Rotary Seal Design Guide - Seals Unlimited

66Parker Oil SealsEngineeringShaft RecommendationsMaterial — Parker recommends a shaftmaterial of carbon steel with a minimum hardnessof Rockwell C30. Soft materials such as bronze,aluminum or plastic should be avoided becausethey are susceptible to grooving and will causepremature seal failure. If a soft shaft material mustbe used, a Parker Quick Sleeve or Parker WearSleeve can be installed over the soft shaft materialto provide a durable sealing surface. See Section 7for details.Shaft Finish — Parker recommends a plungeground finish of 8 to 17 µin Ra (0.20 to 0.43 µm Ra)with zero lead. Shaft finished significantlysmoother or rougher will shorten the service life ofthe seal. For additional information on shaft finishrefer to Page 2-6.Shaft Profile — The shaft profile shouldinclude a lead-in chamfer per the followingexample (see Table 2-2a on Page 2-8). Theleading edge helps prevent lip roll-back and springdumping. The leading and trailing edges should befree of burrs and sharp edges that could cut thecontact point of the seal lip.Housing RecommendationsCatalog EPS 5350/USAMaterial — The most commonly usedmaterials for seal housings are steel and cast iron.Care must be taken when softer materials such asaluminum, bronze or plastics are used for thehousing material.Housing Finish — A finish range of 40 to100 µin Ra (1.0 to 2.5 µm Ra) is recommended.Housing Profile — A lead-in chamfer per thefollowing example is highly recommended for allseal housings. The chamfer aligns the seal duringinstallation and helps prevent the seal fromcocking. Both corners of the chamfer should befree of burrs and sharp edges to minimize ODdamage.15 to 30°Bore Chamfer30°0.060 to 0.090" (1.5 to 2.2 mm)wAt 30°Figure 6-1. Shaft ProfileSee Table 2-2a, Page 2-8 forchamfer lengthShaft Tolerance — To ensure the proper lip-toshaftinterference is maintained, shaft diametersshould fall within the tolerances specified in Tables6-1, 6-2 and 6-3. Shafts significantly over thetolerance will increase the underlip temperaturesand lead to premature failure. An undersized shaftcompromises the amount of lip interferenceavailable to maintain a positive seal.Figure 6-2. Housing ProfileHousing Tolerance — The diametricaltolerance of the housing for Parker Oil Sealsshould be within the limits specified on the nextpage.03/28/066-2 Parker Hannifin CorporationEPS DivisionToll Free: (800) 233-3900www.parkerseals.com