FDM 3D Printing: How Do Filaments Affect Part Strength?

An FDM part’s performance cannot be predicted from the filament name alone. The material is heated, deposited in layers and cooled, while printing settings and part geometry shape the finished structure. Understanding those influences matters when choosing a filament, comparing test results or designing a reliable component.

Key takeaways

• The review covers FDM filaments, physical effects during part formation, mechanical properties and the standards used to assess them.
• Properties are affected by material choice, build orientation, layer height, infill shape and density, temperature, printing speed and other factors.
• The paper’s table lists tensile strength values of 98 MPa for PEEK, 48 MPa for PLA and 28 MPa for ABS for selected materials and manufacturers—not universal values for every printed part.
• Heating and cooling create thermal gradients and residual stresses that can contribute to distortion and changes in mechanical behaviour.
• Existing polymer testing standards are commonly used for FDM materials, although the paper identifies a need for guidance better suited to printed structures.
• Meaningful comparisons require details about the material and manufacturer, colour, printer, process settings, specimen geometry and test conditions.

Why FDM material properties are difficult to compare

Additive manufacturing builds a part by adding material layer by layer. Fused Deposition Modeling (FDM), also known as Fused Filament Fabrication (FFF), is a material-extrusion process. A thermoplastic filament passes through a heated nozzle and is deposited along a path defined by G-code. The technology is used for prototypes, tooling and parts in applications ranging from aerospace to medical devices.

But the filament entering the printer and the printed component are not equivalent in terms of properties. During fabrication, the polymer is heated, extruded and cooled. The resulting part also depends on how its material is arranged and which process settings are used. Saying that a component is “made of PLA” or “made of ABS” therefore does not, by itself, describe its mechanical performance.

The review was written by Adi Pandžić, PhD. It appeared in the Proceedings of the 35th DAAAM International Symposium in 2024. This is a review of existing research, not a report on a single experiment performed by the paper. It does not present one set of specimens, one printer or one fixed combination of printing settings as its own test programme.

Which filaments and materials does the review discuss?

The paper surveys a broad range of materials available or under development for FDM. These include thermoplastics such as PLA, ABS, PC, PETG, nylon, PA6, PA12, PP and PEEK, as well as ASA and the elastic materials TPU and TPE. It also discusses polymer blends, including PC/ABS and PC/PEI, and materials used for support structures.

PLA is popular partly because it can be printed on relatively inexpensive desktop machines without a closed chamber. The review describes its lower printing temperature and lower coefficient of thermal expansion compared with ABS. It also notes limitations: PLA has low heat resistance, can deform at around 50 °C and is relatively brittle. ABS is valued for toughness and impact resistance, but may shrink, particularly when printing larger or more complex geometries. A heated build surface and closed chamber can help control temperature during ABS printing.

PEEK and PEI are examples of high-performance polymers that require more demanding processing. The paper states that nozzle temperatures above 360 °C are needed for these materials. Support material also affects the production process and finished surface. A dual-head printer can use a separate support material: PVA can be dissolved in water, while HIPS is often used to support ABS and dissolves in d-limonene.

How does the formation process affect a printed part?

The filament is heated to a semi-molten state and extruded through the nozzle. Heat then moves through the material and between the printed part and its surroundings. The review describes conduction, convection and radiation as heat-transfer mechanisms involved in the process. Heating and cooling create thermal gradients—temperature differences within the part and between deposited material—which can generate residual stresses. These stresses may cause distortion during printing or after the part has been made.

Mechanical properties also depend on process and structural settings. The factors discussed include build orientation, layer height, infill shape and density, raster angle and width, the spacing between rasters, temperature and printing speed. Infill is the internal structure inside a part’s outer walls. Its shape and density determine how material is distributed through that structure. Because these factors interact, the effect of a particular setting cannot always be predicted by considering it in isolation.

The review reports a result from a cited study in which raising the FDM printer’s working-space temperature from 25 °C to 200 °C improved the crystallinity and mechanical properties of printed PEEK. This is a finding from prior research cited in the paper, not a new experiment in this review. The paper also discusses how higher nozzle temperatures can reduce porosity and increase crystallinity in PEEK and PEI, while warning that overheating can degrade the polymer and worsen its properties.

What do the tensile strength values tell us?

Tensile strength describes the stress a material withstands under tension before failure. The paper’s table summarizes reported mechanical properties for selected FDM materials, including tensile strength, elastic modulus and strain at break. For example, the table lists tensile strength of 48 MPa for PLA from Stratasys, 28 MPa for ABS from Stratasys and 98 MPa for PEEK from Victrex.

These figures should not be treated as results from a controlled, head-to-head comparison performed for the review. Nor do they guarantee that every PEEK part will be stronger than every PLA part. Material formulation, colour, printer model, process settings, specimen geometry and test method can all differ. The paper cites research showing differences in tensile properties between PLA materials of different colours and manufacturers, and between specimens made on different printer models. The deformation rate used during testing can also affect measured tensile properties.

For engineers and product designers, the practical lesson is to look beyond a material’s headline strength value. A useful specification should make clear what was printed, how it was printed and how it was tested. This is relevant to product development wherever mechanical performance matters, whether a printed component is a prototype, a tool or a functional part.

Testing standards and their limitations

The review mentions ISO 17296-3:2014, which describes main additive manufacturing characteristics and corresponding test methods, and ISO/ASTM 52921:2013, which addresses terminology for additive manufacturing coordinate systems and test methodologies. The paper explains that these documents do not specifically establish mechanical testing standards for FDM-printed polymer materials. Research therefore commonly uses existing ISO and ASTM standards for polymers, many of which were developed for materials produced by conventional methods such as injection molding.

That distinction matters because FDM parts can be solid, contain an infill structure, or be designed as lattice and cellular structures. A method intended for conventional polymer specimens may not fully characterize all these printed geometries. The paper argues that additional guidance is needed, particularly for parts with infill and for increasingly common lattice and cellular designs.

For students and researchers, the review underscores why test results need context and repeatable reporting. When describing FDM material properties, reports should specify the material type and manufacturer, colour, printer model, key print settings, specimen geometry, test standard and method, deformation rate and relevant external conditions. Reporting a numerical value without those details can make it difficult to interpret or reproduce the result.

Limitations and future research

Because this article reviews previous work, it does not establish a single property value that applies to every filament or printed part. Its comparisons draw on information from different sources, manufacturers and research settings. The paper also emphasizes that current polymer testing standards have limitations when applied to FDM structures, and that further guidance is needed to assess infill, lattice and cellular materials appropriately.

The paper recommends that material manufacturers provide more complete declarations, including material colour, printer model, important printing parameters and the standard and method used to obtain reported properties. For future research, the paper proposes extending the analysis beyond polymers to composites, metals and other materials, and examining alternative additive manufacturing technologies.

The central conclusion is that reliable FDM 3D printing depends on understanding the relationship between filament, process, part structure and testing method. There is no context-free strength number that describes every printed component. Clear material and process information, supported by appropriate testing guidance, is essential for making results useful and comparable.

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Author: Adi Pandžić, PhD in Mechanical Engineering

This article summarises a published research paper; please refer to and cite the original paper. About the author

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