CNC Machining
PEI (Ultem)
PEI (Polyetherimide), universally recognized by the SABIC brand name Ultem, is an advanced amorphous thermoplastic. Boasting a continuous use temperature of 170°C (340°F), inherent UL94 V-0 flame retardancy, and a distinct translucent amber color, it is the uncompromising standard for aerospace interiors and autoclavable medical devices.
Core Mechanical Properties
PEI sits just below PEEK in the high-performance plastics hierarchy, offering incredible thermal stability and mechanical strength at a more accessible price point. Below are the typical properties for unfilled Ultem 1000.
| Property | Typical Value (Ultem 1000) | Key Benefit |
|---|---|---|
| Continuous Use Temp. | 170°C (340°F) | Maintains structural integrity and electrical properties in extreme heat environments. |
| Tensile Strength | ~ 105 MPa | Exceptionally strong and rigid for an unfilled amorphous plastic. |
| Flammability (FST) | UL94 V-0 | Inherently flame retardant. Meets extremely strict aerospace Smoke and Toxicity (FST) standards. |
| Dielectric Strength | ~ 33 kV/mm | Outstanding electrical insulator, making it ideal for high-frequency microwave and RF components. |
Material Comparison: Ultem Grades
PEI is overwhelmingly manufactured and specified under the SABIC "Ultem" brand name. Choosing between unfilled and glass-filled variants dictates the material's rigidity and machinability.
| Material Grade | Visual Appearance | Key Characteristics & Use Case |
|---|---|---|
| Ultem 1000 | Translucent Amber | Unfilled PEI. Highly ductile, FDA compliant, and offers excellent electrical insulation. Used for medical reusable devices, electrical connectors, and sight glasses. |
| Ultem 2100 | Opaque (Tan / Greenish) | 10% Glass-Filled PEI. Adds significant rigidity and dimensional stability over Ultem 1000 while remaining relatively easy to machine. |
| Ultem 2300 | Opaque (Tan / Greenish) | 30% Glass-Filled PEI. Provides maximum tensile strength and extreme rigidity. Heavily utilized for structural aerospace components and high-load insulating blocks. Highly abrasive to tooling. |
Hardcore Industrial Applications
PEI excels in regulated industries where components must survive radiation, harsh sterilization chemicals, and stringent aerospace fire safety codes.
Aerospace Interiors
Because it meets the FAA's strict Flame, Smoke, and Toxicity (FST) requirements, Ultem is heavily machined into commercial aircraft cabin components, air valves, and custom oxygen brackets.
Reusable Medical Devices
Ultem 1000 can withstand 1,000+ cycles in a steam autoclave without degrading or losing dimensional accuracy. We machine it into surgical tool handles, sterilization trays, and dental devices.
High-Frequency Insulators
With exceptional dielectric strength and stability across a wide range of frequencies and temperatures, PEI is precision-turned for microwave connectors, RF housings, and high-voltage standoffs.
Expert Machining Tips
PEI is prone to a phenomenon known as Environmental Stress Cracking (ESC). Improper machining techniques or wrong coolant choices will instantly ruin the part. Huade engineers apply stringent protocols:
- 1
Strict Coolant Control (Prevent ESC)
Aromatic or halogenated synthetic coolants will attack PEI, causing microscopic stress cracks that shatter the part. We machine Ultem using only approved non-aromatic, water-soluble coolants or pressurized air blasts.
- 2
Mandatory Annealing Cycles
Extruded Ultem billets contain high internal stresses. To maintain tight tolerances (especially on thin-walled components) and prevent warping, we conduct thermal annealing cycles before and often during the machining process.
- 3
PCD Tooling for Ultem 2300
While pure Ultem 1000 machines beautifully with sharp carbide, the 30% glass fibers in Ultem 2300 will chew through standard end mills. We utilize specialized Polycrystalline Diamond (PCD) tooling to manage tool wear and maintain precision.
Machining FAQs
Understanding the specific nuances of PEI helps ensure your project's success and cost-efficiency.
Is PEI (Ultem) better than PEEK?
They serve different tiers. PEI is highly capable (170°C) and significantly more cost-effective than PEEK. However, if your application exceeds 170°C or requires extreme chemical resistance to severe bases, PEEK (250°C) is required. Additionally, unfilled PEI is translucent, whereas PEEK is opaque.
Can machined Ultem 1000 be polished clear?
Yes. CNC machining leaves microscopic tooling marks that make the naturally translucent amber PEI look frosted or opaque. We can restore its beautiful translucent amber appearance through meticulous vapor polishing or mechanical buffing, which is ideal for sight glasses and fluid manifolds.
Is machined Ultem FDA approved?
Yes, unfilled Ultem 1000 is FDA compliant for direct food contact and biocompatible (USP Class VI) for medical applications. We ensure our machining processes and cleaning protocols maintain this compliance.
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