Thermoplastics’ inability to bond to other materials also poses challenges. Spears worked with ORNL and Polynt on coatings for the first-ever, large-scale composite mold – a demonstration CFRP car hood. The mold was 3D printed on a BAAM in eight hours and gel coated. However, when they removed the hood from the mold, the tooling gel coat came off with it. With then President Obama and Vice President Biden visiting the next day, Spears says, “We pulled an all-nighter, sanded the gel coat off the hood and got it to work.”
Since then, multiple coatings have been developed to address these challenges, including TruDesign’s new TD Coat RT, a high-build, sprayable thermoset tooling coating developed in collaboration with ORNL and Polynt and released last year. Kunc says that future coating advances are crucial to the development of 3D-printed tooling. “In tooling, it is about the surface,” he says. “The underlying structure may be 3D printed, but there is a lot of work to be done in how you treat the surface.”
Temperature tolerances have created another challenge. Until recently, 3D-printed tooling applications were only suitable for low-temperature parts. As noted earlier, Sabic’s ULTEM was the first high-temperature 3D-printable material to reach the market. Last year, Techmer PM introduced Electrafil® PPS 3DP and Electrafil® PPSU 3DP high-temperature autoclave tooling materials for composite part production developed in collaboration with ORNL and BASF. Other companies are also racing to develop high-temperature, low thermal expansion solutions for additive manufacturing, including Stratasys and Magnum Venus Products, which is collaborating with ORNL, Polynt and Dixie Chemical to develop an industrial 3D printer and thermoset materials.
Tool life is another issue. For most applications, 3D-printed tooling has a much shorter lifespan than conventionally manufactured tooling. To date, most 3D-printed composite molds have been used to create well under 100 parts. Some conventional tooling can last for thousands – even millions – of parts.
Short tool life cycles mean that, for now, 3D-printed tooling can’t compete with metal tooling for high-volume production. Low-volume production, however, is a growing sweet spot. Consider Dassault Falcon Jet’s FRP printed cabin components. Schniepp says that because business jets are highly customized, the company may only need to build a handful of interior parts at a time. “So, they don’t need a mold that lasts thousands of cycles,” he points out. “They need something immediately that lasts for five [parts]. That’s where 3D printing fits extremely well.”