Additive Blog

FDM – Fused Deposition Modeling (or FFF, PJP, LPD)

These types of 3D printers come under many different names. Fused Deposition Modeling (FDM) was the first technology of its kind and it was commercialized and trademarked by Stratasys around 1991. FFF (fused filament fabrication) is a term that emerged from the RepRap community. It refers to an open source version of technology which is very similar to FDM.

Different companies have developed their FFF printers marketing them under different acronyms. For example, 3D Systems – PJP (Plastic Jet Printing) or Zortrax – LPD (Layer Plastic Deposition) and so on.

How it works:

Every FDM/FFF 3D printer is supplied with a filament – a wire usually made of plastic – which is melted using a print head and extruded onto a build platform underneath. The movement of the print head against the build platform is automated using electronic motors. The print head extrudes the melted filament to “draw” the model one layer at a time. Each time a single layer has been printed, the height of the print head in relation to the build platform increases by an increment. Because the extruded material is hot, all layers are strongly connected together with the first layer sticking to the build platform.

Scheme describing how FDM or FFF 3D printer works

Support structures

Support structures might be required when printing more complex objects. Instances where these supports are used include parts of a model where:

A) Overhang is located

B) Big gaps need to be bridged

C) The part is “floating” in the air

If the 3D printer is a single extruder type, the supports are printed from the same material as the rest of the model. They must be removed manually with small pliers or by hand after the printing is finished. Dual extruder 3D printers use one kind of material for printing the model and a different material for the supports. The support material is usually water soluble, making the removal much easier. The supports will completely dissolve after a few hours of being placed in hot water.


A cool feature of FDM/FFF printers is that you can choose the internal structure of the 3D printed model. You can print models completely filled with material resulting in increased strength. On the other hand, you can print models with internal structure to make them lightweight. You do not have to make the internal structure a part of your 3D design. This can be done automatically in a slicer (software for print job preparation that comes with the 3D printer). You usually enter the infill parameter in %, for example, you want 25% of the interior filled. You then choose the type of pattern, e.g., a honeycomb. There are other settings available which have an effect on the properties of the printed part – for further information see a design guide for FDM/FFF 3D printing.

Photo of an inner structure inside 3D printed part using FDM or FFF 3D printer - honeycomb infill


On a high-end level, the most frequent use is rapid prototyping. Mainly (but not limited to) plastic parts that are intended to be produced by injection molding later on. The technology is also suitable for the production of a small series of functional, durable parts, from a wide range of materials. Starting with custom cable clips and ending with aircraft components. The biggest player in this field is Stratasys, with their production series 3D Fortus printers. These machines are expensive, but have a high accuracy of printed parts (understand: no wrapping during print, holes and other dimensions printed exactly as in 3D model, no delamination). Also, the materials come with tested properties and detailed data sheets.

On a desktop level, imagination is your only limit (well…or what your printer is capable of producing).

The list could look like this:

Cheap prototyping of your designs
Gadgets of all sorts (holders, toys, tools – just look at
Drone parts
Cosplay, simple jewelry
Sculptures of your favorite hero
Parts of a 3D printer (rep-rap 3D printers)

Manufacturers: Stratasys, Ultimaker, Zortrax, Prusa Research, MakerBot, Printbot, LulzBot, 3ntr, FlashForge

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