Greater design freedom is recognized as one of the key benefits of using additive manufacturing (AM) for the final production of parts. Reducing the need for tooling and being able to more freely add and subtract material means that parts can be made with more geometric features than when manufacturing them with conventional processes, and with much greater complexity.

Value can arrive from reduced lifecycle costs, improved aesthetics, better ergonomics and enhanced performance. Wohlers and Campbell suggest this powerful example of enhanced performance using powder-bed fusion of aluminum: an automotive-engine cylinder head, additively manufactured by the German company FIT (Fig. 1). Cylinder heads must exhibit minimal friction, to optimize gas flow (intake and exhaust), water flow (for cooling) and vibration damping. And, the parts are load-bearing so they must be strong.

3D printed engine cylinder head with interior lattice framework
Engine cylinder head with interior lattice framework (Source: FIT)

A key feature of the 3D-printed cylinder head is gas-flow optimization. The design of the combustion chamber, intake tract and exhaust tract can be shape-optimized using computational fluid dynamics (CFD). The need to compromise an optimized design, due to manufacturing requirements, is much less with AM when compared to casting, which requires draft angle on the casting patterns.

While AM indeed offers interesting design opportunities, it also introduces unique design challenges. The mathematically optimized shapes generated by the software may not always be feasible to build. Wall thickness, hole size, and thermal stresses can be challenges. Powder removal represents another critical design consideration.

Most designers and engineers have not yet received formal education and training on designing for AM. Consequently, most companies considering AM for production applications are encountering it for the first time. The demand for education and training on designing for AM exceeds the supply.

Since design freedom is much greater with AM than with conventional processes, it is believed that AM will find increased use for developing entirely new types of parts and products, including automobile-engine parts, that will be superior to their predecessors in many ways.

>Read more by Terry Wohlers and Ian Campbell, 3D Metal Printing, March 11, 2016

Pushing the Design Boundaries with Metal AM