A-A-59588 Silicones for Miltary And Aerospace Gaskets

A-A-59588 silicones meet the requirements of a U.S. General Service Administration (GSA) specification that divides compliant materials into six classes and various durometer-based grades. This specification replaced ZZ-R-765E and is sometimes written as MIL SPEC AA-59588, AA 59588, AA59588, or A A 59588 instead. Although A-A-59588 is used by the U.S. Department of Defense (DoD), this standard is not limited to military gaskets and is commonly used for aerospace gaskets as well.

Stockwell Elastomerics stocks military and aerospace silicones and fabricates A-A-59588 rubber using die cutting, water jet cutting, or molding processes. Sheet materials are also available in custom thicknesses, durometers, and grades to meet customer-specific requirements. In addition, Stockwell Elastomerics can meet custom specifications for military, aerospace, and other demanding applications that require die cut, water jet cut, or molded gaskets in low, medium, or high volumes.

---

A-A-59588 Silicones Overview

As the table below shows, the classes for A-A-59588 silicones each have an alphanumeric identifier. Their grades correspond to Shore A durometers. The Description column provides an overview of the material properties for each class. Note that only silicones in classes 3A and 3B pass the DeMattia Flex Resistance Test, a dynamic test that measures crack growth in inches over thousands of flexural cycles. These two A-A-59588 classes also cover materials that meet tear resistance requirements per ASTM D624.

A-A-59588 Specifications

Class	Grade	Description
1A	40, 50, 60, 70, 80	Low temperature resistant
1B	40, 50, 60, 70, 80	Low temperature resistant Low compression set at high temperature
2A	25, 40, 50, 60, 70, 80	High temperature resistant
2B	40, 50, 60, 70, 80	High temperature resistant Low compression set
3A	30, 50, 60	Low temperature resistant Tear resistant Flex-fatigue resistant
3B	30, 50, 60, 70, 80	Tear resistant Flex-fatigue resistant

The following sections provide more detailed information about each A-A-59588 Class.

A-A-59588 Class 1A and Class 1B Silicones

A-A-59588 silicones that meet the requirements of Class 1A or Class 1B are intended for use where resistance to extremely low temperatures is required. The A-A-59588 specification defines this as approximately -73°C (-100°F). Class 1 materials can also resist extreme high temperatures of approximately 210°C (425°F); however, their length of service at high temperatures is less than that of Class 2 materials. Note that Class 1B silicones have low compression set at high temperatures.

---

A-A-59588 Class 2A and Class 2B Silicones

A-A-59588 silicones that meet the requirements of Class 2A or Class 2B resist extreme high temperatures of approximately 219°C (425°F). They also have low temperature resistance, but only to about -62°C (-80°F). Unlike like Class 2A materials, however, Class 2B silicones have low compression set. In other words, they have high resilience.

---

A-A-59588 Class 3A Silicones

A-A-59588 Class 3A silicones provide resistance to extremely low temperatures of approximately -75°C (-103°F). Importantly, these military and aerospace silicones also resist tearing and flexing. A-A-59588 Class 3A silicones also resist extreme high temperature environments to approximately 204°C (400°F). Applications include engine mounts and exhaust hangars.

---

A-A-59588 Class 3B Silicones

A-A-59588 Class 3B silicones also resist tearing and flexing, but their resistance to extreme low temperature is less than that of Class 3A materials. With A-A-59588 silicones that meet the requirements of Class 3B, the temperature range is approximately between -70°C (-95°F) and 204°C (400°F). Applications include aircraft door seals, window seals, and vibration mounts.