3D Printing ProcessesAerospace AMComposites

Airtech brings production-ready composite tools to aerospace

With its Print-Tech platform and Dahltram tooling resins, Airtech is proving that AM is the way of the future for composite tools and autoclave molds

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Since it was founded in 1973, Airtech Advanced Materials Group has been closely tied to the aerospace industry. The company, which today serves many sectors, began with the mission to supply aerospace manufacturers with the composite tooling materials they needed to produce strong and lightweight components made from fiberglass and carbon fiber. Over the years, as the company has grown and its solutions have evolved—notably with the addition of its large-scale additive manufacturing technology—aerospace still remains one of the company’s leading customer bases for composite tooling.

Airtech’s Print-Tech solution

The ever-strengthening relationship between Airtech and aerospace is owed to Airtech’s commitment to further advancing its composite tooling technologies and materials to meet the demanding requirements of the advancing aerospace sector. Additive manufacturing technologies have played a big role in this. In 2019, Airtech launched Print-Tech, a large-scale additive service for manufacturing composite tooling, such as trim fixtures, holding fixtures, layup molds and more.

The Print-Tech solution utilizes an extrusion-based printing technology, which can produce near-net shaped parts at a scale of 12 x 3 meters, as well as a precision machining post-process stage to ensure that final tools have the required tolerances. This hybrid approach enables manufacturers to accelerate lead times and cut back on tooling and production costs.

Airtech brings production-ready composite tools to aerospace - with its Print-Tech platform and Dahltram tooling resins.

In parallel to its AM service launch in 2019, Airtech also introduced a range of polymer composite resins under the Dahltram brand. These materials, as the company succinctly puts it: “meet the full range of tooling requirements for composite manufacturing industries.” Industries such as automotive, marine, energy and our main focus, aerospace.

The Dahltram range includes five tooling resins reinforced with either glass fibers or carbon fibers. They are:

  • Dahltram S-150CF: a modified ABS with carbon reinforcement ideal for low-temperature applications like rapid prototyping, trim tools, low-temp master models, and metal casting dies.
  • Dahltram C-250CF: a modified PC with carbon fiber reinforcement ideal for medium-temperature applications.
  • Dahltram C-250GF: a modified PC with glass fiber reinforcement ideal for medium-temperature applications and was specifically formulated for aluminum forming applications, like stretch forming or hydroforming.
  • Dahltram I-350CF: a modified PEI with carbon fiber reinforcement ideal for high-temperature applications like hot forming tools, autoclave molds and oven molds.
  • Dahltram U-350CF: a modified PESU with carbon fiber reinforcement ideal for high-temperature applications.

Dahltram use cases in aerospace

The entire Dahltram range is compatible with Airtech’s own large-scale additive equipment as well as numerous other print platforms. For example, in 2021 British aerospace company BAE Systems commissioned a high-temperature mold tool made from Dahltram I-350CF using Ingersoll Machine Tools’ MasterPrint platform. The tool in question was a fairing mold for a next-gen fighter aircraft and successfully underwent autoclave cycles to 355°F (180°C) cure and 100 psi (7 bar).

Airtech also designed and built a large-scale Automated Fiber Placement (AFP) mold for an electric vertical takeoff and landing aircraft company. This mold in particular showcases the complex geometries that additive manufacturing can realize for composite tooling, even at a substantial scale (the final part measures 4.3 x 2 meters). “The very intricate tool really highlights how tool design can change to help lightweight the structure,” says Zach Skelton, Senior Technical Support Engineer at Airtech.

The large AFP mold was built at Airtech’s Center of Innovation in Tennessee using Dahltram C-250CF and is made up of four pieces and two removable details. The tool also benefited from a pre-printing analysis. Skelton explains: “Our advanced knowledge of how our materials perform as printed allowed this structure to undergo stress analysis prior to printing.”

Of course, these two applications are really just the tip of the iceberg: Airtech’s additive technology and its range of Dahltram tooling resins are today used by a number of aerospace OEMs and subcontractors for custom tooling, jig and fixtures, infusion tooling, autoclave molds and metal forming dies.

A breakthrough in autoclave molding

In the aerospace industry, autoclaves are commonly used to process and cure composite materials by subjecting them to specific temperatures and pressures. This process is typically used with prepreg materials and functions to fully cure the polymer resins in the fiber composite sheets to ensure that final parts meet the stringent requirements of the aerospace sector.

Airtech brings production-ready composite tools to aerospace - with its Print-Tech platform and Dahltram tooling resins.

The process of molding prepreg materials and curing them inside an autoclave chamber itself requires the use of mold tools. For obvious reasons, these tools must be able to withstand the high temperatures and pressures of the autoclave, preferably for several cycles. Traditionally, autoclave mold tools were made from metals or from conventionally manufactured composites. In both cases, however, lead times and tooling costs were steep.

Airtech’s Print-Tech tooling and its range of Dahltram resins offer an alternative that several aerospace OEMs are understandably enthusiastic about. The hybrid additive-subtractive process enables users to rapidly produce high-accuracy molds from materials that can withstand varying degrees of autoclave temperatures and pressures. As Skelton says: “All of our materials are vacuum integral and autoclave capable for their respective use temperatures, without the need for any secondary coatings.”

The company’s Dahltram I-350CF resin is a particular standout for aerospace autoclave molding applications. The PEI-based material with carbon fiber reinforcement recently exceeded 500 autoclave cycles of 350°F (176°C) and 100 psi (7 bar) without any signs of failure. The autoclave thermal cycle testing was undertaken at Airtech’s state-of-the-art facility in Huntington Beach, California. There, composite specialists paid particular attention to monitoring the layup mold’s dimensional stability and vacuum integrity.

Airtech also conducted a thermal survey on the composite mold as well as elevated and pressurized leak checks, long-term analysis of dimensional stability, surface finish analysis, part fabrication and inspection and microscopic analysis. These post-autoclave tests confirmed that the 3D printed composite tool could withstand autoclave pressure and thermal stresses over 500 cycles.

Airtech brings production-ready composite tools to aerospace - with its Print-Tech platform and Dahltram tooling resins.

Airtech writes of the recent testing milestone: “Several development programs have been initiated because of the success in fabricating autoclave tooling, but their intent was for limited prototype production. The purpose of this testing is to validate Dahltram I-350CF for continued autoclave service and establish tool life from five hundred autoclave thermal cycles… Long-term analysis in the monitoring of dimensional stability, vacuum integrity, surface finish, part quality, and microscopic inspection all were conducted showing excellent results.”

The recent autoclave tests mark the beginning of the next stage for large-format composite 3D printed tools. Once primarily suitable for prototyping or limited production scales, Airtech composite tools are increasingly viable for larger production runs with autoclave processing. “The testing highlights that the printed tooling is not only capable of being used for rapid prototyping, or low production runs, but it is fully capable of meeting the rigors of full production use,” Skelton emphasizes.

The test results will be of interest to industries like aerospace that rely on autoclave processing in their composite production workflows. Now, the benefits of Airtech’s Print-Tech solution and Dahltram materials can be further maximized for not only large-format applications, but also larger scale production volumes.

The full results of the autoclave mold tests were recently detailed in a white paper published by Airtech, which can be downloaded via Airtech’s official channels.

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Tess Boissonneault

Tess Boissonneault is a Montreal-based content writer and editor with five years of experience covering the additive manufacturing world. She has a particular interest in amplifying the voices of women working within the industry and is an avid follower of the ever-evolving AM sector. Tess holds a master's degree in Media Studies from the University of Amsterdam.

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