Mistakes to avoid when adopting additive into your manufacturing tool kit: Amber Andreaco

A couple months ago, I asked a somewhat controversial question on LinkedIn:

In your opinion, what's the one mistake people should avoid when adding additive manufacturing to their tool kit?

The response rate was considerable, with so many great answers.

One of the replies which received a lot of positive support was from my colleague Amber Andreaco. She shared that the one mistake she would suggest you avoid is "assuming direct transfers of designs and materials. DfAM can often mean you do not need the same material used for the part manufactured using conventional methods.”

I decided to ask Amber to elaborate on her answer and she graciously agreed to let me interview her more on the topic.

Amber, why do you think most people new to additive assume the design and the material both need to remain the same with this new manufacturing process?

I think this perception comes from the desire to avoid costly and timely development and characterization programs needed to validate form, fit, and function of parts. Not to mention the fact that many engineers are risk adverse and lean toward the known versus the unknown when given that binary decision.

I’d liken it to anyone that has a go-to meal in their cooking repertoire. You know the recipe, you know the cost, you know the time, and you know you’ll like it in the end. Why invest in the risk that it will cost more, take longer, and potentially result into something inedible?

I think what people may not always fully appreciate is that moving into an additive modality, while upfront investment costs may be more, the potential benefits may outweigh the costs.

A new design may enable the ability to reduce the weight of the part, resulting in more efficiency. And that new design may now allow you to use a different - and potentially cheaper - material that was not initially considered because it could not withstand the mechanical requirements in the prior design.

Over time, those benefits may justify the development costs.

If you’re making a part with new designs and new materials, are you making a new part all together or are you making an old part, differently?

I’d argue in all cases, it is a new part. Even if I don’t change design/material, the manufacturing process will likely result in different material properties, which in turn, changes at least one of the “F’s” – function.

In your opinion, what is the difference between material availability and material capability? How would you explain this to someone without a background in metallurgy?

While I originally thought the answer would be simple, writing it out shows there are interdependencies that may be nuanced.

We can use a baking analogy. Assume I’m shopping for ovens to bake cookies.

Material availability is akin to checking to see which store may have ovens readily available for me to go buy since I want to start baking cookies tomorrow. As I do not want to wait for shipment, I’ll limit my search so I can pick one up and take it home tonight. So when people talk about material availability in regards to additive, they generally are talking about someone having gone through the development process to provide a customer with an “off the shelf” product, including the feedstock, parameters, and in some cases, associated data.

Material capability, on the other hand, is more specific to the material and process being capable of meeting a certain level of anticipated requirements. Going back to the oven example, to make the cookies, the oven must be capable of 500F during normal operation. Store A has one (1) oven that meets that criteria, and Store B has two (2) ovens. I may then go to the next level of requirements, which for the sake of the analogy, let’s assume is cost. That drives the decision of choosing one of the Store B options, which is only $250 versus the other options that were $500 and $1000, respectively.

Fantastic! Load it up, install, and let’s start baking.

Uh oh.

I went with the cheaper oven. And while the sales document said it was “capable” of achieving the 500F, it failed to indicate that it only could achieve that temperature within a 1” square area, in the middle rack when you aren’t loading the oven with baking trays and cookies. So out of the four dozen cookies I tried to put in the oven at once, a single cookie is edible.

In this example, just because a material (i.e, the oven) is “available” does not necessarily mean it is fully “capable” to meet the needs of end product (i.e., baked cookies).

In other words: buyer beware. Try to go beyond just one or two levels of requirements before making a decision.

Which constraint is greater: the manufacturing process or the material?

I’ll give my favorite answer: it depends!

Sometimes the material is acceptable, but the manufacturing process is not capable of producing the design features of interest. Sometimes the manufacturing process can make the design, but not in the most desired material.

My favorite anecdote for this question: someone telling me they used laser powder bed fusion to print a gas turbine blade, complete with internal cooling channels. The person wanted to know how much material testing they needed to do to validate a material for use in that application. I was just about to go through my typical spiel when I realized this person hadn’t told me what material they printed. Which then led me to the utterance of, “You printed a single crystal?!” Of course the answer was no, which was of no surprise.

So, in this scenario, could a desired material have been atomized? Yes. Could it be consolidated in a laser machine? Possibly. Could it be consolidated as a single crystal in a laser machine to meet the creep requirements of the application? No.

In your opinion, which do you change first: the design or the material? Why?

Design. Don’t get me wrong. I'm all for investigating and developing more materials. I love generating data and characterizing new materials. But to truly take advantage of additive, design is often where the business case will start. Without the design, there are no requirements, and without the requirements, developing the new material and process may not ultimately meet the needs of the application. It works hand in hand, but starts with the application and design.

Why did you decide to study materials science and materials engineering?

I was fortunate enough to be exposed to Materials Science and Engineering during my high school years. Between STEM local outreach engagements and my high school chemistry teacher’s husband, I learned that it was an actual field that seemed to merge my love of chemistry with more tactile engineering. As I love to remind everyone, no other engineering field can exist without materials engineering.

One of my favorite memories as I was deciding to pursue metallurgy was when my grandfather who worked in the Pittsburgh steel industry pulled out copies of “spark patterns." He'd catalogued the compositions of steel based on their spark patterns and colors. It was great to have a connection to my family history.

What frustrates you most about materials and their role in AM today?

The fact that people still think all the “magic” of additive materials happens in the machine. While the machine plays a huge role, there are still fundamental processes and evaluations that need to occur outside the machine.

I jokingly quote from the movie Mean Girls at least once a month in regard to thermal post processing,“Stop trying to make as-built happen!” No matter how much you try, Inconel 718 will not be Inconel 718 without performing the correct heat treatment to create the correct material structure.

I am always excited new materials come to market, improving the “availability” of materials. More coppers, refractories, and multi-material capability will be interesting to see.

I’m also excited to see more metal AM in everyday life. Not that I want to be handling metal powder in my home to create my own parts, but it would be cool to eventually have a shower head or custom tooling within my reach.

As always, I welcome any comments or questions at alison.wyrick@ge.com.

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