Crawl, Walk, Run Your Way into Additive Manufacturing

By Timothy W. Simpson, Director, Additive Manufacturing & Design Graduate Program, Penn State University

Timothy W. Simpson, Director, Additive Manufacturing & Design Graduate Program, Penn State University

The hype for additive manufacturing (AM) continues to exceed our expectations. Market projections continue to skyrocket, corporate investments and venture capital continue to grow, patent applications are on the rise, and job growth is accelerating. Even the law suits and legal battles are starting to pick up—a sure sign that the industry is “real” and quickly maturing.

Having the ability to 3D print complex structures and intricate shapes that were previously too expensive or impossible to manufacture would excite anyone. AM creates new possibilities for lightweight lattices, topology optimized design, enhanced heat transfer, and consolidation of multi-part assemblies, to name a few of its advantages over conventional manufacturing processes. With some AM processes, designers can now engineer multi-material structures that enable functional grading of mechanical and material properties. The design—and material—freedoms afforded by AM far exceed anything we have been able to achieve cost effectively with conventional manufacturing processes such as casting, forging, machining, etc.

While many designers and engineers would love to jump straight to lattice structures and topology optimized designs to show what AM can do, their bosses and managers tend to be more risk averse, particularly in larger, established companies. Established companies tend to want an “apples to apples” comparison between an AM-made part and the same part made by conventional means before they make the leap to more intricate geometries that can only be made with AM. Once they have this comparison, then they begin to understand what AM can (and more importantly cannot do), and they start to adapt their part for AM. Eventually they may have an opportunity “clean sheet” a new design and optimize the part for AM, provided they have built up enough confidence and trust in the AM process itself. 

This “replicate-adapt-optimize” pattern is consistent in almost every company that I have worked with in the aerospace, automotive, consumer goods, defense, energy, medical, nuclear, oil and gas, and space industries in the last six years. The challenge in each stage is reconciling people’s expectations with the freedom that the designer has to (re)design the part for AM.

"Designers can now engineer multi-material structures that enable functional grading of mechanical and material properties"

For instance, when replicating a part with AM, the goal is to reproduce a part exactly with AM so that it can be compared to the conventionally manufactured part in terms of performance, quality, cost, etc. Because the part is being replicated exactly, the geometry is fixed, and the material is the same; so, the AM part will not weigh any less or be any stronger. Worse, the AM part will likely a lot cost more to fabricate given the high cost of material feedstock for AM. Fortunately, there will likely be a lead-time advantage when replicating a part with AM, and expectations need to be carefully managed during this first stage given the limited benefits that are possible.

Replicating with AM reveals many of the inherent limitations of layer-by-layer manufacturing that AM enthusiasts do not want to discuss. Designers can then start to adapt their part for AM, eliminating troublesome features that can increase the cost or post-processing needed for an AM part. The AM part still has to achieve the same functionality, but overhangs, thin walls, internal passageways, etc. can be modified to make it less costly and difficult to fabricate the part with AM. Designers may also be able to add features that enhance part quality, which will start to improve performance and lower the cost of the AM part while still enjoying the lead-time advantages that can often be achieved with AM.

Only when the designer has the freedom to “clean sheet” an entirely new part for AM or redesign an existing part will the full benefits of AM be achieved. Because the part is optimized for AM from the start, the designer can easily address the restrictions inherent in each AM process while leveraging AM’s design freedom to optimize performance, minimize cost, and really capitalize on AM’s lead-time advantages and other benefits.

Replicating, adapting, and optimizing a part for AM enables companies to crawl, walk, and run their way into additive manufacturing. As a company proceeds from one phase to the next, they learn how to design for AM and gain trust and confidence in the process while avoiding the pitfalls that can restrict AM’s potential—or make the AM part too expensive to be competitive.

Anyone can buy a printer now and hit “go”, but if you do not know how to design for AM, you will not be able to take full advantage of the new freedoms that AM’s layer-by-layer process provides. Realizing those freedoms also means managing expectations along the way, which also means learning how to crawl and walk before you can run.

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