What makes designing for 3D printing different from other manufacturing technologies?
NASA mechanical design engineer Richard Hagen, left, and ORNL researcher Michael Borish inspect a lunar rover wheel prototype that was 3D printed at the Manufacturing Demonstration Facility. IMAGE: Carlos Jones/ORNL, U.S. Dept. of Energy
The concept of intentionally designing products to work within the constraints of the available manufacturing technology is not new. Often abbreviated as DFMA (Design for Manufacturing and Assembly), the goal is for design engineers to reduce or minimize the difficulties of manufacturing and assembling a product, thereby reducing its overall cost.
While this sounds simple in principle, in practice it requires extensive knowledge of manufacturing and assembly processes, material behaviors and supplier capabilities. As a result, DFMA encourages broad collaboration across organizations and even whole supply chains. Consequently, the engineering community has made wide efforts to advance DFMA through industry practices (such as integrated product teams), rules and guidelines (such as the Design for Manufacturability Handbook) and technical conferences (such as the ASME IDETC-CIE).
Despite the many nuances of DFMA, there are two ways to reduce the time and cost of production which apply to virtually any product in discrete manufacturing: minimizing the number of parts and eliminating fasteners. With conventional manufacturing technologies, there’s a hard limit on how far this approach could go, with designers having to weigh the time required for assembly against the complexity (and hence manufacturability) of the components involved. In other words, the geometries and physics involved in forming and machining set constraints on designs, and DMFA is about working within those constraints.
However, with the introduction of 3D printing technologies many of those constraints have been eliminated, though certainly not all of them. Depending on the particular additive technology, there are also new constraints (such as the need for supports) that design engineers must consider.
What this means is that the objective of design for additive manufacturing (DfAM) is essentially the same as it is for DMFA: maximize product performance within the constraints of (additive) manufacturing technologies. Alternatively, you could say that DfAM is about finding a balance between the new design opportunities (complex geometries, part consolidation, lattice structures for lightweighting, etc.) and the unique constraints of 3D printing (the need for supports, part orientation, material limitations, etc.).
To sum up: the objectives of DMFA and DfAM may be the same, but the approaches necessary to achieve those objectives are considerably different.
