Vespel SP-1
DuPont's original unfilled polyimide shape-stock grade, offering the highest temperature capability (continuous use to ~260°C, short-term much higher) among thermoplastic polyimides, typically compression-molded then machined.
Reference datasheet — Vespel SP-1 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SP-1 condition
Vespel SP-1 grades and fills
Vespel SP-1 is supplied in 6 conditions, soft to hard. SP-1 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
15 % graphite + 10 % PTFE | Use the 15 % graphite plus 10 % PTFE grade for dry-running, low-load, low-speed sliding parts (friction about 0.1–0.2); strength falls to 45 MPa and service to 260 °C. | 45 | 3.5 | 87 Shore D | |
Graphite + PTFE, higher graphite loading | Pick for reciprocating seals and dry-rubbing contacts: it keeps the load capacity of the 40 % graphite grade while added PTFE cuts break-away friction, at 45 MPa tensile and 2.5 % elongation. | 45 | 2.5 | 88 Shore D | |
40 % graphite filled | Choose for high-PV, high-temperature bearings and seal rings that need low thermal expansion and higher stiffness; the 40 % graphite loading leaves the lowest toughness at 52 MPa and 3 % elongation. | 52 | 3 | 89 Shore D | |
15 % MoS₂ filled | Use in vacuum, extremely dry or inert atmospheres where graphite stops lubricating; the 15 % MoS₂ filler suits spacecraft mechanism bearings and bushings up to 260 °C service. | 52 | 3.5 | 89 Shore D | |
15 % graphite filled | Choose the 15 % graphite filled grade for plain bearings, piston rings and seals: wear rate and friction drop well below unfilled, with 0.87 W/m·K and 288 °C service. | 66 | 4.5 | ||
SP-1Default Unfilled polyimide | Pick the unfilled natural polyimide for electrical insulators, high-temperature structural gaskets and thermal barriers needing the highest toughness and no conductive filler. | 86 | 7.5 | 90 Shore D |
What is Vespel SP-1?
DuPont's original unfilled polyimide shape-stock grade, offering the highest temperature capability (continuous use to ~260°C, short-term much higher) among thermoplastic polyimides, typically compression-molded then machined. Vespel SP-1 has a density of 1.43 g/cm³ (0.0517 lb/in³), heavier than 84% of polymer grades. Its glass-transition temperature is 385°C (725 °F). Vespel SP-1 has a tensile strength of 86 MPa (12.5 ksi), stronger than 86% of polymer grades. Elongation at break is 7.5% and the elastic modulus is 2.5 GPa (0.363 Msi).
What is Vespel SP-1 used for?
- jet engine seals
- high-temperature bushings
- semiconductor process components
- aerospace thermal insulators
Advantages
- High service temperature — 260°C (500 °F), better than 97% of polymer grades
- Good UV / weathering resistance — 70/100, better than 83% of polymer grades
- Conducts heat well — 0.29 W/m·K (0.168 BTU/hr·ft·°F), better than 80% of polymer grades
Limitations
- High embodied carbon — 16 kg CO₂/kg, worse than 98% of polymer grades
- Difficult to weld — 5/100, worse than 89% of polymer grades
- Limited formability — 10/100, worse than 87% of polymer grades
- Heavy — 1.43 g/cm³ (0.0517 lb/in³), worse than 84% of polymer grades
Vespel SP-1 properties
Typical room-temperature values for Vespel SP-1-SP-1; bars are the position among polymer grades.
Physical4
Vespel SP-1 has a density of 1.43 g/cm³ (0.0517 lb/in³), heavier than 84% of polymer grades. Its glass-transition temperature is 385°C (725 °F).
Mechanical12
Vespel SP-1 has a tensile strength of 86 MPa (12.5 ksi), stronger than 86% of polymer grades. Elongation at break is 7.5% and the elastic modulus is 2.5 GPa (0.363 Msi).
Thermal9
Vespel SP-1 is rated for continuous service to 260°C (500 °F). It conducts heat at 0.29 W/m·K (0.168 BTU/hr·ft·°F), better than 80% of polymer grades. Thermal expansion is 54 µm/m·K (30 µin/in·°F).
Electrical5
Vespel SP-1 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 very good (80/100), worse than 52% of polymer grades. UV resistance is very good.
Sustainability3
Producing a kilogram of Vespel SP-1 takes about 300 MJ of energy and emits 16 kg of CO₂ — more than 97% of polymer grades. Typical recycled content is 0%.
Manufacturability4
Vespel SP-1's machinability is good (55/100, worse than 64% of polymer grades); weldability not recommended (5/100); formability not recommended (10/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. Vespel SP-1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Vespel SP-1
Is Vespel SP-1 easy to machine?
Cut dry at high speed with light feeds using sharp uncoated carbide; the material is dimensionally stable but swells with moisture pickup, and dust extraction is required. It grinds and bores to very high accuracy.
Can Vespel SP-1 be welded?
Non-melting material; it cannot be welded. Join with high-temperature epoxy or polyimide adhesives, or by mechanical fastening.
Can Vespel SP-1 be formed, bent or molded?
Cannot be injection moulded or thermoformed. Blanks and shapes are direct-formed from powder by high-temperature, high-pressure sintering and then machined to the finished part.
Vespel SP-1 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.
| Element | Spec limit (wt %) |
|---|---|
| graphite15–40 wt% in SP-21/SP-211/SP-22 variants | ≈ 0 |
| PTFEabout 10 wt% in SP-211/SP-221 variants | ≈ 0 |
| MoS2about 15 wt% in SP-3 variant | ≈ 0 |
| polyimide (PMDA/ODA polymer)PMDA + 4,4'-oxydianiline polycondensate, unfilled | ≥ 100 (balance) |
What surface finishes work on Vespel SP-1?
Normally used as-machined or ground; polishing produces low-roughness sealing faces. Surfaces can be plasma-activated before bonding, but the material cannot be plated.
Equivalent designations
Standards and trade names that resolve to Vespel SP-1 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- PI
How much does Vespel SP-1 cost?
Vespel SP-1 is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Vespel SP-1 — frequently asked
What is Vespel SP-1 used for?
Vespel SP-1 is typically used for jet engine seals, high-temperature bushings, semiconductor process components and aerospace thermal insulators. In short: highest-temperature unfilled polyimide; machined from shape stock; lowest thermal conductivity Vespel.
What is the tensile strength of Vespel SP-1?
Vespel SP-1 has a typical tensile strength of 86 MPa (12.5 ksi) — stronger than 86% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is Vespel SP-1 easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Cut dry at high speed with light feeds using sharp uncoated carbide; the material is dimensionally stable but swells with moisture pickup, and dust extraction is required. It grinds and bores to very high accuracy.
Can Vespel SP-1 be welded?
Not readily — weldability is rated not recommended (5/100). Non-melting material; it cannot be welded. Join with high-temperature epoxy or polyimide adhesives, or by mechanical fastening.
What surface finishes work on Vespel SP-1?
Normally used as-machined or ground; polishing produces low-roughness sealing faces. Surfaces can be plasma-activated before bonding, but the material cannot be plated.
Can Vespel SP-1 be formed, bent or molded?
Cannot be injection moulded or thermoformed. Blanks and shapes are direct-formed from powder by high-temperature, high-pressure sintering and then machined to the finished part.
What is the maximum service temperature of Vespel SP-1?
Vespel SP-1 is rated for continuous use to about 260°C (500 °F), and briefly to 482°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Vespel SP-1 cost?
Vespel SP-1 is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Vespel SP Polyimide Parts and Shapes — Design Handbook & Typical Properties — DuPont (2020)
- MatWeb polyimide (Vespel SP-1/SP-21) property entries — MatWeb LLC (2024)
- Engineering Plastics — Engineered Materials Handbook Vol. 2 — ASM International (1988)
- ASTM D1708 / D790 / D256 / D149 test methods — ASTM International (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.