Design strategies for Additive Manufacturing

​Additive Manufacturing (AM) is a set of manufacturing  technologies capable of producing complex, three dimensional objects without the need for individual tooling.
 
Once designers identify suitable products in a company portfolio , they can select a suitable design strategy to develop new and/or improve existing products. This choice determines the development process and should be made carefully.

Benefits of Additive manufacturing

Various end products (re)designed and manufactured with AM technologies, demonstrate the benefits of AM [link] [1]:

• design flexibility ​and use of innovative design elements
• potential for easy mass customization
• novel materials generation ​and innovative manufacturing strategies. 

In addition, case studies show that AM is capable of industrial productions and that direct part production favours [2]:

• reduction of tooling,
• agile manufacturing operations,
• reduction in inventory,
• decentralized manufacturing,
• part consolidation,
• light weight and lattice structures. 

To take advantage of these benefits, it is necessary to identify parts in a product where additive manufacturing’s benefits create the most value to the customer: typically performance improvements, better efficiency or costs reduction.

Designers are best suited for this task: they have detailed knowledge of the functions and applications of the components. 

Design strategies for additive manufacturing

There are two main general strategies for Design for AM (DFAM). We can take advantage of:

• AM as a manufacturing technology with cost benefits at complex parts and small lot sizes,
• AM’s little restrictions on manufacturability, ie design freedom.

Manufacturing driven design strategy

This option relies on substituting conventional manufacturing with AM to derive benefits such as reduced costs and time-to-market. In this case, the designer still complies with the design rules of other standard manufacturing technologies. This strategy can be useful in a few instances:

• As rapid-prototyping: to rapidly test critical aspects of a new design for mass production or commercial viability for niche markets. Once a design is validated, the production can be scaled up and transferred to a mass production process like injection moulding.
• As part of a sequential systematic test to assess the potential transfer of a product portfolio towards a given AM technique such as SLM. In this scenario, it is critical to establish like for like comparison between conventionally and additively manufactured components. For instance, the material must exhibit similar or superior mechanical properties. If the material characteristics remain equal or superior, AM can only add up benefits by taking advantage of function redesign.
• …

Function driven design strategy

​The function driven design strategy exploits the characteristics of each AM technique to improve the functions of a product. The resulting design often contains complex internal structures or integrated joints which are impossible to manufacture conventionally. Using AM’s flexibility in design usually rules out the transfer to conventional manufacturing without major adjustments to the design.

Take away

​The manufacturing driven design strategy takes advantage of cost benefits at complex shapes and small lot sizes. This strategy requires a designer to comply with the design rules manufacturing process.
 
The function driven design strategy neglects all conventional design rules and focuses on optimising parts’ functions according to users’ requirements and fabrication process characteristics. The benefits of this design strategy include improved performance and efficiency, reduced weight and assembly parts numbers.

References
[1] Gebhardt A. Understanding Additive Manufacturing - Rapid Prototyping - Rapid Tooling - Rapid Manufacturing. 1st ed. München: Hanser; 2011.
[2] Wohlers T, editor. Wohlers Report 2013 - Additive Manufacturing and 3D Printing State of the Industry - Annual Worldwide Progress Report. 18th ed. Fort Collins, CO: Wohlers Associates; 2013.