thanks to a Department of Energy grant that provided $70 million in funding to research entities along the I-75 corridor in Michigan, Indiana, Ohio, Kentucky and Tennessee. The University of Kentucky, Vanderbilt University, University of Tennessee and Oak Ridge National Laboratory are working on ways to drive down the cost of carbon fiber and help meet the challenges of recycling.
Opportunities in materials include resin systems and new fiber sizings designed for use with emerging low-cost carbon fiber and new formulations that provide improved toughness over standard resins. Purdue University’s Indiana Manufacturing Institute opened in the summer of 2016 and focuses on composites design, modeling and simulation. A 3,000-ton Milacron press was recently installed in IACMI’s Detroit facility for structural injection overmolding of large parts. A 4,000-ton compression press from Schuler that is multi-process capable, incuding high pressure RTM, is being installed now.
“With composites, the material properties are defined by the manufacturing process,” said Brosius. “Knowing where the fibers are is critical.”
Moldex 3D and others are offering simulation tools to validate material position at the sub- and full-scale level on parts such as car hoods and roofs.
“Every thermoset mold is a reactor, which means it poses a bigger challenge than thermoplastics for consistently making good parts,” Brosius said. “We can use simulation to create virtual allowable for design, which saves time over making and breaking 3,000 coupons to test materials, as is done in aerospace. Test methods have variables but if a simulation can validate the material virtually, these companies can qualify materials in a matter of weeks instead of months or years.”
Weight reduction is a huge benefit with composite materials, which are 50 to 60% lighter than steel. Brosius cited the BMW i8, which has 45 parts made from carbon composites, but he also noted that it’s a “niche vehicle.” The BMW 7 series has a carbon core and 16 molded components. “They use carbon fiber where it’s most beneficial,” he said, noting that 80,000 metric tons of carbon fiber was used in total for all applications in 2015, and to make nine million cars would require 135,000 metric tons of carbon fiber. Future platforms will be multi-material vehicles that use aluminum, carbon fiber and other materials.
“We have to get the cycle time below three minutes—maybe even below 90 seconds—to manufacture the high-volume components that the automotive industry requires,” said Brosius. “We can drive down costs by 50% if we get carbon fiber down to $5 a pound and reduce cycle times. The aerospace industry is a big user of composite parts, but even they want parts faster and cheaper.”