J160_202505 Thermal Swell, Growth, and Hot Compressibility of Brake Friction Materials and Noise Insulators

This document specifies a universal method of measuring the thickness 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 document describes several methods for thermal swell and growth. Method A is 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.

This document also describes how to test the warmed-up disc brake pads and noise insulators for hot compressibility using Method A.