ISO/TC 22/SC 33/WG 10 - Brake linings and friction couples

This document describes test procedures for assessing the influence of pressure, temperature and water/salt water on the generation of metal pick-up (MPU) for a given friction material in combination with a specific brake disc. There are multiple tests to investigate the MPU generation issue for different types of friction materials (so called NAO and low metallic materials) under critical environmental and working conditions: influence of water and salt water, high temperatures and high pressures and low temperatures and low pressures. This document supports the friction material development process and selection of friction materials for new brake applications.

ISO 26867:2009 describes a test procedure for assessing the influence of pressure, temperature, and linear speed on the coefficient of friction of a given friction material in combination with a specific mating component (rotor or drum). ISO 26867:2009 is intended for use when comparing friction materials under the same conditions, or when controlling friction behaviour against a specification or certain performance limits. In order to take into account the different types of dynamometer cooling systems and to ensure repeatable temperature increments, the brake temperature is the control item during the fade sections. The types of brakes and discs used will vary according to individual projects. Production verification testing can use the results from this test in conjunction with a statistical process control system as part of a quality assurance plan. The specific project or programme will detail the applicable limits and assessment criteria. ISO 26867:2009 also allows for additional sections and brake applications that can prove useful during product development testing.

ISO 6310:2009 specifies a method for test and measurement of the compressive displacement of brake linings or brake pad assemblies due to loading and temperature. It also provides a test method to assess lining thermal swell and growth. ISO 6310:2009 applies to disc brake pad assemblies or coupon samples cut from the friction material.

The procedures in ISO 15484:2008 apply to disc brake pads and drum brake linings for motor vehicles and describe systematic processes for the quality assurance of such brake linings. In conjunction with tolerance ranges, the test methods and results described in ISO 15484:2008 permit a rapid assessment of disc brake pads. Uniform handling of the procedures through various phases ensures that the quality assurance requirements are clearly understood and that a global implementation is possible in the relationship between customers and suppliers. ISO 15484:2008 relates to the completed friction material and is applicable during product development to the quality assurance of ongoing series production, focussing on the “component” friction material. It is advisable that tests with apparent “system” character be avoided. Raw material checks and processing control are outside the scope of ISO 15484:2008.

Friction linings are composite materials with complex structure. Due to their composition and their production process, visual appearance characteristics can occur which in a precisely defined design are to be regarded as specific to the product. ISO/PAS 22574:2007 defines visual aspect for the identification and assessment of such product characteristics in quality assurance, as well as a basis for commercial and technical agreements.