Rubber Durometer and Elastomer Compound Reference
Choosing a rubber compound starts with a short list of families, and the same questions come up on every inquiry: what fluid, what temperature, what hardness and what density. This reference puts the common elastomers side by side so you can narrow choices and fill in specific gravity for the weight calculators.
| Elastomer | ASTM D1418 code | Typical Shore A range | Typical specific gravity | Approx. service range (C) | Strong against | Weak against | Relative cost |
|---|---|---|---|---|---|---|---|
Nitrile (Buna-N) | NBR | 40 to 90 | 1.0 to 1.5 | -30 to 100 | Petroleum oils, fuels, hydraulic fluids, water | Ozone, weathering, polar solvents, brake fluid | Low |
Hydrogenated nitrile | HNBR | 50 to 90 | 1.1 to 1.4 | -30 to 150 | Hot oil, sour gas, abrasion, ozone | Polar solvents, ketones | Medium to high |
Ethylene propylene diene | EPDM | 30 to 90 | 1.0 to 1.3 | -50 to 150 | Water, steam, brake fluid (glycol), ozone, weathering | Petroleum oils and fuels | Low |
Fluoroelastomer (Viton type) | FKM | 55 to 90 | 1.8 to 2.0 | -20 to 200 | Fuels, oils, many acids, heat | Ketones, hot water or steam, amines | High |
Perfluoroelastomer | FFKM | 65 to 90 | 2.0 to 2.2 | -15 to 260 | Nearly all chemicals, very high heat | Cost, low-temperature flexibility | Very high |
Silicone (methyl vinyl) | VMQ | 20 to 80 | 1.1 to 1.3 | -55 to 200 | Wide temperature range, ozone, food and medical grades | Tear and abrasion strength, hydrocarbon fuels | Medium |
Fluorosilicone | FVMQ | 40 to 80 | 1.3 to 1.5 | -60 to 175 | Fuels and oils with low-temperature flexibility | Tear strength, cost | High |
Polychloroprene (Neoprene) | CR | 30 to 90 | 1.2 to 1.5 | -40 to 100 | Weathering, flame resistance, moderate oils, refrigerants | Strong oxidizers, aromatic solvents | Low to medium |
Natural rubber | NR | 30 to 90 | 0.95 to 1.3 | -50 to 80 | Resilience, tear and fatigue, abrasion | Oils, ozone, heat | Low |
Styrene butadiene | SBR | 40 to 90 | 1.0 to 1.3 | -50 to 100 | Abrasion, water, general purpose | Oils, ozone | Low |
Butyl | IIR | 40 to 80 | 0.9 to 1.3 | -45 to 120 | Low gas permeability, ozone, vibration damping | Petroleum oils | Low to medium |
Chlorosulfonated polyethylene | CSM | 50 to 90 | 1.1 to 1.5 | -30 to 120 | Ozone, weathering, oxidizing chemicals | Aromatic and chlorinated solvents | Medium |
Polyacrylate | ACM | 50 to 90 | 1.1 to 1.4 | -20 to 150 | Hot oil, transmission fluid, ozone | Water, steam, low-temperature flexibility | Medium |
Ethylene acrylic | AEM | 40 to 90 | 1.1 to 1.4 | -30 to 160 | Hot oil, ozone, wide fluid mix | Fuels, strong acids | Medium |
Epichlorohydrin | ECO | 40 to 90 | 1.3 to 1.6 | -40 to 130 | Fuels, ozone, low gas permeability | Steam, strong acids | Medium |
Polyurethane (cast or millable) | AU / EU | 60A to 75D | 1.1 to 1.3 | -40 to 80 | Abrasion, tear, load bearing, oils | Hot water, steam, acids | Medium |
Values are typical industry ranges for general guidance, not specifications. Real compounds vary with fillers, cure system and grade, so always check the supplier data sheet and test against the actual fluid, temperature and duration. Shore A is measured with a durometer per ASTM D2240 or ISO 48-4: roughly 30 to 40 is soft like a rubber band to a pencil eraser, 60 to 70 is firm like a tire tread, and 90 is hard like a shoe heel. Shore D is used for harder plastics and urethanes.
Clean up compound data in your ERP
Optional: a short review of how compound codes, density and cost are stored in your item master and where they conflict.
Optional. The tool and every export work without this. No spam.
How to use it
Search by abbreviation or by the fluid or property you care about, for example oil, steam or ozone. Compare the strong and weak columns with the part's environment, then use the typical specific gravity to feed the weight and cost calculators. The cost column helps an early budget conversation. Once you pick a family, request a data sheet for a specific compound, since two NBR 70 materials can differ in density, fluid swell and compression set.
- Match the fluid first, then temperature, then hardness.
- Check low-temperature limits for outdoor and aerospace use.
- Treat the ranges as starting points, not specifications.
Understanding durometer
Hardness is reported on a Shore scale measured with an indenter and a calibrated spring, standardized in ASTM D2240 and ISO 48-4. Shore A covers soft to medium-hard rubber from about 20 to 90, and Shore D covers harder materials. Readings are sensitive to specimen thickness (at least 6 mm is typical for a stable reading), temperature and dwell time, so a molded part may read a few points differently from a test slab. Tolerances of plus or minus 5 points are common on drawings.
Compound naming and callouts
ASTM D1418 gives each rubber a short code such as NBR, EPDM or FKM. Specifications such as ASTM D2000 and SAE J200 use a line callout that combines type, class, hardness, tensile strength and suffix requirements for heat, fluid and compression set. Customers and drawings may instead cite a military, OEM or proprietary compound number. Always capture the full callout at quote time, because it controls which materials are allowed.
Common mistakes
Common errors include specifying EPDM for an oil seal, using standard FKM in hot water or steam where a peroxide-cured grade is needed, and overlooking that silicone is weak in tear strength and in hydrocarbon fuels. Another is ordering by durometer alone: a 70 Shore A NBR and a 70 Shore A silicone behave completely differently in fluid, heat and wear. Match the compound to the environment, not only the hardness.
Frequently Asked Questions
What does Shore A durometer mean?
It is a hardness reading from an indenter pressed into rubber, defined in ASTM D2240 and ISO 48-4. Higher numbers mean harder material. Most rubber parts fall between 40 and 90 Shore A, with 70 being a very common general-purpose value.
Which rubber is best for oil resistance?
NBR is the economical standard for petroleum oils and fuels. HNBR, FKM and ACM handle hotter oil. EPDM and natural rubber swell badly in petroleum, so avoid them for oil contact.
Which elastomer has the widest temperature range?
Silicone offers a very wide range, roughly -55 to 200 C, and fluorosilicone adds fuel resistance. FFKM reaches the highest heat but has poor low-temperature flexibility and very high cost.
Is specific gravity the same for all compounds of one type?
No. Fillers, plasticizers and fluoropolymer content change density. NBR can range from about 1.0 to 1.5 depending on formulation. Use the figure from the data sheet for the exact compound when calculating weight and cost.
If your item master holds compound codes inconsistently, Netray can help normalize them and link them to specific gravity and cost for quoting. Ask for a review of your material data.
Related Tools
Rubber Part Weight and Compound Charge Calculator
Turns ring, washer or bushing geometry into part volume, weight, mold charge weight with flash allowance, and compound cost per part and per shot.
Costing & FinanceO-Ring Compound Volume and Cost Calculator
Computes O-ring torus volume and weight from inside diameter and cross-section, then compound required and material cost for a production run.
Costing & FinanceRubber Part Quote Worksheet
A line-by-line costing sheet for molded rubber parts that builds unit cost, selling price and extended value from compound, press time, labor, secondary operations, scrap and margin.
Quality & InspectionRubber Part RFQ Review and Quotation Checklist
Thirty-plus checks to run on a molded rubber RFQ so compound, tolerance, tooling, process and commercial risks are caught before the quote goes out.
More Engineering & PLM tools
See all- SAP Super BOM Design Worksheet
- SAP Engineering Change Number Checklist
- SAP Document Info Record Template
- SAP Change Master and Revision Level Log
- SAP Engineering Change Request (ECR) Template
- SAP BOM Usage and Item Category Reference
- SAP Engineering Change Obsolescence Exposure Calculator
- SAP Engineering Change Affected Materials Impact Worksheet
- Cloud MRP BOM Data Cleanup Worksheet
Keep exploring
Free tools
- Rubber Part Weight and Compound Charge CalculatorTurns ring, washer or bushing geometry into part volume, weight, mold charge weight with flash allowance, and compound cost per part and per shot.
- Rubber Part Quote WorksheetA line-by-line costing sheet for molded rubber parts that builds unit cost, selling price and extended value from compound, press time, labor, secondary operations, scrap and margin.
- O-Ring Compound Volume and Cost CalculatorComputes O-ring torus volume and weight from inside diameter and cross-section, then compound required and material cost for a production run.
Guides
- AI RFQ Quoting for Rubber and Elastomer ManufacturersHow AI helps rubber and elastomer manufacturers quote faster: reading RFQs and prints, matching past jobs, drafting cost builds for estimator approval, on-prem.
- ERP for Rubber Molding and Extrusion Manufacturers: What to RequireERP for rubber molding and extrusion manufacturers: what to require for compound lots, cure data, mold tracking, scrap and costing, and how common systems compare.
- Rubber Compound Lot Traceability and Shelf Life ControlControl rubber compound shelf life and lot traceability: storage, re-test dates, FEFO issue, rheometer release and genealogy from batch to shipped part.