In summary, it is important to note AM design terminology and how they apply to product benefits.
- Direct Part Conversion – Reproducing a conventionally manufactured product using AM.
- MfAM – Modifying a conventionally manufactured product to be successfully fabricated with AM.
- DfAM – Re-architecting a product form to take advantage of AM design flexibility.
As a company shifts from a strategy of direct part conversion to DfAM, more value is driven into the product in terms of performance, part count reduction, assembly labor reduction and lighter weight.
MfAM of parts is a common transition when a company is working to leverage all the benefits of AM. Mainly this includes MfAM of features to ensure that an AM part is able to be fabricated successfully, in which the main drivers are cost and time savings. Though there are similarities when using MfAM for various AM processes, there are also many process specific rules of thumb to keep in mind when modifying parts for AM.
DfAM could be considered a more mature state in the transition to leverage all of AM’s benefits. It is a systems level rethinking of a product that starts with concept ideation with the VOC. Ideas are developed by a multi-skilled team to perform a morphological analysis that decomposes system level functions to ideate new concepts. These concepts are sorted using the VOC on a Pugh Concept Selection Matrix. Concept solutions are then evaluated for what software is needed to construct the concept, following generally along the same digital chain. Generative design and/or topology optimization are used to guide AM hardware concepts that are later refined in analysis to be printed, and later inspected for iterative improvement.
Exciting design tools are available in the world of AM to increase performance, reduce weight and provide thermal solutions currently not manufacturable with conventional fabrication technologies. From cellular features found in metallic PBF to Functionally Gradient Materials found in DED blown powder systems, to support-free designs in polymeric SLS and material extrusion. incredible options exist to use AM as a way to enhance product offerings.
However, there are some caveats to heed. These would include modifying existing internal passageways, being mindful of inspection and certification of cellular features, and the machine sizing considerations for each process.
Design for Additive Manufacturing (DfAM) fundamentally challenges engineers’ and companies’ ways of thinking when it comes to advancing their products. Unconventional build processes permit unconventional shapes that improve designs, product or system performance, lead time, and part counts. Specifically this is achieved through a flexible toolpath and layer-by-layer nature of the build process.
This chapter discussed the general approach to DfAM, the tools available to aid the process, intermediate steps such as MfAM when working towards fully advantageous DfAM designs, tools and techniques based on build process and software constraints, and strategies for overcoming developmental challenges that the present industry is faced with.
Mastery of these methods and understanding the progressive design maturity phases of AM enables companies and designers to viably fabricate with additive manufacturing to fully leverage the many benefits and opportunities the technology has to offer today.
References
Daley et al, Journal of Mechanical Design, October 2016, Vol 138 http://www-personal.umich.edu/~gonzo/papers/daly-comparing-ideation.pdf
L. Hao, et al., "Design and additive manufacturing of cellular lattice structures." The International Conference on Advanced Research in Virtual and Rapid Prototyping (VRAP), Taylor & Francis Group, Leiria (2011)