All you need to know about PEI filament


Polyether Imide or PEI is a polymer first developed by Joseph Wirth of GE in the early 1980s. Along with PEEK (Polyether ether ketone). PEI is one of the plastics that fall under the PAEK (polyaryletherketone) chemical group.
Today, almost all PEI filaments in the market are manufactured under the ULTEM brand by the SABIC company.


Characteristics of PEI:

  • It is an amorphous plastic with a characteristic semi-transparent amber colour.

  • It has high mechanical strength, stable electronic properties, and excellent chemical stability at high temperatures.

  • PEI has exceptional mechanical strength.

  • It is resistant to chemical attack and there is no degradation on exposure to outdoor conditions.

  • It is safe for 3D printing as it does not release toxic fumes when heated.

  • It is rigid and strong like PEEK, with a tensile strength of 85 MPa and a Young’s modulus of 3.2 GPa.

  • It has a glass transition temperature of 217 °C and its melting point is 240 °C, indicating its excellent use in case of functional parts that need to endure a lot of friction and medical tools required to be autoclaved regularly.

  • It has good resistance to attacks by acids, bases, and oils.

  • it is intrinsically flame-retardant and has a high flame resistance, low smoke emission and low toxicity.

  • The material also has a high strength-to-weight ratio.

  • It has good resistance to automotive fluids, hydrocarbons, alcohols and aqueous solutions.

  • It is biocompatible and can also withstand steam sterilization.

  • It has good dimensional stability and creep resistance.


Applications of PEI:  

  • PEI is used widely in various engineering and industrial components because of its high-performance characteristics.

  • PEI is used particularly for parts that are often used outdoors and exposed to UV radiation.

  • Being more expensive and having limited availability than other filaments like ABS, printing with PEI can be attempted only for the most commercially relevant applications.

What to check for if you want to print with PEI:

  • Check whether your 3D printer will be able to handle PEI, especially the capability of heating element of the hot end nozzle.

  • Due to operation at elevated temperatures, an all-metal nozzle would be required.

  • Check if your print bed is able reach high temperatures.

  • Check if you have a good enclosure which will maintain the print chamber at a high temperature.

Precautions when using PEI:

  • PEI being more rigid than most other 3D printing filaments, there is a risk of it snapping and hence needs to be handled carefully.

  • Ensure right alignment of the print bed and filament nozzle, to prevent, the print and the PEI surface getting damaged

  • The print chamber needs to be heavily insulated to prevent warping and layer adhesion issues.

  • No cooling fan is to be used during the entire printing process; it is better to have an actively heated chamber.

  • While setting the print speed, it is better to start low and then slightly ramping it up to a maximum speed.

  • Watch out for signs of under-extrusion, such as skipping of your extruder gears. 


To conclude, PEI filament has now found its a place among the other popular 3D printing materials, such as PEEK and PEKK. It also competes with the most broadly used thermoplastics in the engineering industry (polysulfones, polyphenylene sulphides and polyketones).
The PEI filament has all the desired characteristics for 3D printing service that an advanced material requires, of which thermal resistance is one of the most sought after by the market.