3D printing methods can be complex. You shouldn't rush in to printing if you don't know what method would work best for what you're trying to print. If you’re printing with plastic, you should use FFF/FDM. However, if you’re trying to print with steel or resin you should use DMLS or SLA respectively. So, how do you know which method of 3D printing to choose? This article is here to give you a brief run-through of all the major 3D printing methods, so you know what’s going to work best for what you’re printing with.
FFF/FDM (Fuse Filament Fabrication/ Fuse Deposition Modelling)
Plastic filament is heated and pushed onto a bed through a nozzle. With the help of a moving platform, the model is gradually built up, layer-by-layer. If you look closely, you can see the layers in the finished product as the object has been gradually built up. This method of 3D printing is for use with specific FDM materials –which we’ve talked about before. As well as this, FFF/FDM can print with a wide variety of materials. Typically, you’ll be printing models made of thermoplastic polymers, but food pastes and biological pastes can also be 3D printed using FFF/FDM. FFF/FDM, while it's the cheapest method of 3D printing, isn't as good at handling intricate models. It also isn't as good at SLS or SLA at printing mechanical parts that require high precision.
This 3D-printed pumpkin is an example of FFF printing.
SLS (Selective Laser Sintering)
The basic principle in SLS is that a laser is used as a power source to sinter powdered materials together, creating a 3D model by sintering the materials together to form the model. A powdered material is scattered in a thin layer on the machine’s build platform. The laser then sinters or melts these powders, causing them to fuse together according to a pattern set by a computer. When this is done, the build platform moves slightly, exposing another layer of powder to the laser, and causing the product to be built up gradually, layer-by-layer. SLS is used predominantly on plastic, ceramic, or glass powders in order to create models. However, it is impossible to fabricate a hollow but enclosed creation, as the lasers simply do not allow this, and SLS is slightly more expensive than FFF/FDM, but not as expensive as SLA. SLS is predominantly used for creating prototype parts - but it also can be used to create final-end products for use in electronics and medical hardware.
This pendant was made by SLS out of Polyamide (Source: i.materialise on Pinterest)
All of these samples were created with SLS (Source: FormLabs)
DMLS (Direct Metal Laser Sintering)
DMLS operates on the same principles as SLS, with the difference that it’s applied directly to metal, and can only be used on metal. With a laser aimed on to a bed of metal powder, the finished product is gradually built up, layer by layer. The only real difference between DMLS and its sibling SLS is the temperature the powder is heated to. In DMLS it’s heated to a lower temperature than when SLS is when it’s used on metal powders. The final product with DMLS will be nearly completely dense – given it operates on the same principles as SLS, it’s impossible to create hollow objects. As such, DMLS is useful for quickly building metal prototypes that cannot be built by casting.
SLA (Stereolithography)
Also known as optical fabrication, photo-solidification and resin-printing, SLA is quite similar to SLS and DMLS – but it’s definitely different enough to earn a mention in its own right. Basically, the laser draws a shape into a resin, which solidifies, and after one layer is done, a platform moves to allow the next layer to be “printed”. Stereolithography works quickly, and is extremely useful in that it can make almost anything you want, but it’s extremely expensive as 3D printing methods go, much more expensive than FFF/FDM. The trade-off for this, however, is that SLA can produce more intricate and detailed parts than FFF/FDM, so is much better for printing prototypes and final models that require precision; these extremely intricate parts can be produced in a much shorter length of time than in cheaper methods.
This illustrates the difference between an object printed with SLA (Left) and the same object printed with FFF/FDM (Right) (Source: FormLabs)
MJF (Multi Jet Fusion)
Multi jet fusion is like SLS and DMLS as well, except for one important difference: MJF does not use any lasers. This is how it works: the powder is spread on the bed. Then two agents, for fusing and detailing, are applied. The heat, which fuses the powder together, is supplied by lamps constantly passing over the surface, and the jetted material captures and distributes the heat from the lamps. The part is gradually built up, layer-by-layer, and after the loose powder is removed, it’s basically finished. MJF produces parts that need minimal finishing after production, and products are smooth straight after printing. This is ideal for functional prototypes, and MJF also produces models that are water and chemical resistant. It’s great for fast, quality results when you’re printing something complex. However, it’s not as cheap due to the newer nature of the technology. MJF isn't as expensive as SLA in general, but it is still more expensive than FFF/FDM and SLS.
This model was produced by MJF (Source: Sculpteo)
While these are some of the most popular 3D printing methods, there are always new methods and technologies being developed. That’s part of what’s so exciting about 3D printing right now: we don’t know what’s coming next! As 3D printing methods develop, we can print better things, faster, and with less labour. If this sounds interesting to you, or you have an idea you think that we can put into action, you can get into contact with us here – and we’ll see if we can make your vision into reality.
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