Never heard of Jud Hall? Look up United States Patent 3962394 and you’ll find all you need to know about his invention, if not the man. His “method for molding fiber-reinforced composite tube” opened the door to plastic pipe and tubing with increased corrosion resistance, lower thermal expansion, greater insulative properties and significantly higher strength than existing products. Along the way, Hall helped raise awareness of his craft by participating in and leading the group once known as the Composites Manufacturing Association of SME (CMA/SME), now the SME Composites Technical Community.
Despite his significant industry contributions, the former TRW Inc. researcher didn’t invent composite manufacturing. With all that’s going on in the 3D printing world these days, it’s easy to overlook “the other” additive manufacturing. It’s been around far longer, is in many ways more mature, and like many of its newer counterparts, is increasingly automated. Historians credit the Mesopotamians, who created an early form of plywood more than five millennia ago, followed by Genghis Khan and his hordes of Mongol warriors, who many centuries later conquered large parts of Asia with little more than fearsome ambition and silk-wrapped bows made of wood, bone and glue.
Mick Maher is an expert on the subject. This explains why he recently received SME’s J.H. “Jud” Hall Composites Manufacturing Award, which honors Hall (1931-85) for his contributions to the composites industry. He’ll tell you that Hall helped advance modern composite manufacturing, which some suggest began in 1907 with chemist Leo Baekeland’s development of the synthetic resin Bakelite.
The president of Baltimore-based consulting firm Maher and Associates LLC, he has a bachelor’s degree in chemistry and has worked in the composites field since 1983, holding positions at Martin Marietta, DuPont, ASTRO America and the Defense Advanced Research Projects Agency (DARPA), among others. Manufacturing Engineering (ME) had an opportunity to speak with Maher recently. The following is an edited transcript of the conversation.
ME: Tell us about your company. What do you do there?
MAHER: After leaving DARPA in 2016, I decided to go into consulting and engineering development. Much of that work is focused on helping companies transition to advanced material and manufacturing technologies, including hypersonics, additive manufacturing and composites. But we’re also in the process of standing up a facility down in Greenville, South Carolina, that specializes in press-based processing of thermoplastic, resin infusion and short-fiber composites, and ways to reduce manufacturing costs without sacrificing performance.
ME: How do you achieve this last part?
MAHER: Automation is a big part of it, but there’s also a need for an intimate understanding of the process so that you can optimize all the various steps, whether it’s preforming, curing or what have you. As with most manufacturing technologies, it’s mainly about removing variability and waste, including setup time. That’s because much of the composites work today is medium-volume, high-mix, so we’ve invested in quick-change tooling and other technologies to speed changeover and maximize press uptime.
ME: Earlier, you mentioned hypersonics, which to me suggests military work. Can you share any details?
MAHER: We’re primarily military right now—attritable [disposable, purpose-designed] drones and collaborative combat aircraft for the most part. But there’s also great interest in urban air mobility. Both have similar requirements from a cost and production rate perspective, and both are made more feasible with advanced composites.
As for hypersonics, refractory or “carbon-carbon” composites are typically used in boost glide vehicles and various weapon systems. But the fundamentals of the manufacturing process are much the same.
ME: Which drone components are made of composites? Is it the exterior?
MAHER: Yes, as are many of the structural components. People tend to think these are aluminum, but with these attritable aircraft, it’s all about cost versus performance, making composites a clear winner. Collaborative combat aircraft raises the bar on that somewhat, in that you’re not worried about life and limb, but you’d still like to get them back after the mission. Again, composites take a lead role.
ME: Given that much of the composites industry has traditionally relied on hand layup—a highly skilled, somewhat artistic manufacturing method—what’s the state of the knowledge base as we move into higher-volume, more automated production?
MAHER: One of the goals for the facility I mentioned earlier is workforce development. As we integrate automation into these press-based composite processes, you’re not going to need the skillsets that were developed during the days of hand layup, which is very much an on-the-job learning approach. I think we and others need to work hard on developing the future workforce, whether through collaboration with vocational/technical schools, universities or community colleges. In our case, we’ve collaborated extensively with universities in South Carolina on this and several other initiatives.
ME: As an outsider, it seems that much of the secret sauce in composite manufacturing comes down to fiber orientation. Thoughts?
MAHER: It’s not that simple. When I started at Martin Marietta in the ’80s, many manufacturing people were saying the key is to align the fiber with the load direction. There’s some truth to that, and today’s automated machinery does an excellent job at achieving this orientation.
But you also need to consider the inspection and qualification process, the need for design flexibility and the fact that you must be able to handle load cases that aren’t exactly what you planned for during design. Simply put, the more optimized you make that structure, the more susceptible you are to failure from an unexpected direction.
ME: What about inspection and qualification? I’ve heard from some of the additive manufacturing people that they’re being held to a higher, somewhat unfair standard compared to traditional processes like casting or welding. Where are we at on composites?
MAHER: I’m not sure I agree with that. The challenge with additive and composites is that you’re making the material at the same time you’re making the part. Consider laser-powder-bed fusion. Here, you can test the powder before the build and get a handle on the material properties, but then you’re faced with what could be miles and miles of welded joints, one on top of the other. People will naturally want to do more inspection there because you really don’t trust it as much as you would a single weld joining two pieces of plate stock.
Composite parts present a similar situation. At the end of the day, we have to get to the point where there’s sufficient confidence in both the processes and the materials that go into them.
ME: So how do we get there?
MAHER: It will take more time and successful use cases, but it goes without saying that we’re much closer than when I started in the industry. For instance, finite element analysis (FEA) was so new back then that no one would dream of using it for qualification—they would have to do intensive hand calculations and make sure that the results matched.
FEA is more widely accepted today, but the fact remains that when you talk certification, the airworthiness officials don’t trust the model. They want testing, and if I were one of the people signing their name, I’d want it too.
Qualification (the step that precedes certification) is a little bit different, in that you can use these models—assuming they’re properly calibrated—to reduce the amount of testing needed to bring products to market. That’s some of what I did at DARPA, through its “open manufacturing” program.
ME: In closing, what do you see as the biggest obstacles—or opportunities—facing the composites industry today?
MAHER: Going forward, I think everything is about adopting digital transformation. It’s our relatively newfound ability to connect all the different pieces of the manufacturing process that will have the most significant impact on the industry over the next 10 years.
To that end, I have developed a concept for direct-to-certification manufacturing, where we use the models to their full capability. If you understand your processes well enough, and have a high-resolution grasp of the raw materials and their properties, and everything is digitized and tied together in a comprehensive way, then there’s really no reason to qualify anything, right? But there’s also the need to look at additive and composites differently.
Right now, most of us take a macro view of the process and parts, but people are beginning to realize the immense opportunities for multifunctional, multidomain performance that will come when you manage the microstructure. So while we’ve come a long way since the day in 1975 when Jud Hall and TRW filed for a patent on his fiber-reinforced tube manufacturing method, we still have a long way to go. It’s an exciting time.
