Silicone · grade
Silicone High Temp
Properties of the High Temp condition, compared with the other Silicone grades.
Pick for oven gaskets, exhaust/turbo seals, ironing and heater components where continuous service exceeds 200 °C.
What is Silicone High Temp?
Silicone High Temp is Silicone in the High Temp grade — pick for oven gaskets, exhaust/turbo seals, ironing and heater components where continuous service exceeds 200 °C. Silicone High Temp has a tensile strength of 7 MPa (1.02 ksi), weaker than 81% of polymer grades. Elongation at break is 350% and the elastic modulus is 0 GPa (3.19×10⁻⁴ Msi). Silicone High Temp has a density of 1.22 g/cm³ (0.0441 lb/in³), heavier than 61% of polymer grades. Its glass-transition temperature is -125°C (-193 °F). Medical Grade is the default condition FabDigit quotes; High Temp is available on request or by drawing note.
Advantages
- Forms and bends easily — 95/100, better than 99% of polymer grades
- Good UV / weathering resistance — 97/100, better than 98% of polymer grades
- High service temperature — 250°C (482 °F), better than 94% of polymer grades
- Polishes to a fine finish — 85/100, better than 93% of polymer grades
- Ductile — tolerates forming and impact — 350%, better than 84% of polymer grades
Limitations
- Difficult to machine — 20/100, worse than 97% of polymer grades
- Low stiffness — 0 GPa (3.19×10⁻⁴ Msi), worse than 95% of polymer grades
- High mold shrinkage — 2.5%, worse than 93% of polymer grades
- Difficult to weld — 20/100, worse than 78% of polymer grades
Silicone High Temp properties
Typical room-temperature values for Silicone High Temp — 8 properties are specific to this condition; the rest are grade-level values shared by every Silicone grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical5
Silicone High Temp has a density of 1.22 g/cm³ (0.0441 lb/in³), heavier than 61% of polymer grades. Its glass-transition temperature is -125°C (-193 °F).
Mechanical9
Silicone High Temp has a tensile strength of 7 MPa (1.02 ksi), weaker than 81% of polymer grades. Elongation at break is 350% and the elastic modulus is 0 GPa (3.19×10⁻⁴ Msi).
Thermal8
Silicone High Temp is rated for continuous service to 250°C (482 °F). It conducts heat at 0.22 W/m·K (0.127 BTU/hr·ft·°F), better than 60% of polymer grades. Thermal expansion is 270 µm/m·K (150 µin/in·°F).
Electrical7
Silicone High Temp is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 81% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of Silicone High Temp takes about 110 MJ of energy and emits 6.5 kg of CO₂ — more than 64% of polymer grades. Typical recycled content is 0%.
Manufacturability7
Silicone High Temp's machinability is poor (20/100, worse than 97% of polymer grades); weldability poor (20/100); formability excellent (95/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Silicone grades and fills
Silicone is also supplied in 17 other conditions. The full side-by-side table is on the Silicone overview.
- Medical GradeDefaultPick for implantable-short-term, tubing, masks and any skin/fluid contact where biocompatibility documentation is required.9 MPa tensile
- FVMQPick when silicone-level cold flexibility is needed together with resistance to fuels, hydrocarbon oils and solvents.8 MPa tensile
- High TempPick for oven gaskets, exhaust/turbo seals, ironing and heater components where continuous service exceeds 200 °C.7 MPa tensile
Working with Silicone High Temp
Is Silicone easy to machine?
Cured silicone is not conventionally machinable — use die cutting, waterjet, laser (with fume control) or cryogenic deflashing; sharp new blades and water lubrication prevent tearing.
Can Silicone be welded?
No thermal welding; join by uncured silicone adhesive, self-bonding primers, RTV, or oxygen-plasma bonding for PDMS microfluidics; secondary overmolding onto cured silicone requires primer.
Can Silicone be formed, bent or molded?
LSR: cold runner, 165–210 °C mold, 15–60 s cure, allow 2–3 % shrink and vacuum-vented tools; HCR: compression/transfer or extrusion + hot-air/steam cure; post-cure 200 °C/4 h to remove volatiles for medical/food use.
What surface finishes work on Silicone?
Surface finish is fully set by the mold (mirror EDM or texture); paints do not adhere without silicone-specific primer — use plasma/corona treatment, parylene or silicone inks; talc-free anti-block coatings for tack reduction.
Silicone chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| fumed silica (reinforcing filler)surface-treated, sets modulus and tear strength | 15 – 35 | 25 |
| hydride crosslinker (Si-H siloxane)addition-cure systems | 0.5 – 3 | 1.5 |
| platinum catalyst (Karstedt)peroxide (DCBP/DBPMH) used instead in HCR peroxide cure | 2×10⁻⁴ – 0 | 5×10⁻⁴ |
| extending filler / pigment / heat stabile.g. ground quartz, Fe2O3, Ce compounds | 0 – 15 | 5 |
| polydimethylsiloxane (PDMS) base polymermay contain vinyl-methyl and phenyl or trifluoropropyl substitution | ≥ 55 (balance) | — |
Silicone High Temp — frequently asked
What is Silicone High Temp used for?
Silicone High Temp is typically used for O-rings and moulded gaskets, medical tubing and implant seals, keypads and button mats, baby bottle nipples and food-contact seals, electronic potting and encapsulation and high-temperature oven and appliance seals. In short: biocompatible soft silicone.
What is the tensile strength of Silicone High Temp?
Silicone High Temp has a typical tensile strength of 7 MPa (1.02 ksi) — weaker than 81% of polymer grades. Strength varies by condition: see the 18 listed tempers.
Is Silicone High Temp easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of polymer grades). Cured silicone is not conventionally machinable — use die cutting, waterjet, laser (with fume control) or cryogenic deflashing; sharp new blades and water lubrication prevent tearing.
Can Silicone High Temp be welded?
Not readily — weldability is rated poor (20/100). No thermal welding; join by uncured silicone adhesive, self-bonding primers, RTV, or oxygen-plasma bonding for PDMS microfluidics; secondary overmolding onto cured silicone requires primer.
What surface finishes work on Silicone High Temp?
Surface finish is fully set by the mold (mirror EDM or texture); paints do not adhere without silicone-specific primer — use plasma/corona treatment, parylene or silicone inks; talc-free anti-block coatings for tack reduction.
Can Silicone High Temp be formed, bent or molded?
LSR: cold runner, 165–210 °C mold, 15–60 s cure, allow 2–3 % shrink and vacuum-vented tools; HCR: compression/transfer or extrusion + hot-air/steam cure; post-cure 200 °C/4 h to remove volatiles for medical/food use.
What is the maximum service temperature of Silicone High Temp?
Silicone High Temp is rated for continuous use to about 250°C (482 °F), and briefly to 315°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Silicone High Temp?
Yes — Silicone High Temp is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D2000 — Classification System for Rubber Products (VMQ/FVMQ) — ASTM (2023)
- ASTM D412 / D624 / D395 / D2240 — tensile, tear, compression set, durometer — ASTM (2022)
- SILASTIC / Dow LSR and HCR product datasheets — Dow (2023)
- ELASTOSIL LR / R silicone rubber datasheets — Wacker Chemie (2023)
- Silopren LSR and thermally conductive silicone data — Momentive (2022)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics/Elastomers — ASM International (1988)
- CAMPUS / UL Prospector elastomer entries — UL / CAMPUS (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.