GERMAN metal powder man- ufacturer Norddeutsche Af finerie (NA) has developed a copper fibre designed for use in disk brake pads. The copper tibres consist of fine copper wire, guaran- teed to be at least 99.5% pure, that has been cut into short lengths. The surface of the wire is roughened to improve the reinforcing characteris- tics of the material, although it remains dry and free flow- ing for quick and even blend- ing into granular or powder mixtures. The copper libre has been developed for incorporation into mixtures of granulated resins from which the brake pads are produced. These mixtures usually contain some form of fibrous reinfor- cement. Steel libre is now commonly used, although as- bestos has been favoured in the past. Other additives in the brake pad formulation include some non-ferrous me- tal powders, which are added to modify the braking perfor- mance of the pads and to aid in conducting heat away from the contact surface of the brake disk. During the service life of the disk brake pad, the steel fibre incorporated into it. wears away and forms a ferrous powder. IJnder oper-
ating conditions, the dust becomes mixed with road surface wear to form an abrasive and corrosive paste which can adhere to alumi- nium alloy wheels to cause unsightly discoloration and surface damage. NA says the subst.itution of the steel fibre with its copper fibre avoids this problem. It also allows the formulation of the brake pad material to be modified as the copper fibres will replace, at least in part, the necessity of adding non-fer- rous powders for braking performance. The company says the dual benefits make the copper fibre an economic- al addition to most brake pad formulations. The quality of NA’s cop- per libre is controlled under an IS0 9002 approved sys- tem. NA itself is the largest copper smelter in Europe and produces the high purity continuous cast copper rod from which the wire is subse- quently fabricated. Samples of the copper libre are now available, to- gether with technical specifi- cations, health and safety data and pricing information.