TPE vs silicone rubber is one of the most common specification decisions in moulded component sourcing, because both materials deliver soft-touch, rubber-like parts that can bond to rigid substrates. The choice is rarely about softness. It comes down to service temperature, sterility requirements, tooling budget and volume. TPE, typically an SEBS-based thermoplastic elastomer, runs on standard injection machines at a fraction of the cost. Silicone rubber, a thermoset supplied as LSR, survives heat and steam that no TPE grade tolerates and carries the medical documentation that regulated applications demand. Sound elastomer selection at the RFQ stage avoids tooling and re-certification costs later.
TPE vs Silicone Rubber: Property Comparison
| Property | TPE (SEBS-based) | Silicone rubber (LSR) |
|---|---|---|
| Service temperature | -40 to 70 C typical; special grades higher | -50 to 200 C; steam sterilizable |
| Density | 0.90-1.05 g/cm3 | 1.10-1.20 g/cm3 |
| Hardness | 20-90 Shore A | 10-80 Shore A |
| Tensile strength | 5-12 MPa | 6-11 MPa |
| Elongation at break | 500-800% | 400-700% |
| Mould shrinkage | 1.0-2.0% | 2.0-3.5% |
| Cycle time | 15-45 s on standard machines | 60-300 s on dedicated LSR presses |
| Regrind recycling | Yes, sprues can be re-used | No, thermoset cannot be remelted |
| Biocompatibility | Food and skin-contact grades; no medical implant documentation | ISO 10993 and USP Class VI grades available |
| Relative cost | Low | High |
Values are typical published datasheet ranges for unfilled grades; always confirm against the specific grade's datasheet before specifying.
Temperature and Chemical Resistance
Silicone rubber properties stay stable from roughly -50 C to 200 C, and the material tolerates steam sterilisation, which is why it dominates medical valves, baby bottle teats, baking ware and engine-bay seals. TPE grades typically top out near 70 C in continuous service, so a soft-touch grip beside a heat source or a part that sees dishwashers will soften and creep over time. TPE also swells in contact with some oils and solvents, while silicone resists UV, ozone and most chemicals. Before comparing prices, list every thermal and chemical exposure the part will actually see.
Processing, Tooling and Cycle Time
TPE behaves like any thermoplastic: melt at 180-220 C, mould at 20-40 C, no pre-drying for most grades and no post-cure step. Matched grades bond chemically to ABS, PP and PE during overmoulding without a primer, so tpe overmolding runs in standard two-shot or insert cycles of 15 to 45 seconds. Silicone needs a dedicated LSR press feeding cold, low-viscosity material into a hot tool at 160-200 C, tighter shut-offs to prevent flash, and a post-cure step; cycles run 60 to 300 seconds and tooling carries a clear premium. Sprue waste from TPE can be reground and re-used, while silicone scrap must be discarded. Published supplier listings commonly quote unfilled TPE compounds at a fraction of LSR pricing, so on cost-sensitive consumer volumes the gap compounds across cycle time, material yield and tooling.
Compliance and Documentation
Both families offer food-contact and skin-contact certified grades. The difference sits in medical-grade documentation: silicone is available with ISO 10993 and USP Class VI test reports, the default expectation for patient-contact components, while TPE is not specified for implant or sterile applications. For EU food contact, silicone documentation is covered in our FDA vs LFGB silicone guide, and the same evidence discipline applies to TPE grades that claim skin-contact compliance.
How to Specify
Choose silicone rubber when the part sees sustained heat above 70 C, steam sterilisation, patient contact or long-term seal compression. Choose TPE when the part is touched at room temperature, overmoulded onto PP or ABS, or produced in volumes where cycle time and regrind savings dominate cost. For further reading, our PPS vs PBT resin guide applies the same comparison method to engineering polymers, the plastic materials section lists available grades, and our manufacturer directory profiles qualified moulding plants.
