Rocket engines are now mainly 3D printed

3D printing comes in many shapes, forms, and materials. Most people think of popular brands like Bambu Lab and Prusa Research, which extrude plastic one microlayer at a time, but some printers can quickly produce more complex metal components than those made by traditional manufacturing methods and at a fraction of the cost. This is perfect for industries as explosive as the space exploration sector, in every sense of the word.

In the past, rocket engines were constructed from countless parts, manufactured piecemeal, then bolted and welded together like the world’s largest puzzle. The result was long and heavy (several tons). To solve these problems, organizations like NASA have started exploring 3D printing technologies. This investment allowed NASA to build rocket engines as big as the old ones, but without all that extra mass weighing them down. 3D printed components are not only easier to install, but also more fuel efficient because rockets need less thrust to take off.

3D printing also offers benefits beyond physical properties. The speed of the 3D printing process allows users to mass produce components. An impossible feat for engines of traditional construction. Although organizations won’t use 3D printing to build a fleet of rockets a la Starfleet from “Star Trek” (even though the series predicts the rise of technologies like 3D printers), they can use these engines to test new designs. And if the engine explodes – as is often the case during the prototype phase – engineers can quickly build a new one within days. Now if only engineers could solve the problem of rocket explosions that threaten the safety of commercial airlines.

As 3D printing technology has evolved, so have the items it produces. 3D printed parts are more reliable than ever, but there are some items you should never 3D print. The more demanding the goal, the less likely a 3D printed part is to survive, so why would anyone rely on it to launch rockets into space? Because new alloys were invented just for this process.

Elementum 3D, the company NASA collaborates with for 3D printing, was founded to pioneer new methods of printing difficult-to-work metals. Elementum 3D’s solution was a new form of reactive additive manufacturing (reactive printing for short) that adds special particles to aluminum and triggers a chemical reaction during printing. The result was a new aluminum alloy that was strong and heat-resistant without adding weight to the rockets. More importantly, the alloy is inexpensive compared to traditional manufacturing methods and can be welded to other parts. Not that you need a lot of soldering, since 3D printed products can be shaped almost any way engineers want.

Aluminum alloys aren’t the only rocket engine material coming out of 3D printers. SpaceX, for example, created a nickel-chromium alloy called Inconel for its first SuperDraco engines. Like NASA’s 3D-printed aluminum alloy rockets, Inconel is strong and lightweight, and the process allows engineers to build complex components while minimizing welding and other assembly techniques, speeding construction.

When you clicked on this article, you may have noticed that the headline said “Rocket engines are now mostly 3D printed.” It wasn’t a typo. While we’ve discussed how NASA (and SpaceX) are using 3D printing to quickly make rocket engines, we have to temper your expectations with the fact that some parts are still made the old-fashioned way. 3D printing is downright futuristic, but has certain limitations.

According to calculations from sites such as 3DPrintersBay, modern rocket engines comprise approximately 80% 3D printed parts. Specifically, rocket engines made by companies like Ursa Major and Relativity Space are 80% and 85% 3D printed components, respectively. These mainly include parts such as oxidizer and propellant tanks, combustion chambers, fuel injectors, pumps and valves. However, this still leaves at least 15 to 20% of the parts for traditional manufacturing.

Instead of asking what parts rocket engineers don’t 3D print, you should ask what those parts are for. The answer is anything beyond the limits of what 3D printing can produce. Yes, Elementum 3D designed a strong, heat-resistant aluminum alloy, but if a component needs to survive even more extreme temperatures and stresses, engineers can’t use reactive additive manufacturing or any other 3D printing process. The same goes for components that must resist certain chemicals or maintain foolproof dimensional consistency. You could say that 3D printing only works for rocket engine components when the phrase “It’s not rocket science” accurately describes the level of manufacturing difficulty.