Industrial designers do not yet have a clear framework to review, redesign, and optimise existing designs in order to take full advantage of the benefits that SLM can offer.
In this post, we present the methodology used to redesign an aluminium bracket for SLM in order to save weight while maintaining performance. The key objective is to take into account the manufacturing constraints, user’s requirements and take advantage of technology’s design freedom.
1. Capture and analysis of requirements: capture of functional specifications: structural (loads) requirements, DFM rules, material characteristics,…
2. Conceptualisation: creation of initial CAD concepts, FEA analysis (loads map), topology optimisation,
3. Manufacturability assessment: review of concepts for manufacturability for SLM according to process characteristics (layer thickness,… ), SLMed material characteristics (anisotropy, surface roughness… ) best efforts to minimise of post-processing (supports,…).
4. Evaluation of proposed designs against initial functional and user requirements.
5. Decision: multi-criteria decision making to pick most suitable option.
1. Capture and analysis of functional and user’s requirements
- reduce weight by 20%;
- maintain equal or superior performance;
- prevent permanent deformation.
- provide the same recess features as in the original design;
- operate using the existing clamping components;
- be compatible with the interfaces of the existing mounting rail in the bottom of the bracket;
- handle three orthogonal, non-concurrent shock loads equal to 1200N.
From this, a wide range of 3D models are produced using a standard CAD software in order to explore and document a catalogue of concepts. In turn, FEA is carried out to analyse whether these concepts can bear the mechanical forces without failure.
- avoid closed cavities;
- promote self-supporting structures;
- choose proper clearances;
- consider surface finish;
- consider post-processing.
This leaves us with a set of potentially viable designs that fit design, functional, manufacturability and structural requirements.
4. Performance evaluation
If some requirements are not met after verification, designers can make minor changes in the design and remodel it. However, if most of the requirements have not been met, designers should start from step 2 and build a new concept.
5. Decision making
In this case, the analytical hierarchy process (AHP) is used to decompose the decision into a hierarchy of easier sub-questions.
- minimum displacements,
- manufacturing cost
- and surface quality.
K. Salonitis, S. Al Zarban, Redesign Optimization for Manufacturing Using Additive Layer Techniques, CIRP 25th Design Conference Innovative Product Creation, Procedia CIRP 36 ( 2015 ) 193 – 198, doi: 10.1016/j.procir.2015.01.058