It may sound like a pop band, but μ-WAAM is actually a 3D printing technique for making small metal parts from the NOVA University Lisbon. Of course, WAAM stands for wire arc additive manufacturing, a well-known technique for 3D printing in metal. The difference? The new technique uses 250 μm wire stock instead of the 1mm or thicker wires used in conventional WAAM.
The thinner feed wire allows μ-WAAM to create fine details like thin walls that would be difficult to replicate with traditional methods. Typically, for fine structures, printers use fused metal powder. This is good for fine details, but typically slower and has higher waste than wire-based systems.
Most of us want our 3D prints to be perfect. But at Cornell University, they’ve been experimenting with deliberately introducing defects into printed titanium. Why? Because using a post-print treatment of heat and pressure they can turn those defects into assets, leading to a stronger and more ductile printed part.
The most common ways to print metal use powders melted together, and these lead to tiny pores in the material that weaken the final product. Using Ti-6Al-4V, the researchers deliberately made a poor print that had more than the usual amount of defects. Then they applied extreme heat and pressure to the resulting piece. The pressure caused the pores to close up, and changed the material’s internal structure to be more like a composite.
Reports are that the pieces treated in this way have superior properties to parts made by casting and forging, much less 3D printed parts. In addition, the printing process usually creates parts that are stronger in some directions than others. The post processing breaks that directionality and the finished parts have equal strength in all directions.
The hot isostatic pressing (HIP) process isn’t new — it is commonly used in metal and ceramic processing — so this method shouldn’t require anything more exotic than that. Granted, even cheap presses from China start around $7,000 and go way up from there, but if you are 3D printing titanium, that might not be such a big expenditure. The only downside seems to be that if the process leaves any defects partially processed, it can lead to fatigue failures later.
People really want to 3D print metal, but while true metal printers exist, they still are expensive and out of reach of most hackers. However, even if you can afford an exotic printer or use metal-impregnated polymer, you don’t often see copper as a print material. Copper has high electrical and thermal conductivity which makes it very useful. But that thermal conductivity also makes it very difficult to print using any process that involves heating up the material and copper reflects common lasers used in the 3D printing process. However, a German company, Infinite Flex, is claiming a breakthrough that will allow printers that use a standard IR laser to produce copper parts. The material, Infinite Powder CU 01 is suitable for selective laser sintering and several other laser-based techniques.
The powder has 99.5% copper and particle sizes of between 10 and 45 microns. There are some copper alloys that reduce thermal conductivity to allow printing, but often the reason you want a copper part is for its thermal properties. A kilogram of the powder will set you back nearly $100, so it isn’t dirt cheap, but it isn’t astronomical, either.
You don’t think of hobby-grade 3D printing as a good method for creating rocket nozzles. But [Mister Highball] managed to create a copper nozzle using a common printer, a kiln, and some special copper-bearing filament.
The copper filament is about 90% metal. Virtual Foundry recommends preheating it before printing and you have to sinter it in an oven to remove the plastic and leave a solid metal piece which will, of course, shrink.
Most of our 3D printers lay down molten plastic or use photosensitive resin. But professional printers often use metal powder, laying out a pattern and then sintering it with a laser. [Metal Matters] is trying to homebrew a similar system (video, embedded below). And while not entirely successful, the handful of detailed progress videos are interesting to watch. We particularly enjoyed the latest installment (the second video, below) which showed solutions to some of the problems.
Because of the complexity of the system, there are small tidbits of interest even if you don’t want to build a metal printer. For example, in the most recent video, a CCD camera gives up its sensor to detect the laser’s focus.
While the jury is still out on 3D printing for the consumer market, there’s little question that it’s becoming a major part of next generation manufacturing. While we often think of 3D printing as a way to create highly customized one-off objects, that’s a conclusion largely based on how we as individuals use the technology. When you’re building something as complex as a rocket engine, the true advantage of 3D printing is the ability to not only rapidly iterate your design, but to produce objects with internal geometries that would be difficult if not impossible to create with traditional tooling.
SpaceX’s SuperDraco 3D Printed Engine
So it’s no wonder that key “New Space” players like SpaceX and Blue Origin make use of 3D printed components in their vehicles. Even NASA has been dipping their proverbial toe in the additive manufacturing waters, testing printed parts for the Space Launch System’s RS-25 engine. It would be safe to say that from this point forward, most of our exploits off of the planet’s surface will involve additive manufacturing in some capacity.
But one of the latest players to enter the commercial spaceflight industry, Relativity Space, thinks we can take the concept even farther. Not content to just 3D print rocket components, founders Tim Ellis and Jordan Noone believe the entire rocket can be printed. Minus electrical components and a few parts which operate in extremely high stress environments such as inside the pump turbines, Relativity Space claims up to 95% of their rocket could eventually be produced with additive manufacturing.
If you think 3D printing a rocket sounds implausible, you aren’t alone. It’s a bold claim, so far the aerospace industry has only managed to print relatively small rocket engines; so printing an entire vehicle would be an exceptionally large leap in capability. But with talent pulled from major aerospace players, a recently inked deal for a 20 year lease on a test site at NASA’s Stennis Space Center, and access to the world’s largest metal 3D printer, they’re certainly going all in on the idea. Let’s take a look at what they’ve got planned.
If you’ve ever been to Amsterdam, you know there are plenty of canals and, therefore, plenty of bridges. Next year, a unique pedestrian bridge in the old city center will go into service. The stainless steel bridge will be 3D printed and also embed a number of sensors that will collect data that the printer — MX3D — and their partners Autodesk, the Alan Turing Institute, and the Amsterdam Institute for Advanced Metropolitan Studies, hope will help produce better 3D printed structures in the future. The bridge will cross the Oudezijds Achterburgwal which is near the city’s infamous red light district.
Since the bridge matches exactly with the model used to print it, scientists hope to be able to map the sensor data to a virtual twin of the bridge very easily. You can see a few videos about the bridge’s construction below. This month, during Dutch Design Week, visitors had a chance to walk across the bridge to generate some of the first live datasets.
