Your sealing project failed because you choose the wrong material. EPDM leaked at high temperatures while silicone couldn't handle the pressure. Picking between these materials determines success or costly rework.
EPDM offers superior mechanical strength and chemical resistance at lower cost, while silicone provides exceptional temperature range (-60°C to 200°C) and flexibility. EPDM suits outdoor applications and automotive uses, whereas silicone excels in food-grade and extreme temperature environments.
Choosing correctly saves money and prevents failures. I'll break down each material's strengths so you make the right decision.
How do temperature ranges compare between EPDM and silicone?
Last month, a German client's EPDM gaskets failed in their 180°C steam system. They needed silicone but didn't realize the temperature difference. Understanding limits prevents disasters.
EPDM operates from -40°C to 150°C continuously, while silicone functions from -60°C to 200°C. Silicone maintains flexibility at extreme temperatures where EPDM becomes brittle or degrades, making temperature the primary selection factor.
Temperature Performance Analysis
Here's the real-world temperature performance data from our testing:
| Temperature Range | EPDM Performance1 | Silicone Performance | Winner |
|---|---|---|---|
| -60°C to -40°C | Brittle, cracks | Flexible, reliable | Silicone |
| -40°C to 0°C | Good flexibility | Excellent flexibility | Silicone |
| 0°C to 100°C | Excellent | Excellent | Tie |
| 100°C to 150°C | Good, some aging | Excellent stability | Silicone |
| 150°C to 200°C | Degrades rapidly | Stable performance | Silicone |
| Above 200°C | Fails quickly | Gradual degradation | Silicone |
Critical Temperature Thresholds
EPDM Limitations: Beyond 150°C, EPDM starts cross-linking changes that make it hard and brittle. I've seen automotive radiator seals fail after prolonged exposure to 160°C.
Silicone Advantages2: Maintains rubber-like properties even at -60°C. Our Dutch client uses silicone O-rings in freezer applications at -40°C with zero failures over two years.
Thermal Cycling3: Silicone handles temperature swings better. EPDM can crack after repeated heating and cooling cycles, especially in HVAC outdoor units.
What about mechanical strength and durability differences?
A conveyor manufacturer switched from silicone to EPDM after silicone belts tore under normal load. Mechanical properties matter more than temperature in many applications.
EPDM provides superior tensile strength (20-25 MPa vs 8-12 MPa), better abrasion resistance, and higher durometer ratings. Silicone offers better compression set resistance and maintains elasticity longer, but lacks the mechanical robustness for high-stress applications.
Mechanical Property Comparison
Based on standard compound testing in our laboratory:
| Property | EPDM Value | Silicone Value | Better Choice |
|---|---|---|---|
| Tensile Strength | 20-25 MPa | 8-12 MPa | EPDM |
| Elongation | 300-600% | 400-800% | Silicone |
| Hardness Range | 30-90 Shore A | 10-80 Shore A | EPDM (range) |
| Tear Resistance | Excellent | Good | EPDM |
| Compression Set | 15-25% | 10-20% | Silicone |
| Abrasion Resistance4 | Excellent | Poor | EPDM |
Durability in Real Applications5
EPDM Strength: Perfect for automotive door seals, window gaskets, and roofing membranes where mechanical stress is constant.
Silicone Flexibility: Better for applications requiring repeated compression and release, like pump diaphragms or valve seats.
Wear Patterns: EPDM wears gradually while maintaining seal integrity. Silicone can tear suddenly under excessive force but recovers better from deformation.
How do chemical resistance properties differ?
An HVAC contractor used silicone gaskets with hydrocarbon oils and watched them swell and fail. Chemical compatibility determines seal life more than any other factor.
EPDM resists polar chemicals, acids, alkalis, and steam excellently but swells in hydrocarbon oils. Silicone resists most chemicals and oils moderately but excels with oxygen, ozone, and UV exposure where EPDM degrades.
Chemical Compatibility Matrix
Critical chemical resistance comparison for common industrial fluids:
| Chemical | EPDM Rating | Silicone Rating | Best Choice |
|---|---|---|---|
| Motor Oil | Poor (swells) | Good | Silicone |
| Hydraulic Oil | Poor | Fair to Good | Silicone |
| Water/Steam | Excellent | Excellent | Tie |
| Acids (mild) | Excellent | Good | EPDM |
| Alkalis | Excellent | Fair | EPDM |
| Alcohols | Good | Excellent | Silicone |
| Ozone | Fair | Excellent | Silicone |
| UV Light | Fair | Excellent | Silicone |
Specific Application Guidelines
Automotive Applications6: EPDM dominates cooling systems, brake fluid applications, and weather sealing because of superior chemical resistance to automotive fluids.
Food Industry7: Silicone wins for FDA compliance and resistance to cleaning chemicals, though EPDM can work for water-only contact.
Outdoor Exposure: Silicone handles UV and ozone better, explaining why it's preferred for glazing applications and outdoor electrical insulators.
What are the cost and manufacturing considerations?
Budget matters in every project. A school district chose EPDM over silicone for 500 window seals and saved 40% while getting better durability for their application.
EPDM costs 30-50% less than silicone rubber, processes faster with conventional equipment, and offers better dimensional stability. Silicone requires specialized mixing and curing but provides easier demolding and better surface finish quality.
Cost Analysis Breakdown
Real pricing from our production experience:
| Factor | EPDM | Silicone | Cost Impact |
|---|---|---|---|
| Raw Material | $3-5/kg | $6-10/kg | EPDM 40% cheaper |
| Processing Time | 10-15 min cure | 5-20 min cure | Variable |
| Tooling Life | 100K+ parts | 50K+ parts | EPDM advantage |
| Reject Rate | 2-3% | 1-2% | Silicone better |
| Secondary Ops | Often needed | Rarely needed | Silicone saves |
Manufacturing Differences
EPDM8 Processing: Uses standard rubber equipment, sulfur curing systems, and conventional compression molding. Higher pressure requirements but proven processes.
Silicone Processing9: Requires platinum-cure systems, careful contamination control, and specialized equipment. Lower pressure molding but material costs more.
Quality Considerations: Silicone typically has better surface finish and fewer defects, while EPDM may need secondary trimming operations.
Conclusion
EPDM excels in mechanical strength and chemical resistance at lower cost, while silicone dominates in temperature extremes and flexibility applications.
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Understanding EPDM's performance can help you choose the right material for your specific needs. ↩
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Explore the benefits of silicone to see why it's preferred in many demanding environments. ↩
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Understanding thermal cycling can help you choose the right material for temperature-sensitive applications. ↩
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Explore how abrasion resistance impacts the longevity of materials in high-wear applications. ↩
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Learn about the practical durability of these materials in everyday applications. ↩
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Find out why EPDM is favored in automotive applications for its durability and chemical resistance. ↩
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Explore silicone's compliance and performance in food-related applications for safety and effectiveness. ↩
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Explore the benefits of EPDM, including cost savings and tooling advantages, to enhance your manufacturing decisions. ↩
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Learn about the complexities of Silicone Processing to better understand its impact on production efficiency and costs. ↩
