In more than 80% of the premature failures we analyze in industrial silicone gaskets, the root cause is not the material nor the manufacturing process, but decisions made during the design phase.
Selections that appear correct — a Shore A hardness considered standard, a conventional geometry or an assumed certification — ultimately lead to premature deformation, loss of sealing and maintenance cycles far below expectations.
1. Why selecting silicone only by Shore A hardness causes hidden failures
In most projects that reach us with in-service issues, the Shore A hardness is within the catalog-recommended range. The problem is not the hardness itself, but using it as the sole selection criterion.
Under real operating conditions, hardness directly affects thermal creep, compression set and dimensional stability under continuous load — factors that are not reflected in simplified technical datasheets.
| Hardness | Typical behavior | Main in-service risk |
|---|---|---|
| 50 Shore A | High adaptability to wide tolerances | Accelerated deformation under continuous compression or elevated temperature |
| 60 Shore A | Balance between elasticity and stiffness | Limitations under prolonged constant loads |
| 70 Shore A | High dimensional stability | Reduced initial adaptability during assembly |
High-performance extrusion compounds such as EQ150, EQ160 and EQ170 achieve tensile strengths of 7.5–8 MPa and elongations above 400%. These values enable thousands of cycles without visible fatigue when hardness is correctly defined at the design stage.
2. When a gasket works mechanically but cannot be legally installed
One of the most costly errors identified in industrial projects is not mechanical, but regulatory. There are technically functional solutions that become blocked during approval due to misinterpreted or incomplete certification.
| Sector | Typical critical requirements |
|---|---|
| Food contact | EC 1935/2004 + FDA 21 CFR 177.2600, documented batch traceability |
| Medical devices | ISO 10993-1, USP Class VI, ISO 13485, declared absence of CMR substances |
| Railway | EN 45545-2, specific validation by material reference |
| All sectors | REACH, RoHS and up-to-date declaration of conformity |
If the supplier does not provide this documentation with each manufactured batch, the risk is not technical: it is regulatory, contractual and financial.
3. Real thermal resistance: the problem is not the declared temperature range
The nominal thermal range of a silicone (-60 °C to +200 °C) is rarely the root cause of failure. Problems arise when prolonged exposure and dimensional stability under load are ignored.
In continuous service, what matters is not reaching a peak temperature, but maintaining geometry, contact pressure and elastic recovery over thousands of operating hours.
4. ISO 3302 tolerances: the error that leads to complete redesigns
ISO 3302-1 (extrusion) and ISO 3302-2 (molding) define the real tolerances of elastomers. Ignoring them is one of the most frequent causes of costly redesigns after initial assembly trials.
- Minimum internal radii, avoiding sharp corners
- Wall thickness ≥ 1.5 mm to ensure dimensional stability
- Post-curing shrinkage of 1–3% calculated at the design stage
- Clear definition of working mode: compression, tension or expansion
5. Common errors identified in real projects
- Applying CNC machining tolerances to elastomeric profiles
- Failing to account for shrinkage in production lengths
- Designing without considering the assembly method or load sequence
Technical conclusion
Selecting industrial silicone is not a table of equivalences nor a catalog decision. It requires a multidisciplinary analysis integrating mechanics, regulations, thermal behavior and real manufacturing tolerances.
Projects correctly defined from the design stage perform reliably for years. Those approached with partial criteria fail within months, regardless of manufacturing quality.
Do you need to validate your design before manufacturing?
Our engineering team reviews drawings under ISO 3302 and selects the optimal compound (EQ150, EQ160 or EQ170) based on real application conditions, not catalog assumptions.
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