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Welding is typically used to join two parts together, whether those parts be metal or plastic. There are various styles of welding, but we won’t go into those here.
Casting is the act of pouring a molten metal into a mold, allowing it to cool, and then removing the cooled part from the mold to reveal the castings. After this, it’s quite common to utilize many other manufacturing methods to attain the final part.
Machining is starting out with a block of raw material, and subtractively removing it to eventually carve out the final shape. Much like a rock being chipped away to reveal the final statue. These methods can include manual milling, CNC milling, turning on a lathe for cylindrical objects, and laser/waterjet/EDM cutting, just to name a few.
Additive manufacturing is the process of adding material, rather than taking it away. Whether that be via the fused deposition manufacturing (FDM) seen on many plastic 3d printers, Stereolithography (SLA) using UV light to expose layers to harden a resin, or selective laser sintering (SLS) using a laser to melt particulate together, typically nylons. There are a myriad of technologies out there that fall outside of the ones we just mentioned, but we also won’t go into those here. We’re here to find out about metal 3d printing.
Method 1: Laser Powder Bed Fusion (LPBF)
This umbrella covers a wide range of metal printing processes, such as:
- Selective laser sintering ( SLS)
- Direct metal laser sintering (DMLS)
- Direct metal printing (DMP)
And many others..
This method of 3d printing is done by using a laser to weld the powder together. This laser is focused to a fine point within the powder bed plane, and can weld the powder within that point very quickly.
Method 2: Electron Beam Melting
Using an electron beam, rather than a laser, to melt the metal into the desired shape. This method is much faster than the LPBF process, but is sacrifices precision for speed.
Method 3: Direct Energy Deposition
This is a mix of welding and additive manufacturing. There is a print head that uses a laser similar to the LPBF method, but instead of the powder sitting still and the laser traces the outline of the part, this has a single printhead that moves along and dispenses the metal feedstock, whether it be a wire, or powder.
Method 4: Binder Jetting
This is most akin to an ink jet printer. The metal powder is spread across the bed, and a binding agent is sprayed to form the shape. Then another layer powder is added, followed by the binder. After the print is complete, this requires the other step of sintering it by heating it in an oven, much like a kiln used for clay. After the binder is burned away and the powder sintered together, you get a robust part that typically has shrunk from it’s original dimensions.
Just like other methods of manufacturing, additive has both its strengths and weaknesses. When you have a part with geometries that are not possible with other means of manufacturing, that is where additive really comes into play.
On the flip side, if you have parts that are easily manufactured using other methods, that is where additive isn’t the best option. Due to the relative infancy of additive compared to other methods, costs are still quite high in comparison. Along with that, subtractive methods are usually used in conjunction with additive, usually requiring additional machining to bring the printed part into design specifications.
In short, if it’s a one off prototype or a part that can’t possibly be made using other methods, additive might be an attractive and affordable option. It isn’t yet to the point of being the easy “click print and go” button that many people and groups desire. Rest assured, however, knowing that is exactly what the entire industry is working towards.
If you are not sure about whether or not your part should be printed, we are more than happy to help you determine that, and point you in the right direction.
See also Manufacturing Methods Overview.
Powder amount depends on project scope and size, which can vary greatly. As an example, a part that’s only an inch high may still require a significant amount of powder to complete it. A consultation may be needed where we estimate powder needs volumetrically based on part sizing (essentially the print bed cube size at the end of the print), and thus required amounts for the powder hoppers.