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TEFLON®AND SINTERED BRONZE FOR LEAD-FREE AND EASILY MAINTAINED SLIDE BEARINGS
These maintenance-free, energy-saving components are used in many different applications, such as automotive drive trains and interiors, plant construction and any system involving parts in relative motion that have to operate maintenance-free and yet with extremely low friction and wear. Current applications include the common rail fuel pumps produced by Bosch and Siemens for high-performance diesel engines. Glycodur®1 F slide bearings have a copper-plated steel back, onto which a 0.2 to 0.4 mm thick, porous layer of tin bronze is sintered. The pores of this layer are filled with Teflon® PTFE from DuPont in a rolling process. A 5 to 30 µm topcoat of the same material is transferred onto parts of the sliding components during the running-in phase to achieve the extremely low friction and wear values in operation. The composite is sliced into strips, which are then cut to length and formed into a ring shape. The joint in the ring is closed when these bushings are press-fitted into the bearing seat. In Glycodur®1 F slide bearings, the good mechanical properties of the sintered bronze are optimally combined with the good slip and lubricating properties of Teflon®PTFE. The material structure ensures good dimensional stability and thermal conductivity. As Dr Achim Adam, head of Glycodur®1 development at Federal Mogul explains: 'We opted for the DuPont fluoroplastic for two main reasons – because the PTFE specialists at this company have given us expert assistance in developing our eco-friendly production process and on account of the excellent batch-to-batch consistency of the PTFE supplied to us as a dispersion – an essential requirement to meet the extremely tight wall thickness tolerances of around 20 µm.' In the latest generation of common rail diesel pumps, high-precision Glycodur®1 F slide bearings are used for the front and rear shaft mountings and the roller mounting. In this application, the bearings are flooded with fuel injected at a pressure of 1600 bar and more. The Teflon® surface is exposed to peak sliding speeds of 7 m/s and more at pressures of over 15 MPa. For such extreme applications, in which mixed friction must also be possible for a short time, the composite Glyco®1 92 (Glycodur®1 F) has the necessary reserves up to an operating temperature of 250°C. Federal Mogul also supplies Glyco®1 97, an optimised alternative for unlubricated operation, and Glyco®1 198, for permanently oil-lubricated use. Both these products have a PTFE sliding layer.
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