It’s official: 3-D printing has captivated the world. It’s gotten to the point where individuals can purchase a home model for as little as a few hundred dollars. And it’s also gotten to the point where Local Motors, an American motor vehicle manufacturing company focused on low-volume production, says it will offer a car for sale next year that’s made on-demand with a 3-D printer. Billed as a low-speed neighborhood vehicle, the cars can be printed in a way that allows customers to customize colors and trim.
Despite the major strides, there is still much anticipation in terms of how 3-D printing can serve the greater automotive community. Challenges currently facing the industry include the large work envelope necessary for automotive manufacturing, the limited number of metals that can be used and the cost of those powdered metals.
Although 3-D printing is just now drawing attention from the general public, it’s been in use in the manufacturing world for decades. Referred to as additive manufacturing, or AM, the process of building components in layers with the gradual depositing of material has been used for prototyping and in short production runs for some time. Since the 1980s, in fact, Ford Motor Co. has produced prototypes of cylinder heads, brake rotors and rear axles via AM.
Other than its use for prototyping and in small production runs, the technology hadn’t made much leeway with the traditional metals used in automotive applications. According to a report by the U.S. International Trade Commission titled “Additive Manufacturing Technology: Potential Implications for U.S. Manufacturing Competitiveness,” that trend might be changing. The report states that the auto industry is “increasingly applying the technology to metals, with a focus on aluminum alloys, to construct lightweight vehicles.”
And although the specific metals aren’t named in the U.S. Trade Commission’s report, further adoption of AM can be seen at Daimler AG, which funded the development of a laser fusing machine that uses powdered metals to additively manufacture components for the carmaker’s vehicles and engines.
Printing details of the Strati 3-D printed car, the world’s first 3-D printed electric car. Produced by Local Motors in collaboration with the Association For Manufacturing Technology, Oak Ridge National Laboratory and Cincinnati Inc., the carbon-fiber car was printed and assembled during the week of IMTS 2014.
Time for titanium
The challenge with using AM in traditional metal applications – like those needed for the automotive industry – is inherent to the process. Additive manufacturing can happen through laser sintering, where powdered metals are heated just below their melting point, and through direct laser melting, where the powdered metals are taken to their melting point.
The former method requires a downstream step to compress and close up the resulting pores that come from the AM process while the latter can create stress and cracking in the material. Currently, neither have been ideal for the automotive industry’s stringent standards for strength and safety.
So although classic steels might not be ready for AM – because of the degradation to the material or the downstream processing required – titanium is proving to be an appropriate fit. With its low density, high strength and corrosion resistance, the material has a strong appeal in the automotive industry.
According to a report from Deloitte titled “3-D opportunity for the automotive industry: Additive manufacturing hits the road,” that appeal comes from “[titanium’s] ability to make lightweight, high-performance parts.” The powdered titanium doesn’t come cheap, but strides are being made to reduce those costs.
In terms of AM, the use of titanium is limited because “the metal powder produced through current methods is expensive, costing about $200 to $400 per kilogram,” the Deloitte report relayed. “U.K.-based Metalysis has developed a one-step method to produce titanium powder, with the potential of reducing the cost by as much as 75 percent. Jaguar Land Rover is looking to partner with Metalysis to use the low-cost titanium powder in AM.”
Watch a video from Metalysis, which gives an overview of the process to produce powder titanium.
The goal at Metalysis is to position itself “at the intersection of two powerful fundamental trends that will reshape industrial manufacturing: powder metallurgy and additive manufacturing.” The company goes on to admit, however, that traditional powder metallurgy is an expensive, complex and a niche market. But it’s working to change that.
“Metalysis has proven that its electrolytic process can transform natural rutile sands directly into titanium metal powder in a single step, which could be even more disruptive. Rutile is a naturally occurring titanium ore present in beach sands and is a highly cost effective feed stock for metal powder production. Metalysis developed the process itself and has patented it.”
The cost of manufacturing high-purity titanium had previously been a major barrier for adoption, but by cutting the number of production steps, Metalysis is making the material more financially approachable. In doing so, it will be able to compete with other performance alloys. For automotive and industrial applications, it could displace certain types of stainless steel and nickel-based alloys.
According to the company, “another significant issue in [AM] for metals is the gradual degradation of metal powders during processing as a result of the powder bed being exposed to oxygen and other contaminants. There is large potential demand for cost-effective methods of reconditioning metal powders. Metalysis’ technology is particularly suited to remove surface oxidized coatings.”
With companies like Metalysis working to overcome one of the challenges behind AM, the future looks bright for the technology. The next order of business, however, will be to unlock more material options to give the technology a broader appeal.