The most common material classification system used in rubber parts specification is probably "Standard Classification System for Rubber Products in Automotive Applications." or ASTM D 2000. This system is designed to aid in the selection of practical rubber products for specific environments and provides a "line call-out" designation for the specification of elastomer seal materials.
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Table 1
Type | Test Temperature |
A | 70°C (158°F) |
B | 100°C (212°F) |
C | 125°C (257°F) |
D | 150°C (302°F) |
E | 175°C (347°F) |
F | 200°C (392°F) |
G | 225°C (437°F) |
H | 250°C (482°F) |
J | 275°C (527°F) |
Class | Volume Swell, max |
A | no requirement |
B | 140% |
C | 120% |
D | 100% |
E | 80% |
F | 60% |
G | 40% |
H | 30% |
J | 20% |
K | 10% |
Type of Polymer most often used | |
AA | Natural rubber, reclaimed rubber, SBR, butyl, EP polybutadiene, polyisoprene |
AK | Polysulfides |
BA | Ethylene propylene, high temperature SBR, butyl compounds |
BC | Chloroprene polymers (neoprene), cm |
BE | Chloroprene polymers (neoprene), cm |
BF | NBR polymers |
BG | NBR polymers, urethanes |
BK | NBR |
CA | Ethylene propylene |
CE | Chlorosulfinated polyethylene (Hypalon), cm |
CH | NBR polymers, epichlorohydrin polymer |
DA | Ethylene propylene polymers |
DE | CM, CSM |
DF | Polyacrylic (butyl-acrylate type) |
DH | Polyacrylic polymers, HNBR |
EE | AEM |
EH | ACM |
EK | FZ |
FC | Silicone (high strength) |
FE | Silicones |
FK | Fluorinated silicones |
GE | Silicones |
HK | Fluorinated elastomers (Vito, Fluorel, etc.) |
KK | Perfluoroelastomers |
Hardness (Durometer) | ||||||||||||||||||||||||||||||||||||
This number indicates durometer range in Shore A units (plus or minus 5 points). In our example, the material specified would possess a hardness of 70±5 durometer. | ||||||||||||||||||||||||||||||||||||
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Tensile Strength | ||||||||||||||||||||||||||||||||||||
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The next two digits indicate the material's minimum tensile strength. If measurements are in metric units, the digits show MPa. If measurements are in English units, the digits show psi and only the first two digits of that measurement are indicated. In our example (which is in metric units), the two tensile strength digits are "14" thus the minimum tensile strength required would be 14MPa. If this example were non-metric, this callout would be 20 (14 Mpa = 2031 psi). | ||||||||||||||||||||||||||||||||||||
Additional Requirement Suffixes | ||||||||||||||||||||||||||||||||||||
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Suffixes appended to the Line Call-Out are letter and number combinations that indicate a material's test and performance criteria per the Grade number indicated. In our example, A1-10 indicates a heat resistance test. B38 indicates a compression set test. C12 indicates resistance to ozone. EF31 and EO88 indicate fluid resistance criteria. F15 indicates low temperature brittleness criteria. Z1 indicates a user-defined requiremen, t as must be specified including test criteria. Refer to ASTM D 2000 for expanded suffix call-out details. | ||||||||||||||||||||||||||||||||||||
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