PEEK and PEI are both thermoplastics that are a step above standard materials like PLA or ABS on the performance ladder. But they’re not interchangeable, and using the wrong one can deliver a failed print. Here’s how to figure out whether PEEK or PEI is right for your application.
What PEEK Brings to the Table
PEEK (polyether ether ketone) is one of the highest-performing polymers available for 3D printing. It’s got a continuous service temperature around 250°C, excellent chemical resistance, and mechanical properties that rival some metals. You’ll find it in aerospace components, medical implants, and other industrial parts.
The trade-off is that PEEK demands an equally capable printer. You need a hotend that reaches 360–400°C and a heated bed running at 120°C or higher, plus an enclosed, temperature-controlled build chamber to prevent warping. Some examples include the CreatBot PEEK-300 and CreatBot PEEK-250.
What PEI Brings to the Table
PEI (polyetherimide), often sold under the trade name Ultem, is a step down from PEEK in raw performance, but it’s still far ahead of commodity filaments. It handles continuous temperatures up to around 170°C, resists hydrolysis and many chemicals, and offers solid strength-to-weight performance. It’s also somewhat easier to process than PEEK, though it still requires a high-temperature setup.
How the Two Compare Head-to-Head
Let’s compare each option according to the most important features:
- Heat resistance: PEEK wins. If your part continuously faces temperatures above 170°C, PEI isn’t an option.
- Chemical resistance: PEEK handles a broader range of solvents and chemicals, including concentrated acids. PEI is resistant to many chemicals but not all.
- Mechanical strength: PEEK generally has higher tensile strength and stiffness. For load-bearing parts under significant stress, it’s often the stronger choice.
- Printability: PEI is relatively more forgiving. PEEK has a narrower processing window and is less tolerant of suboptimal printer settings.
- Cost: PEEK filament costs significantly more than PEI. If PEI meets your specs, the savings make a compelling case.
How to Match the Material to Your Application
The right question isn’t which material is better. It’s which one is sufficient for your specific use case.
If your part needs to survive in a high-heat environment above 170°C, faces aggressive chemical exposure, or carries mechanical loads, PEEK is your material. Medical-grade and aerospace structural applications almost always land here.
But if your part needs solid thermal and chemical resistance in a less extreme environment, PEI can handle those conditions at a more affordable price point. Electrical components, aircraft cabin interiors, and general industrial housings often fall into this category.
Make the Right Call for Your Next Print
To decide whether PEEK or PEI is right for your application, evaluate your product requirements and budget. Identify the most demanding condition your part will face and work backward from there.
If you’re ready to take on a high-temperature material and want to explore compatible hardware, check out the options available at 3D Printers Depot. We have products for PEI and PEEK 3D printing, so you’re sure to find a printer and accessories that match your material and application.