Swell, Growth, and Dimensional Stability of Friction Materials and Noise Insulators when Exposed to Elevated Temperatures
This performance standard specifies a universal method of measuring the dimensional change of friction materials to determine the effects of temperature. The test applies to both, disc and drum type linings commonly used in hydraulic and air brake systems for automotive or commercial vehicle applications.
This standard describes two main test procedures. Method A, where the friction material is in contact with a heated surface to simulate the heat input to the pad that occurs during actual usage. Method B uses an oven to heat the freestanding material and is an approximate procedure requiring less instrumentation. Method A is recommended for disc brake pad assemblies, noise insulators, or flat coupons; while Method B is recommended for curved drum brake linings.
Rationale: This revision includes changes to definitions, requires the use of a cover around the machine to reduce external effects on temperature build-up, provides more details on the measurement points, increases the number of measurement points to increase the accuracy of the measurement, harmonizes test temperatures with the ISO 6313 and the JIS D4416, and allows different types of samples for the test. In addition, it allows other means of preloading the sample different from a mechanical device, and indicates five samples as the default number per product. This revision also incorporates a direct reference to ISO 6313:1980 and JIS D4416:1998. When a product or platform specification migrates to or from the ISO 6313:1980 or the JIS D4416:1998 procedures, the task force recommends proper accuracy studies for repeatability, reproducibility, and correlation between the legacy and the new procedure.