How metal can now be 3D printed (additive manufacturing?) like you can with by dripping plastic layer by layer and it dries up over time?
In: 51
There are two main ways, either some sort of binder is used to provide a matrix for the metal powder, and then the resin is cured.
OR
The metal powder is fused with some sort of heat source, such as a laser or oven.
Most metal 3d prints use the laser sintering method. Powdered metal is spread in a thin layer and a laser melts the metal powder into a solid lump where the part is. Another layer of powder is added and the laser melts the next layer and fuses it to the first layer and so on until the part is built. Then all the unused powder is removed and you are left with a 3d printed metal part. As all the metal is melted together the part has no layers and is almost equally as strong in all directions. The process is called DMLS or SLM (direct metal laser sintering or selective laser melting).
You can print plastic parts in a similar way – MJF (multi jet fusion) which uses Nylon powder.
SLS or selective laser sintering is essentially using a high powered laser to melt powdered metal and weld it together layer by layer. A machine deposits a layer of the required metal powder. Then a laser traces the outline of the outline layer melting the powder in that spot and welding it to the layer below.
Three ways:
You have powder which you selectively melt, with a laser or electron beam. This is sort of like resin printing. This has the best resolution, finish and pretty good material properties, but it’s pretty slow and expensive.
You use a binder in a giant inkjet printer to glue powder together, then sinter it in an oven. It’s the cheapest and easiest way, pretty good detail too, but not much faster than the above and the strength of the parts will be comparatively trash. Good for ornamental stuff, not really for structural parts.
You directly melt a metal wire, like a filament polymer printer. Pretty cheap and comparatively fast, but pretty rough in detail and will need heat treatment because the material properties won’t be great right after solidifying. But you can print gigantic parts compared to the others, meters by meters instead of like 20-50cm.
There are multiple methods.
The motion system can be a regular 3d printer, an articulated industrial robot, or anything else that moves how you need it to, like CNC machining equipment.
The metal can be deposited directly at a single point, like sticking a MIG welder on your motion system and continually building up layers, a more advanced version that sprays powdered metal and melts it with a laser, a filament or resin with metal particles mixed in(that then get put in an oven to sinter after printing), or you can have a bed of powdered metal where a laser melts one layer of metal, then spreads another layer of powder on top before melting the next layer.
We look into Markforged’s metal printers for possible prototyping at work. They use a binder during printing and then you sinter the part in an oven. Their process allows for hardened materials and is pretty cool.
https://markforged.com/3d-printers/metal-x
You can’t quite drip metal the same way you drip plastic, because metal doesn’t hold its shape as well. But there are other ways people have gotten around this.
The most popular method nowadays is Selective Laser Sintering (SLS). The machine lays down a thin layer of metal powder, then uses a laser to sinter parts of the powder in the shape the layer is supposed to be. Then the machine puts down another layer of powder, and the process repeats.
Another way is very similar to how FDM printers print plastic (and can even be used with the same printers): they mix some plastic with the metal powder, turn this into filament, and then print the way you would print with just plastic. By itself, this just creates a plastic object with a lot of metal powder in it, but there’s a way to use a kiln to burn away the plastic and sinter the metal together.
More recently, a method has been patented that acts very similar to resin printing. There’s a big tank of electrolyte, and a grid of electrodes on the bottom. This grid is used to electroplate a thin layer of metal onto a build plate, in the shape you want the layer to be. Then the build plate is raised up a small amount, so the next layer can be plated on.
Metals are more like plastic than you think. Heat them up, they melt and flow . In fact if you understood metals more you’d know that intuitively 3D printing is a natural option for metal
Here’s a video from GE demonstrating one method. Sintering is one already method of processing metals that don’t machine or melt well enough. The short version is you have a powder and heat it so that it fuses together. The 3D print is using a laser to melt just the slice, then laying down more powder.
Latest Answers