This is your periodic Publice Service Announcement regarding the use of “FDM”. 

This week I’ve been watching some 3D printing videos and reading stories on the technology, as I do daily, and again realized that the “FDM” terminology continues to be misused. 

Desktop, professional and industrial 3D printers that use a filament-extrusion process are routinely being termed as “FDM 3D printers”, or using the “FDM process”.  

What Is FDM?

FDM is an acronym standing for “fused deposition modeling”, and it refers to the method of 3D printing in which a thermoplastic filament is heated and extruded through a hot nozzle. Layers of an object are gradually built through these extrusions over sometimes long periods, depending on object size. 

Wait, you, say, that is exactly what my 3D printer is doing! It extrudes through a hot nozzle, too! Is it not FDM?

It could be. Let me explain.

“FDM” and “Fused Deposition Modeling” are in fact trademarked terms by Stratasys, the company that first invented the process in the 1980s. In that era they decided to call the process “Fused Deposition Modeling” because they were the inventors and I presume they liked the way “FDM” sounds. 

It didn’t really matter much then because they were the only company that could then offer this type of 3D printing: they held exclusive patents over the process. Then, if you said “FDM”, you implicitly meant “Stratasys”. 

Things began to change in 2009 when some of Stratasys’ patents began to expire. This opened the door to others developing machines using the same technical process, more or less. 

At that point we had machines on the market using the same process, but what was it be called? The industry then had been using “FDM” as the terminology for literally decades, and having no other obvious option and force of habit, many people used the “FDM” term to refer to these non-Stratasys machines and their processes. 

But that was wrong. “FDM” is a trademarked term by Stratasys and therefore, legally speaking, only machines from Stratasys can be said to use the FDM process. 

This practice is very often seen in non-US-based 3D printer manufacturers who mistakenly assume that these are generic English terms for the process. They are not. 

Using FFF Instead of FDM

Some time ago others came up with the more generic “Fused Filament Fabrication” or “FFF” term. It’s not owned by Stratasys and essentially refers to the same process. Thus it can be freely and legally used when referring to the extrusion process on any non-Stratasys gear. 

To use an analogy, saying “FDM” is like “Kleenex” when you mean “tissue”, or “iPhone” when someone is holding an Android device. FDM is a brand name. 

Going forward, I strongly encourage everyone to make more use of the term “FFF” instead of using “FDM” – unless you literally are Stratasys, of course!