Designs and variants
PTFE composite stripsSKF PTFE composite strips (fig. 1) are self-lubricating as well as maintenance-free and provide a long service life due to low friction. Despite of their compact design, these strips can accommodate heavy loads and are suitable for relatively slow rotational or oscillating movements. They also have good dimensional stability and thermal conductivity.
PTFE composite strips consist of a sheet steel backing on which a 0,2 to 0,4 mm thick porous layer of tin/bronze is sintered (fig. 2). Furthermore, by a rolling process the pores of the sintered layer are filled with a mixture of PTFE (polytetrafluoroethylene) and molybdenum disulphide additives. This additional 5 to 30 μm thick running-in layer provides an optimum combination of the mechanical properties of the sintered tin/bronze and the good sliding and lubricating properties of the PTFE mixture.
During a short running-in period, minute amounts of the PTFE material from the running-in layer are transferred to the counter surfaces. After this transfer has taken place, the characteristics low friction and wear properties of these strips are reached.
POM composite strips
SKF POM composite strips have pockets in the sliding surface (fig. 3), which serve as grease reservoirs and should be filled with grease prior to installation. This makes these strips suitable for applications that require minimal maintenance under difficult operating conditions, for example in contaminated environments where lubricant cannot be supplied continuously or frequently. Despite of their compact design, POM composite strips can accommodate heavy loads and are less sensitive to misalignment. They are suitable for slow rotational or oscillating movements.
POM composite strips consists of a sheet steel backing on which a 0,2 to 0,4 mm thick layer of tin/bronze is sintered. The principal characteristic of these strips is their relatively thick (0,3 mm) covering layer of acetal resin (POM – polyoxymethylene) with additives. This covering layer has pockets to retain grease and is firmly attached to the sintered tin/bronze layer (fig. 4).
The thickness of the covering layer makes these strips less sensitive to misalignment and the edge loading associated with that misalignment.