Page 6 of Fiberglide by RBC Bearings

® bearings engineering section many factors affect the overall performance of fiberglide® bearings those of primary concern include applied load surface velocity operating mode surface temperature mating surface finish and running clearance all performance values referred to in this section are based on dry operation when running in a fluid atmosphere fiberglide® bearings may have limitations where application requirements exceed those shown consult transport dynamics engineering department for specific recommendations fiberglide® lined bearings are designed to be used under oscillating motion interrupted start-stop or axial motion they are recommended where high loads are combined with low surface speeds velocity limit under dry running conditions the maximum allowable surface velocity will depend on the applied load and other operating parameters in general surface speed should be kept below 35 fpm feet per minute at 10,000 psi load or 600 fpm at 100 psi load pv factor for plain dry-running bearings it is often helpful to reference a pressure-velocity pv factor as a guide in determining bearing capability it should be understood that this factor is actually a variable which reflects the point where surface temperatures are at a maximum but are still stable the maximum pv established for fiberglide® is pv continuous-60,000 pv intermittent-150,000 design calculations journals-oscillating motion cpm=cycles per minute proj area sq.in shaft dia max or nom i.d x length p pressure psi load lbf ÷ by proj area v velocity fpm shaft dia max x 12 temperature limit normal operating temperatures should be kept below 300°f for standard fiberglide® bearings an increase in wear rates may be experienced at temperatures above 350°f note that at elevated operating temperatures the pv limit will be decreased in order to prevent the surface temperature from exceeding 300°f environmental temperature plus friction heat generated when temperatures exceed 300°f or fall below -200°f consult transport dynamics engineering department for specific recommendations x 4 x osc angle°x cpm 360 bearing wear bearing wear is affected by many factors for the most part tests conducted by transport dynamics subject journal bearings to 20,000 psi loads with the bearing fixed and the shaft oscillating the values shown in the charts on page 6 are representative of the normal wear rate range that can be expected when amplitude is ±45° frequency is 10 cpm and shaft finish is 16 rms under room temperature conditions it will be noted that a wear-in period takes place during the first few thousand cycles during this period some ptfe is transferred to the mating surface in addition the fibers are generally reoriented the high points of the weave are flattened and adjacent fibers tend to blend together after the break-in period the bearing surface will become smooth and shiny because of the many variables which influence wear it is extremely difficult to project bearing life for all types of applications for this reason the transport dynamics engineering department should be consulted when questions of this nature arise wear life calculations are based on rubbing distance of travel coefficient of thermal expansion when bonded to a metal backing fiberglide® s coefficient of expansion can normally be regarded as identical to that of the backing with steel backing 8.4 x 10-6 in/in/°f mating surfaces fiberglide® being non-metallic will operate against most metals but better performance is obtained with the hardest available mating surfaces hardened steel hard anodized aluminum hard chrome or nickel plate are recommended a surface hardness of 45-50 rc is desirable but satisfactory performance can also be obtained with softer materials generally a surface finish on the mating components of 16-32 µ inch should be provided shaft materials or surface treatments should be selected that will effectively resist corrosion transport dynamics recommends a max surface finish of 32 rms and minimum hardness of 40rc to determine the approximate reduction in life for different values of shaft finish and hardness see below surface finish µ in life factor hardness rockwell reading life factor bearing load limits standard fiberglide ® static pressure limit constant pressure 10,000 psi with phenolic backing 30,000 psi with steel backing dynamic pressure limits while oscillating 20,000 psi suggested maximum where repeated impact loading is applied these values should be reduced to meet fatigue life requirements 8-16 32 63 1.00 0.55 0.20 rc 50 rc 40 rc 30 1.00 0.60 0.40 4

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