3D printing is a cool way to create real-world replicas of 3D computer models. There are several different ways to do so in your own home. FDM printing with thermoplastics and MSLA printing with photosensitive resins are both relatively affordable and easy to buy. There are other, more exotic methods of 3D printing that can offer unique advantages. Unfortunately, these are much more expensive and generally not suitable for most people’s homes. One of these techniques is called cold spray metal 3D printing.
Most forms of 3D printing with metals require a lot of heat to melt or sinter the metal in question. The “cold” in the name indicates that this method of 3D printing metals is very different. Instead of being heated, the powdered metal is accelerated to supersonic speeds. On impact with the target, the metal bonds properly, allowing the creation of fully dense parts.
The exact speed needed depends on the metal, with tougher materials needing speeds above Mach 3. The acceleration is achieved through the use of compressed gas. Where possible, normal air is used. But for higher speeds, nitrogen or even helium is needed.
There is a broad range of advantages that this technique of 3D printing offers over other metal printing technologies. Generally, as a lot of heat is required, other surrounding parts will have a negative effect. Requiring potentially time-consuming and costly disassembly and reassembly to prevent the fix from causing more damage. Cold spray metal printing doesn’t affect nearby parts as it doesn’t involve heat and is precisely targetable.
This allows for in-situ repairs of complex parts of machinery. For example, the US Air Force demonstrated the ability to repair an active combat-ready plane’s wing fairing slip joint. Traditional methods would have required eight weeks to remove the part. This would cost half a million dollars to remove and replace the part.
Aside from allowing in-situ repairs, the process itself is up to 100 times faster than other forms of metal 3D printing, allowing for even faster turnaround times. It works with a wide range of metals and even allows working with multiple metals at once. This allows a part to be solid titanium at one end and transition through a range of alloy compositions before making solid gold at the other end. This allows for highly customizable alloy properties. There are no harmful fumes emitted. All of the metal powder is used with no wastage.
Cold spray metal printers are small enough to be transportable via truck for on-site repairs or manufacturing. It’s even possible to embed sensors and electronics within the part and print over them. Though this assumes they’re protected from the impact of the printing process.
Limitations and Drawbacks
Unfortunately, despite being cheaper than traditional methods, it’s still not affordable for home use. The limited number of providers and current markets (mostly defense, with some aerospace applications) suggest that this won’t change for a while. Printed parts need to be post-processed somewhat to smooth and sharpen the print. Additionally, it’s simply not possible to print some geometry due to the physics of the process.
Cold spray metal printing is a unique process that offers unique advantages while operating in challenging environments. Unfortunately, the upfront cost of the machines will keep this technology out of mainstream use. The limited geometry will likely also restrict potential applications. Future improvements to the technology may negate this issue.
Have you got any projects where this technology would be helpful? Let us know down below.