In order to gain regulatory compliance, Tronosjet Manufacturing had to demonstrate the quality and reliability of printed parts to the FAA and its regulatory group - which included material scientists and aerospace engineers.
To do this, Renishaw provided multiple laser powder bed fusion AM systems to Tronosjet to help produce various aircraft components.
These include an engine thrust control pulley bracket — one of the first additively produced metallic parts to be certified by the Federal Aviation Administration (FAA) under its Parts Manufacturer Approval (PMA) scheme.
“Over the years, we have communicated with the FAA many times on different projects, and we understand how it works as a regulatory body,” added Campbell. “This gave us an advantage because we knew what to expect. We knew that we’d need to prove the bracket’s safety using tensile, fatigue and non-destructive testing (NDT) and to show that it wouldn’t degrade over time.”
Tronosjet relied on Renishaw to not only prove that the bracket could pass NDT and tensile testing, nut also needed to show the repeatability of the titanium alloy in its manufacturing process. Renishaw provided the AM system to produce complex metallic components and help sway regulators.
“Our relationship with Renishaw goes way back, and we first came to the UK to meet with its CEO in 2018,” added Campbell. “The reason we decided to go for a Renishaw system is the brand - it’s a trust marker and we knew it was a company that offers excellent engineering and process capability. Its RenAM 500 series are world-class AM machines, and of the quality we needed to achieve FAA certification. Also, we were impressed with Renishaw’s presence across North America, and its local support was important for us as a small business taking on new technology.”
Tronosjet has since purchased three RenAM series machines from Renishaw — the AM250, the 500S Flex and the 500Q. All use LPBF for metal component volume production and have a build volume of 250 mm x 250 mm x 350 mm. The AM250 and RenAM 500S Flex are both single-laser machines, while the RenAM 500Q is a four-laser system, with the latter offering automatic powder recycling.
Tronosjet chose the AM250, which can produce complex metal components directly from computer-aided designs (CAD) models using materials including titanium, aluminum and nickel. It chose this system because the AM250 can produce parts with the high material properties expected by the FAA, and it doesn’t employ multiple lasers or reuse powder — these are still highly innovative production features, which may have sparked caution among some of the FAA’s regulators.
Tronosjet printed the engine bracket on the AM250 using a Ti-6Al-4V titanium alloy.
Its team then conducted extensive NDT, static, functional and destructive testing and compared its performance with the original cast magnesium bracket, finding that the titanium-printed version was five times stronger. The printed bracket survived loads over 22,000 lb, while the original broke at just 4,000 lb.
“The numbers put things into perspective,” continued Campbell. “The bracket’s superior tensile strength shows that the titanium print is capable of withstanding significantly higher loads then required, when the aircraft is in flight. This helped convince the regulators that AM was more than up to the job.”
After receiving the FAA, Tronosjet can now produce and supply it to customers.
“We’re grateful for Renishaw’s engineering prowess and support — it delivered great products, which have been critical for us achieving certification,” concluded Campbell.
Founded in 2016, Tronosjet uses additive manufacturing to produce different aerospace parts. The team designs, prints, heat treats and metallurgically tests parts.
