I started metal 3D printing back in 2018 for a small startup based on Florida’s Space Coast. Our primary customers were large aerospace and industrial companies, and yes, we printed cool classified stuff I can’t talk about. But we also saw plenty of startups looking to make prototypes, automotive hobbyists looking for replacement parts, university students looking to make the next big innovation, and regular folk who were merely curious about what we could (and could not) make. People love the idea of metal printing.
But most hobbyists feel boxed out of the metal additive industry because the printers come with a six- or seven-figure price tag. These are industrial pieces of capital equipment used to manufacture anything from satellites, tanks, airplanes, and supercars down to microchips and semiconductors. But don’t let the sticker shock stop you from exploring what’s possible! Consider this guide as your glance behind the curtain — at not just ways to get parts printed, but also at a possible career in industrial 3D printing.
Types of Industrial Metal 3D Printing
There are a variety of exotic approaches in high-end metal printing, but most systems are one of these two types:
Metal powder bed fusion (PBF) is a welding process wherein lasers — or sometimes electrons — hit tiny particles of metal powder and melt them together. And when you perform that melting layer by layer, it’s roughly called metal 3D printing.
PBF systems may also be called direct metal laser sintering (DMLS), selective laser melting (SLM), or electron beam melting (EBM) machines. Some familiar names are SLM, EOS, Velo3D, Stratasys, Freemelt, and Renishaw.
Metal binder jetting is a process of layer printing wherein a liquid binder is used to bond the metal powder rather than a laser. Then, those very fragile parts — in what is called a green state — will be sintered (or cured) in an oven to strengthen them. The cured parts may be more porous and weaker than PBF-welded parts, but binder jetting is less expensive and suffers less warping. Examples are ExOne, Desktop Metal, Markforged, and HP.
How Do I Get Parts Made?
If you’re a hobbyist looking to have prints made in metal, consider this a starter guide.
- Material: First and foremost, understand your material needs: Will a stainless steel or aluminum suffice? Or do you need something stronger like titanium or a nickel super alloy?
- Size: How big is the overall part? Size not only determines which printers can make your part, but it also has an influence on overall resolution.
- Tolerance and surface: How tight are your tolerances? If it’s within 0.005 inches or less, then your part will most likely require machining post print. Resolution also plays an important role in surface finish. In the aerospace and energy industries, surface roughness can affect the way fuel flows through a part, for example, and can impact overall performance.
Once you have an understanding of the material and part size you need, that will narrow down the available printers. From there, select your printer based on your manufacturing requirements, tolerances, etc.
After you’ve found your printer, the next step is to get a clean and acceptable file type. Metal printing is slowly moving away from STLs; it’s more and more common that solid CAD files or 3MF files are becoming the print standard.
The most common question I get about metal printing is, “Where can I go to have parts made?” The easiest option from my experience is to check out Xometry, which is an online manufacturing hub. There, you can get cost and lead time estimates up front based on the printer and material selected. The offerings are limited to mostly aluminum and steel alloys, but it’s still a fantastic starting point.
If you need a more expensive alloy such as nickel or copper, start by figuring out who has the printer you’re looking for and then giving them a call. This second option will be quite frustrating as many manufacturers are reluctant to take in a one-off job that requires so much paperwork, but some can be persuaded with enough time and patience.
Limitations
For someone coming from the hobbyist world, it’s important to keep in mind that metal printed parts can in some ways outperform conventionally made parts, but not without limitations. For example, binder jet parts in the green state are often weak and brittle, requiring more care in handling; they obtain their material strength through post process sintering, curing, and other finishing steps. Parts made with laser powder bed fusion tend to have rougher surfaces than machined parts.
The other limitation is consistency. If you order a large batch of metal printed parts, you may see some variation/warpage depending on which printer it was made on, especially if the parts are removed from the plates with no post processing in order to save on cost.
Challenges in Metal 3D Printing
The biggest challenge we have in metal 3D printing right now is qualifying parts for actual use, especially if that use involves human lives. We have to certify that all the parts we’ve printed are sound, safe, and proven to perform in the most extreme operating conditions. In many cases, that means we need to be better than conventionally made parts. But the industry is currently in deep discussion over which data in the manufacturing process is most important for this qualification — is it temperature, powder quality, oxygen content, all of the above?
The second biggest challenge we have is scaling our operations. In metal printing, the printing aspect is a small part of what goes into making a part. There are thermal treatments that occur after printing to adjust the material properties, machining to rein in tight tolerances, surface finishing to get a smooth polish, and so on. These additional steps are easy when we’re talking batches of two or four or eight parts, but on the grand scale of hundreds it can be quite costly and turn into a logistical nightmare if not managed properly.
Our third largest challenge is workforce. We need more makers — more people who think outside the conventional way things are done.
This article appeared in Make: Volume 86.
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