Joule Printing? Vs. Wire DED

We are frequently asked about the difference between Joule Printing? and Wire Directed Energy Deposition (DED). Wire DED processes and Joule Printing? are alike in that they can both rapidly melt low-cost metal welding wire into near-net-shape parts. However, the physics of Joule Printing? are fundamentally different than those of Wire DED, allowing advantages in resolution, quality, and cost. In this post we explain why Joule Printing? is unique from wire DED and highlight the pros and cons of each.

Wire Directed Energy Deposition (DED)

Wire DED encompasses metal AM technologies that utilize low resolution robotic welding processes to print wire at high deposition rates. Wire DED systems use an electric arc, plasma, laser or electron beam to melt wire into a molten deposit pool. The print head is usually controlled by a 2-axis gantry system or a robotic arm. You can read more about DED in our prior post on this subject.

Joule Printing?

Digital Alloys’ patented Joule Printing? technology leverages joule (aka resistive) heating to rapidly and efficiently melt metal wire into high-quality near-net-shape parts. The process works as follows:

1. Precise wire feed and motion systems position the tip of the wire in contact with the desired printing (melting) location.
2. Once the wire is positioned, the system pushes current through the wire and into the part being printed. The current melts the wire tip using joule heating (aka “resistance heating”), the same physics that heat a coil in a toaster.
3. Wire feed and melting continue while the print head moves, laying down beads of metal which are fused together to form fully dense metal parts.

Resolution and Print Speed

Joule Printing? delivers an order of magnitude higher print resolution than wire DED processes at similar print speeds. DED processes have a max linear speed. As a result, there is a near-linear relationship between resolution (usually measured by deposition width) and volumetric print speed. Wire DED can achieve high volumetric deposition rates, but only with thick wire that results in low process resolutions that are not useful for most applications. Joule Printing? has a much higher linear speed, thus delivering high print speeds at a resolution that is adequate for a broad range of potential applications, from conformally cooled automotive tooling to titanium aerospace brackets. The below chart highlights the relationship between print speed and resolution for various DED systems as well as Joule Printing?. (The Joule Printing? data point is for current wire size, 0.9mm diameter)

Process deposition width has significant implications on feasible part sizes as well as the amount of excess material wasted in post-processing. DED systems typically use 1-3 mm diameter wire. The melt pool (deposition width) is usually 5-10x wider than the wire, yielding a print bead about the size of a finger (10-20 mm). Joule Printing? currently utilizes 0.9 mm diameter wire and deposits a bead of similar width to the wire (a wide range of wire diameters will be supported in the future). The images below illustrate Joule Printing’s order of magnitude resolution advantage vs Wire DED.

If you would like to keep reading, you can find the full article here:  https://www.digitalalloys.com/blog/joule-printing-vs-wire-ded/