Many military aircraft, especially fighters, require engines with significant differences from commercial aircraft. They fly different flight profiles and perform various jobs. These differences continuously lead engine manufacturers to reassess priority and resources at the manufacturing level. Interestingly, with the wide range of technologies that can be leveraged to deliver the desired performance, Additive Manufacturing remains a technology of choice as it serves different purposes. A conversation with Pratt & Whitney’s Jesse Boyer sheds light on these purposes.
Acknowledged for the design, manufacture and service of aircraft engines and auxiliary power units, Pratt & Whitney (P&W), a subsidiary of RTX Corporation (formerly Raytheon Technologies), also manufactures gas turbine engines for industrial use, and marine propulsion.
Like most advocates of Additive Manufacturing, Pratt & Whitney’s first years as a user were dedicated to understanding and answering the 4Ws of the technology: what, why, where, and who. We were in the 1980s.
This meant “what is Additive Manufacturing (at the time rapid prototyping), where do we think the technology could be leveraged and who are the key stakeholders,” Jesse Boyer, Senior Technical Fellow for Additive Manufacturing at Pratt & Whitney explains. While answering the 4Ws is still pivotal along the adoption curve, the beauty of the journey lies in the way each user has made the most of the technology’s maturation and the applications they achieve.
Pratt & Whitney’s AM strategy: First steps and progression35 years later after their first investments in SLA 3D printing, P&W’s evolutionary processes reveal that if engine manufacturers haven’t received the same headlines as other industrials, this doesn’t mean they’ve been standing still.
“In the mid-1990s we continued to expand our experience in plastics, polymers and wax into powder-based non-metallic components. The advances in powder bed fusion expanded the capabilities and knowledge with such things as nested parts and unsupported structures. Beyond using the technology for basic demonstration pieces, P&W was very innovative by utilizing these advanced materials throughout the shop floor for tooling, fixturing, and visual aids. In the early 2000s, we continued to monitor the progress of the metallic powders that were available and started our internal journey into metals. This journey was aided by our unique capability of manufacturing powder and the increased maturity of the available additive equipment,” Boyer outlines.
What’s interesting to note is, P&W’s AM strategy is quite similar to most multi-national corporations exploring the technology at the time. This strategy can be summarized in two key steps: First acquisitions of AM processes and establishment of dedicated AM production facilities/centers.
VAT photopolymerization being the only AM process developed at the time for rapid prototyping, it made sense to see a first focus on “non-metal adoption for design aids.” This is followed by the “widespread use of non-metal AM for shop floor applications and tooling (VAT photopolymerization, Material Extrusion, Material Jetting, Binder Jetting, Powder Bed Fusion)” and over time, “the use of metal AM for non-production tooling, hardware and production repairs (Powder Bed Fusion, Directed Energy Deposition)”.
Today, P&W manufactures production metal 3D printed components using Powder Bed Fusion and continues to expand its Additive Manufacturing portfolio by methodically seeking other available AM processes.
As AM-dedicated facility centers are instrumental in the deployment and uptake of AM solutions, RTX Corporation established the RTX Additive Manufacturing Process Capability Center (AMPCC) in 2017 to accelerate the development and deployment of AM solutions across the entire corporation. Boyer notes: “The team is co-located with the RTX Technology Research Center in East Hartford, CT. The mission of the AMPCC is as follows:
- Accelerate maturation & certification of AM materials and processes. This includes process control expertise to further industrialization of additive manufacturing at both RTX production sites and within the external supply chain;
- Establish a tool chain to enable design-for-additive to meet performance targets while minimizing producibility iterations;
- Demonstrate the effectiveness of developed techniques through prototype builds;
- Develop additive training curricula and deploy across RTX; and
- Act as an interface to external additive consortia, academia, industry and national labs.
Over the past 7 years, AMPCC has grown to become RTX’s primary development site for AM with a large inventory of commercial & experimental laser powder-bed additive equipment sourced from multiple equipment OEMs. Materials under development include titanium, nickel, aluminum and ultra-high temperature alloys.
In addition to the AMPCC, RTX has multiple facilities domestically (Florida, Iowa, Connecticut, North Carolina, Minnesota, California) and around the world (Canada, Poland, Singapore) to support various efforts utilizing Additive Manufacturing.”
The use of AM in the development of military engines
We may have discovered P&W’s AM activities through the manufacture of aero-engine MRO components, but the company has been quietly making strides in the development of military engines.
It’s probably due to the sensitivity of the topic, but AM’s impact in the military and defense fields has often been highlighted through the production of spare parts or the deployment in remote environments. As one digs further, one realizes that AM has led to a myriad of applications in military contexts.
Boyer shares with 3D ADEPT a few of these applications:
“When it comes to Additive Manufacturing military or commercial, we typically look at four use cases. These use cases form the overall strategy for technology development and alignment of various initiatives, both at the product level and in the supply chain. The use cases include:
Part Substitution/Part Adaptation
- This use case applies when we have an existing part or component that we try to additively manufacture to address a casting, forging or conventional manufacturing concern. The advantage of this use case is a reduction in cost or lead time. Minimal design and material changes are required.
Sustainment (Aftermarket applications/lifecycle agility)
- This use case typically applies to a replacement or repair of a fielded part. The advantage of this use case is a reduction in lead time. In this use case, there are no design changes, but may possibly be a material change.
Unitization (combining several parts into one component)
- The advantages of this use case are supply chain optimization as well as an improvement in material usage, lead/assembly time, and cost. In this use case, there are some material changes and significant design changes.
Optimized design (generative or design for purpose)
- This use case fully leverages Additive Manufacturing design freedoms and is a clean sheet design for purpose.
For our military platform, we are very focused on Sustainment and how we can use Additive Manufacturing to ensure warfighter readiness, especially for our legacy applications. And Unitization and Optimized design, for use in our next generation propulsion systems that will potentially lower cost/weight and enable increased capabilities necessary for the advanced propulsion systems.”
Saving costs and time: Key examples of engines that benefited from AM
P&W has recently demonstrated three of these AM techniques (part adaptation, unitization and optimized design) in the development of the TJ150 engine.
Pratt & Whitney’s GATORWORKS team redesigned the TJ150 engine to ensure quick iteration. They have been able to reduce the total part count from over 50 to just a handful. Within eight months, from concept to engine test, using their in-house AM technologies, they have been able to redesign and test the 3D-printed parts of the TJ150 engine. Needless to say, this production would have taken way too much time via traditional manufacturing processes as it would have included supply chain sourcing.
Another engine that benefitted from all the four use cases mentioned above, is the F135 engine, which powers the F-35 Lighting II fighter aircraft. P&W explained that in 2018, its team started collaborating with a supplier to 3D-print the Turbine Exhaust Case trailing edge (TE) box, which directs the flow of exhaust gases. In general, such boxes require the use of hydroforming, an advanced process where a high-pressure fluid bends metal plates into precise shapes that can withstand the forces of jet propulsion. Rather than outsourcing for casting and machining, the supplier relied on unitization, then 3D-printed and finished the unitized part in-house. To give you a rough idea of how much P&W saved, keep in mind that the potential savings on castings and moldings alone approach $1 billion.
When asked what technical challenges are related to the development of safety-critical parts, the Senior Technical Fellow for Additive Manufacturing at Pratt & Whitney answered “confidence” before adding:
“The technical aspects to that [underlying challenge] are how to translate that confidence in how we communicate the components of variation, the impact of variation to the product, and develop tools (aka technology) that ensure that our processes are in control. Once we know these items, we can continue to develop Additive Manufacturing like many other manufacturing technologies for safety-critical parts.”
On another note, since post-processing remains one of the most challenging aspects of the manufacturing process chain with AM and given the fact that it contributes to increasing the cost of the final part, we couldn’t help but ask Boyer if it would be possible to reduce costs in post-processing through digitalization.
For Boyer, the good thing about AM is that it is already a “digital” process. While he didn’t emphasize these opportunities at P&W, he did believe that “there are many opportunities in Additive Manufacturing to potentially apply digitalization from cradle to grave related to the entire process.”
“Regarding post-processing, the largest opportunity is using digital tools to be predictive relative distortion, surface roughness, and defect generation to minimize things like machining and surface treatment and optimize processes such as inspection. Post-processing can “make or break” an AM application, so it is imperative to minimize/optimize that upfront in creating your manufacturing process to ensure the most cost-effective and robust application and digitalization is the tool for that,” he adds.
Future outlooks: The next military engines that will benefit from AM and more
The story of P&W reveals that we still have a lot to learn from the use of AM in the military field. While the use of the technology in this field is still controversial, at 3D ADEPT, we would like to focus on how the technology highlights the beauty of engineering in its simplest form.
Currently, more than 7,000 Pratt & Whitney military engines are in operation across 34 armed forces globally. With AM [and other digital manufacturing technologies] onboard, I do not doubt P&W will keep establishing new benchmarks for performance and reliability. Moving forward, the team will explore opportunities regarding the sustainment of legacy platforms such as the F100 and TF33.
“We are progressing with unitized components on our small TJ150 platform and the F135 to provide cost savings and lead time improvements, and we are also utilizing Additive Manufacturing as a key enabler for unitized and optimized components in our advanced programs.
Currently, our Additive Manufacturing candidate parts compete with those that are optimized for conventional manufacturing. Those conventional designs have been rigorously tested for flight safety and certification – and our additively manufactured components undergo the same rigor. We see continued potential for Additive Manufacturing to be applied across our value chain. We have gathered extensive experience in a number of applications and are now at a tipping point for greater use. We are always looking to evaluate where the technology can be used in new products as well as supporting the sustainment of our legacy engine programs. And, although AM may not work for every application, it clearly compliments existing and advanced P&W manufacturing approaches. We develop these options to innovate and provide sound benefits to our customers. We also continue to support the regulatory bodies, standards development organizations, and various academic, government and industry groups to support the transition to production,” Boyer concludes.
Editor’s notes
I am one of those people who believe that to understand how efficient a company is, it’s crucial to know the people who make the magic happen. In AM especially, there are different profiles that can help position a company at the forefront of its field. Jesse Boyer is one of them. He joined the AM department at P&W in 2015 and quickly spread the word about what’s happening behind the scenes through his participation in AM-dedicated panels.
In his role as Senior Technical Fellow for Additive Manufacturing, like the other fellows at RTX, he is driven to grow in technical leadership, create product innovation, provide coaching and training to increase workforce capability, and capture knowledge for reuse and to share with others.
Fellows apply their technical skills and experience in organizing, leading, and guiding the resolution of top technical challenges and issues of importance to the company. More specifically, he is focused on the maturation, industrialization, strategy, and curriculum of Additive Manufacturing.
This article has first been published in the 2024 September/October edition of 3D ADEPT Mag.
