Terminology Turmoil: FDM, FFF, MEX, and the Quest for Accuracy

By on August 16th, 2023 in Ideas, news

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Now the question is whether to use “FFF” or “MEX” [Source: Fabbaloo / LAI]

The plot thickens regarding the use of “FFF”.

The other week I wrote a piece suggesting that people use the term “FFF” instead of “FDM” when referring to filament 3D printing. That’s because FDM is a registered trademark of Stratasys, and legally anything that isn’t a Stratasys machine isn’t “doing FDM”.

Instead the popular term being used widely these days is “FFF”, or “Fused Filament Fabrication”. It’s the same process as FDM, it’s just a generic, non-registered term.

My hope was that people would use the term FFF instead of FDM, because I continue to see FDM misused, even by large 3D printer manufacturers.

However, we received a couple of interesting comments that in fact the ISO term, “material extrusion” should be used.

Reader Mario writes:

“Well actually we should be using the correct ISO term, which is MEX (Material extrusion) because regardless of who is the manufacturer or machine brand. They all share the same principle including Stratasys.

If as a media you inform the public both specialized and not so much, you SHOULD divulgate correct information and not the same wrong definitions over and over.”

In spite of MEX being the ISO term, I disagree with this.

But let’s back up a bit. ISO, the International Standards Organization, made an official list of seven additive manufacturing processes. They are:

  • Material Extrusion
  • Sheet Lamination
  • Binder Jetting
  • Material Jetting
  • Directed Energy Deposition
  • Powder Bed Fusion
  • Vat Polymerization

Some of these have acronyms you might be familiar with, such as “DED” or “PBF”. Some you might not have heard, like “MEX”. I don’t think I’ve ever heard anyone use the term “MEX”. Some don’t have acronyms, as far as I know.

As for the suggestion that we should use “MEX” instead of “FFF”, I don’t believe this is appropriate at all.

The seven ISO processes are really high-level categories of 3D printing processes, not specific 3D printing processes.

For example, Powder Bed Fusion might be done with metal powder and lasers (LPBF) or it might be done with polymer powder.

Vat Polymerization might be SLA, Stereolithography, MSLA, or even volumetric 3D printing.

Each of the ISO categories has multiple specific processes underneath them.

In the case of “MEX”, we have FFF. But we also have paste extrusion. And concrete extrusion. These are utterly different processes, yet are all “material extrusion”.

Should we use “MEX” when referring to filament extrusion? I suppose you could, but that’s like saying you are in the kitchen cooking, instead of saying you are deep-frying or baking or boiling.

FFF is more specific than material extrusion. It’s a type of material extrusion, like other extrusion processes.

Therefore, when you use “FFF” you are being quite specific and descriptive in referring to a method for material extrusion of filament.

I’m staying with FFF.

By Kerry Stevenson

Kerry Stevenson, aka "General Fabb" has written over 8,000 stories on 3D printing at Fabbaloo since he launched the venture in 2007, with an intention to promote and grow the incredible technology of 3D printing across the world. So far, it seems to be working!

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