Understanding the Different Additive Manufacturing Processes

If you’re reading this, you probably already know what a 3D printer is (if you don’t, then read this article about 3D printing vs. injection molding). But do you understand the differences between the vast number of additive manufacturing processes, technologies, and their applications?

To start, here are three easy ways to categorize the various additive manufacturing technologies:

1. Melted Solids 

There’s a whole band of additive technologies that rely on melting a material down and extrude it out of a nozzle or end effector of some kind. These additive technologies essentially reconstitute a “complete” material (like from a spool) into a new shape by melting and layering into a new form. 

2. Solidifying Liquids  

You probably didn’t see this coming, but yes, there is a process of additive technology that is the total inverse of melting solids. Relying typically on photosensitive resins or polymers, these 3D printers will usually work by applying a laser or a projection to solidify a thin film of the resin into a solid object. 

3. Fusing Powders 

Possibly the most widely known technology format, powder fusion works exactly as the name suggests. The material you’re working with is a powder in its “raw” format and fuses together either through a binding agent or by melting the material with a heat source. 

Having dealt with a handful of the different ways you can additively manufacture things, let’s dive into the specific additive manufacturing options. 

Additive Manufacturing Processes FFF: Fused Filament Fabrication 

Chances are, when someone says 3D printing, you think of this additive technology. Easily the most prolific additive technology from the boom in desktop machines that started around 2010, FFF machines manufacture products with a spool of plastic that is driven through a hot end extruder that melts the plastic to liquid form, which is then laid out in a pattern that is one slice of the object. You may be aware of FFF thanks to additive manufacturing hardware companies like Ultimaker

FFF Applications

FFF is a fantastic workhorse additive technology for prototyping, making basic products, testing ideas rapidly, and general ideation workflows. Of course, FFF can also be used with more “permanence” in mind to manufacture products too. FFF is a reliable technology for additive manufacturing, with few things that can go wrong, minimal downtime, and generally well-produced objects. It’s limited mostly by the resolution of printing, which will create a trade-off on accuracy for speed. FFF parts also require some post-processing for finishing, and the ridgelines usually need to be removed for painting. 

SLA & DLP– Selective Laser Additive & Digital Light Processing  Formlabs Form 3 printer.

Arguably the second most popular/famous 3D printing process after FFF, this additive technology also benefitted from a boom in companies starting around 2010. These 3D printers use a photosensitive tank of resin, with the object being made by passing a laser over the layer to solidify the resin in place. DLP differs from SLA by projecting the entire image layer using a projector instead of a laser. Arguably DLP is faster, as the entire layer is projected at once instead of using a laser to trace, but there are again trade-offs, typically around the surface finish. You are most likely aware of SLA printing through companies like FormLabs

SLA & DLP Applications 

There are a lot of resin options available, most of which simulate a plastic’s material properties. SLA benefits over FFF are typically accuracy and surface finish, so if you’re printing objects with lots of fine small details, SLA will serve you better. However, the SLA process demands more of you as an end-user, requiring extra steps after the printing is done for the part to be ready. SLA can also print big parts and is used at scale. You may recall seeing the Adidas Futurecraft 4D shoes with a 3D printed sole, which were achieved with SLA-based tech from Carbon.

MJF –

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