3D printing filament is the thermoplastic feedstock for fused filament fabrication 3D printers. There are many types of filament available with different properties.

Filament comes in a range of diameters and types, most commonly 1.75 mm and 2.85 mm, with the latter often being confused with the less common 3 mm. The most common materials are PLA (polylactic acid), PETG, and Thermoplastic polyurethane (TPU).

Filament consists of one continuous slender plastic thread spooled into a reel.

Production 3D printing filament is created using a process of heating, extruding and cooling plastic to transform nurdles into the finished product. However, unlike a 3D printer, the filament is pulled rather than pushed through the nozzle to create the filament. The diameter of the filament is defined by the process that takes place after the plastic has been heated rather than the diameter of the extruder nozzle. A different force and speed is applied to the filament as it is pulled out of the extruder to define the width of the filament, most commonly 1.75 mm or 2.85 mm diameter.

Commercially produced filament

In commercial production, the plastic nurdles are always either white or clear. Pigments or other additives are added to the material before it is melted to create coloured filament or filament with special properties, e.g. increased strength or magnetic properties. Before the filament is extruded the nurdles are heated to 80 °C to dry it and reduce water content. The nurdles must be dried, as many thermoplastics are hygroscopic and extrusion of damp plastic causes dimensional flaws (this is also the case when the finished filament is being printed). From there, the nurdles are fed into a single screw extruder where it is heated and extruded into a filament. The diameter is often measured by a laser beam(not melting) as part of a quality control mechanism to ensure correct diameter of the filament. The filament is then fed through a warm water tank which cools the filament which gives the filament its round shape. The filament is then fed through a cold water tank to cool it to room temperature. It is then wound onto a spool to create the finished product.

DIY filament production DIY filament production machines use the same method as FDM 3D printers of pushing the filament through the extruder to create the correct diameter filament. There are several DIY filament machines available as both open source plans and commercially available machines.

A food dehydrator can be used to remove water from hygroscopic materials at above 70 °C.

Usage

The process of transforming 3D printing filament into a 3D model is as follows:

The filament is fed into the FDM 3D printer The thermoplastic is heated past its glass transition temperature inside the hotend The filament is extruded and deposited by an extrusion head onto a build platform where it cools The process is continuous, building up layers to create the model

Materials

Filament Special properties Uses Strength Density(kg/m) Flexi-bility Dura-bility Difficulty to print Print temperature(°C) Bed temperature(°C) Printing notesPLAConsumer Products1240180–230No heated bed needed or, 60– are recommended alsoABSFunctional Parts1010210–25050–100Use enclosed heated chamber at around to ABS Carbon FiberIncreased strength and stiffness then pure ABSFunctional PartsMediumMediumHighMedium210-26050-100PETG (XT, N‑Vent)All1270rigid.ink Filament Comparison Guide "Complete 3D Printing Filament Comparison Guide" , rigid.ink, 2017-12-14220–235No heated bed neededPCTGAll1230250–270 90–110NylonAll1020220–26050–100Hygroscopic, keep sealed when not in useTPE225–23540Print very slowlyTPU1200-1240Raise3D. Premium TPU-95A Technical Data Sheet (V2.2). Raise3D, 2024. PDF.225–235No heated bed neededPrint slowlyWoodWood-like finishHome Decor1400195–220No heated bed neededHIPSSupport structures when using ABS on a dual extrusion printer.1040210–25050–100PVASupport structures when using PLA or ABS on a dual extrusion printer.180–230No heated bed neededHygroscopic, keep sealed when not in usePET (CEP)All220–250No heated bed neededPLA MetalMetal FinishJewelry195–220No heated bed neededUse hardened nozzlePLA Carbon FiberFunctional PartsLow195–220No heated bed neededUse hardened nozzlePLA Glass FiberStronger than PLA, weaker than PLA Carbon FiberAllMediumLowMediumLow195-220No heated bed neededUse hardened nozzleLignin (bioFila)190–22555PolycarbonateFunctional Parts1180 – 1200270–31090–105Use enclosed heated chamber at around Conductive (usually a graphite-plastic blend)ConductiveElectronics215–230No heated bed neededUse hardened nozzleWax (MOLDLAY)Melts AwayLost wax Casting170–180No heated bed neededPETT (T‑Glase)Functional Parts235–240No heated bed neededASAOutdoor1070240–260100–120PPFlexible Components1040210–230120–150POM, AcetalFunctional Parts210–225130PMMA, AcrylicLight diffusers235–250100–120Sandstone (LAYBRICK; styled plastic)Sandstone FinishArchitecture165–210No heated bed neededGlow-In-The-Dark plasticPhosphorescenceFun215No heated bed neededUse hardened nozzleCleaningCleaningUnclogging of NozzlesN/AN/AN/A150–260No heated bed neededPC-ABSFunctional Parts260–280120Magnetic (PLA blend)MagneticFun195–220No heated bed neededColor Changing (plastic blend)ThermochromismFun215No heated bed needednGen (co-polyester)All210–2406021060–100PORO-LAYPartially Water SolubleExperimental220–235No heated bed neededFlexibleFlexible Parts205–25075PEI (Ultem)Functional Parts1270340–380180–200Use enclosed heated chamber at PPSFunctional Parts1350-1360300–370100–160Use enclosed heated chamber at to PEEKFunctional parts1300-1320360–450100–160Use enclosed heated chamber at to PEKKFunctional parts, aerospace, high-temperature applications1320-1360370–450120–180Use enclosed heated chamber at to Among commonly used fused filament fabrication (FFF) materials, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are frequently compared due to differences in thermal and mechanical performance. ABS is typically printed at higher extrusion and bed temperatures and is generally associated with greater impact resistance and higher heat deflection temperature. PLA, by contrast, is commonly processed at lower temperatures and is often noted for stiffness and ease of printing. Reported mechanical properties for both materials vary depending on grade, print orientation, infill structure, and post-processing conditions, and are commonly evaluated using standardized test methods such as ASTM D638, ASTM D256, and ISO 527.

References