Rolling Bearings Made of Cronidur 30

Tenfold service lifeunder the severestconditionsRolling BearingsMade of Cronidur 30 ®FAG OEM und Handel AG

Cronidur 30 ® is a newrolling bearing materialwhich one has yet to becomeaccustomed to –in the positive sense.For rolling bearingsmade from this materialdo not merely exceedall known standardsrelating to corrosionresistance andfatigue life.In the sports fieldyou might say:”Rolling bearingsmade of Cronidur 30 ®pulverise allprevious records”.A new materialCronidur 30 ® is a new material employedin the manufacture of severely stressedrolling bearings. It was developed by FAGin cooperation with Ruhr-UniversitätBochum and VSG Energie- undSchmiedetechnik Essen. The developmentof Cronidur 30 ® achievedrecognition in the form of the SteelInnovation Award of the GermanStahlinformationszentrum(steel information centre).Rolling bearings today are normally manufactured fromthe well-proven standard rolling bearing material100Cr6 or the corrosion-resistant steel X102CrMo17(AISI 440C). Nevertheless it had become necessary tocreate a material which could accept a higher load at therolling bearing surface and elevate the limiting valuesrelating to life, especially under difficult ambient conditions.Cronidur 30 ® meets these demands admirably.Ten times the service lifeLife comparison between 100Cr6 and Cronidur 30 ®Failure probabilityService lifeMultiple service lifeof Cronidur 30 ® bearings:At least Factor 10 in the Space ShuttleAt least Factor 10 in motor sawsAt least Factor 4 in mining pumpsConsiderable improvementsThe most important alloying components ofCronidur 30 ® are nitrogen, carbon, chromium andmolybdenum. Their new quantitative compositionresulted in a material which offers considerable improvementswhen compared to former alloys. Inparticular this applies to the criteria cycling strength,corrosion resistance and high-temperature hardness.Cronidur 30 ® is a martensitic through-hardening steelwhich has been remelted in a special process.Cronidur 30 ® has an extremely fine grain structure.Heat treatmentThe heat treatment used gives Cronidur 30 ® excellenthardness values even at higher temperatures.Consequently, rolling bearings of Cronidur 30 ® can beused at higher temperatures than bearings made of100Cr6.

Insusceptible to dirtRolling bearings of Cronidur 30 ® are lesssusceptible to contaminants. Although dirtparticles that penetrate into the bearings leaveindentations in the raceways, these indentationsdo not cause premature fatigue damage.Any bearing damage that does develop spreadsfour times slower than in conventionalbearings.Media lubrication possibleUltimate life with Cronidur 30 ®Tests document that rolling bearings of Cronidur 30 ®stand out for their substantially extended materialfatigue life. At a contact pressure of 2,800 MPa underEHD conditions the calculated life values are exceededby the factor of 80 without failure. In hybrid bearingsincorporating ceramic balls, Cronidur 30 ® accepts a25 per cent higher contact pressure. This would relateto a 40 per cent increase in rolling element with pointcontact.Reliability under conditions of mixed frictionEven in the mixed friction range, Cronidur 30 ® provesits superiority. Tests carried out under a defined conditionof mixed friction (p 0 = 2,500 MPa) have shownthat bearings of Cronidur 30 ® reach a tenfold servicelife compared with bearings made of standard material100Cr6. Furthermore, the wear behaviour of the bearingis considerably improved with Cronidur 30 ® . Thisbecomes particularly apparent in the case of hybridbearings with rings consisting of the new material andceramic rolling elements. Here, the wear rate lies considerablybelow the former usual values.Corrosion-resistantAlthough the amount of chromium is lower inCronidur 30 ® than in rolling bearing steel 440C,which has so far been used as standard material forcorrosion-resistant bearings, the combined effect of itsother components makes Cronidur 30 ® far morecorrosion-resistant. In a sulphuric acid solution, itspassive current density – a measure for the corrosionresistance – is 100 times lower than that of 440C.Due to the small amount of wear particlesthere is hardly any contamination of the lubricant.As the few wear particles do not corrode,there is no catalytic effect – both with grease and oillubrication the quality of the lubricant remains at a constantlevel over a long period. The favourable characteristicswith respect to mixed friction and corrosionresistance also permit Cronidur 30 ® to be used withmedium lubrication in many applications, for instancewith liquid hydrogen or liquid oxygen. The use inpumps for hydrous hydraulic fluids was especiallyuseful.Comparison of the two systems’ life cycle costsStandardCronidurSavingsInvestment and capital costOperating cost• Lubricant acquisitionand disposal• Energy consumptionMaintenance cost• Maintenance• Repairs• Replacement parts• Scheduled and unplanneddowntimes

Fields of application and system costCronidur 30 ® was developed for applications in theaircraft and aerospace field, for instance for the mainengines of the Space Shuttle, where the cost of bearingreplacement is several times that of the material costof the bearings.The life cycle cost of complete systems includingrolling bearings made of Cronidur 30 ® is clearlyreduced:• Fewer unexpected bearing failures, and consequentlyfewer machine standstill periodsdue to- a reduced damage probability- a slowdown in the progress of damage• Fewer scheduled machine downtime periodsfor bearing replacement due to- longer service lives, even under extremelyadverse ambient conditions- corrosion resistance- insusceptibility to contamination• Reduced cost of lubricant acquisition anddisposal• Reduced personnel cost for mounting anddismounting• Reduced demand for replacement bearingsCronidur 30 ® also makes possible an increase inthe power density of machines as well as downsizingand light-weight constructions.Give us a ring! We will be happyto advise you individually.FAG OEM und Handel AGA member of the FAG Kugelfischer GroupGeorg-Schäfer-Str. 30D-97421 SchweinfurtTel. ++49-9721-91-1111Fax ++49-9721-91-1112e-mail: cronidur@fag.deInternet: www.fag.deThe fields of application for rolling bearings ofCronidur 30 ® or bearing components made of thismaterial are very diverse, and individual solutions aredeveloped to every problem.Rolling bearing components made of Cronidur 30 ®are used for many applications, including:• swashplate bearings in helicopters• two-stroke engine crankshafts in chain saws• hydraulic pumps• wire guiding rollers• cutter head bearings in oil production• spindle bearings• turbine bearings• bearings in turbomolecular pumps• bearings in bordering tools for beverage cans• ball screw and nut assemblies for flap adjustment inaeroplanesFAG – worldwide distribution of rolling bearingsmade of Cronidor 30 ®With the new rolling bearing material Cronidur 30 ® ,FAG OEM und Handel AG is pursuing the goal ofdeveloping individual problem solutions for customersin a large variety of applications, especially applicationswhere• the previously used rolling bearing materials havereached their limits• standard bearings must be replaced quite frequently• the downtimes of entire systems, and consequentlythe system cost, are to be reduced.WL 51 133 EA/95/11/99keep things rolling