How often have you printed a 3D model and thought everything was okay until you added a little pressure? That’s why tensile strength matters. Tensile strength for 3D printing materials measures their maximum resistance before being pulled apart or stretched before breaking. The strength, flexibility, impact-resistance, and layer adhesion of your 3D model will depend on its tensile strength.
Understanding what tensile strength is and why it matters is crucial to creating durable 3D models that are fit for purpose. In this guide, we’re covering everything that you need to know about tensile strength, including how tensile breaking strength is different, and the typical tensile strength for 3D printing materials like PLA, ABS, and PETG.
Understanding Tensile Strength
Tensile strength is the maximum stress that a material can withstand while being stretched before breaking. It is measured in MPa (megapascals) or PSI, and a higher number indicates a stronger resistance.
Tensile strength is different from a material’s hardness, which correlates to its resistance to scratching or indentations, and toughness, which is the material’s ability to absorb energy without breaking. It’s important to remember that a material can be hard, but brittle; the same way it can be tough but flexible.
Tensile Breaking Strength vs Tensile Strength
Tensile breaking strength is the stress applied to a material at the exact point of fracture. By comparison, the tensile strength is the maximum stress before the material becomes permanently deformed. It’s common for these terms to be used interchangeably, but they differ from an engineering perspective.
Tensile strength for 3D printing materials matters because these models are built layer by layer, meaning that the strength can differ when pressure is applied in certain directions. Layer separation is not uncommon for 3D models, especially for models made with materials that have a lower tensile breaking strength. You’ll want to pay extra attention to tensile strength when printing brackets, clips, hooks, and load-bearing parts.
Why Tensile Strength Matters in 3D Printing
Tensile strength is what will determine whether your 3D model snaps at stress points, if it will deform over time, or crack under tension. It’s extremely important for functional parts, including wall-mounted brackets and mechanical connectors.
Print orientation also impacts a 3D model’s tensile strength. While a model is typically strongest on the X/Y plane, it is weakest along the Z axis. You’ll want to consider tensile strength when designing 3D parts to ensure each axis aligns with its expected load direction. Layer height also matters, as a smaller layer height improves layer bonding, as there is better interlayer contact, increasing the model’s strength.
Similarly, infill density and pattern also matter. A higher infill will increase the model’s overall strength, but the outer walls often matter more than the infill, as increasing the perimeter count can drastically improve the tensile strength. Considering these aspects will help you avoid common pain points when 3D printing, including having a model snap because the layers have separated under tension.
How to Find The Tensile Strength of 3D Printed Parts
Knowing how to find tensile strength is important, even as a hobbyist, but especially if you’re planning to sell your 3D models.
Standard Tensile Testing Methods
ASTM D638 and ISO 527 are international standards for standardized testing that use tensile testing machines and a controlled pulling force. ASTM D638 is preferred in North America, while ISO 527 is common in Europe and Asia. Although these tests are similar, they can have up to a 10% difference for the same material due to the different specimen shapes and speeds they use.
Specific tests for 3D printed objects will often account for layer height, infill, and print orientation. It’s important to remember that manufacturer filament specs are typically tested under controlled conditions in a laboratory, so your print results may differ from what you see in standard testing.
Practical Tips for 3D Printing
Whether you’re a hobbyist or a small business making 3D models, it’s always worth printing test samples in different orientations and materials. It’s a good idea to make your model with PLA, PETG, and ABS, while also adjusting the wall count and infill accordingly to find your optimized settings to boost the model’s tensile strength.
You can also optimize your Creality print settings to improve a model’s tensile strength by increasing the infill to 40% – 60% and slowing down the print speed for improved layer bonding. We recommend using the same settings on your Creality printer when conducting tensile strength tests for more accurate results when comparing different materials.
Tensile Strength for 3D Printing Materials
Below, we’re comparing the tensile strength for 3D printing materials that are popular amongst hobbyists and beginners to the world of 3D printing.
1. PLA Tensile Strength
PLA has a typical tensile strength of 50 – 65 MPa, although this will vary depending on the printer settings that you choose. Although PLA filament has a high stiffness and offers strength in the X/Y direction, it is also brittle with low heat resistance. You’ll typically want to use PLA when making initial prototypes or decorative models.
2. ABS Tensile Strength
ABS filament is a durable thermoplastic that is typically used in FDM printing for functional parts that need to have high-temperature resistance. It has a typical tensile strength range of 40 – 50 MPa, making it more durable in the long term. You can improve the tensile strength of ABS filament by using a heated bed, reducing the cooling fan speed, and printing in an environment with a stable temperature.
3. PETG and Other Materials
Although PLA and ABS are two of the most popular filaments for 3D printer hobbyists, there are other filaments that you might use instead. PETG has a typical tensile strength of 45 – 55 MPa and is more flexible than PLA with better layer adhesion. By comparison, nylon filament offers a higher toughness and has good tensile strength, usually between 63 – 65 MPa, due to its flexibility. Alternatively, polycarbonate has high strength and heat resistance with a tensile strength of 60 – 70 MPa.
Tips to Improve Tensile Strength in 3D Printing
You can improve the tensile strength of 3D printing materials by adjusting your printer settings and design. Below, we’re sharing 6 of the most effective options.
1. Align your print orientation with the load, ensuring that the tensile force runs parallel to the layers.
2. Increase the wall thickness, as this contributes highly to tensile strength.
3. Enhance the infill density, especially for load-bearing components like hooks.
4. Try adjusting your temperature settings to have a slightly higher extrusion temperature for improved fusion between layers.
5. Carbon fiber reinforced filaments can improve your model’s tensile strength, and you can use a heat treatment if appropriate.
6. If tensile strength is crucial for your design, opt for composite materials, such as carbon fiber reinforced filaments, to improve the stiffness of your 3D model.
Frequently Asked Questions About 3D Printing Tensile Strength
What is tensile strength vs compressive strength?
Tensile strength shows a material’s resistance to a pulling force, while compressive strength measures its ability to withstand a pushing force.
How does layer adhesion affect tensile strength?
Weak layer adhesion negatively impacts tensile strength by reducing the durability along the object’s Z-axis.
Which Creality materials have the highest tensile strength?
Polycarbonate, nylon, and carbon fiber reinforced filaments have the highest tensile strength.
Can 3D printed parts achieve industrial-grade strength?
3D printed parts can have the same strength as industrial-grade parts when they’re made using engineering materials, such as PEI and Peek, with optimized print settings.
Why Understanding Tensile Breaking Strength Matters in 3D Printing
Understanding tensile strength matters as it depends on how durable your 3D model will be in real life. While your choice of material is important, the print orientation matters just as much, so it’s important to pay attention to your print settings. Consider how you’re planning to use your 3D model and make sure to optimize its print parameters and use a high-performance filament. Start planning your next 3D printer project with our range of Creality filament rolls.