fluorosilicone gaskets

Fluorosilicone Gaskets and Sheets

Fluorosilicone, denoted by the abbreviation FVMQ, is an elastomer that is used in a variety of applications. To get an idea of the applications fluorosilicone is used in, it is helpful to break down the word. Fluoro, coming from the word fluorine is in fluorosilicone, this is a chemical that provides the elastomer its fluid resistance in the harsh environments the elastomer sees. The second part of the word, silicone is another part of the elastomer; this is where the elastomer gets its advantageous operating temperature range, electrical properties, and excellent ozone resistance. Fluorosilicone is resistant to a number of different fluids, including oil, hydrocarbons, and other solvents.

Fluorosilicone is an elastomer that can be manufactured in a number of different ways. It can be manufactured in accordance with (IAW) many different standards, including but not limited to, MIL-R-25988, AMS 7273, AMS3383A and many others. These standards provides different Types, Classes, and Grades, that the fluorosilicone can be manufactured to.

The requirements of the standard are met by starting with the compound of the rubber. The rubber is blended with different additives, fillers, and elastomers to meet the standard set forth by the callout. Some standards have a line callout, such as ASTM D2000. ASTM D2000 sets forth requirements of the rubber through certain letters and numbers. FK is the ASTM D2000 designation for fluorosilicone, but ASTM D2000 also has many other designations to be more specific about the requirements the rubber must meet.

The types, classes, and grades of the standards listed vary from standard to standard. For example,  MIL-R-25988 has a type which designates the form the elastomer must come in. The class designates the physical requirements of the rubber, including the durometer it can be provided in. A typical callout of the MIL-R-25988 would be Type I, Class I, Grade 40. In this callout, Type I is indicating the fluorosilicone will be provided in the form of O-Rings, or other compression seals. Class I designates General Purpose fluorosilicone, which can be provided in the following grades: 40, 50, 60, 70 and 80. The grade designates the durometer the elastomer would be provided in. This standard comes with a set of tables that the types must be tested to, to ensure conformance with the standard. These physical requirements must be tested IAW with different commonly accepted test methods. For example, the test method for testing compression is normally ASTM D395, Method B. This method is outlined within the specification.

Fluorosilicone can be supplied in a number of different forms, while the form is normally dictated by the application. Fluorosilicone can be provided in die cuts, waterjet cuts, extruded shapes, molded parts, strips, and bonded (o-rings). Fluorosilicone can be manufactured in sheets (standard thicknesses include .020″, .031″ .062″ .125″ .250″ and .500″), although NEDC can provide die-cut and waterjet cut parts in custom thicknesses because of NEDC’s unique in-house molding capabilities.