Fused Deposition Modeling (FDM): 3D Printing with Thermoplastic Filament

Fused Deposition Modeling (FDM) – also known as Fused Filament Fabrication (FFF) – is a 3D printing process from the material extrusion group: a plastic wire, the filament, is melted in a heated nozzle and deposited path by path onto a build platform. The strand solidifies and bonds with the layer below. This is how the part is built up layer by layer.

FDM plays to its strengths above all in two cases: when a specific material is required – for example flame-retardant, fiber-reinforced, electrically dissipative, elastic or for sliding applications – and when parts are larger. For industrial functional parts or parts where appearance matters, it is worth taking a look at laser sintering (SLS): it needs no support structures and shows no pronounced layer lines.

• How it works
• FDM or SLS?
• Advantages
• Materials
• Technical data
• Limits & alternatives
• Applications
• FAQ

How it works

How does FDM work?

Drive wheels feed the filament into a heated nozzle, where the plastic melts. The print head traces the contour and infill of the current layer and deposits the strand on the build platform or the previous layer. Once a layer is complete, the distance between nozzle and part increases by one layer thickness – and the next layer follows. Overhangs are supported by support structures during printing.

1. 1 Filament spool with thermoplastic
2. 2 Drive wheels feed the filament to the nozzle
3. 3 Heated nozzle melts the plastic
4. 4 Melted strand is deposited path by path
5. 5 Part, built up layer by layer
6. 6 Support structure under overhangs, removed after printing
7. 7 Build platform – after each layer, the distance to the nozzle increases by one layer thickness

1. Prepare data The 3D model is oriented and sliced into layers. The nozzle paths and – where necessary – support structures are calculated.
2. Melt the filament The filament is fed to the heated nozzle and melted there.
3. Deposit path by path The nozzle deposits the strand along the contour and the infill. It solidifies and bonds with the layer below.
4. Layer by layer After each layer, the distance to the nozzle increases by one layer thickness until the part is complete.
5. Remove supports After printing, support structures are removed – mechanically or, with some systems, by dissolving.
6. Finishing Whether further finishing steps are possible depends on the supplier – you can see the available options in the configurator.

FDM or SLS?

What is the difference between FDM and laser sintering?

In FDM, a filament is melted and deposited as a strand; in laser sintering, a laser melts plastic powder. Laser sintering needs no support structures, is suitable for complex geometries and shows no pronounced layer lines – which makes it the obvious choice for many industrial plastic parts. FDM plays to its strengths with special materials and larger parts.

Which process suits your part better depends on material, geometry, load, appearance, size and quantity. Upload your file and compare the offers directly in the configurator – or contact us.

Advantages

What are the advantages of FDM?

The strengths of FDM lie in the choice of materials – including flame-retardant, fiber-reinforced, conductive and elastic thermoplastics as well as sliding materials – and, depending on the machine, in larger part dimensions. Parts are created directly from the CAD data, without tooling.

Materials

Which materials are available for FDM?

FDM processes thermoplastics. FDM is particularly interesting for special materials: fiber-reinforced and high-temperature types, materials with UL 94 V-0 classification, electrically dissipative and conductive filaments, elastic TPU and sliding materials.

The choice of material affects strength, temperature resistance, surface, dimensional stability and price. You can see which materials and colors are currently available in the configurator after uploading – where you will also find the suppliers’ datasheets.

Material data: fiber-reinforced and flame-retardant plastics

Material data: conductive, elastic and special plastics

Material data: other thermoplastics

Values from the datasheets on the PROTIQ Marketplace (as of 04/2026), without the variations stated in some cases; they do not constitute guaranteed properties. First value in the print plane (X-Y), in brackets – where listed here – in the build direction (Z). The values were determined partly according to ISO and partly according to ASTM standards and are therefore only comparable to a limited extent. HDT = heat deflection temperature, where stated at a test load of 0.45 MPa; Vicat = Vicat softening temperature; neither is a continuous service temperature. The supplier’s information is authoritative.
¹ Tensile strength or stress at yield
² Flexural modulus
³ Elongation at yield
⁴ The UL 94 V-0 classification applies from a wall thickness of 0.7 mm (ABS-FR), 0.75 mm (PETG V0) or 1.5 mm (PPS-CF10, ABS/PC-FR, PVDF); it refers to the material, not to a specific part.
⁵ Upper service temperature

Conformity and classification information such as EU 1935/2004, EU 10/2011, FDA, ISO 10993, USP Class V, UL 94 or EN 45545-2 refers to the material. Whether a printed part is suitable for food contact, medical applications or fire protection requirements depends on design, processing and use and must be checked on a case-by-case basis.

Technical data

Technical data and design guidelines

For the FDM materials listed here, the general tolerance DIN ISO 2768‑m is specified as the dimensional tolerance. The minimum wall thickness is 0.6 mm, and 0.7 to 1.5 mm for materials with UL 94 V-0 classification. The maximum part size depends on the machine; a maximum part size of 100 mm is specified for POM.

Guide values, not guaranteed properties. The information provided by the supplier in the ordering process or in the quote is authoritative.

What to consider when designing

• Consider the load direction Strength between the layers is usually lower than in the print plane – for ABS about 28 instead of 33 MPa, for PPA-CF 57 instead of 168 MPa. Orient parts so that the main load lies in the print plane wherever possible.
• Reduce overhangs The flatter an overhang, the more likely it needs supports. Fewer supports mean less rework and cleaner surfaces.
• Observe wall thickness Plan at least 0.6 mm. For materials with UL 94 V-0 classification, the classification only applies from 0.7 to 1.5 mm.
• Fine details with a margin FDM reproduces very small radii, fine lettering and thin webs only to a limited extent. Design such details somewhat larger.
• Rework fits Tight fits and holes can be machined afterwards – ABS, for example, by drilling, grinding or thread cutting. Plan some machining allowance for this.
• Choose material by function Heat, chemicals, fire protection, elasticity or sliding friction? The material data tables help with preselection. Test the part under real conditions before using it.

Limits & alternatives

When is another process the better choice?

If no specific special material is required and the part is not particularly large, another process may be a better fit – for industrial functional and visual plastic parts, for example laser sintering.

• Surface and details Layer lines are typical for FDM; fine structures and small radii are only possible to a limited extent. Stereolithography is suitable for smooth surfaces and fine details.
• Direction-dependent properties The bond between the layers is usually weaker than within a layer. Suitability for highly stressed or safety-relevant applications must be checked by testing on a case-by-case basis; if you have questions, feel free to contact us.
• Support structures Overhangs and undercuts need supports that are removed after printing. The surface can be rougher at these points. Powder bed processes such as SLS need no supports.
• Material-dependent limits Not every thermoplastic can be processed equally well. Warpage, layer adhesion and dimensional stability depend strongly on the material. For POM, for example, a maximum part size of 100 mm is specified.

FDM and Fused Deposition Modeling are trademarks of Stratasys. Multi Jet Fusion, iglidur, Green-TEC PRO and other material and process names mentioned are trademarks or designations of their respective owners. They are mentioned only to describe the process or materials.

• Process selection guide
• Finishing and post-processing

Applications

What is FDM used for?

FDM is used above all when a specific material is required or parts are larger: for housings with fire protection requirements, ESD-compliant brackets, sliding parts, thermally stressed parts, elastic elements or large-volume fixtures. Appearance and fine details are not the priority here.

Prototyping

Housings and functional samples that are to be made of a specific material even at the prototype stage – for example flame-retardant or fiber-reinforced. (Photo: Harscher)

To prototyping

Operating equipment

Containers, brackets and fixtures – including larger parts, for example electrically dissipative, metal-detectable or made of sliding materials. (Photo: Harscher)

To series production

• Tool making
• Model making

Ordering

How do I order parts made with FDM?

Upload your 3D file, choose material and process and see the available offers.

1. Upload file Upload your 3D data in the configurator. The system automatically checks whether the part fits into the build space.
2. Choose material Choose from more than 160 materials and more than 12 processes – for example PPA-CF with FDM.
3. Check the offer As a rule, you immediately see the price and production time of the available suppliers.
4. Order You order directly online at the selected price.

If a material cannot be selected directly, feel free to ask us.

Upload file now

FAQ

Frequently asked questions about FDM

Further information

• Upload file now
• All 3D printing processes
• Laser sintering (SLS)
• Prototyping