¶ PEEK
¶ Difficulty level: Advanced
PEEK (polyetheretherketone) is a high performance polymer with a number of unique properties that make it an attractive material for 3D printing. It is known for its high temperature resistance, chemical resistance, and good mechanical properties. However, working with PEEK can be challenging due to its high processing temperatures and the need for specialized equipment. In this documentation, we will explore the pros and cons of printing with PEEK in its amorphous and semi-crystalline states, as well as some best practices for working with this material.
¶ Amorphous and Semi-Crystalline States
PEEK is a semi-crystalline polymer, which means that it has both amorphous and crystalline regions within its structure. At low temperatures, PEEK is predominantly amorphous, meaning that the molecules are disordered and have a random arrangement. At higher temperatures, PEEK becomes more crystalline, meaning that the molecules are more ordered and have a more defined structure. The transition from amorphous to crystalline occurs at a specific temperature known as the glass transition temperature (Tg).
The Tg of PEEK varies depending on the specific formulation, but it is generally in the range of 143-158°C. At temperatures below the Tg, PEEK is brittle and prone to cracking. At temperatures above the Tg, PEEK becomes more flexible and has better impact resistance.
Print settings to achieve Amorphous status are usually much lower than those found in the default profiles in 3D Labs Studio. Consult 3D Labs support for more information and guidance.
¶ Pros and Cons of Printing with PEEK in Its Amorphous State
- One of the pros of printing with PEEK in its amorphous state is that it can result in parts with good dimensional stability and a smooth surface finish. This is because the amorphous nature of the material allows it to flow more easily during the printing process, resulting in fewer defects and a smoother surface.
- However, the low impact resistance and brittleness of amorphous PEEK can be a drawback, as parts may be prone to breaking or cracking under stress if not annealed.
- Recent research has shown that parts printed in the amorphous, or "cold" state, are actually stronger than semi-crystalline parts when properly annealed.
¶ Pros and Cons of Printing with PEEK in Its Semi-Crystalline State
- Printing with PEEK in its semi-crystalline state can result in parts with improved strength and impact resistance. This is because the crystalline structure of the material gives it better mechanical properties.
- However, the higher processing temperatures required to print semi-crystalline PEEK can be a challenge, as the material can degrade at temperatures above its Tg. This can lead to reduced strength and other defects in the finished part.
¶ Best Practices for Working with PEEK
- Print challenging parts in an amorphous state. 80C Chamber, 110C Bed, 450C nozzle is a good starting point.
- Use a supported brand of high quality PEEK filament and follow the manufacturer's recommendations for printing with PEEK.
- Use proper post-processing techniques, such as cryogenic treatment or annealing, to improve the strength and durability of PEEK prints.
- Store PEEK filament properly to prevent moisture absorption.
- Dry PEEK filament in a professional lab oven or drying product for at least 6 hours before use.
- Keep part sizes within 150mm in any direction for maximum success.
- Long, flat parts lend themselves to warping moreso than rounded geometries. Keep this in mind when designing parts to print with PEEK.
- Consider printing the parts with PEEK-CF whenever possible as you will generally have a much better experience in terms of part warping, and dimensional accuracy.
You can consult our cheat sheet for reference on drying times.
DANGER
DO NOT LEAVE PEEK IN YOUR HOTEND OVERNIGHT. PEEK loves metal, and will cause an irreversible clog if left in your nozzle for several hours after your print is completed. For this reason you MUST remove the PEEK material from the hotend after printing. Here at 3D Labs we've experienced this first hand, trust us!
Use appropriate protective equipment when handling PEEK. The material can produce harmful fumes when heated, so it is important to use ventilation and personal protective equipment to avoid inhaling these fumes.