🧩 FKM – Fluoroelastomer
(Heat-resistant fluorinated material with exceptional chemical stability, used for gaskets, seals, hoses, and valves exposed to oils, fuels, and high temperatures. FKM is a fluoro-carbon copolymer known for its extreme durability.)
🔹 What is FKM
FKM (Fluoroelastomer) is a synthetic rubber based on fluorinated monomers. At ReplastMD, we categorize it within the same elite family as FPM and Viton®. It offers unique resistance to hydrocarbons, acids, and bases. As a thermoset material, it does not melt, providing perfect sealing in high-pressure systems even at temperatures up to +250 °C.
🔧 Composition & Properties
- Polymer Base: Fluorocarbon copolymer (VDF + HFP + TFE).
- Density: 1.80 – 2.10 g/cm³ (very high density).
- Hardness (Shore A): 55 – 90.
- Operating Range: –20 °C to +250 °C.
- Chemical Resistance: Exceptional across all automotive fluids.
🚗 Where FKM is used in the automotive industry
| Component | Example parts | Observations |
| Engine & Transmission | O-rings, seals, covers | High pressure and oil resistance |
| Fuel / EGR Systems | Valves, hoses, fittings | Thermally stable, no chemical swelling |
| Braking Systems | Seals, membranes, rings | Compatible with DOT / ATF fluids |
| Electrical / Sensors | Plugs, protective gaskets | Reliable insulator, UV stable |
🔧 Welding Temperature and Methods
| Method | Compatibility | Observations |
| Hot Air | ❌ Cannot be welded | Thermoset material – does not flow |
| Heat Plate (Mirror) | ❌ Impossible | Thermally degrades above 250 °C |
| Extrusion | ❌ N/A | Cannot be reshaped after curing |
| Chemical Bonding | ✅ Recommended | Specialized FKM / Viton® bonding systems |
💡 ReplastMD Recommendation: FKM cannot be melt-welded. For repairs, we use specialized Viton® adhesives, fluorinated primers, and hot-press bonding (180 °C). However, for critical high-pressure seals, complete replacement is the professional standard.