How To Build A Metal 3D Printer

One of the most interesting metal 3D printing technologies is using lasers to melt a wire. Wire Laser Metal Deposition is a Directed Energy Deposition (DED)

Meltio
- Laser Type: 6 x 200 W direct diode lasers
- Laser Wavelength: 976 nm
- Total Laser Power: 1200 W
- Layer Height: From 0.6 to 1.2 mm layer heights.
- Wire Feedstock Diameter: 0.8 – 1.2 mm

Metals absorb lower wavelengths of light (approaching UV) better than higher wavelengths (IR). 1064nm fiber lasers are popular for engraving and cutting metals, but that is because of the intensely small focused spot that can be achieved. A common blue diode laser of ~450nm has much better absorption in most metals (reference). In fact these low-power lasers can cut 0.15mm stainless steel in a single pass using only 24W.

For the 3D printer to work it has to form a melt pool to feed the wire into, similar to tig welding. Tig welder could also be used, but it would need to be pulsed to control the amount of heat imparted into the part. It's more difficult to control where the tig arc goes. The laser(s) need to be strong enough to create a small melt pool and feed the wire into it. Meltio's method is to use 6 lasers, which are probably slightly defocused so that they don't just vaporize the metal (like a focused fiber laser does). Their goal is to apply enough heat to form a small melt pool, not vaporize the metal.

Although the consumer-grade blue laser diodes can cut through 0.15mm of stainless, they are probably focused small enough to vaporize the metal, versus heating it to melting. Will adding more blue laser diodes be enough to melt the metal at a spot and feed wire into it? 6 blue laser diodes are an expensive experiment.

LASER MODULES