Technical Services Notes Sheets

Roll Material

Friction material in roll form provides an effective and economical means of relining brake shoes of widely varying sizes, where the quantities concerned are not large enough to justify making rigid linings, finished to size. Such materials can be used to service both automotive and general industrial brakes, and they enable a highly satisfactory product to be produced quickly with only a relatively small stock holding. Roll is also needed for relining brake bands, although semi-rigid material in short lengths may also be used.

Roll material can be classified in a number of ways, important when a selection is to be made:

Woven and Moulded

Woven materials are usually stronger, whereas moulded roll maybe more flexible and have better temperature resistance.

Metallic and Non-Metallic

Metallic materials have a less variable friction level but may require a better quality mating surface; also, in marine or other aggresive environments, the metal content may be affected by the salt or othey chemicals.

Asbestos or Non-Asbestos Based

Non asbestos materials include the long established cotton based ones, which have very high friction but only limited temperature resistance; the newer, high performance non asbestos roll materials have similar temperature resistance to the asbestos based materials.

Woven roll material is the original category of friction material made by the company, although it has undergone a number of refinements and is now available in several formulations. The yarn from which the fabric is made is woven by the traditional textile process into a strip of appropriate width and thickness, and cut into standard lengths, which are formed into rolls. These rolls are stacked into a tank from which the air is then exhausted; the tank is then filled with the impregnant, to which air pressure is then applied, after which the surplus is drained from the tank. The impregnant is then cured by the application of heat, after which the rolls are - in most cases - ground to finished thickness.

Moulded roll manufacture is akin to that of other moulded products, in that all the constituents of the material are mixed together before forming to shape; the material is then fed into a roll forming machine, from which it emerges in a continuous strip of the predetermined width and thickness, and is coiled into rolls. As with woven rolls, these are then cured by the application of heat and finished by grinding on both surfaces.

With only one exception, the impregnants used in the manufacture of roll materials are thermosetting; that is to say, they do not again soften with rising temperature. The exception is Ferodo BA, which has a thermoplastic impregnant, making it possible to soften it by warming to not more than 100'C to facilitate fitting; the temperature limit of BA is, however, lower than that of other asbestos based materials.

The degree of flexibility varies between the materials in the range and must be taken into account with the thickness when considering which material to choose for relining a shoe of a particular radius. Those materials

described as semi-flexible must be treated with particular care when forming to shape; the company can advise on maximum and minimum radii for the various thicknesses on offer. If the friction material is required to be used in flat strip form, it should be ordered as such, rather than endeavour to flatten a length of roll.

For information on cutting roll material, for advice on riveting and bonding to metal parts, or for information on any of the individual materials offered in roll form, ask for the respective data sheets.

Contact us now for guidance and advice, or to discuss a specific project, by telephone on 01254 397561, by fax on 01254 389722 or by email at david@frictioncomponents.co.uk

"Solving Industries Braking Point"

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Friction Components and Systems Ltd - "Solving Industries Braking Point"
Unit 103, 25 Clydesmill Road, Clydesmill Industrial Estate, Cambuslang, Glasgow, G32 8RE

part of the Friction Components and Systems group of companies