Friction liners (disc brake liners or drum brake liners) are mainly used in vehicle brakes. The volume of friction liners produced in Europe amounts to 150,000 tonnes/annum. At the point of replacement, the friction liners are only used to approximately 50%. Therefore, every year up to 75,000 tonnes of used friction liners are produced. These are normally disposed of as hazardous waste or partially smelted to low quality steel. In addition to the used liners, approximately 22,000 tonnes of filter dusts from the industrial production of friction liners are also produced every year. In the past, the car manufacturing industry used only original material for the production of brake liners. This project aimed to facilitate the use of used friction liners and filter dust to produce new brake linings.
The objective of the project was to develop a new system for the reprocessing of used friction liners and filter dust accumulated during the production process. Both fractions would be recovered for re-use in the friction liner production process. This would reduce the volume of waste going to disposal sites, reduce the use of raw material and as a result, reduce the disposal costs and the cost of friction liner material. Based on the results of a research project, which had investigated the redistribution of friction materials on a laboratory scale, the current project aimed to emulate larger-scale production. Another important objective was to demonstrate the complete material cycle ('from cradle to grave'), beginning with the production of the friction liner, its subsequent application in the car, its collection and recycling after use, and terminating with its re-use in the manufacturing of new friction liners. The cycle was an important precondition to ensure the recycling of friction materials and the benefits to the environment. The specific objectives of the project were:
- the realisation of a recycling plant
- procurement and assembly of machines and equipment
- a test run of the recycling plant
- the achievement of normal production in the recycling plant
- national and international organisation of the collection of old friction material
- identification of national and international markets for the recycled materials
- the dissemination of results.
In the case of a successful demonstration, a transfer of the technology to other European sites was envisaged. This would provide considerable environmental benefits, while at the same time also securing the transfer of know-how and technology.
The assembly of plant and machinery were completed successfully. The construction of the plant was divided into two phases. The first construction phase allowed the recycling of drum brake liners and the production of base material. The second phase allowed the recycling of disc brake pads. This was followed by a successful trial operation and then the establishment of regular operation.
During the latter stage detailed criteria for a continuous quality control of the recycling friction material throughout the recycling process were defined. On the basis of these criteria, regular operation of the plant has been achieved since April 1999. About 850 t of recyclates were produced in 2000. It is estimated that the plant established during the project has a capacity of about 4,000 t of recyclates per annum.
The system for collecting used linings has been in operation since June 1998 and has been extended considerably since. About 1200 t of old brake lining were collected and delivered to the recycling plant in 2000 (about 35,000 t of old brake linings are produced every year in Europe).
Most of the Damlier-Chrysler garages are involved in the distribution system. It is expected that Volkswagon and Ford will also join. Since 2001, brake linings have also been collected in Austria. It is expected that the system will also be extended to the Netherlands, Belgium, Luxembourg and Italy.
The establishment of a production waste recovery system was only partially successful. This was mainly due to the lack of interest among brake lining manufacturers to recycle their production waste (due to the low cost of disposing production waste). The recyclates are already being delivered to BBA Friction GmbH in Leverkusen, the cooperation partner, to be used in the production of new brake linings. A number of other clients have also expressed an interest, due mainly to the fact that the recycled products can easily compete with the quality of new brake linings.
An ex-post evaluation of the project, carried out by the LIFE external monitoring team in July 2004, showed that the collection of recyclable waste material has been extended to regions in the Netherlands, Belgium, Austria, France and Italy. In addition, the recycled base material is now being shipped to France, England and Sweden to be used for the production of new friction liners.