Cutaway view of a generic liquid chilled liquid cooler or heat exchanger – the blue fluid represents the cooler unused fuel that is removing heat from the hotter red fluid, the oil that is circulated and heated as it passes through the engine.
This project seeks to demonstrate advanced manufacturing technologies to the Air Force for developing sustainment solutions for legacy aircraft, by doing a deep dive into using advanced manufacturing technology to learn how to qualify these Bell Crank parts for flight, transitioning this to AFLCMC for implementation.
The AF faces significant challenges to replace out of production spares, replace low-volume parts, and repair legacy tooling to support aging aircraft. The fuel-oil cooler family of parts was identified by the AF as a challenging part to develop direct part fabrication capability to include initial process and part qualification strategies.
The fuel-oil cooler part was chosen because:
- Difficult to fabricate using convention technologies such as tube joining, thin walled bonding,
- Opportunity to develop the powder bed fusion process structure for future sustainment implementation,
- Very complex component with extremely thin walls, strict structural and thermal requirements,
- It has performance requirements and requires air worthiness certification.
- Challenging part to inspect and test.
Because the AM process produces a full component in fewer steps, access to complex internal geometries may become limited, compounding the difficulty involved with the inspection of fuel-oil coolers and heat exchangers. These AM parts will require greater scrutiny via proof testing and geometry inspection of the final part. If unresolved, the current lack of confidence in the process will cause unique qualification problems for future AM components. Phase 2 manufacturing demonstrations target direct part production of components and develop the necessary technology, data, and repeatable processes needed for future implementation of additive manufacturing for a series of part families.
The objective of the project is to technically substantiate a qualification pathway by generating data through coupon, sub-element, and full component testing, modeling, and data correlation. The data gathered on the program can be used to aid in future heat exchanger development, inspection, and qualification. In addition, the program will compare the fuel-oil cooler printing capability of an experienced OEM partner against that of a smaller, more typical supply chain partner, to provide a snapshot in current heat exchanger AM capability.
- Understand the critical parameters throughout the end-to-end oil cooler manufacturing process.
- Coupon and part level test data informing mechanical and functional performance characteristics.
- Demonstrate the transferability between critical steps of the manufacturing process (digital design, LPBF, NDE, QA/QC, etc.) to maximize supply chain capacity.
- Find solutions for challenges in metal AM production of thin walled elements (thermal effects, distortion, microstructural defects, and post-processing issues).
- Create a metal AM standard work procedure that ensures consistent repeatable part production.
- Find and capture the unexpected supply chain, manufacturing and production barriers, challenges and potential countermeasures associated with the oil cooler.
- Prove out that material and process has the nominal structural and functional properties for actual oil cooler parts, such as burst strength, heat transfer, etc. and that is repeatable over several parts leading to a path for qualification (MRL improved to 4).
For this proposed effort, the research team will use Laser Powder Bed Fusion (LPBF) technologies to investigate end-to-end AM production of an AF oil cooler. The general oil cooler to be investigated on this program is approximately 8’’ long and 4’’ in diameter. This oil cooler is representative of a family of parts which are lightly loaded, complex, and functional. Oil coolers and heat exchangers are two common examples of components which exist in the part family. The intent of this proposed effort is to bring to light enabling technologies which will both aid in qualification and also highlight those areas which need technical development and represent a qualification barrier. The project team will begin by investigating what is required to assemble the Technical Data Package (TDP). AM is unlike traditional manufacturing techniques, where the material properties are mostly distinct from the manufacturing process. Parts produced by AM have mechanical properties which are tied characteristics such as geometry and process parameters. The team will model residual stresses and optimize the build for orientation and supports. During the build, the project team will investigate possible in-situ monitoring techniques which can aid in qualification. A significant portion of the program is testing: non-destructive evaluation (NDE), destructive, and functional tests will all be performed.
Other Project Participants
- GE Aviation
- DRT Medical
- Youngstown Business Incubator (YBI)
- Youngstown State University
- U.S. Department of Defense
- Air Force Research Laboratory
- Air Force Life Cycle Management Center