WIXLIB

BallsCagesFor 100Cr6 bearings the standard ball material is thesame as that used for the raceways, whereas for SV30bearings the balls are made from X65Cr13 as standard.However, for particularly arduous applications many ofour bearings are fitted with ceramic balls made fromsilicon nitride (Si3N4). Only balls of grade 3 and 5 areused for our spindle bearings as these classes complywith the highest tolerances in terms of size, roundnessand roughness.Proper selection of cage design and materials is essentialto the successful performance of a precision ball bearing.The basic purpose of a cage is to maintain uniform ballspacing, to prevent them coming into contact, thusensuring an even load distribution within the bearing.They can also be designed to reduce torque andminimise heat build-up.Our spindle bearings have a window cage made of fabricreinforced phenolic as standard. If required, cages canalso be produced from high-performance plastics suchas PEEK or Polyamide-imide (such as Torlon ). Thesematerials are used on account of their low weight, theircorrosion resistance and low friction, which results inreduced wear and less heat generation. This enables thebearings to operate at higher speeds while prolonginggrease service life.Hybrid BearingsHybrid spindle bearings are used to meet therequirements of particularly demanding applications.The inner ring and outer ring are made of either 100Cr6or highly wear-resistant SV30 steel, while the balls areceramic (silicon nitride).Cage TypesShortDesignationTATBCeramic balls used in place of steel balls can radicallyimprove bearing performance in several ways: Standard cage type. Oil impregnation possible. Suitable for spindle ball bearings withhigh accuracy. High strength. Good low lubricant runningcharacteristics.TAHigh running speeds. Ceramic hybrid bearings run atsignificantly lower operating temperatures, allowingrunning speeds to increase by up to 50% (as shownopposite).Machine-made single-piece window cagemade of fabric reinforced phenolic resin.(Outer ring guided only) As standard TA cage, plus: Bore grooves to reduce friction andimprove lubricant circulation. Typical cage design for 7000, 7200series from bore size 5 (25mm) andabove.Low wear and long operating life. Bearings withceramic balls have been proven to last up to five timeslonger than conventional steel ball bearings. Theinherent properties of silicon nitride mean the ballsdrastically reduce the predominant cause of surfacewear in conventional bearings. Lower operatingtemperatures also help extend lubricant life andthey provide excellent performance where there isinsufficient lubrication.Please consult our bearing specialists for moreinformation on how hybrid bearings can improveapplication performance.Machine-made single-piece window cagemade of fabric reinforced phenolic resin.(A outer ring guided,B inner ring guided)Features Very high speeds.Low vibration and noise. Vibration levels can be upto seven times lower than conventional steel ballbearings. This is because ceramic balls are 60%lighter than steel balls and because their surface finishis almost perfectly smooth.Systems equipped with ceramic hybrids show higherrigidity and higher natural frequency making them lesssensitive to vibration.Cage TypeTxATxBMachine-made single-piece window cagemade of high-performance plastic (PEEK,Polyamide-imide, etc.).(A outer ring guided,B inner ring guided,x material) For spindle bearings with very highspeeds.Machine-made single-piece window cagemade of high-performance plastic (PEEK,Polyamide-imide etc.) with a pitch for betterguidance in outer ring and higher speeds.(A outer ring guided,x material) For spindle bearings with very highspeeds.Hybrid BearingsSteelTxAF50,000 rpm100,000 rpm150,000 rpmLimiting speed for hybrid spindle bearings (illustrative) High strength. Best low lubricant runningcharacteristics. Also suitable for high temperatureapplications (operating temperature ofpolyamide-imide (such as Torlon ) up to260 C). High strength. Best low lubricant runningcharacteristics. Also suitable for high temperatureapplications (operating temperature ofPolyamide-imide (such as Torlon ) up to260 C).Cage types1011

LubricationGrease LubricationGood lubrication is critical to the performance of antifriction bearings. Increased speeds, higher temperatures,improved accuracy and reliability requirements resultin the need for closer attention to lubricant selection.Lubricant type and quantity have a marked effect onfunctional properties and service life of each application.A good lubricating film:The main task of a lubricant is to form a hydrodynamiclubricating film between the rolling element and theraceway, thereby preventing direct contact between thefriction surfaces of the individual components. Reduces friction.Minimises wear.Protects against corrosion.Dissipates heat from the bearing.Acts as barrier to contaminants.Lubricant SelectionThe lubricant type is typically selected according to theoperating conditions and limitations of the applicationwhile taking into account specific customer requirements.The most significant factors in selecting a lubricant are: Viscosity of the lubricant at operating temperature.Maximum and minimum allowable operatingtemperatures. Operating speed. Required friction values.Lubricants are available in two basic forms: Oils (fluid lubricants).Grease lubrication is characterised as oil, bound by a thickener which is continuously dispensed to the contact pointduring the lifetime. The primary advantage of grease over oil is that bearings can be pre-lubricated with grease,eliminating the need for an external lubrication system.Our sealed spindle bearings are lubricated with a high-performance grease for the entire lifetime, and attainablerunning speeds are generally lower compared with oil lubrication.The bearing grease is based on synthetic oil and polyureathickener as standard. The grease exhibits optimalperformance during tests at speed factors of two millionn·dm (speed x PCD of balls). Bearing run-in occurs muchfaster and the starting torque is greatly reduced.Grease lubrication also requires less maintenanceand has less stringent sealing requirements than oilsystems. Grease tends to remain in proximity to bearingcomponents, metering its oil content to operating surfacesas needed.Other considerations to grease selection include:Greases – solid to semi-solid products consisting of anoil and a thickening agent. More than 300 different greases and oils are available forthis purpose. Speedability.Temperature.Consistency (stiffness).Bleeding.Advantages of Sealed SpindleBearings with Grease Lubrication Lifetime lubrication.Maintenance-free.No external lubrication system required.Optimal grease quantity.Use of a high-performance lubricant (speed factorn·dm 2,200,000).Greasing, sealing and packaging in a clean roomClass 7.Factory pre-lubrication of bearings is highly recommended, since the correct quantity of applied lubricant can be asimportant as the correct type of lubricant. This is especially true of greases, where an excess can cause high torque,overheating and — if the speed is high enough — rapid bearing failure. Based on our vast experience in this field, wehave established standard quantities of lubricants that are suitable for most applications.In grease lubricated bearings life is often not determined by the internal design, fitting and specification of the bearingbut by the grease itself. It is important for this reason to ensure appropriate running conditions to optimise usefulgrease life.In addition, we can offer special finishing of the spindle bearing itself or its individual components. This could include,for example, vacuum impregnation of the cage, special coating of the rings and dispersion greasing.Grease DistributionBefore operating under load, spindle bearings withlifetime lubrication first need to be run in to distribute thegrease evenly. This distribution process should be carriedout at intervals with pauses at rest, so that the oil can flowback into the track.The procedure for grease distribution is as follows:Three process steps with increasing speeds (0 .4 xnmax; 0 .8 x nmax; nmax) in relation to the maximum speedof the application, and five intervals composed of one30-second run and a two-minute stop. It is recommendedto monitor the temperature and continue the last iterationwith max. speed, longer run procedures and shorter stopsuntil a steady temperature is reached.12Run In IntervalsSpeed0.4 x nmax0.8 x nmaxnmax30s 2min30s 2min30s 2minRunStopGrease Distribution13

Oil LubricationDesign of Spindle BearingsOil lubrication can offer advantages when comparedwith grease lubrication, particularly in the case of spindlebearings rotating at high speed.a significant cost-saving effect for the end user. If regularrelubrication of the bearings is necessary, an external oilair lubrication system can be integrated into the system.Our open spindle bearings are supplied oil lubricatedas standard. In contrast to lifetime lubrication, if losslubrication is intended, the bearing must be lubricatedregularly with exactly the right amount of lubricantin order to achieve the expected bearing life. Therelubrication interval may vary widely - from a continuoussupply to every two years for example. The optimisationof relubrication intervals and lubricant quantity can haveOil-air lubrication or oil minimum quantity lubrication(MQL) is often used in modern machine tool spindlesand is shown in the diagram below. In this process, anoil film is formed in front of the spindle and conveyed tothe bearing. It enables exceptionally high speeds to beachieved and dissipates heat from the bearing. Ideallyeach bearing has its own oil-air supply.OilOpen DesignOpen spindle bearings make optimum use of theinternal space by allowing large balls and a windowcage. This results in maximum load carrying capacitiesand therefore maximum bearing life. This opendesign is recommended for oil lubrication, as it allowsrelubrication using spacers. Contamination should beprevented from entering the bearing and continuousrelubrication should be used.Sealed DesignAirSeals exclude contamination, contain lubricants andprotect the bearing from internal damage duringhandling.Open DesignOur sealed spindle bearings typically have non-contactseals on both sides, which ensure good protectionagainst contaminants, such as dust, which coulddamage the internal workings of the bearing. Thisdesign also limits lubricant leakage from the bearing.They are recommended for applications where lifetimegrease lubrication is required or where air flow throughthe bearing is present.Since the seals are non-contact there is no negativeeffect on friction or speed ratings. Our seals are madeof fluoroelastomer as standard, which can withstandpeak temperatures of 230 C, and the materialpossesses a very high resistance to grease and mineraloil.Smaller balls are typical in a sealed design allowingfor higher speeds. Further advantages of the sealeddesign include ease of handling and trouble-freeinstallation, making it particularly suitable wherebearings are being replaced.Sealed DesignOil - Air LubricationOil minimum quantity lubrication (MQL)Special Design - ACIAs a general rule, spindle bearings have an openshoulder on the outer ring (ACO). However, forsome special applications the open shoulder can bepositioned on the inner ring (ACI) (e.g. dismountablebearings). Our engineers are happy to discuss specificrequirements.Direct LubricationFor high speed spindle applications, many bearing typescan be supplied with radial lubrication holes to position oilin close proximity to the ball to raceway contact zones.The number and size of the lubricating holes can be variedto suit the application, and these holes are connected by aradial oil distribution groove. O-rings on either side of thedistribution groove prevent losses, ensuring the correctquantity of oil is delivered to the correct area.Please contact our engineers for further detaills andavailability.ACOACIDirect lubrication1415

NomenclatureContact AngleBall MaterialRing Material-100Cr6 (for 100Cr6 rings)-X65Cr13 (for X30CrMoN15-1 rings)HYQSi3N4-100Cr6SVX30CrMoN15-1Contact angle is the nominal angle between theball-to-race contact line and a plane through the ballcentres, perpendicular to the bearing axis. Load istransmitted from the shaft via contact angle (α) tothe inner ring, then via the balls to the outer ring. Toensure an even load on all bearings within a system,they should all have the same contact angle.Angular contact bearings are assembled to a constantcontact angle by varying the radial clearance. Ourspindle bearings are available with a contact angle of15 or 25 . The larger the angle, the higher the axialcapacity and rigidity as axial forces can be absorbed.Conversely, bearings with a smaller contact anglehave better radial capacity and rigidity and are able tooperate at higher speed. Deviating contact angles areavailable on request.See page 8SeriesDimensions according to ISO 15Contact AngleαC15ºAC25ºInternalGeometrydDeviating inner ring ø (e.g. d3)DDeviating outer ring ø (e.g. D7WDeviating width (e.g. W4)-Without seal2VZBoth sides, non-contact FPM(fluoroelastomer)ACOOne shoulder on outer ringACIOne shoulder on inner ringTATBOuter ring guided, phenolic resinInner ring guided, phenolic resinSealVersionCageα 15ºDimension SeriesThe nomenclature diagram opposite shows howthe spindle bearing part number is derived from thebearing’s components, tolerance classes and design.Our spindle bearings range from 3mm inner diameterto 120mm outer diameter and the following tablesindicate the dimensions, the dynamic and static loadrating and the limiting speed for the various designsof bearing. The diagram opposite shows the areaswhich are referred to by the abbreviations d, D and B.See page 11AccuracySpecificCalibrationType ofPairingP4SAccording to DIN 620See page 64-66XSee page 67UUniversalDBBack-to-back arrangementDFFace-to-face arrangementDTTandem arrangementMost bore diameter sizes have a number ofF-F (7 : 1)progressively increasing series of outside diameters,width and ball size. The diagram below shows thedifferent dimension series with a fixed bore diameterof 6mm. These series are termed 776, 786, 796, 706and 726 and are shown in the product tables.Bearing Sets - 2UL, 3UL, 2DT.Bearings are packed as sets with alignedbore and outer diameterPreloadLubricationLLightMMediumSHeavyAll bearings are supplied with highperformance lubricants, either grease(sealed bearings) or oil (open bearings).α 25ºFDimension abbreviations776786796706726776786796706726FSee pages 12-1416Dimension series for 6mmfixed bore17

Spindle Bearings - Product meterStandardWidthdDB[mm][mm]SV773 C TA3HYQ SV773 C TA3SV773 AC TAHYQ SV773 AC aled723774784*Limiting SpeedDynamicStaticαCC0[mm][ ][N][N][min ]6215215606215215423622520636225206SV783 C TA37215295HYQ SV783 C TA37215295SV783 AC TA37225285HYQ SV783 AC TA37225285SV793 C TA38315HYQ SV793 C TA383SV793 AC TA383Basic Part NumberPreload Fva / Axial R

bearing products and services. Barden (BUK) brings more than seven decades of expertise and well-established practices to the partnership. HQW Precision was founded in 2010 and brings state-of-the-art facilities and a fresh, moder