When it comes to choosing the right nylon filament for demanding, high-temperature applications, nothing is more valuable than real-world data. For those looking to get the best out of their 3D printer, especially when performance under heat stress is crucial, it’s worth exploring COPA, PA6, and PA12—three of the most trusted nylon-based filaments in the industry. If you want an in-depth look at the best nylon filaments for 2025, check out this expert roundup: best COPA and nylon filaments in 2025. Now, let’s dive deep into how these materials stack up under heat-ageing tests.
Why Heat-Ageing Matters in 3D Printing
Heat-ageing tests are designed to simulate the real-life thermal stresses a material might endure over extended periods. For parts used in automotive, aerospace, electronics, and industrial applications, the ability to resist deformation, retain strength, and avoid significant color or texture changes is vital. Heat-ageing can be the difference between a part that lasts for years and one that fails unexpectedly.
Understanding COPA, PA6, and PA12
Before getting into the test results, it’s essential to understand the differences between these three filament types:
- COPA (Co-Polyamide): Known for its excellent balance of flexibility, toughness, and printability. COPA is a blend that typically offers lower warping and better layer adhesion compared to traditional nylons.
- PA6 (Nylon 6): Highly regarded for its strength and wear resistance. It’s used in automotive and industrial parts that must withstand continuous mechanical stress.
- PA12 (Nylon 12): Famous for its low moisture absorption, dimensional stability, and resistance to chemicals, making it a favorite for precision applications.
Each material brings unique strengths to the table, but how do they fare when put through a heat-ageing test?
The Heat-Ageing Test Methodology
In the controlled heat-ageing test, standardized samples of COPA, PA6, and PA12 were subjected to elevated temperatures (usually between 120°C and 150°C) for periods ranging from 72 to 168 hours. Post-exposure, the samples were evaluated for key mechanical properties:
- Tensile Strength (how much pulling force the material can withstand)
- Elongation at Break (flexibility after ageing)
- Dimensional Stability (warping or shrinkage)
- Surface Appearance (discoloration, cracks, or texture changes)
Results: COPA vs. PA6 vs. PA12
COPA
COPA demonstrated outstanding stability in terms of both mechanical strength and dimensional retention. After 168 hours at 130°C, the decrease in tensile strength was minimal—averaging just 8–12%. The elongation at break remained high, showing that COPA preserved its flexibility even after prolonged exposure. Surface analysis revealed very minor yellowing, but no significant cracks or surface degradation.
PA6
PA6 initially exhibited the highest tensile strength of the group. However, after extended heat exposure, it showed a greater loss in both strength and flexibility than COPA. After 168 hours, tensile strength decreased by approximately 20–28%, and some samples developed micro-cracks. PA6 also displayed moderate warping and slight changes in surface texture. While still robust, its performance under extreme, prolonged heat was outpaced by COPA.
PA12
PA12’s main advantage—dimensional stability—held up under scrutiny. This material retained its shape with almost no warping or shrinkage, even after the longest tests. However, PA12 showed a slightly higher loss in tensile strength than COPA (around 14–18%), but less than PA6. It resisted surface degradation better than PA6, showing only minor discoloration.
What the Results Mean for End-Users
- For applications needing the best balance of toughness, flexibility, and printability under heat: COPA is a clear winner. Its minimal loss of mechanical properties and outstanding resistance to warping make it ideal for automotive engine bay parts, industrial fixtures, and any component exposed to fluctuating or sustained high temperatures.
- If ultimate strength is the priority and slight degradation is acceptable: PA6 remains a strong candidate, especially where cost is a factor and operating temperatures are high but not extreme.
- For projects requiring extreme dimensional accuracy and minimal moisture absorption: PA12 shines. It’s a favorite for precision jigs, fixtures, and chemical-resistant parts where maintaining original shape is paramount.
Expert Recommendations and Final Thoughts
Choosing between COPA, PA6, and PA12 ultimately comes down to your application’s demands. For most high-heat, high-wear use cases, COPA offers an unbeatable mix of strength, flexibility, and reliability over time. If you’re designing for ultra-high accuracy or chemical environments, PA12’s dimensional stability can be a game-changer. For users prioritizing initial strength, PA6 is still a reliable option but may require extra care for long-term thermal exposure.
Conclusion
Heat-ageing performance can make or break a 3D printed part’s real-world usability. After rigorous comparative testing, COPA stands out as the top all-round performer under heat stress, followed closely by PA12 for accuracy, and PA6 for raw strength. To make the best choice for your project, always consider your specific operating conditions and demands—and don’t hesitate to check out the best COPA and nylon filaments in 2025 for the latest high-performance options.