Traceable Methods
Every parameter maps to an ASTM, ISO, SAE or MIL specification, so results can be audited against the standard.
Advanced Characterization & Testing
Beyond standard hardness, tensile strength and compression set, CYES characterizes silicone, LSR, FVMQ and specialty molded components by advanced, application-critical parameters. These metrics support PPAP, aerospace, medical device, EV and high-reliability sealing qualification. All test methods are traceable to ASTM, ISO, SAE and MIL specifications; full test reports are available by project request.
Group 1 — Elastomer Properties
Advanced Mechanical & Thermal Characterization
Long-term and dynamic properties that separate premium compounds from datasheet-only grades — the parameters engineers ask for when static sealing, vibration and thermal cycling are the real failure modes.
| Parameter | Method / Detail |
|---|---|
| Stress relaxation | ASTM D6147 / ISO 3384. Stress retention under constant deflection, reported as percentage retained load after 168 h @ 125 °C, 25 % compression. Typical target for FVMQ automotive seals: ≥72 % retained stress. Distinct from compression set; critical for long-term static sealing creep. |
| Temperature retraction (TR test) | ASTM D1329. TR10 / TR30 / TR50: temperature at which 10 %, 30 %, 50 % of stretch recovers. FVMQ typical TR10: −58 °C. Used widely by aerospace to define the low-temperature sealing threshold, not simply "service temperature". |
| Rebound resilience | ASTM D2632, ISO 4662. Vertical rebound percentage. Low-resilience grades for damping pads; high resilience for dynamic keypads and reciprocating seals. |
| Dynamic / complex modulus (DMA) | Storage modulus E′, loss modulus E″ and loss factor tan δ across a temperature sweep. The tan-δ peak identifies glass transition Tg; vital for vibration isolators, bumpers and dynamically loaded bellows. |
| Tear propagation resistance | Slow crack growth under cyclic loading, measured on pre-notched specimens (not just initial tear strength). Important for repeatedly flexed bellows, diaphragms and thin-wall LSR valves. |
| Permanent set after thermal shock | Distinct from standard compression set; measured after cycling between −40 °C and +150 °C for 500 cycles. Used for turbocharger and EV thermal-management seals. |
| Volume swell & property retention in fluids | ASTM D471. Reported separately for IRM 903, Reference Fuel B / Fuel C, biodiesel RME, Dexron transmission fluid and phosphate ester hydraulic fluid. We record hardness shift, tensile loss and elongation change after immersion — not merely "oil resistant". |
| Heat-ageing property retention | ASTM D573. Percent retention of tensile / elongation after 700 h air-oven ageing at 175 °C. Many datasheets only quote initial values; retention separates stable premium compounds. |
Group 2 — Purity & Outgassing
Extractables, Leachables, Siloxane & Outgassing
For medical, vacuum and semiconductor applications, invisible contaminants are the specification. These parameters qualify silicone for lens, wafer, implant-adjacent and analytical-instrument environments.
| Parameter | Method / Detail |
|---|---|
| Total mass loss TML & CVCM | ASTM E595. Vacuum outgassing: TML < 1.0 %, CVCM < 0.1 %, NASA standard. For satellite, optical and semiconductor chamber components; condensable volatiles that fog lenses or contaminate wafers. |
| Extractables & leachables (E&L) | ISO 10993-12. Soxhlet extraction in polar / nonpolar media; total extractables, pH shift, non-volatile residue and cytotoxic eluate testing. |
| Cyclic siloxane residual control: D4, D5, D6 | Low-siloxane post-cured LSR; residual cyclic siloxanes controlled below 1000 ppm by extended nitrogen post-cure. Critical for mass-flow sensors, analytical instruments and vacuum systems. |
| Endotoxin level (LAL testing) | Endotoxin < 0.5 EU/mL for non-implant medical silicone. |
| Platinum catalyst residual | Platinum residue < 5 ppm for medical platinum-cured LSR, after controlled post-cure. |
| Volatile organic fraction (VOC) | Weight loss after vacuum stripping; residual cure by-products. |
| PFAS screening / PFAS non-detect | Multi-analyte panel per EPA 537.1 / ISO 21675; reporting PFOA, PFOS, GenX and short-chain PFAS at ppb detection limits, for food, medical and automotive green programs. |
| Odour transfer & sensory evaluation | LFGB / AP(2004)-4. Sensory transfer testing, odour threshold and taste migration for food-contact silicone — not only migration numbers. |
Group 3 — Molding & Metrology
Shrinkage, Tolerance & Measurement Capability
Dimensional control is where tooling, material and measurement meet. These parameters pair with our FAI, Cpk and Gage R&R records to close the loop from cavity to certificate.
| Parameter | Method / Detail |
|---|---|
| Linear mould shrinkage | Conditioned vs as-molded. Shrinkage measured after post-cure and moisture conditioning; separate values for thick and thin cross-sections, gated / ungated regions. LSR typical: 2.0–3.2 %; FVMQ often lower. |
| ISO 3302-1 tolerance grade | M1 / M2 / M3 precision rubber tolerance class; dimension tolerance by feature size and cross-section. Engineers search this exact standard. |
| Post-cure dimensional drift | Dimensional shift over the first 72 hours after demoulding / post cure; stabilization period before FAI and Cpk sampling. |
| Gate vestige height & flash threshold | Maximum permissible flash, flash-free gate design target, gate vestige height controlled < 0.03 mm for optical / sealing faces. |
| Shrinkage anisotropy | Directional shrinkage difference parallel and perpendicular to the material flow front; important for asymmetric bellows, grommets and multi-cavity layouts. |
| Cure-gradient inhomogeneity | Cross-section cure mapping by hardness gradient and residual volatile sampling; thick LSR parts risk skin/core cure mismatch. |
| Gating-induced fibre orientation (PA66-GF) | Fibre orientation vector, local shrinkage and warpage prediction for reinforced thermoplastic inserts overmolded with silicone. |
| Gauge R&R for critical features | Measurement system capability, repeatability and reproducibility study, paired with Cpk. Not just "Cpk > 1.33" — we validate the measuring system itself. |
Group 4 — Qualification & Exposure
Environmental Exposure & Specialized Qualification
Automotive, aerospace and battery programs demand proof of survival, not a generic "resistant" label. These are the exposure tests behind serial-production release.
| Parameter | Method / Detail |
|---|---|
| Ozone cracking threshold | ASTM D1149. Ozone concentration, strain level and time to crack initiation — not just "ozone resistant". |
| Salt-spray corrosion (bonded assemblies) | ASTM B117. Delamination threshold for insert-molded silicone to aluminium / stainless steel. |
| Hydrolysis resistance | 85 °C / 85 % RH. Property retention after 1000 h damp-heat exposure; widely used for EV battery seals. |
| Sterilization-cycle retention | Property retention after repeated sterilization: 20× autoclave, gamma 25 kGy, EtO. |
| Flammability & LOI | UL 94 V-0, V-1, HB; limiting oxygen index (LOI). Low-smoke low-toxicity grades for rail and battery. |
| Tracking index (CTI) | Comparative tracking index for silicone insulation; dielectric breakdown after surface contamination, for high-voltage EV and electronics grommets. |
| Dielectric dissipation factor (tan δ) | Frequency-dependent dielectric loss, critical for high-frequency sensors and high-voltage insulation. |
| MIL-DTL-25988 qualification package | Full suite for aerospace FVMQ, including low-temperature retraction, fluid ageing, compression set and accelerated thermal exposure. |
Group 5 — Tactile & Interface
Human-Interface & Tactile Parameters
For keypads, valves and soft seals, the specification lives in feel and long-cycle consistency — the niche metrics a datasheet rarely covers.
| Parameter | Method / Detail |
|---|---|
| Actuation force, travel & tactile ratio | Peak force / valley force, travel distance and hysteresis (click ratio) for silicone keypads; standard metrics for membrane and elastomer switches. |
| Contact resistance drift | Carbon or silver printed keypad resistance shift over millions of cycles. |
| Stiction threshold | Static adhesion between mating silicone surfaces, relevant for valves, suction cups and soft seals. |
Why It Matters
Extended Characterization for Serial-Production Release
Our engineering team selects the correct compound, cure route, post-cure schedule and sampling plan based on these application-specific metrics. Where standard data sheets omit long-term creep, fluid ageing, vacuum outgassing or measurement system validation, CYES provides the extended characterization required for customer qualification, gate review and serial production release.
Paired with FAI & Cpk
Dimensional metrics run alongside our FAI, Cpk and Gage R&R records, not in isolation.
Reports on Request
Full test reports are released by project, supporting PPAP, aerospace, medical, EV and high-reliability qualification.
Request an Extended Characterization Package
Tell us the application, environment and qualification standard — we'll confirm which of these parameters apply and quote the testing and production scope.
Get a Free Quote