AM expands defense manufacturing possibilities

Knight’s Armament Company (KAC) has been manufacturing suppressors from welded stainless steel since the early 1980s, starting with a large contract for SOCOM. Since then, the company has received numerous additional contracts for different types of suppressors – from machine guns to handguns. Original manufacturing included investment-cast baffles produced by an outside service provider. At KAC, the stacks would be welded together and then fitted into an outer tube. Next, that assembly would be precision-welded by hand.

“While over the years the process improved with new, better welders and welding equipment, that was the process we used for years,” says C. Reed Knight Jr., founder and owner of KAC. “That is until we started to consider moving to additive manufacturing.”

According to Knight, by using additive manufacturing (AM), they can now design and manufacture items not possible with subtractive manufacturing. “It gives us an added dimension of possibilities. By using the Renishaw RenAM 500Q systems we can create channels and baffles unlike conventional manufacturing, but probably one of the most important things is we can manage the thermal dissipation of the heat much better with AM produced suppressors.”

KAC does this by evaluating the parts after destructive testing and by using thermal cameras to evaluate the heat dissipation throughout the suppressor body. Knight notes that after this testing they can then make parts thicker, thinner, or lighter – wherever the change is needed to improve desired performance characteristics – and they can do so quickly when producing them with AM.

“Beyond this, probably the biggest benefit to investing in AM is we can go from an idea to a prototype in a shorter period of time, often having multiple ideas going at one time and then we pick the best solution for production – something very time consuming and costly before using AM,” Knight notes.

Just ‘dipping our toes into AM’

The company had a well-honed manufacturing method for building a significant number of suppressors monthly and had improved on it dramatically throughout the years. Because of that, Knight, and Murphy Walden (additive manufacturing lead at KAC) admit they were concerned that the cost of the AM method would not be practical, anticipating that high volume would be needed to justify the investment.

“Jumping into a whole new way of thinking for suppressor production was quite a challenge,” Knight says. “So, we began by buying what we call our prototype machine – the Renishaw AM250 single laser machine, agreeing that we’ll try this and see what works on this machine, then either stop or move forward with AM. Well, it took a few years really tinkering with the process to make sure we were happy with the results and had a solid product that we could bring to market before investing in this as a production-ready process we were going to change to.”

As Knight and Walden started seeing the benefits, they could achieve with the Renishaw AM250, they realized a single-laser machine was not going to be cost-effective when moving from prototyping to mass production, they knew they had to stop dipping their toes into AM and go all in.

Moving to full production

Moving up to the RenAM 500Q with four lasers would be faster, and after purchasing one of them, they ended up achieving 600% increased throughput – more than expected. But that, too, was not an overnight decision, working through the process over a 3-year span with support from Renishaw throughout.

“Going down the path of AM was really a team effort with Renishaw. We’ve used other Renishaw products for the past 30 years for quality and inspection across our range of mills and lathes, so we have a great relationship with our local sales representatives and technical representatives. And Walden has a great relationship with the team as there’s not a question that he has asked them that they haven’t been able to get back to him with a solid answer,” Knight says.

Walden has been on this project since they turned on the Renishaw AM250 to get it up and running, agreeing about the support they received. “Renishaw has been with us from the very beginning. They sent a technician out to train us, making sure everything was qualified and running right from the start, and their application team has also been with us from the beginning,” Walden notes. “The application team helped us develop our material profiles, working out any bugs as well as answering any question we had. Additionally, their service team has been phenomenal, getting answers back to me within a day, expediting parts if we need them urgently, and sending people out to troubleshoot within the same week we needed assistance. The support from Renishaw is key to getting us where we are today with additively manufacturing suppressors.”

Another benefit was that moving from the Renishaw AM250 to the RenAM 500Q was that no change was needed to anything with the production of the suppressors, except for increased throughput, which gave Knight and Walden the confidence that what they prototyped on the single-laser system would be the same on the 4-laser system. This is key, as Knight notes the company does massive amounts of testing on a suppressor design from the very beginning, shooting hundreds of thousands of rounds to evaluate life cycle, thermal characteristics, flash signature, back pressure performance, noise characteristics, and durability.

“This amount of testing to determine the safety and durability is mandatory as these are military suppressors for military customers who don’t have the choice of how many rounds will be shot,” Knight says. “The military can’t get into a firefight and then stop to let a suppressor cool down before continuing to shoot. Our suppressors must not only be lightweight and efficient, but also handle a battle-type scenario and whatever amount of rounds a soldier would fire. In addition to handling the heat, it can’t come apart, as that could injure the operator or cause collateral damage. Quality, safety, and consistency is a must.”

AM enables modifications

With the range of firearms used, the range of suppressors must keep pace. Depending on what the customer needs, such as the barrel length, different bullets have different powder burn rates. So, according to Knight, there are thousands of variables of suppressors based on the case and caliber, along with other factors.

“You have to take all these factors into consideration, as some are consistent across suppressors and some are not,” Knight explains. “AM production has really helped because we’re able to make small tweaks to our designs to optimize for certain use cases without needing to change-out tooling if we were manufacturing like we used to. Now we’re just modifying through CAD, testing, validating, and back to production.”

Walden goes on to explain, “Knight’s Armament currently manufactures 10 unique additive suppressors in a variety of calibers for military use. The attachment methods for these suppressors vary per customer requirements, which adds to the number of supplied configurations.

Additionally, if you’re shooting less, the suppressor can be light and if you’re shooting more they will require more thermal mass. That results in quite a few configurations, but it’s easier to manage when they’re additively manufactured.”

Material, post-processing

Printing these suppressors on the RenAM 500Q is done with Inconel powder, as Knight notes that it has great mechanical properties at elevated temperatures and holds its strength with no corrosion, making it a great choice for suppressors.

After the suppressor is printed and removed from the print-plate, there is still quite a bit of post-processing required. First is post-print machining, followed by deburring, and then the suppressor is laser-welded to the required attachment interface. The attachment is a machined part – either direct thread or a quick-disconnect of various types. Next, they qualify the bore with additional post-machining, followed by proof testing, and complete the process by coating them with a durable heat and corrosion resistant ceramic protectant layer.

While the move to AM for suppressors was not necessarily intended to save manufacturing time, the lack of skilled and qualified workers was certainly a driver – along with figuring out how to move to a consistent, repeatable “lights-out” process.

“It’s basically a lights-out process while the cores are printing, so we can have our employees working on the other steps in suppressor production, freeing them up to handle the post-processing steps, such as welding, post-machining, and coating,” Knight explains.

In addition to looking at areas where the company could expand use of AM, it is not a quick process because Knight notes it’s a whole new way of thinking about designing and manufacturing a product. The process begins by acknowledging that the product is going to be an additive product rather than a subtractive product, not just taking a subtractive product and re-engineering for AM. And while the company is not rushing through the change of other products to AM, they continue to use it for prototyping in many of those areas, as well as using it behind the scenes to help develop fixtures and tooling.

Always aiming higher

Producing the best with the right partners is key. Knight and Walden summarized that one of the reasons they chose to partner with Renishaw was that upfront the company showed its willingness to not just be a sales company or furnish an AM machine, but they became a team partner with KAC. The team at Renishaw helped the company understand a new method they were not familiar with, and they were alongside the whole way to demonstrate and help make improvements as the project progressed.

“There’s nothing here at Knight’s Armament that we build that’s just ‘good enough,’” Knight says. “We’re constantly looking at the improvements we can make for several reasons. If one of my employees makes a mistake, or we don’t produce something just right, somebody doesn’t come back alive. We know if a soldier is going to put their life on the line that we need to give that soldier the absolute best tool to use to defend their life and do their job out in the field that needs done. It’s our responsibility to do that, and that’s what makes me get up and go to work every morning.”

Knight’s Armament Company https://www.knightarmco.com 2024 SHOT Show Booth #10367

Renishaw Inc. https://www.renishaw.com 2024 SHOT Show Supplier Showcase Booth #51610

About the author: Elizabeth Engler Modic is editorial director for GIE Media’s Manufacturing Group of magazines. She can be reached at 216.393.0264 or emodic@gie.net.