Frictional Torque for bearings

Frictional Torque This affects the free-running of the bearing. Spin a bearing containing stiff grease with your finger and not much happens - relatively high frictional torque. Try a bearing with no lubrication and it will spin freely - low frictional torque. The effort required to rotate a bearing depends greatly on the roundness of the bearing, the load applied, the lubrication and the closures. Better roundness and surface finish of the balls and raceways means less effort is needed to rotate the bearing. The greater the load, the greater the deformation of the bearing components leading to increased resistance. As for lubrication, instrument oils will often produce lower torque levels especially at very low speeds but the difference between these and many low torque greases is actually very small, particularly if a low grease fill is used. A standard low torque grease such as Multemp SRL grease may give an increase of only 20 percent over a Aeroshell 12 oil. This can drop to under 5 percent for very low torque greases if a low (e.g 10 to 20 percent) fill is used. High viscosity lubricants can significantly increase bearing torque due to greater lubricant drag. Torque levels for a greased bearing are briefly higher to start with as the grease takes a short time to "run in" or be distributed inside the bearing. Contact seals will greatly increase the torque figures.The effort required to rotate a bearing from rest (starting torque) is slightly greater than the effort required to keep it rotating (running torque). Approximate figures for frictional torque for can be calculated using a simple formula. This is only valid if the bearing has low torque lubrication (and the grease fill is not high), is open, shielded or has non-contact seals and is subjected to low speed and low load. For radial ball bearings, the axial load should be less than 20 percent of the radial load while the load should be purely axial for thrust bearings. Contact us if you need more accurate figures taking into account the speed and the lubricant viscosity. The measurements are in Newton millimetres (Nmm). This is a compound unit of torque corresponding to the torque from a force of one newton (approx 0.1 Kgf) applied over a distance arm of one millimetre. Frictional torque (measured in Nmm or Newton millimetres) Radial ball bearings: 0.5 x 0.0015 x radial load in Newtons* x bearing bore (mm) Axial ball bearings: 0.5 x 0.0013 x axial load in Newtons* x bearing bore (mm) *10 Newtons = 1 Kgf

Inner Ring Tolerances

Inner Ring Tolerances (a) Inner Ring and Width – up to 2.5 mm bore (Tolerances in .001 mm) Grade Mean Bore Deviation Single Bore Variation Mean Bore Variation Width Deviation Width Variation Radial Runout Face Runout /Bore Face Runout/ Raceway 7,8,9 0 2,3 P0 +0/-8 10 8 6 6 +0/-40 12 10 - - P6 +0/-7 9 7 5 5 +0/-40 12 5 - - P5 +0/-5 5 4 4 3 +0/-40 5 (1) 4 7 7 P4 +0/-4 4 3 3 2 +0/-40 2.5 (1) 2.5 3 3 (1) applies to inner ring only (b) Inner Ring and Width – over 2.5mm to 10 mm bore (Tolerances in .001 mm) Grade Mean Bore Deviation Single Bore Variation Mean Bore Variation Width Deviation Width Variation Radial Runout Face Runout /Bore Face Runout/ Raceway 7,8,9 0 2,3 P0 +0/-8 10 8 6 6 +0/-120 15 10 - - P6 +0/-7 9 7 5 5 +0/-120 15 6 - - P5 +0/-5 5 4 4 3 +0/-120 5(1) 4 7 7 P4 +0/-4 4 3 3 2 +0/-120 2.5 (1) 2.5 3 3 (1) applies to inner ring only (c) Inner Ring and Width – over 10mm to 18 mm bore (Tolerances in .001 mm) Grade Mean Bore Deviation Single Bore Variation Mean Bore Variation Width Deviation Width Variation Radial Runout Face Runout /Bore Face Runout/ Raceway 7,8,9 0 2,3 P0 +0/-8 10 8 6 6 +0/-120 20 10 - - P6 +0/-7 9 7 5 5 +0/-120 20 7 - - P5 +0/-5 5 4 4 3 +0/-80 5(1) 4 7 7 P4 +0/-4 4 3 3 2 +0/-80 2.5 (1) 2.5 3 3 (1) applies to inner ring only (d) Inner Ring and Width – over 18mm to 30 mm bore (Tolerances in .001 mm) Grade Mean Bore Deviation Single Bore Variation Mean Bore Variation Width Deviation Width Variation Radial Runout Face Runout /Bore Face Runout/ Raceway 7,8,9 0 2,3 P0 +0/-10 13 10 8 8 +0/-120 20 13 - - P6 +0/-8 10 8 6 6 +0/-120 20 8 - - P5 +0/-6 6 5 5 3 +0/-120 5(1) 4 8 8 P4 +0/-5 5 4 4 2.5 +0/-120 2.5 (1) 3 4 4 (1) applies to inner ring only (e) Inner Ring and Width – over 30mm to 50 mm bore (Tolerances in .001 mm) Grade Mean Bore Deviation Single Bore Variation Mean Bore Variation Width Deviation Width Variation Radial Runout Face Runout /Bore Face Runout/ Raceway 7,8,9 0 2,3 P0 +0/-12 15 12 9 9 +0/-120 20 15 - - P6 +0/-10 13 10 8 8 +0/-120 20 10 - - P5 +0/-8 8 6 6 4 +0/-120 5(1) 5 8 8 P4 +0/-6 6 5 5 3 +0/-120 3 (1) 4 4 4 (1) applies to inner ring only Outer Ring Tolerances (f) Outer Ring– up to 6mm O.D. (Tolerances in .001 mm) Grade Mean O.D. Deviation Single O.D. Variation Mean O.D. Variation Width Variation Radial Runout Face Runout /O.D. Face Runout/ Raceway 7,8,9 open 0 open 2,3 open 0,2,3 ZZ,2RS P0 +0/-8 10 8 6 10 6 (2) 15 - - P6 +0/-7 9 7 5 9 5 (2) 8 - - P5 +0/-5 5 4 4 - 3 5 5 8 8 P4 +0/-4 4 3 3 - 2 2.5 3 4 5 (2) same as inner ring value (g) Outer Ring– over 6mm up to 18mm O.D. (Tolerances in .001 mm) Grade Mean O.D. Deviation Single O.D. Variation Mean O.D. Variation Width Variation Radial Runout Face Runout /O.D. Face Runout/ Raceway 7,8,9 open 0 open 2,3 open 0,2,3 ZZ,2RS P0 +0/-8 10 8 6 10 6 (2) 15 - - P6 +0/-7 9 7 5 9 5 (2) 8 - - P5 +0/-5 5 4 4 - 3 5 5 8 8 P4 +0/-4 4 3 3 - 2 2.5 3 4 5 (2) same as inner ring value (h) Outer Ring– over 18mm up to 30mm O.D. (Tolerances in .001 mm) Grade Mean O.D. Deviation Single O.D. Variation Mean O.D. Variation Width Variation Radial Runout Face Runout /O.D. Face Runout/ Raceway 7,8,9 open 0 open 2,3 open 0,2,3 ZZ,2RS P0 +0/-9 12 9 7 12 7 (2) 15 - - P6 +0/-8 10 8 6 10 6 (2) 9 - - P5 +0/-6 6 5 5 - 3 5 6 8 8 P4 +0/-5 5 4 4 - 2.5 2.5 4 4 5 (2) same as inner ring value (i) Outer Ring– over 30mm up to 50mm O.D. (Tolerances in .001 mm) Grade Mean O.D. Deviation Single O.D. Variation Mean O.D. Variation Width Variation Radial Runout Face Runout /O.D. Face Runout/ Raceway 7,8,9 open 0 open 2,3 open 0,2,3 ZZ,2RS P0 +0/-11 14 11 8 16 8 (2) 20 - - P6 +0/-9 11 9 7 13 7 (2) 10 - - P5 +0/-7 7 5 5 - 4 5 7 8 8 P4 +0/-6 6 5 5 - 3 2.5 5 4 5 (2) same as inner ring value (j) Outer Ring– over 50mm up to 80mm O.D. (Tolerances in .001 mm) Grade Mean O.D. Deviation Single O.D. Variation Mean O.D. Variation Width Variation Radial Runout Face Runout /O.D. Face Runout/ Raceway 7,8,9 open 0 open 2,3 open 0,2,3 ZZ,2RS P0 +0/-13 16 13 10 20 10 (2) 25 - - P6 +0/-11 14 11 8 16 8 (2) 13 - - P5 +0/-9 9 7 7 - 5 6 8 8 10 P4 +0/-7 7 5 5 - 3.5 3 5 4 5 (2) same as inner ring value Flange Tolerances (k) All Sizes (Tolerances in .001 mm) Grade Mean O.D. Deviation Mean Width Deviation P0 +125/-50 +0/-50 P6 +125/-50 +0/-50 P5 +0/-25 +0/-50 P4 +0/-25 +0/-50 Thrust Bearing Tolerances (l) All Sizes (Tolerances in .001 mm) Grade Mean Bore Deviation Mean Bore2 Deviation Mean O.D. Deviation Mean O.D.2 Deviation (1) Mean Height Deviation P0 +0/-8 +0/-50 +0/-11 -5/-20 +0/-075 (1) Japanese thrust bearings with grooved washers have a smaller OD on one washer. The Chinese version do not.

DLT Bearing Tolerances

DLT Bearing Tolerances According to ISO & AFBMA specifications Do you understand bearing tolerances and what they really mean? If not, you're not alone. These are often quoted but often without any real understanding of what they mean. Websites with simple explanations of bearing tolerances are extremely rare so we decided to fill the gap. Many thanks to EZO in Japan for their help. So, if you want to know what "Mean Bore Deviation" and "Single Bore Variation" actually mean? Read on as we hope to make this much clearer. Deviation This dictates how far away from the nominal dimension, the actual measurement is allowed to be. The nominal dimension is the one shown in the manufacturer's catalogue e.g. 6200 has a nominal bore of 10mm, 688 has a nominal bore of 8mm etc. Limits on the maximum deviation from these dimensions are extremely important. Without international tolerance standards for bearings (ISO and AFBMA), it would be up to each individual manufacturer. This could mean you order a 688 bearing (8mm bore) only to find that it is 7mm bore and won't fit the shaft. Deviation tolerances usually allow the bore or OD to be smaller but no bigger than the nominal dimension. Mean Bore/OD Deviation ... or single plane mean bore diameter deviation. This is an important tolerance when looking to closely mate inner ring and shaft or outer ring and housing. First you need to understand that a bearing is not round. Of course its not far off but when you start measuring in microns (thousandths of a millimetre) you realise the measurements vary. Lets take the bore of a 688 bearing (8 x 16 x 5mm) as an example. Depending on where in the inner ring you take your measurement, you may get a reading of anywhere, say, between 8mm and 7.991 mm so what do you take as the bore size? This is where Mean Deviation comes in. This involves taking a number of measurements in a single radial plane (we'll come to that in a minute) across the bore or OD to average out the diameter of that ring.. This drawing represents an inner or outer bearing ring. The arrows represent various measurements taken across the bore or OD in different directions to help discover the mean size. This set of measurements have correctly been taken in a single radial plane i.e. at the same point along the length of the bore or OD. Sets of measurements should also be taken in different radial planes to make sure the bore/OD is within tolerances along its length. This diagram shows how NOT to do it. Each measurement has been taken at a different point along the length of the bearing ring, in other words, each measurement has been taken in a different radial plane (tut, tut). This is an end view of the bearing inner ring. You will see that we now show the different measurements taken in the same radial plane. To calculate the mean bore size, we add the largest measurement to the smallest measurement and divide by 2. In this case, 8.000 plus 7.994 divided by 2 = 7.997 So in this case the mean bore size is 7.997mm which is far more useful when calculating the shaft tolerance than a single bore measurement which might be misleading. The nominal bore of a 688ZZ is 8mm, the mean bore size here is 7.997mm so the mean bore deviation for this bearing is -0.003mm. The mean bore deviation tolerance for a P0 bearing of this size is +0/-0.008mm. This means that the mean bore can be between 7.992mm and 8.000mm. The same principle applies to the outer ring. Width Deviation ... or deviation of the single inner or outer ring width from the nominal dimension. Not much explanation needed here. As with bore and OD dimensions, the width must be controlled within certain tolerances. Since the width is usually less critical, the tolerances are wider than for the bearing bore or OD. A width deviation of +0/-120 means that if you measure the inner or outer ring width at any single point around, say, a 688 (4mm wide) bearing, it should not be wider than 4mm (the nominal dimension) or narrower than 3.880mm. Variation Variation tolerances ensure roundness. In this drawing of a badly out-of-round 688 inner ring, the largest measurement is 9.000mm and the smallest 7.000mm. If we calculate mean bore size (9.000 + 7.000 ÷ 2) we come up with 8.000mm. We are within the mean bore deviation tolerance but the bearing would clearly be unusable so you see that deviation and variation can be useless without each other. Single Bore/OD Variation ...or more accurately, Bore/OD Diameter Variation in a Single Radial Plane (of course, now you know all about single radial planes!). Look at the diagram on the left where the bore measurements are between 8.000mm and 7.994mm. The difference between the largest and smallest is 0.006mm, therefore, the bore diameter variation in this single radial plane, is 0.006mm or 6 microns. Mean Bore/OD Diameter Variation Ok, thanks to mean bore/OD deviation and single bore/OD variation, we are happy that our bearing is close enough to the correct size and is round enough but what if there is too much of a taper on the bore or OD as per the diagram on the right (yes, it is greatly exaggerated!). This is why we also have mean bore and OD variation limits. To obtain mean bore or OD variation, we record the mean bore or OD in different radial planes and then check the difference between the largest and smallest. Assume that on the left here, the top set of measurements gives a mean bore size of 7.999mm, the middle is 7.997mm and the bottom is 7.994mm. Take the smallest away from the largest (7.999 - 7.994) and the result is 0.005mm. Our mean bore variation is 5 microns. Width Variation Again, very straightforward. Let's assume, for a particular bearing, the permitted width variation is 15 microns. If you were to measure the inner or outer ring width at various different points on a 688 bearing, the largest measurement should not be more than 15 microns larger than the smallest measurement. Radial Runout ...of assembled bearing inner/outer ring is yet another important aspect of bearing tolerances. Suppose the mean deviation for both inner ring and outer ring is within limits and the roundness is within the allowed variance, surely that's all we need to worry about? Look at this diagram of a bearing inner ring. The bore deviation is OK and so is the bore variation but look at how the ring width varies. Like everything else, ring width is not exactly the same at every point around the circumference but radial runout tolerances dictate how much this can vary. Inner ring runout ... is tested by measuring all points on one circle of the inner ring during one revolution while the outer ring is stationary and taking the smallest measurement away from the largest. This radial runout figures given in the tolerance tables show the maximum variation allowed. The difference in ring thickness here is exaggerated to illustrate the point more clearly. Outer ring runout is tested by measuring all points on one circle of the outer ring during one revolution while the inner ring is stationary and taking the smallest measurement away from the largest. Face Runout/Bore This tolerance ensures the bearing inner ring surface is close enough to a right angle with the inner ring face. Tolerance figures for face runout/bore are only given for bearings of P5 and P4 precision grades. All points on one circle of the inner ring bore close to the face are measured during one revolution while the outer ring is stationary. The bearing is then turned over and the other side of the bore is checked. Take the largest measurement away from the smallest to get the face runout/bore bore tolerance. Face Runout/OD ... or variation of outside surface generatrix inclination with face. This tolerance ensures the bearing outer ring surface is close enough to a right angle with the outer ring face. Tolerance figures for face runout/OD are given for P5 and P4 precision grades. All points on one circle of the outer ring bore next to the face are measured during one revolution while the inner ring is stationary. The bearing is then turned over and the other side of the outer ring is checked. Take the largest measurement away from the smallest to get the face runout/OD bore tolerance. Face Runout/Raceway are very similar but, instead, compare the inclination of the inner or outer ring raceway surface with the inner or outer ring face.

Bearings Tolerances

Tolerances control the dimensional accuracy of a bearing. We use ISO bearing tolerances which start at P0 and then move upwards in precision grade to P6, P5 and then P4. ISO tolerances are measured in thousandths of a millimetre (or microns). AFBMA or ABEC bearing tolerances are also commonly used and these are measured in ten-thousandths of an inch starting at ABEC1 then upwards to ABEC3, ABEC5 and ABEC7. Very few manufacturers are capable of manufacturing the aerospace grade ABEC9 (or P2 in ISO language). Tolerances have no effect on radial play although it is sometimes mistakenly thought that improving the tolerances will produce a bearing with less play. Assuming that the shaft and housing are manufactured to the same tolerances as the bearing, higher bearing tolerances will produce better mating between shaft/housing and bearing, lower noise and vibration due to improved roundness and lower starting and running torque (also subject to radial play and lubricant). Read more: http://www.smbbearings.com/SMBtechdata8.htm#ixzz22Zs62mPu

Shaft/Housing Fit

Shaft/Housing Fit The ideal fit is where the shaft/housing is the same size as the bore/O.D. of the bearing. This is known as a line-to-line fit and gives optimum bearing performance. Looser fits are commonly used and often preferred for ease of assembly or where spring preloading is used (see "Preload" in the Radial Play section). Where heavy radial loads or excessive vibration are present, bearing rings under a rotating load may need to be firmly located by an interference fit or other means such as a nut or adhesive. This prevents them from creeping in a circumferential direction which gives rise to increased wear. A bearing ring is subjected to a rotating load when the load is applied to all points of that ring during operation. For example: Inner ring rotating load: e.g. a bearing in a vacuum cleaner motor belt driving the roller brush. The shaft and bearing inner ring are rotating. The load is in a constant direction in relation to the bearing so as the inner ring turns, all parts of it are subjected to the load. The outer ring does not rotate so the load acts on only one point of the outer ring. This application requires an interference shaft fit and a clearance housing fit. Another possibility is a static inner ring and rotating outer ring but this time, the load rotates with the outer ring. As above, the load acts on only one point of the outer ring while all parts of the inner ring are subjected to the load. This applications require an interference shaft fit and a clearance housing fit. Outer ring rotating load: e.g. a bearing in a pulley. The shaft and inner ring are fixed while the outer ring and housing (the pulley) do rotate. The load is in a constant direction in relation to the bearing so as the outer ring turns, all parts of it are subjected to the load. The inner ring does not rotate so the load acts on only one point of the inner ring. This application requires a clearance shaft fit and an interference housing fit. This example involves a static outer ring and rotating inner ring, the load rotating with the inner ring. As above, the load acts on only one point of the inner ring while all parts of the outer ring are subjected to the load. Both of these applications require a clearance shaft fit and an interference housing fit. This means that usually only one ring is subjected to an interference fit. There may be instances where a fluctuating load direction will require interference fits for both shaft and housing. This may also be true where there is excessive vibration associated with the application. Make sure that interference fits do not reduce the radial play of the bearing to an unacceptable level or early failure will occur. These fits will stretch the bearing inner ring or compress the outer ring, reducing the bearing's internal space. Excessive interference fits can also cause high stress which may fracture rings. It should be noted that an interference fit can reduce radial play by up to 80% of the size of the interference fit. Let's use a shaft with a 10mm diameter and a bearing with a 10mm bore as an example. Imagine the shaft diameter is actually 10.007mm and the actual bearing bore is 9.993mm. This gives an interference fit of 0.014mm (i.e. the shaft is 0.014mm or 14 microns larger than the bearing bore). The radial play of the bearing may be reduced by as much as 80 percent of this figure or approx 0.011mm. If the bearing radial play (before fitting) is less than 0.011mm, the bearing may become tight and fail quickly. The material of the shaft and housing should be taken into consideration. An aluminium housing will expand more than a steel housing so requires a greater interference fit than a steel housing. Greater interference fits are required in thin walled or plastic housings and also on hollow shafts. Care should also be taken where shaft and housing materials have a different expansion coefficient to the bearing steel. This may lead to an increase or reduction in radial play. This is a danger when using ceramic bearings on a steel shaft. Silicon nitride has a very low coefficient but will withstand very high temperatures so if a silicon nitride bearing is used on a stainless steel shaft at 500 °C, there is a risk of the inner ring breaking or cracking particularly as ceramics are more brittle than steel. Much looser fits should be considered to accommodate these differences. There is less of a risk with zirconia as the expansion coefficient is much higher but the differences in expansion should always be considered. For commonly used bearing materials the coefficients are: 52100 chrome steel - 12.5 x 10-6 (0.0000125) per °C 440 stainless steel - 10.5 x 10-6 (0.0000105) per °C 316 stainless steel - 16 x 10-6 (0.000016) per °C ZrO2 (Zirconia) - 10.3 x 10-6 (0.0000103) per °C Si3N4 (silicon nitride) - 3.3 x 10-6 (0.0000033) per °C To calculate the expansion, first work out the difference in initial temperature and final temperature. Next multiply this figure by the expansion coefficient and multiply that new figure by the relevant bearing dimension. For example, a 440 stainless steel bearing bore is 30mm at ambient temperature 20°C. What is the bore size at 250°C? Final temperature 250°C minus initial temperature 20°C = 230°C increase in temperature Expansion coefficient of 440 grade steel is 0.0000105 per °C so... 230 (temperature increase) x 0.0000105 (expansion coefficient) x 30mm (bearing bore) = 0.072mm Therefore, at 250°C the bearing bore will be 30mm + 0.072mm = 30.072mm Interference fits can affect rotational accuracy by distorting bearing rings. The standards of roundness and surface finish which apply to the bearing should also apply to shaft and housing. This is very important for electric motor and other quiet-running applications. Miniature and thin-section bearings are particularly susceptible to distortion which leads to higher noise and vibration levels. If rotational accuracy is important, a combination of close bearing tolerances and close shaft/housing tolerances should be used to obtain the correct fit with the minimum interference. If further advice on shaft and housing fits is required, please contact us.

Spherical Bearings

Maximum Speed A number of factors affect speed limitation such as temperature, load, vibration, radial play, retainer, lubricant, ball material and closures. The speeds quoted in our catalogue pages are only approximate and valid for bearings used on a horizontal shaft with a metal cage, standard tolerance grade and radial play, medium loading, rotating inner ring and suitable lubricant (see below). Vertical shaft applications will necessitate a reduction of approximately 20 percent. Temperature excesses and heavy loadings will also require slower speeds. Bearings fitted with contact seals cannot achieve the same speeds due to increased friction between seal lip and bearing inner ring. The choice of lubricant may also have a significant effect on the speed rating. The maximum rpm at which a lubricant can effectively operate varies from type to type. The following adjustment factors are approximate and are based on bearings with a metal crown or ribbon cage. The maximum speed of a bearing can be increased by the use of a delrin or phenolic cage provided a suitable lubricant is used. The use of ceramic balls will increase bearing speed by up to 30 percent. Speed reduction Table Rotating Inner ring Rotating outer ring Open/ZZ 2RS Open/ZZ 2RS Petroleum oil Nil reduction 40% reduction 20% reduction 40% reduction Synthetic oil Nil reduction 40% reduction 20% reduction 40% reduction Silicon oil 20% reduction 40% reduction 30% reduction 40% reduction Standard grease Nil reduction 40% reduction 40% reduction 40% reduction High speed grease Nil reduction 40% reduction 20% reduction 40% reduction Silicon grease 20% reduction 40% reduction 30% reduction 40% reduction

Closures for bearings

Closures Shields (ZZ) Most sizes are available with metal shields. Shields are designed to prevent larger particles from entering the bearing and also to keep grease inside the bearing. They may be pressed into the bearing’s outer ring (non-removable) or retained by a circlip (removable). As the shields make no contact with the inner ring, they do not increase starting or running torque. Shields on stainless steel bearings are generally made from AISI 304 grade stainless steel. • Prevent contamination by larger particles • Reduce lubricant leakage • Do not increase torque Contact seals (2RS) The standard bearing seal consists of nitrile/BUNA-N rubber bonded to a metal washer. High temperature teflon seals (up to 250C) or Viton seals (up to 230C) are available on some sizes. The inner lip of the seal rubs against the bearing inner ring to provide an effective seal against smaller particles such as dust and moisture while preventing lubricant leakage. Contact seals produce much higher frictional torque levels than shields and reduce the maximum speed of a bearing. Below -30°C nitrile rubber and viton will stiffen and provide a less effective seal so teflon seals or metal shields should be considered for very low temperatures. • Good protection against contamination • Greatly reduce lubricant leakage • Reduce maximum speed by approx. 40% • Greatly increase bearing torque • Temp. range –40°C/+110°C (nitrile rubber) or up to 230C (Viton) and 250C (Teflon) Non-contact seals (2RU) These seals are also made of nitrile rubber bonded to a metal washer but do not rub against the bearing inner ring and therefore do not have the same effect on bearing torque and maximum speed as contact seals so can be used for low torque, high speed applications. They offer superior protection over metal shields but do not provide as effective a seal as the contact type. • Good protection against contamination • Reduced lubricant leakage • No torque increase • Do not affect maximum speed • Temp. range –40°C/+110°C

Load Rating for bearings

Load Rating Load ratings are expressed in Kgf (kilogramme force)on this website. That is the force exerted by a mass of 1 kilogramme at the Earth's surface. You will often see force expressed in Newtons elsewhere. A Newton is defined as the force that will accelerate a mass of one kilogram at the rate of one meter per second per second (or 1 m/s²). Since the force of gravity at the Earth's surface is 9.80665 m/s², 1 Kgf = 9.80665 Newtons but, to keep it simple, we say 1 Kgf = 10 Newtons. Dynamic load rating The official explanation for this is... "The dynamic load rating is that constant stationary radial load which 90% of a group of identical chrome steel bearings, with only the inner ring rotating, can endure for one million revolutions before the first signs of fatigue develop". Yes, 1 million revolutions sounds a lot but is it really? If you take a bearing running at 5000 rpm with the max dynamic load applied to it, it will last for 1,000,000 revs divided by 5000 = 200 minutes or 3 hours and 20 minutes!! This should tell you that these figures are used in the calculation of life ratings but bearings should not be subjected to such loads in normal application unless you don't expect them to last very long. AISI440C/KS440 stainless steel bearings will achieve approximately 80% of the figure quoted. Load ratings for thrust bearings are based on the constant axial load endured for 1 million revolutions. For life ratings, please contact SMB. Static load rating This rating represents the purely radial load (or axial load for thrust bearings) which will cause a total permanent deformation of the balls or raceway equal to one ten-thousandth of the ball diameter. This may be tolerable for certain applications but not where any smoothness or accuracy is required. Static load ratings for stainless steel bearings are approximately 75% of the load ratings for chrome steel bearings. The load capacity of a bearing may be limited by the lubricant. Certain lubricants are only suitable for light loads while others are designed for high load applications. Load ratings are higher for full complement bearings (see Retainer). The axial load capacity of a radial ball bearing can be increased by specifying loose radial play. Axial load rating Thin-section deep groove ball bearings can support axial loads of approximately 25 percent of the bearing's static radial load rating. Larger series such as 6200, 6300 can take axial loads of about 50 percent of the static radial load rating. To exceed the recommended limits will have a detrimental effect on bearing life.

Japanese Bearing

Retainer Retainers keep the balls evenly spaced around the raceway preventing ball to ball contact and thus allowing higher speeds. They also help to retain grease around the balls and raceways. For greater accuracy and to prevent any additional friction, it is important that the retainer is not allowed too much radial movement. To achieve this, the retainer is guided by either the balls or one of the rings. See the sections below for information on how each cage type is guided. Metal crown/ribbon This standard retainer is manufactured from carbon steel for chrome bearings and AISI304 or AISI430 grade stainless steel for stainless bearings. These were often made from brass which also offered a high temperature capability but this is much less common due to higher cost of brass and advances in steel technology. For higher temperatures, stainless steel is usually recommended. The crown cage and ribbon cage perform the same function but the crown cage is used primarily on smaller miniature bearings and thin-section bearings where space is more limited.Steel cages are preferred for arduous operating conditions and where high levels of vibration are experienced. • Good for low to medium speeds • Can withstand higher temperatures according to the type of steel (see "Bearing Material" section) • Crown type - inner ring guided • Ribbon type - mainly ball guided Nylon crown (TW) This moulded synthetic retainer has better sliding characterisitics than the steel cage and produces fewer fluctuations in running torque. It can increase maximum speeds by up to 60 percent so is generally used in high speed applications and has good low noise properties. This retainer is not suitable for low temperature applications as it loses elasticity below about 35°C. In vacuum applications, it may become brittle. • High speed and low noise • Max temperature range approx -35 to +110°C • Ball guided Phenolic crown (TP) This retainer is also used for high speed applications. Generally more expensive, it does have advantages over the synthetic type such as absorbency allowing it to be vacuum impregnated with oil for long life application. • Good oil retention. • Can operate well with marginal lubrication • Max temperature approx 140°C • Inner ring guided Full complement (F/B) A full complement (or full ball) bearing contains extra balls and has no retainer. It is used for its greater radial load capacity although axial load capacity is very small. These bearings can only be used at low speeds and bearing torque is increased due to ball to ball friction. An exception is a hybrid full complement bearing (ceramic balls) which can be used for very high speeds. Improved steel and hardening techniques have increased the load capacities of bearings with cages and the full complement bearing is much less common now. • Higher radial load capacity • Low speed only (except with ceramic balls) • Low axial load • Increased bearing torque

SAE52100 Chrome Steel

STEELS SAE52100 Chrome Steel (no prefix) • Higher hardness so longer lfe ratings • Lower cost • Good for temperatures up to 150C • Poor corrosion resistance This is the standard steel for most ball bearings. It is harder than stainless steel and gives greater life ratings. It also has superior low noise qualities to standard 440 grade stainless steel. Chrome steel actually has a low chromium content and is not corrosion resistant so not suitable for corrosive environments or for dry (no lubricant) bearings as chrome bearings require an oil coating on the exterior surfaces to protect against corrosion which can contaminate the inside of the dry bearing. Chrome steel can tolerate continuous temperatures of up to 120C. Above this temperature, chrome steel undergoes greater dimensional change and the hardness is affected, reducing load capacity. It can withstand up to 150C intermittently but above this temperature, bearing life is significantly reduced. 440 Grade Martensitic Stainless Steel (prefix "S") • Good corrosion resistance to water and many weak chemicals • Corrosion resistance can be improved by passivation. • Good for temperatures up to 300C • Slightly softer than chrome steel so lower load ratings • Will corrode after prolonged exposure to salt spray and poor resistance to acids/alkalis • More expensive than chrome steel More resistant to corrosion due to the greater chromium content and the addition of nickel, 440 grade stainless steel is the most commonly used for corrosion resistant ball bearings. The chromium reacts with oxygen in the air to form a chromium oxide layer, known as the passive film, on the surface of the steel. It is hardenable and gives a good combination of strength and corrosion resistance. It is magnetic unlike some 300 grades. AISI440C grade The load capacity of AISI440 grade is approximately 20 percent less than chrome steel so life ratings will be slightly reduced. This grade exhibits good corrosion resistant when exposed to fresh water and some weaker chemicals but may corrode in seawater environments or in contact with many aggressive chemicals. The corrosion resistance also depends on the surface finish. Iron particles and other impurities left on the surface during maching can lead to premature localised corrosion while surface irregularities or poorly finished surfaces also increase the likelihood of corrosion. KS440/ACD34/X65Cr13 grade stainless steel with a lower carbon content is used by EZO Japan and has greater corrosion resistance, greater load capacity (approx 10 percent less than chrome steel) and superior low noise qualities to the standard AISI440C grade. The corrosion resistance of stainless steel can be increased by passivation (see section below). 400 grade stainless steel will also withstand higher temperatures than chrome steel, coping with up to 250C constant and up to 300C intermittent with reduced load capacity. Above 300C, bearing life can be considerably shortened. A note on passivation.... Passivation is a process by which free iron particles and other impurities are removed from the surface of stainless steel by immersion in nitric or citric acid, thus regenerating the passive film. This reduces the likelihood of surface discolouration so making it a useful process in some corrosive environments. Passivation does not increase the resistance of stainless steel to pitting corrosion. This means that where a bearing has incidental contact with, say, salt spray, passivation may be beneficial but it will not offer long term protection in harsher applications. AISI316 Austenitic Stainless Steel (prefix "S316") • Excellent corrosion resistance to water, salt water and chemicals • Non magnetic • Expensive due to low production quantities. • Only semi-precision grade is possible • Suitable for very low load and low speed only Used for greater corrosion resistance or where bearings must be non-magnetic, bearings made from this material are semi-precision and fine for applications such as marine pulleys but not suitable for precision instrument use. The smoothness and close tolerances possible with 52100 or 440 grade steel cannot be achieved with 316 grade bearings. Also 316 grade stainless steel is non hardenable so as a softer steel, will only support low loads and low speeds. The dynamic load rating of a 316 grade bearing may only be 10% of the 440 grade equivalent whereas the maximum speed may be 5% or less of the 440 stainless steel version. 316 grade stainless steel exhibits good corrosion resistance in sea atmosphere and may perform well submerged in seawater. However, as the passive film on the surface of stainless steel relies on the presence of oxygen to regenerate itself, in a low oxygen underwater marine environment (e.g under washers or o-rings) the steel may be prone to pitting or crevice corrosion although 316 grade is still much more resistant to corrosion than 440 grade. Bearings made from 316 grade stainless steel can be used at high temperatures provided a suitable cage material is used. Due to the difficulty of using 316 grade for the cage, 304 grade stainless steel is normally used for metallic cages and nylon for non-metallic cages. Please remember that, as 316 grade bearings are far less popular, minimum quantities may apply and some smaller instrument bearings may not be available. PLASTICS Acetal resin (prefix "AC") • Excellent corrosion resistance to water, salt water and weak chemicals • Non magnetic • Only semi-precision grade is possible • Maximum temperature 110C • Suitable for very low load and low speed only Polypropylene (prefix "PP") • Excellent corrosion resistance to water, salt water and many chemicals • Non magnetic • Only semi-precision grade is possible • Maximum temperature 80C • Suitable for very low load and low speed only PTFE (prefix "PTFE") • Excellent corrosion resistance to water, salt water and most chemicals • Good high temperature performance. • Non magnetic • Only semi-precision grade is possible • Maximum temperature 260C • Suitable for low load and low speed. PEEK (prefix "PEEK") • Excellent corrosion resistance to water, salt water and most chemicals • Good high temperature performance • Non magnetic • Only semi-precision grade is possible • Maximum temperature 260C • Greater strength so suitable for higher load and speed than other plastics Our standard plastic corrosion resistant bearings have acetal resin (POM) rings, nylon (PA66) cages and balls made from 316 stainless steel or glass. They will however, corrode in the prescence of certain chemicals and PA66 cages will absorb water after long exposure causing loss of tensile strength. A number of alternative materials for rings, cages and balls are available such as polypropylene, PTFE or PEEK. All plastic bearings are semi precision and like 316 stainless steel bearings, should not be used for precision applications. Due to the softer material, they are not suitable for anything other than low loads and low speeds although PEEK has better load bearing capabilities. Corrosion resistance varies between the materials with PTFE and PEEK giving the best all round chemical resistance. Care should be taken to choose the correct material when using plastic bearings at elevated temperatures. Acetal bearings should not be used in temperatures of greater than 110C and polypropylene should only used up to 100C but other materials have good high temperature resistance such as PVDF (polyvinylidene) which can be used at up to 150C and PTFE or PEEK which are both suitable for temperatures of up to 260C. Generally.plastic bearings are not recommended for vacuum applications. PEEK is the exception with very good outgassing characterisitics. CERAMICS (prefix "CB"hybrid or "CC" all-ceramic) Zirconia (suffix "ZrO2") • Good corrosion resistance to cold water and many chemicals • Good high temperature performance up to 300C without cage • Non magnetic and electrically insualting • Lower speed and load than steel bearings • Not suitable for low noise applications • Higher fracture toughness than other ceramics so better for small shock loads • Expansion similar to steel so not a problem to use with steel shaft at high temperature. Silicon Nitride (suffix "Si3N4") • Very good corrosion resistance to water, salt water and most chemicals. • Good high temperature performance up to 1000C without cage • Non magnetic and electrically insulating • Lower speed and load than steel bearings but Si3N4 balls are used in high speed hybrid bearings. • Not suitable for low noise applications • Much lighter than steel or Zirconia • Very low expansion at high temperature. Silicon Carbide (suffix "SiC") • Best corrosion resistance of the ceramics. • Best high temperature performance up to 1600C without cage • Non magnetic • Electrically conductive • Much lighter than steel or Zirconia • Very low expansion at high temperature. Bearings can be supplied with steel rings and ceramic balls (hybrid) or "all ceramic" bearings with ceramic rings and balls. These all-ceramic bearings may have steel, nylon, PTFE or PEEK retainers or be supplied as full complement type. There are many advantages to ceramic materials such as a lower friction coefficient, much greater hardness and temperature resistance. Hybrid Bearings have steel rings and ceramic balls. Silicon nitride is the most popular for the balls as it has only 40 percent of the density of bearing steel but is much harder giving greater wear resistance. Zirconia is heavier with 75 percent of the density of steel so is less suitable for hybrid bearings.. Hybrid bearings are also capable of higher speeds. Sometimes, excessive claims are made about the high speed capabilities of hybrid bearings. They can run faster than all steel bearings due to the lower centrifugal force generated by the ceramic balls but this is partially counteracted by the lower elasticity of the balls. As the balls are harder, the contact area between the balls and the raceway is smaller which causes a higher contact pressure. Under load, this can cause the raceways to wear faster than they would with steel balls. The speed increase for hybrid bearings is approximately 30-40 percent with adequate lubrication. Hybrid bearings can also operate better with limited lubrication as the lower friction material generates less heat but running speed should be reduced. Hybrid bearings are also less subject to ball skidding under inital acceleration due to the lower ball density. All-ceramic bearings have good to excellent corrosion resistance, are non-magnetic and, apart from silicon carbide, are electrically insulating. All-ceramic bearings can be used in high to very high temperatures if supplied without a cage (full complement). Electrical resistance: Si3N4 best, then ZrO2, then SIC which is conductive. High temp resistance: SiC best (1600C), then Si3N4 (1000C), then ZrO2 (300C) Corrosion resistance: SIC (excellent), then Si3N4 (very good) and ZrO2 (good) Load capacity: SIC highest then Si3N4, then ZrO2 Fracture toughness: ZrO2 best, then Si3N4, then SiC All-ceramic bearings have lower load and speed ratings than steel or hybrid bearings. The speeds are lower due to the lower precision and roundness of the rings and the loads are lower because the material is more brittle. Under heavy loads and particularly heavy shock loads, there is a risk of cracking. For the same reason, great care should be taken with interference fits. Zirconia is the least brittle so it will handle shock loads and very small interference fits better than the other ceramic materials with silicon carbide being the most brittle. Shock loads should be avoided with all-ceramic bearings. Great care should be taken when using ceramic bearings (especially silicon nitride and silicon carbide) on steel shafts at high temperature due to the difference in expansion coefficient and the relative brittleness of ceramics. For more information see Shaft/Housing Fit WARNING: Customers often expect very low frictional torque with low noise and vibration levels from hybrid bearings. This may be possible but the bearing rings must have very good roundness and a high quality raceway finish while the balls must also have very good roundness and surface finish. A hybrid bearing with poor roundness and raceway finish will have much higher friction levels, higher vibration and a lower maximum speed than a good quality all-steel bearing. Drag in a hybrid bearing can be reduced by reducing lubrication or running the bearing without lubrication and there are greater possibilities with hybrids than with conventional steel ball bearings but noise and vibration levels will still be high unless the roundness and surface finishes are of a high standard. All-ceramic bearings should not be used for low noise/low vibration applications. It is not possible to achieve the high standards of roundness with ceramic rings that are possible with steel rings.

SAE 52100

DLT Bearing Material Selection Non-Corrosive environment: Normal use, low to moderately high speed, all loads, low to medium temperature (less than 120C constant and/or 150C intermittent). Use chrome steel bearings. Check grease capabilities if in the higher temperature or higher speed range. Nylon or polyamide cage not desirable for 110C or more. High speed use, low to medium temperature (less than 120C constant and/or 150C intermittent). Use chrome steel bearings with high speed grease. Consider polyamide cage and/or ceramic balls for higher speeds. Consider high temperature grease if in the higher temperature range. High temperature use (121C to 250C constant and/or 151C to 300C intermittent). Use 440 stainless steel bearings with stainless steel cage. Check grease speed rating if in the higher speed range. High speed & high temperature use (121C to 250C constant and/or 151C to 300C intermittent). Use 440 stainless steel bearings with stainless steel cage and ceramic balls. Very high temperature use (up to 1200C). Use unlubricated full complement (no cage) all-ceramic bearings. The maximum working temperature for Zirconia (ZRO2) is approx 1100C and for Silicon Nitride (Si3N4) it is 1200C Moderately corrosive environment: Depending on the amount of moisture or liquid present, it may be necessary to use a water resistant or chemical resistant lubricant for corrosive environments. Normal use, low to high speed, all loads, low to medium temperature (less than 120C constant and/or 150C intermittent). Use corrosion resistant 440 stainless steel bearings.. Low load and speed use, low to medium temperature (up to 100C constant). Use corrosion resistant 440 stainless steel bearings or plastic (acetal) corrosion resistant bearings. Beware lower rolling accuracy of plastic bearings. Also check load/speed ratings for plastic bearings. High speed use, low to medium temperature (less than 120C constant and/or 150C intermittent). Use corrosion resistant 440 stainless steel bearings. Consider polyamide cage and/or ceramic balls for higher speeds. High temperature use (up to 250C constant), very low load/speed. Use corrosion resistant 440 stainless steel bearings with high temp grease or unlubricated plastic PTFE/PEEK bearings. Beware lower rolling accuracy of plastic bearings. Check load/speed ratings for plastic bearings. High temperature use (up to 250C constant), medium to high load/speed. Use corrosion resistant 440 stainless steel bearings with high temp grease Highly corrosive environment (more highly concentrated acids & alkalis, saltwater): Highly corrosive environment, very low load/speed. Use unlubricated corrosion resistant plastic or all-ceramic bearings or 316 stainless steel bearings with a chemical or saltwater resistant lubricant. Beware lower rolling accuracy of plastic and 316 stainless steel bearings. Consider more corrosion resistant bearing materials such as PEEK, PTFE or HDPE for acids/alkalis (consult DLT for compatibility). Highly corrosive environment, moderate to high load, low speed. Use unlubricated all-ceramic bearings with PEEK or PTFE cage or full complement type (no cage). Non magnetic environment: Very low load/speed. Use plastic, 316 stainless steel or full ceramic bearings. Beware lower rolling accuracy of plastic and 316 stainless steel bearings. Moderate to high load, low speed. Use full ceramic bearings with nylon or PTFE cage or full complement type (no cage). Food environment: Depending on the location of the bearings, some type of USDA approved lubricant will be required in the bearings. H1 grade lubricants are used where there is a possibility of incidental contact with food and H2 where there is no possibility of contact. Normal use, low to high speed, all loads, low to medium temperature (less than 120C constant and/or 150C intermittent). Use corrosion resistant 440 stainless steel bearings with food grease. Low load and speed use, low to medium temperature (up to 100C constant). Use corrosion resistant 440 stainless steel bearings with food grease or plastic (acetal) bearings with no lubrication. Beware lower rolling accuracy of plastic bearings. Also check load/speed ratings for plastic bearings. High speed use, low to medium temperature (less than 120C constant and/or 150C intermittent). Use corrosion resistant 440 stainless steel bearings with food grease. Consider polyamide cage and/or ceramic balls for higher speeds. High temperature use (up to 250C constant), very low load/speed. Use corrosion resistant 440 stainless steel bearings with high temp food grease or unlubricated plastic PTFE/PEEK bearings. Beware lower rolling accuracy of plastic bearings. Check load/speed ratings for plastic bearings. High temperature use (up to 250C constant), medium to high load/speed. Use corrosion resistant 440 stainless steel bearings with high temp food grease Vacuum environment: Normal use, low speed, all loads, low to medium temperature (less than 120C constant and/or 150C intermittent). Use 440 stainless steel bearings with stainless steel cage, either unlubricated or with vacuum grease or with MOS treatment. Consider hybrid bearings (stainless steel rings & ceramic balls) or all-ceramic bearings. High speed use, low to medium temperature (up to 150C constant). Use 440 stainless steel bearings with stainless steel cage, ceramic balls and vacuum grease. High temperature use (up to 250C constant), medium to high load/speed. Use 440 stainless steel bearings with stainless steel cage and high temp vacuum grease. Consider ceramic balls or unlubricated all-ceramic bearings Very high temperature use (up to 1200C). Use unlubricated full complement (no cage) all-ceramic bearings. The maximum working temperature for Zirconia (ZRO2) is approx 1100C and for Silicon Nitride (Si3N4) it is 1200C

Chemical composition of bearing steel

Steel Specification Tables (a) Chemical composition of bearing steel Spec C% Si% Mn% P% S% Cr% Mo% Ni N Hard- ness Chrome SAE52100 SUJ2 0.95 - 1.10 0.15 -0.35 0.50 max 0.025 max 0.025 max 1.30 -1.60 - - - 60-64 HRC Stainless Steel AISI440C SUS440C X105CrMo17 0.95 -1.20 1.00 max 1.00 max 0.04 max 0.03 max 16.0 -18.0 0.75 max - - 58-62 HRC KS440 ACD34 X65Cr13 0.60 -0.75 1.00 max 1.00 max 0.04 max 0.03 max 11.50 -13.50 0.75 max - - 58-62 HRC AISI420B SUS420J2 X30Cr13 0.26 -0.35 1.00 max 1.50 max 0.04 max 0.03 max 12.0 -14.0 - - - 53-57 HRC AISI304 SUS304 X5CrNi1810 0.08 max 0.75 max 2.00 max 0.045 max 0.03 max 18.0 -20.0 - 10.5 0.1 max 92 HRB AISI316 SUS316 X5CrNiMo17-12-2 0.08 max 0.75 max 2.00 max 0.045 max 0.03 max 16.0 -18.0 2.0 -3.0 10.0 -14.0 0.1 max 95 HRB (b) Stainless steel grades for EZO Japan bearings Stainless Steel Grade Bearing Types Comments Inner and outer rings AISI440C SUS440C X105CrMo17 S6709 upwards S6809 upwards S6907 upwards S6006 upwards S6206 upwards S6305 upwards KS440 ACD34 X65Cr13 0.6mm - 9mm bore 0.04" - 0.75" bore S6700 - S6708 S6800 - S6808 S6900 - S6906 S6000 - S6005 S6200 - S6205 S6300 - S6304 Balls AISI440C SUS440C X105CrMo17 All Shield AISI304 SUS304 X5CrNi1810 All Cage AISI304 SUS304 X5CrNi1810 0.6mm - 9mm bore 0.04" - 0.75" bore S6701 upwards S6800 upwards S6900 upwards S6000 upwards S6200 upwards S6300 upwards ribbon cage only +SMR128/SMR137 crown cage ribbon cage only S6000-2RS - S6006-2RS have nylon crown cage S6200-2RS - S6206-2RS have nylon crown cage SUS420J2 X30Cr13 0.6mm - 9mm bore 0.04" - 0.75" bore S6700 crown cage only + SMR137/ SMR128 ribbon cage crown cage only (c) Stainless steel grades for SMB China bearings Component Stainless Steel Grade Bearing Types Comments Inner and outer rings AISI440C SUS440C X105CrMo17 All Balls AISI440C SUS440C X105CrMo17 All Shield AISI304 SUS304 X5CrNi1810 All Cage AISI304 SUS304 X5CrNi1810 All

Automotive Bearings

Our bearings are used in a wide range of applications. We list some of the more common ones below: At DLT Bearings, we are proud of our ability to service a wide range of industrial, manufacturing, and design applications. We started in 1985 as a specialty provider of miniature and small ball bearings, including inch and metric ball bearings. Though we remain specialists, we have also expanded our selection to better meet the diverse needs of our customers. Some of the more common applications for our bearings are listed below: Automotive Bearings Our miniature bearings can be supplied with a range of special lubricants in standard or low vibration grade as wiper motor bearings, alternator bearings, steering system bearings etc. Bakery Bearings Our stainless steel bearings can be supplied with very high temperature perfluorinated grease to give maintenance free performance in temperatures of up to 300C. Specially loose bearings can be offered for very high temperature environments. Bicycle Bearings (Cartridge Bearings) Our thin-section cartridge bearings can be used as bottom bracket bearings or hub bearings and are available with metal shields or low friction seals and waterproof lubricants. If you are buying for your own bike or as a shop, there is no minimum order quantity. Click here for an article on how to replace your bottom bracket bearings. Thanks to Sam Bennet from the RAF Cycling Club for the article. Clock Bearings Our miniature bearings and instrument bearings can be supplied with a very light instrument oil or completely dry for free movement. Remember, we have no minimum order quantity. Corrosion-resistant Bearings Our corrosion resistant bearings can be used in marine environments or with aggressive chemicals. We stock most of our range in 440 grade stainless steel. We can also supply some sizes in 316 grade stainless steel. We stock a range of plastic bearings with balls made out of glass or 316 stainless steel. Both 316 stainless and plastic bearings are only suitable for low load/low speed use. We keep a stock of water/chemical-resistant lubricants which can be applied to any of our corrosion resistant bearings. Domestic Appliance Bearings Low noise bearings or electric motor bearings (EMQ grade bearings) can be supplied for use i many different domestic appliances such as vacuum cleaners, food mixers or washing machines. Electric Motor Bearings Low noise bearings (EMQ or V2) and extra low noise bearings (EMQ2 or V3) can be supplied for noise or vibration critical applications. These include miniature motors such as hard disk drive motors, servo motors, encoders, vcr capstan motors, vcr drum spindles and polygonal mirror scanner motors. Fishing Reel Bearings Many of our thin-section bearings are used as high spec reel bearings and our EMQ2 low vibration bearings with oil lubrication spin freely and quietly. These low noise bearings are more popular than many hybrid steel-ceramic bearings as they are much quieter and smoother than the low grade hybrid bearings that are sold worldwide. No minimum order quantity. Food Machinery Bearings Our stainless steel food grade bearings with approved food greases can be used as food industry bearings for example motor bearings or food conveyor bearings. Instrument Bearings We hold stock of many sizes of high precision, oil lubricated or lubricant free instrument bearings for use in small measuring instruments. Medical Equipment Bearings We supply stainless steel instrument bearings and larger bearings to many manufacturers of medical equipment. RC Models We stock many model bearings for use in radio control cars, slot cars, planes, boats and helicopters as well as model trains. Most of the applicable sizes will be found in the miniature (metric or inch) bearing catalogue section. Check thin-section bearings for anything bigger. Thrust bearings are listed separately. If you are unsure of the sizes, send your bearings to us to be measured. We have no minimum order quantity. Skate Bearings Roller skate bearings, skateboard bearings and in-line skate bearings are available with low noise and easy rotation. These are all noise and vibration tested and we offer these with steel balls or ceramic balls and also stock a stainless steel version. Vacuum Bearings We can supply dry bearings, moly-disulphide treated or specially greased bearings for vacuum applications.

Mounting/dismounting tapered bore roller bearings

Mounting/dismounting tapered bore roller bearings Mounting Roller bearings with a tapered bore are either fitted directly onto a tapered shaft or onto a cylindrical shaft with an adapter_sleeve or a withdrawal sleeve. By driving up the inner ring on the shaft or sleeve, the tight fit required is obtained and is measured by checking the radial clearance reduction due to the expansion of the inner ring or by measuring the axial drive distance. Check the drive up distance for spherical roller bearings in the 1:12 taper table and the 1:30 taper table. The use of a good quality feeler gauge is imperative for measuring the radial clearance. Small bearings up to approximately 80mm bore can be pressed with a locknut onto the taper seat of the shaft or the adapter sleeve. A hook spanner should be used to tighten the nut. Small withdrawal sleeves are also pressed with a locknut into the gap between the shaft and the inner ring bore. Considerable force is required to tighten the nut with medium sized bearings. Locknuts with thrust bolts facilitate mounting in such cases (not suitable for FAG spherical roller bearings of the 'E' design. It is advisable to use a hydraulic press for driving-up larger bearings or pressing them onto the sleeve. Hydraulic nuts are available for all popular sleeve and shaft threads. For bearings with a bore of 160mm and upwards mounting and dismounting are greatly facilitated by the hydraulic method. Dismounting When bearings are directly on the tapered seat or an adapter sleeve, the locking device of the shaft or sleeve is loosened first. The nut is then turned back by the amount corresponding to the drive up distance. The inner ring is then driven off the sleeve or the shaft by means of a hammer and a piece of tubing. When a press is used the adapter sleeve is supported and the bearing pressed off. Withdrawal sleeve mounted bearings are removed by means of an extraction nut. High forces are required for large sized bearings. Extraction nuts with additional thrust bolts are then used. A washer should be inserted between the bearing inner ring and the thrust bolts. The dismounting of withdrawal sleeves is much easier and cost effective with hydraulic nuts. The hydraulic method is applied to facilitate the dismounting of large size bearings. Oil is injected between the mating surfaces and enables the mating parts to be moved separately without risking surface damage. Tapered shafts must be provided with oil grooves and supply bores. The required oil pressure has to be created with a pump. When dismounting, an oil with a viscosity of about 150mm2/s at 20 degrees C is used (nominal viscosity 46mm2/s at 40 degrees C. Fretting corrosion can be dissolved by adding rust removing additives to the oil. For tapered bore bearings, oil is pressed between the mating surfaces. Since the press fit is released abruptly, a stop such as a nut should be provided to control the movement of the bearing. Contact us

cage

Cage The bearing cage is a device used to seperate the rolling elements of a bearing (also known as a retainer). Case Depth The depth given which meets the hardness requirements layed down by the bearing manufacturer. Case Hardening The act of hardening a bearing component all the way through - also known as through hardening. Ceramic Bearings A material being used increasingly for its high temperature and low density properties for rolling element production. Chrome Plating A plating process applied to provide a hard wear resistant surface to possible abrasives. Cone Bearing The phrase given to describe the inner portion of a taper roller bearing. Conrad Bearing An older phrase describing a standard deep groove ball bearing. Corrected Life A set of factors applied to the standard bearing life equation which adjusts it for factors such as fitting, environment, temperature etc. Cup Bearing The phrase given to describe the outer portion of a taper roller bearing.

Ball Bearing

Ball Bearing A very general term used to describe a deep groove ball bearing. BDL Basic Dynamic Load - The load underwhich a bearing can operate whilst rotating Bearing A mechanical component that is designed to support two or more parts which articulate in differing directions. Bearing Tolerance The degree of precision to which a bearing is made. Block bearing An alternative phrase used to describe a pillow block or flange unit bearing. Brinelled The result of rolling elements being forced onto inner or outer raceways, leaving indentations in the raceway, thus leading to premature bearing failure.

Automotive Bearing

ABEC The Annular Bearing Engineering Committee. Air bearing A bearing which uses an air cushion to separate its rotating surfaces. Anodizing An oxidant coating applied to a metal surface. Automotive Bearing A General description given to cover many bearing types found on a wide verity of vehicles. Axial Clearance The amount of play or movement displayed when a bearings inner ring is moved axially in ralation to the outer ring.

High speed Bearings

How can I keep contamination out in a high speed application? By use of a labyrinth seal. The labyrinth seal is a non-contact seal with special internal construction which centrifuges dirt back out to where it came. AHR can supply data on these specialist seals if you require them.

Bearings lubricant

Can I flush out a bearings lubricant and use another? Not unless you use a prescribed flushing agent in a properly environmentally controlled area and the bearing is thoroughly dried post flush and lubricated with the correct amount and type of grease.

Bearing replacement

How do I know when my bearing needs replacing before it causes a catastrophic failure? Bearing failure of the catastrophic nature is usually very rare. In cases where a foreign object is introduced or the bearing is running near its design speed limit, then it is potentially possible. A bearing's life can be calculated using various factors. If you require help in life calculations contact Truck bearings. We can provide an unbiassed assessment of your application and its effects on bearings.