🧩 FEP – Fluorinated Ethylene Propylene (Melt-processable Fluoropolymer)
(Transparent and flexible fluoroplastic from the same family as PTFE and PFA, but with excellent processability. FEP features a non-stick surface, very low friction, and continuous heat resistance up to 200–220 °C.)
🔹 What is FEP
FEP (Fluorinated Ethylene Propylene) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). It shares the same chemical inertness as PTFE but can be melted and reshaped, making it suitable for injection molding, extrusion, and thermal welding. It is clearer and softer than PFA, often used for high-end wire insulation and chemical tubing.
🔧 Composition & Properties
- Base: 85–90% TFE, 10–15% HFP.
- Density: 2.12–2.17 g/cm³.
- Melting Point: ≈ 260 °C.
- Chemical Resistance: Total.
- Continuous Heat Resistance: 200–220 °C.
🚗 Where FEP is used in the automotive industry
| Component | Example parts | Observations |
| Fuel / Fluid Systems | Hoses, fittings, gaskets | Resistance to fuels, oils, solvents |
| Electrical / Sensors | Wire insulation, connectors | Excellent dielectric, heat stable |
| Cooling / Chemical | Tubes, valves, nozzles | Chemically inert, smooth, leak-proof |
| Technical Protection | Sleeves, jackets, membranes | Non-stick, superior durability |
🔧 Welding Temperature and Methods
| Method | Optimal Temp | Observations |
| Hot Air | 280 – 300 °C | Easy melting, stable flow |
| Heat Plate (Mirror) | 280 – 300 °C | Clean, airtight joint |
| Plastic Extrusion | 290 – 310 °C | FEP or compatible PFA rods |
| Heat Fusion | 280 – 300 °C | Ideal for FEP tubes and fittings |
🔩 Material Compatibility
- ✅ Compatible: FEP, PFA, ETFE, PTFE (with surface treatment).
- ⚠️ Good Compatibility: PVDF, ECTFE, MFA (fluoropolymers).
- ❌ Incompatible: ABS, PP, PE, PC, PA, POM, PVC, PET.
💡 ReplastMD Recommendation: Use FEP or PFA rods at 300 °C. Ensure the surface is perfectly clean; avoid forced air and impurities. Allow for natural cooling to achieve a clear, glossy bond.
🧠 How to Identify FEP
- Engraved marking: >FEP<, >TEFLON FEP<, >DYNEON<, >HYFLON<.
- Texture: Glossy, smooth, translucent surface.
- ReplastMD practical test: If the part is glossy, translucent, and softens at 280 °C, it’s confirmed as FEP. Burns with a clean flame and self-extinguishes.
🛠️ FEP Welding at ReplastMD:
At our ReplastMD service center (Chisinau, Ciocana sector), we perform professional FEP welding for hoses, fittings, and technical sleeves, ensuring a clear, smooth, and leak-proof finish.