Friday, 28 November 2008


Originally formed in 1985 to cater for a growing demand for miniature ball bearings and small ball bearings in the UK, SMB Bearings has grown over the years to become a major specialist supplier worldwide.

We have expanded the range slightly from the original micro ball bearing, miniature ball bearing and small ball bearing range but are still very much specialists in our field. We still concentrate on a fairly narrow range of ball bearing types. We continue to supply miniature ball bearings,instrument ball bearings (mini bearings and micro bearings) but we have added stainless steel bearings, plastic bearings and electric motor bearings. Being specialists allows us to know our products better and serve you more effectively.

Most of the micro/miniature bearing, stainless steel bearing and thin section bearing range is supplied either in high precison EZO brand or, for low cost applications, SMB China brand. EZO are a well respected and highly reputable Japanese manufacturer of precision miniature bearings, thin section bearings and stainless steel bearings and our association with them goes back many years to the first days of SMB Bearings.

Miniature Bearings / Micro BearingsThis is a range of miniature ball bearings or mini bearings starting with micro ball bearings of only 0.6mm bore up to 9mm bore (plus inch equivalents). These include micro and miniature radial ball bearings (including the smaller instrument bearngs) and miniature thrust ball bearings.

The range encompasses both metric and inch micro bearings and miniature bearings, miniature flanged bearings and miniature extended inner ring bearings while for specialist applications, ceramic bearings and hybrid bearings are available in many sizes.

We supply miniature bearings for a wide variety of uses including instrumentation, small motors, gearboxes, fishing reels, cycles, skates, skateboards and inline skates. We stock radio control model ball bearings for radio control cars, helicopters and engines, in fact most model engineering applications.Stainless Steel BearingsStainless steel ball bearings are available from 0.6mm bore up to 50mm bore or inch equivalent. Most of the range of miniature bearings and thin section bearings are also available in 440 grade stainless steel. The larger "popular metric" stainless steel bearings are from 10mm bore up to 40mm bore and often used in the food industry or for high temperature applications. We can also supply 316 grade stainless steel bearings in many sizes but these may need to be made to order.

Plastic Ball BearingsPlastic bearings can be supplied from 6mm bore up to 25mm bore from stock and even larger sizes of plastic bearing can be supplied to order. Generally made from acetal resin with 316 stainless steel balls or glass balls, plastic bearings are used where greater corrosion resistance is required.
Thin Section Ball BearingsThin section bearings can be supplied from 10mm bore up to 50mm bore. Many of the miniature bearings are also thin section bearings but the term generally applies to 10mm bore and upwards.

Electric Motor BearingsElectric motor ball bearings are designed to run with low noise and vibration for any noise critical application. The term "Electric Motor Bearing" is often loosely used which is why our electric motor ball bearings have been tested in comparison with leading brands.

Supply from StockOver the years we have developed extensive product knowledge and offer technical help with all apsects of our range. We keep comprehensive stocks across the whole range so offer a same day despatch worldwide on most sizes if required. We receive incoming shipments every week so stocks are always changing. For the most up to date stock situation on any item, please contact us.

RelubricationOur relubrication facility has been in operation for over 15 years allowing us to provide miniature bearings, stainless steel bearings, thin section bearings and electric motor bearings with any one of a wide range of lubricants from oils and greases to dry lubricants or no lubricant at all. In addition to cleaning and re-lubricating bearings with a range of customer specified oils and greases, we also have the facility to treat bearing raceways with molybdenum disulphide for vacuum applications. We re-lubricate our own bearings and customer supplied bearings every day. The benenfit of having an in-house operation means we can supply you with small quantities, quickly. Our customers find this particularly useful for urgent, small or one-off requirements or sample approval although we regularly deal with larger quantities too.

Miniature, corrosion resistant & motor bearings and re-lubrication of bearings

Bearing Technical Talk... Radial Play

Radial play, or internal clearance, is an important consideration when choosing a bearing. Quite simply, there must be at least enough play in a bearing to allow rotatation without too much resistance after fitting or it will fail quickly. It is normally preferable to only have a small clearance left once the bearing has been fitted to minimize ball skidding and reduce axial play (end play). Selecting the correct radial play can avoid faster wear and reduce unwanted play. Radial play before fitting is called "initial" radial play. "Residual" or "operational" radial play is what exists after fitting.

So what might change the radial play in the bearing? A shaft that is slightly larger than the bearing inner ring (an interference fit or press fit) will stretch the inner ring reducing radial play. The same thing happens if the outer ring is a tight fit in the housing. This can compress the outer ring so a bearing with a greater radial play may be needed. High temperature can also be a problem where the shaft and housing temperatures differ. If a bearing inner ring gets hotter than the outer ring, it will expand more and reduce radial play. If the outer ring gets hotter, radial play can increase. These problems can also occur where inner and outer ring are the same temperature but made of materials with different expansion coefficients.

In most cases, a standard radial play is suitable and, of course, easier to obtain but there are certain conditions where a non-standard clearance is preferred. A tight radial play gives greater rigidity and running accuracy which is important in low noise, low vibration applications. This is why many of our small electric motor bearings are MC3 radial play. In fact, to further eliminate vibration and noise, a small axial preload is often applied to reduce the radial play to zero. Elsewhere, a loose radial play is desirable. For example, a loose radial play should be considered for high axial loads as it increases the bearing's axial load capacity. Also, a loose radial play will better accommodate misalignment between the shaft and housing and cope better with heavy loads or shock loads.

Finally, it is sometimes thought that when there is too much play, a higher precision grade will solve the problem. Actually, the answer is often to use a bearing with a tighter radial play or introduce an axial preload to the bearing to eliminate the play. When a bearing is manufactured, the balls and rings are carefully matched to produce the desired radial play so a higher precision grade will make no difference to the "looseness" of the bearing. Its just as possible for a high precision bearing to have a large radial play as it is for a standard grade bearing to have a tight radial play. Remember, loose does not necessarily mean poor quality!!
For more information, see the "Technical" page on our website and scroll down to the Radial Play section.

We recently added material specification tables in the Technical section of our website. These give details of the different grades of chrome and stainless steels used in the rings, balls, cages and shields in our bearings. For more details, go to the web page at: www.smbbearings/materialtables.htm
We now have stocks of plastic (acetal resin) bearings with glass balls to complement our existing stock of plastic bearings with 316 stainless steel balls.

Miniature & instrument bearings Stainless steel and plastic corrosion resistant bearingsLow noise electric motor bearings Cleaning and re-lubrication of bearings.

See the range and lots more online at www.smbbearings.comor telephone sales on 01993 842555 or fax us on 01993 842666