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- Quality in metal AM
- Case: GE engine bracket
Case: GE engine bracket
We use a case of the GE engine bracket for discussing quality during design and processing of metal AM aerospace parts. The value chain chapters are used to discuss quality issues for this particular case. The page gives a summary, whereas the complete document can be downloaded HERE.
Illustration of the GE bracket for topology optimization.
Keywords: Engine bracket, quality in aerospace
- Product description
- Product requirements
- Machine and process parameters
- Post processing
- Metrology & Maintenance
1. Product description
Loading brackets pay a very important role within the engine of an airplay: they must support the weight of the engine during handling without breaking or warping. The brackets may be used only periodically, but they stay on the engine at all times, including during flight.
2. Product requirements
The product requirements in terms of material- and functional requirements, loading conditions, metrology and quality management system (ISO 9001 for supplier) are discussed in the full document.
For design of the bracket, we use the structure, as presented in the AM value chain, considering of four main steps and several sub-steps:
- Original part
- Definition of geometry (CAD)
- Definition of load cases and constraints
- Part requirements
- Analysis of original component
- Topology optimisation
- Optimisation parameters
- Assessment of results
- Assessment of mesh sensitivity study
- Part re-design
- Materialise 3-Matic software
- Regularise, smooth, and replace unwanted aspects
- Add substructures
- Final verification
- Analyse under design loads
- Verify adequacy of solution
Requirements for material consists of the following standard: ASTM F2924-14 “Standard Specification for Additive Manufacturing Titanium-6-Aluminium-4 Vanadium with Powder Bed Fusion”.
5. Machine and process parameters
Are discussed in the full document
6. Post processing
In order to obtain a final part it is necessary to develop these steps:
- Remove part from the build platform
- Remove supports
- Sandblasting the surface
- Clean the part to ensure that there is not dust
- Machine the holes
- Heat treatment: HIP (Hot Isostatic Pressure treatment) that is a post-process used to reduce the porosity of metals and improves the material's mechanical properties (fatigue behavior) and workability.
7. Metrology & Maintenance
Test requirements are specified in ASTM E192. Standard Reference Radiographs of Investment Steel Castings for Aerospace Applications. Other considerations will include determining load at failure and long term durability.
For aerospace specific quality issues, we refer you to the chapter 'Aerospace'.
For further reading about this particular case we refer you to the following sources:
This website contains information on the GrabCad challenge, during which a competition was held to optimize the GE bracket:
- The GE Aircraft Engine Bracket Challenge: An Experiment in Crowdsourcing for Mechanical Design Concepts
Scientific article on the GE grabcat challenge as a crowdsourcing experiment.