🧩 LSR – Liquid Silicone Rubber
(Two-component elastomeric material, heat-cured, used in applications requiring extreme temperature resistance, permanent elasticity, and chemical stability. LSR is a high-temperature vulcanized silicone (HTV), ideal for high-precision parts.)
🔹 What is LSR
LSR (Liquid Silicone Rubber) is a two-component (A+B) material from the elastomeric silicone family that solidifies through heat vulcanization (platinum or peroxide cured). At ReplastMD, we treat LSR as a high-performance material for sensors and cooling systems. It offers exceptional stability between –50 °C and +230 °C. As a thermoset, it does not return to a liquid state once cured and cannot be welded by heat.
🔧 Composition & Properties
- Polymer Base: Two-component polysiloxane.
- Curing System: Platinum / Peroxide (thermal vulcanization).
- Density: 1.10 – 1.15 g/cm³.
- Hardness (Shore A): 10 – 80.
- Operating Range: –40 °C to +230 °C.
- Chemical Resistance: Excellent (oils, antifreeze, steam).
🚗 Where LSR is used in the automotive industry
| Component | Example parts | Observations |
| Gaskets & Seals | O-rings, headlight seals, covers | Flexible, heat and oil resistant |
| Electrical / Sensors | Plugs, insulation, sensor housings | Superior dielectric insulation |
| Cooling / EGR | Rings, bellows, valve caps | Resists antifreeze and hot steam |
| Anti-vibration | Precision mounts, buffers | Stable elasticity, no permanent set |
🔧 Welding Temperature and Methods
| Method | Compatibility | Observations |
| Hot Air | ❌ Cannot be welded | Silicone does not melt, it only burns |
| Heat Plate (Mirror) | ❌ Impossible | Thermoset material, vulcanized |
| Extrusion | ❌ N/A | Cannot be reshaped after curing |
| RTV Bonding | ✅ Recommended | Neutral/acetoxy silicone RTV adhesives |
💡 ReplastMD Recommendation: LSR cannot be melt-welded. Repairs are done exclusively via specialized RTV silicone bonding or complete part replacement. Surfaces should be cleaned with isopropyl alcohol for better adhesion.