In the late 1970s, GE Plastics invested roughly $50 million into developing a single polymer. Adjusted for inflation, that represents nearly a quarter of a billion dollars spent on one material. The result was ULTEM™ polyetherimide (PEI), a high-performance engineering plastic that would eventually become indispensable in aerospace, medical devices, and industrial manufacturing.
Today, ULTEM appears everywhere from commercial aircraft cabins to surgical sterilization systems. Yet for decades, very few companies had the ability to successfully 3D print this remarkable material.
The Quest to Create a Heat-Resistant Thermoplastic
Researchers at GE Plastics faced a difficult challenge. Existing polyimides possessed exceptional heat resistance and flame retardancy, but they were nearly impossible to process using conventional manufacturing methods. Instead of melting cleanly, these materials decomposed before they could be molded or extruded.
The objective was ambitious: create a polymer with the thermal performance of polyimides while maintaining the processability of ordinary thermoplastics.
In 1982, the breakthrough arrived. The resulting material became known as ULTEM.
Why ULTEM PEI Is Unique
ULTEM belongs to a family of polymers known as polyetherimides. Its molecular structure combines rigid imide groups with flexible ether linkages.
- Imide groups provide outstanding thermal stability.
- Ether linkages allow the material to melt and flow during processing.
- Glass transition temperature: approximately 217°C.
- Natural flame resistance: does not sustain combustion under normal atmospheric conditions.
- UL94 V-0 rating: achieved without halogen additives.
These properties make ULTEM particularly attractive for applications requiring compliance with strict flame, smoke, and toxicity standards used throughout the aerospace industry.
Why 3D Printing ULTEM Is So Challenging
Many desktop printers can reach nozzle temperatures above 350°C, leading some to believe that printing ULTEM is straightforward. In reality, temperature at the nozzle is only one part of the equation.
1. Internal Stress Becomes Trapped
Unlike semi-crystalline materials, ULTEM is amorphous. As parts cool, residual stresses become locked into the structure. This can result in:
- Layer separation
- Microcracking
- Warping
- Long-term mechanical failures
2. Large Temperature Differences Cause Problems
Freshly extruded material exits the nozzle between 350°C and 380°C. If the build chamber remains relatively cool, enormous temperature gradients develop, causing parts to tear themselves apart during printing.
3. Moisture Is the Enemy
ULTEM is highly hygroscopic, meaning it absorbs moisture from the atmosphere very quickly. Even brief exposure to ambient air can introduce enough water to create:
- Steam bubbles during extrusion
- Surface defects
- Internal voids
- Reduced mechanical strength
Successful printing depends on controlling the entire build environment, not simply increasing nozzle temperatures.
The Patent That Defined High-Temperature FDM Printing
In 2008, Stratasys partnered with SABIC to introduce ULTEM 9085 filament for certified FDM manufacturing. At the heart of this capability was a patented heated-chamber design.
The innovation allowed printers to maintain chamber temperatures approaching 200°C while keeping motors and sensitive components outside the oven-like environment. Flexible bellows enabled the print head to move without exposing electronics to extreme heat.
This patent effectively gave Stratasys exclusive control over industrial ULTEM printing for nearly two decades.
Real-World Applications of ULTEM 3D Printing
Aerospace Components
ULTEM 9085 became a preferred material for aircraft interiors thanks to its lightweight properties and flame resistance. Companies such as United Launch Alliance have even flown 3D-printed environmental control ducts aboard Atlas V rockets.
Space Manufacturing
Additive manufacturing reached orbit when 3D printers aboard the International Space Station began producing PEI-based components and tools on demand.
Medical Devices
ULTEM 1010 introduced additional capabilities, including:
- Autoclave compatibility
- ISO 10993 biocompatibility
- Reusable surgical trays
- Patient-specific medical devices
- Surgical guides produced from CT scans
These applications demonstrate that ULTEM is far more than a prototyping material. It is routinely used in mission-critical environments.
The Expiration of Stratasys’ Heated Chamber Patent
On February 27, 2021, the heated chamber patent expired. This marked a turning point for industrial additive manufacturing.
Manufacturers that had spent years preparing alternative platforms suddenly gained the ability to incorporate advanced thermal management systems into open-material printers. As a result, access to ULTEM printing expanded dramatically.
For many businesses, this meant obtaining aerospace-grade material capabilities without investing millions of dollars in proprietary systems and expensive annual service contracts.
Can a Desktop Printer Really Print ULTEM?
Technically, yes. Extruding ULTEM from a nozzle is possible on some lower-cost systems.
However, producing reliable, durable parts suitable for long-term industrial use requires far more than simply achieving the correct extrusion temperature.
Questions worth asking include:
- What chamber temperature is being maintained?
- How is filament moisture controlled?
- Will the part retain its properties after months under load?
- Can the system consistently reproduce the same results?
Industrial success with ULTEM depends on mastering chemistry, thermal management, process control, and machine reliability.
The Future of High-Temperature Polymer 3D Printing
The science behind ULTEM remains unchanged. What has changed is accessibility.
Decades of chemical development and process engineering have transformed what was once an exclusive capability into a practical manufacturing solution available to many more companies.
As high-performance materials continue to move into mainstream additive manufacturing, ULTEM PEI stands as one of the clearest examples of how advanced polymers can replace metal, reduce weight, and enable entirely new manufacturing possibilities.