How Composite Materials Challenge the Automotive Manufacturing Industry - Part 1 Cost BarriersGary Kardys | October 28, 2017
The latest commercial aircraft, Boeing 787/777 and the Airbus A350XWP, contain up to 50% carbon fiber reinforced plastics (CFRP) composites by weight. The average amount of fuel used per flight by US airlines in 2013 was 2,790 gallons, which cost $8,575 dollars according to “Fuel Burn Reduction: How Airlines Can Shave Costs”. In 2013, the combined fuel consumption by all U.S. airlines amounted to 13.2 billion U.S. gallons resulting in total fuel costs of $40.5 billion USD. The reduction of aircraft mass justifies the price of composite materials through reduced drag and improved fuel efficiency. An improvement in fuel efficiency and drag lower the amount of fuel required for a flight, which further reduces fuel costs. In aircraft, fuel consumption is generally reduced by about 0.75% for each 1% reduction in weight.
The use of composites in automobiles is not new. Chevrolet Corvette bodies have been made of fiberglass-reinforced plastics since 1953 and more than 1.5 million cars have been sold. In 2018, Corvettes with the Carbon 65 Edition package (Z30) will have carbon fiber composite rear spoilers, quarter ducts, steering wheels, ground effects, hood sections, and roofs and tonneau inserts. The Z30 carbon fiber upgrade package will cost $15,000. Carbon-fiber composite monocoque structural cores, reinforced body panels, molded suspensions, wing or spoilers, transmission-housing components and brake rotors are utilized to improve performance in many sports and racing supercars – where cost is not a factor. The video shows the Alpha Romeo chassis being manufactured from carbon fiber composites in a labor intensive process, which is viable for high-end vehicles.
While composites and carbon fiber composites, in particular, have specific strength and specific modulus property advantages over steel and aluminum in light-weighting vehicle designs for high-performance, composites adoption remains low in high volume production vehicles due to cost considerations, property limitations, manufacturing process factors and automotive design methods. The Vehicle Technology Office of U.S. Department of Energy states, “A 10% reduction in vehicle weight translates into a 6 to 7% increase in fuel economy…. Using lightweight components and high-efficiency engines enabled by advanced materials in one-quarter of the U.S. [automotive] fleet could save more than 5 billion gallons of fuel annually by 2030.”
The carbon fiber reinforced plastic (CFRP) composite parts are orders of magnitude higher than the aluminum and steel options. Composites parts cost more because the raw material input costs are higher (fibers and resins) and manufacturing composite parts costs are higher. Carbon fiber costs have come down from the $35 per pound of a decade ago to $10 to $15 per pound cost today for automotive grade carbon fibers according to a 2014 Plastic News article based on surveys of a composite trade show attendees. The attendees thought that more widespread adoption of carbon fiber in the automotive industry would occur when carbon fiber costs drop to ~$5 to $6 per pound. Glass fiber reinforced plastic (GFRP) composites are less costly, but they do not provide the degree of weight reduction of CFRPs.
Even at $5 per pound, carbon fiber composites will continue to be cost prohibitive considering the “further material processing costs” such as intermediate processing and part fabrication costs. Raw carbon fiber has to be treated and then converted into the required reinforcement form such as woven fabric, chopped fibers, roving, strands, lay-up tape, braided tube or nonwoven mats. A percentage of the material will be lost during the weaving and converting processes, which will increase material costs. In an intermediate processing step, the reinforcement fiber is saturated or blended with the matrix resins. In a final fabrication step, the fiber-reinforced composite parts are manufactured using molding, winding or lay-up processes.
As a result of the “further processing costs,” current carbon fiber composite parts using raw materials costing $11/lb for carbon fiber and $2/lb for resin will have an end product cost of $45/lb. A 70 percent carbon fiber – 30 percent epoxy resin CFRP composite would have ~$8 of raw material cost. Carbon fiber costing $5/lb would reduce these raw material costs to $4/lb. However, the lower cost carbon fiber might only reduce the end product or processed material cost in the part to $25 to $35/lb depending on the specific part fabrication methods.
Another cost factor often overlooked in selection of alternative materials is life cycle assessment (LCA) costs. LCA examines the complete life of a product and the energy and resources required to fulfill each life phase of that product. While lower weight car materials reduce weight and fuel consumption during their useful life (use phase), the total impact on the environment over the car's total life from manufacturing (production phase) to end-of-life recycling and disposal (end-of-life phase) needs to be considered. Current composites consume more energy during manufacturing and good recycling processes have not yet been developed, which means incineration or landfill disposal.
Fiberglass or GFRP composites can cost a fraction (1/3 to 1/10) of CFRP composites, but fiberglass composites have only half the strength of carbon fiber composites. Aluminum can range from $1.5/lb for general purpose grades up to $10/lb or more for advanced aircraft aluminum alloys. Carbon steel and high strength low alloy steels can range from $0.5 to less than $2/lb. Steel and aluminum producers continue to optimize processes and create new metal alloys to deliver increased strength to enhanced light weighting. Advanced high strength steel (AHSS) or "efficient" steel has the potential to cut component weight in half. An improved steel is attractive to automakers because less capital equipment expense and design methods development area required.
Composites will continue to be a more expensive material alternative compared to metal alloys. As carbon or other reinforcement fiber, high performance resins, and converision and fabrication costs are reduced, then wider scale adoption in the automotive industry will occur.