🧩 PEI – Polyetherimide (Ultem®)
(A high-performance technical material with exceptional heat resistance, high rigidity, and dimensional stability, capable of continuous operation above 200–220°C without warping. A superior alternative to PC and PSU in critical applications.)
🔹 What is PEI
PEI (Polyetherimide) is an amorphous aromatic polymer originally developed by General Electric (now produced by SABIC) under the brand Ultem®. It is characterized by its exceptional thermal stability, natural flame retardancy (UL94 V-0), and high mechanical strength. PEI retains its properties even after thousands of thermal cycles, making it the primary choice for precision parts exposed to high heat or mechanical stress.
🔧 Composition & Properties
- Base: 100% Polyetherimide.
- Density: 1.27–1.29 g/cm³.
- Vicat Softening Temperature: ≈ 215–220 °C.
- Chemical Resistance: Exceptional.
- Continuous Heat Resistance: 200–220 °C.
🚗 Where PEI is used in the automotive industry
| Component | Example parts | Observations |
| Engine / Thermal | Sensor covers, EGR parts, pumps | Stability at 220 °C, high rigidity |
| Electrical / Sensors | Housings, sensor plates, insulators | Superior electrical/thermal resistance |
| Fuel / Braking | Fittings, valves, pressure parts | Chemically inert, zero shrinkage |
| Technical Structures | Covers, clips, ECU frames | Lightweight, stable, flame retardant |
🔧 Welding Temperature and Methods
| Method | Optimal Temp | Observations |
| Hot Air | 340 – 360 °C | Slow melting, controlled viscous flow |
| Plastic Extrusion | 330 – 350 °C | PEI or compatible PPS+PEI rods |
| Heat Plate (Mirror) | 330 – 350 °C | Clean bond, zero oxidation |
🔩 Material Compatibility
- ✅ Compatible: PEI, PPSU, PES, PSU, PPS+PEI, PPS, PEEK.
- ⚠️ Good Compatibility: PPA, PPS+CF, PPS+Noryl.
- ❌ Incompatible: PP, PE, PS, ABS, PC, PET (completely different melting points).
💡 ReplastMD Recommendation: Use PEI or PPS+PEI rods at 350°C. Slow and uniform heating ensures a bubble-free bond and clear texture. Gradual cooling provides a compact finish without internal stress.
🧠 How to Identify PEI
- Engraved marking: >PEI<, >ULTEM<, >ULTRASON E<, >TECAPEI<.
- Texture: Semi-glossy or glossy, extremely rigid.
- ReplastMD practical test: If the part is rigid, glossy, and does not deform under 250°C hot air, it is confirmed. Burns with a clean flame and a faint imide scent.
🛠️ PEI Welding at ReplastMD:
At our ReplastMD service center (Chisinau, Ciocana sector), we perform professional PEI / Ultem® welding for EGR components, pumps, and thermal sensors, ensuring a dense, durable, and factory-grade finish.