Rotary Seal Design Guide - Seals Unlimited

Catalog EPS 5350/USAEngineering22Shaft TolerancesShaft diameters should be held to thetolerances specified below:Table 2-1. Shaft Tolerance for Inch/FractionalShaft DiameterToleranceUp to 4.000" ± .003"4.001 – 6.000" ± .004"6.001 – 10.000" ± .005"Over 10.000" ± .006"Special precautions should be taken whenreplacing a seal over a used shaft because it iscommon for shafts to become grooved duringservice. Grooving is normally caused by eithercarbonized oil or an abrasive foreign mattergetting trapped between the lip and the shaft.Over time, deep grooves can form.Table 2-2. Shaft Tolerance for Metric*Shaft DiameterUp to 10 mmOver 10 – 18Over 18 – 30Over 30 – 50Over 50 – 80Over 80 – 120Over 120 – 180Over 180 – 250Over 250 – 315Over 315 – 400Over 400 – 500*ISO Standard 286-2, h11The leading edge of the shaft should have aburr-free chamfer to ease installation bypreventing lip roll-back, spring dumping anddamage (nicks or cuts) to the seal lip. Both ends ofthe chamfer should be free of sharp edges.Spring dumping can occur during seal installationwhen the lip rolls back on itself, causing it to fallout of the spring pocket. Heavy shock loads thatcan occur when installing a metal cased sealusing a direct blow from a metallic driving tool canalso force the spring out of the spring pocket andis also referred to as spring dumping.wAt 30°Figure 2-7. Shaft Profile30°Tolerance+0 to -.09 mm+0 to -.11 mm+0 to -.13 mm+0 to -.16 mm+0 to -.19 mm+0 to -.22 mm+0 to -.25 mm+0 to -.29 mm+0 to -.32 mm+0 to -.36 mm+0 to -.40 mmSee Table 2-2a for chamfer lengthShaft GroovingReplacement seals should never be installedover a grooved shaft. Dressing the shaft withemery cloth is not recommended because it isextremely difficult to obtain an optimal finish andlead will normally be imparted. If the shaft is worn,it should either be re-ground or fitted with a shaftrepair sleeve. See Section 7 for shaft repairoptions.Underlip Operating TemperatureWhen selecting a seal design, lip material andsystem lubricant, the operating temperature underthe seal lip should be used as the upper limitrather than using the sump temperature.Underlip temperature can exceed sumptemperature by 60 °F (33 °C) or more, dependenton shaft diameter, shaft speed, fluid type andlevel. The increased temperature can exceed thelimits of both the lip material and lubricant that isselected based on the sump temperature alone.Table 2-2a Min. Chamfer LengthEnglishMetricShaft Dia Length Shaft Dia LengthUp To And "w" Up To And "w"Including (inch) Including (mm)0.375 0.051 10 1.30.750 0.068 20 2.01.250 0.085 30 2.21.500 0.102 40 2.62.000 0.119 50 3.02.750 0.136 70 3.53.750 0.153 95 3.95.000 0.188 130 4.89.000 0.239 240 6.1+18.000 0.375 480 10.02-8 Parker Hannifin CorporationEPS DivisionToll Free: (800) 233-3900www.parkerseals.com