Additive Manufacturing with Composites in Aerospace and Defense
Insights from an air force engineer on the DoD’s applications of additive manufacturing and 3D printing’s growing influence in industry
Jordan Weininger is an Advanced Composites engineer for the United States Air Force. He works at the Advanced Composites Office on Hill Air Force Base. The opinions shared by Jordan Weininger here are based on his own experiences and do not reflect the opinions of the U.S Air Force.
Future manufacturing technologies are already here, but the challenge is getting these technologies into the industries where they can make a difference. It’s not just about creating the technology, it’s about ensuring you have repeatable processes and B-basis allowables — the minimal allowable mechanical properties needed to design a part with a specific material — in order to implement these new technologies in the real world.
Through my current work in composite engineering with the advanced composites group at Hill Air Force Base, I’ve been fortunate enough to gain insight into applications of advanced additive manufacturing technology in the aerospace and defense industry, as well as the larger implications for industrial 3D printing outside of the DoD.
Composite Engineering in the U.S. Air Force
Composite engineering is a field that's applied to more and more industries every year. The desire to work in this type of field led me to the Air Force, and specifically to the Advanced Composites Office. This is an Air Force office, but we support all DoD organizations. In addition to the design, analysis, engineering, and repair problems of composites we also instruct week-long courses for DoD organizations and their employees. These courses include curriculum covering an introduction to composites engineering and a more advanced technician training course. In these courses, students from all over the DoD can get hands on experience designing and repairing composite materials.
Industrial Expansion of 3D Printing
In my time working in various industries, I've seen countless stories about additive solving prototyping problems for businesses, especially for small businesses. In the small business manufacturing lifecycle, the ability to prototype functional components before going through the steps it takes to ramp up mass production is crucial to success.
With today's diverse printable materials — ranging from metals to composites to thermoplastics more useful than just PLA — 3D printing allows for fit and functional testing for engineers, and it really provides the digitalization medium necessary to make a business case in the early stages of product development. It's not necessarily the additive piece that solves one issue completely, but 3D printing in general. The technology of 3D printing enriches so many crucial steps in the design process that it makes production problems easier to solve.
I think we're going to see additive manufacturing growth in tooling: brackets and hinges, mounts, and shop aids. In the near future we will see 3D printing encompassing the functional end use parts space. It started with PLA, which everyone can print in their garage. Now, with companies like Markforged being able to print composites and metals, these stronger and more useful materials open a whole new door for additive manufacturing.
The quality and strength of materials available for 3D printing changes the economic and technology choices for all types of businesses. Now, if it’s a low production part, 3D printing is cheaper than running a mold or to CNC parts from a billet. This really opens the door to a set of new industries to adopt 3D printing.
Why the Air Force is Turning to Additive
The direct applications for 3D printing in the air force and military is also growing. There are two key areas that apply directly to the military's usage of additive manufacturing.
1. Small Batch Production: For the aircrafts we work on specifically, we're not making hundreds of thousands of parts, like you would a production part. Aerospace and military applications are mostly small production runs, and sometimes these parts can be produced in the field depending on the additive manufacturing technology available.
2. Distributed Manufacturing: The power of additive also lies in it’s distributed properties. When the 3D printers can be placed cheaply on various bases, if something breaks, you don't have to ship a new part from across the world. You don't have to rely on a single production source with additive manufacturing. Multiple printers in multiple locations can create parts.
Due to these factors, I see additive manufacturing developing a much larger role in military and aerospace applications.
Additive Tooling for Aging Aircraft Repairs - MRO
The advanced composites office is tasked with finding solutions in composite design, analysis, engineering and repair specifically through the Life Cycle Management Center, which covers aging aircraft repairs. Often, original tooling for aircrafts has been destroyed or misplaced, and we can use additive to potentially make new tooling for those aircrafts in order to keep them flying.
One of my main objectives is developing additive tooling so that we can make composites for those aircrafts. When making parts for an aging aircraft that we don't have the tooling or CAD data on anymore, sometimes we create a 3D scan of an existing part and then backtrack from there to make a model that we can then 3D print and use as a tool for that part.
Additive Manufacturing for Composite Tooling
When it comes to the advanced composites office, we have been interested in 3D printing from a composites perspective and how it can help the manufacturing process. Currently, many companies use large scale Fused Deposition Modeling (FDM) 3D printed parts for tooling, but they have to post machine parts after they come off the printer before they prep them for a composite lab. This means they have to 3D print an accurate CAD drawing or CAD model, and then put this on a CNC machine, machine back, and then prep for composite layup with a mix of sealants to make it vacuum tight and mold release agents. This is a step — putting it onto the CNC — that we'd like to eliminate because it takes away a lot of the advantages of additive manufacturing tooling.
From my perspective, a lot of the advantages of additive manufacturing tooling is that you get a part accurate to your CAD design quickly and easily. If you have to post machine that mold before using it to make a composite part, you might as well use some kind of tooling board, which is going to be way cheaper and just as easy to machine. However, if we can eliminate the post machining step, you can save serious time and energy. If we produce a 3D printed part with a vacuum tight surface finish without post machining, hand sanding, or anything where you could decrease the accuracy of the geometry, I can see a world where additive manufacturing is used extensively for composite tooling. That's a really high impact area that’s just on the horizon for 3D printing.
Image Credits: Hill Air Force Base photo gallery
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