SMB's new non-magnetic bearings brochure...

We're delighted to be starting work on a new brochure, to showcase our non-magnetic bearings - we have plastic (acetal resin), ceramic & 316 grade stainless steel bearings available for a diverse range of applications...

Sometimes applications require bearings to be non-magnetic or non-conductive. Such bearings may be required in medical equipment such as MRI scanners, electron beam process equipment, semiconductor equipment, liquid crystal manufacturing, magnetometers and other areas of the electronics industry for example.

Acetal bearings with glass balls

Acetal bearings with 316 stainless steel balls

Different materials for rings, balls and cage are required where a bearing is required to be non-magnetic or non-conductive. We have various options. Our semi-precision acetal resin bearings have either 316 stainless steel balls or glass which fit these requirements. 

Flanged plastic/acetal bearings...

We can supply full ceramic bearings most commonly made from zirconium dioxide or silicon nitride or, alternatively, austenitic stainless steel bearings made from 316 grade stainless steel. The cages are made from non-magnetic and non-conductive material such as acetal resin or PEEK and the balls are either 316 stainless steel or ceramic.

Ceramic bearings ...

316 grade stainless steel bearings

If you'd like to find out a little more (before our swanky new brochure is unveiled 😉) then please contact us or you can find more details at our website.

SMB's July newsletter is now available...

Click on the image below to see the full newsletter online:

SMB (we love our) Bearings!...

As we're a bit geeky at SMB, we've made a video montage from a small selection of the bearings that we can offer you.  For details of our full range, please see our website's product pages.

Please contact us if you have any enquiries.

SMB Bearings LTD Website - new pages launched...

Our technical department have been extremely busy lately, fine-tuning aspects of our website so that we can offer the maximum amount of product & technical information to our customers & the newly developed pages have gone live this morning.

Whole new ranges have been added to our portfolio & we can now source ceramic & 316 stainless steel bearings for specialist applications. 

We hope that you can now find all the information that you could possibly ever need on our bearing ranges & support services, but do please feel free to contact us if you need pricing information or advice on bearing selection/ answers to technical questions - we'll look forward to helping you with any enquiries that you may have.

In a short while the site's bearing interchange & search facility will also go live, giving access to (& explanations of) thousands of different manufacturer's part references - we'll let you know just as soon as it's been completed.

SMB Skate Crew welcomes Joe Baldwin...

We're delighted to introduce a new friend - a very warm SMB welcome goes out to downhill rider
 Joe Baldwin - although, given his brilliant results in the last couple of years, you probably know him already!

Joe Baldwin at Eat Concrete 2014

Check out these results & the man in action:

"My 2013-present results are here: 2014 – 1st Place Ride The Dragon Downhill (Wales)

2013 – Highest IDF Ranked Rider in the UK

2013 – 1st Place – Sheepy Outlaw (UK)

2013 – 1st Place – Hogtoberfest (UK)

2013 – 1st Place – Hog Hill – The Crackling (UK)

2013 – 5th Place – IDF WCQS – BoPeep Crash ‘n’ Burn (UK)

2013 – A’ Bracket Rider – IDF WC – Peyragudes Never Dies (FRA)

2013 – 1st Place Hogtoberfest Slide Competition (UK)

2013 – 1st Place Dangerous Decks Mini-Moto Challenge at Hogtoberfest "

Top notch results Joe - hopefully our ceramic bearings will only add to the speed-demon reputation you're already building!  We look forward to bringing you more news from Joe as the 2014 season progresses.

Aaron Skippings, downhill skater update...

Our friend & SMB skate-crew member Aaron Skipping has already had a hectic start to his downhill skating season.  Aaron is competing using our ceramic hybrid skate bearings this year & it sounds like he's getting pretty impressive results with them.

Aaron says:
"I am in love with the ceramic bearings! Sooooooooooo fast!  I've been really busy lately with my skating! Just been in Belgium for the championships and did really well - I had 7 qualifying races to determine a position and I never finished below a 3rd place.   Unfortunately, because of time pressures they cut it down to 16 people bracket for the semi-finals so i didn't qualify!! Bit lame but hey, I had fun and the UK kicked ass in Belgium! 

I also just booked my flight to California for September!!! Exciting! I will be doing the Angies Curves in California and the famous Pikes Peak in Colorado! 2 of the gnarliest races on the IDF World Cup tour!  Too excited!!!"

Thanks for the update Aaron, it sounds like you were robbed in Belgium, but we're sure you'll make up for it during your US invasion later this year!  We can't wait to bring you more updates from Aaron as the downhill skating season progresses...

SMB Ceramic bearings...

Just a little update on the full ceramic (ceramic rings & balls) & hybrid ceramic (steel rings & ceramic balls) bearings that we currently have in stock.  Please just call us (01993 842555) or email (sales@smbbearings.com) if you'd like to make a purchase or just need some more information/advice...

Full Ceramic:



Full ceramic bearing ZR02 (Zirconia rings & balls/PTFE cage)

Zirconia ZR02 bearings

CC6000 ZRO2 - full ceramic bearing/PTFE cage, dimensions 10x26x8mm

CC608 ZRO2 - full ceramic bearing/PTFE cage, dimensions 8x22x7mm

CC626 ZRO2 - full ceramic bearing/PTFE cage, dimensions 6x19x6mm

Full ceramic bearing Si3N4
(silicon nitride rings & balls/PTFE cage or full complement)

Silicon Nitride Si3N4 bearings

CC608 Si3N4 F/B - full ceramic bearing/full ball complement, dimensions 8x22x7mm

CC6806 Si3N4 F/B - full ceramic bearing/full ball complement, dimensions 30x42x7mm

CC687 Si3N4 F/B - full ceramic bearing/full ball complement, dimensions 7x14x3.5mm

CC689 Si3N4 F/B - full ceramic bearing/full ball complement, dimensions 9x17x4mm

CC6806 Si3N4 F/B - full ceramic bearing/full ball complement, dimensions 30x42x7mm



Hybrid ceramic bearing- steel/stainless steel rings & ceramic balls)

Hybrid ceramic bearings
Our famous skate bearings - CB608TW-2RU P5 - chrome rings & ceramic balls, rubber seals, dimensions 8x16x5mm - buy these direct from our EBAY SKATE SHOP.

SCB6002 - stainless steel rings & ceramic balls, dimensions 15x32x.9mm
SCB626 - stainless steel rings & ceramic balls, dimensions 6x19x6mm
SCB6801 - stainless steel rings & ceramic balls, dimensions 12x21x5mm
SCB6807 - stainless steel rings & ceramic balls, dimensions 35x47x7mm
SCB6810 - stainless steel rings & ceramic balls, dimensions 50x65x7mm
SCB6902 - stainless steel rings & ceramic balls, dimensions 15x28x7mm
SCBR144TWZW09 - stainless steel rings & ceramic balls, one metal shield, dimensions 0.1250x0.2500x0.1094"


We can order other sizes in from the factory for you, so please contact us if you need any further information or advice.

Some notes on CERAMICS...

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.

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 PTFE or PEEK retainers or be supplied as full complement type.

Hybrid bearings (CB/SCB prefix) 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 which can can cause the raceways to wear faster. The speed increase for hybrid bearings is approximately 30-40 percent with adequate lubrication. Hybrid bearings can also operate better with limited lubrication but running speed should be reduced. Hybrid bearings are also less subject to ball skidding under inital acceleration.

All-ceramic bearings (CC prefix) 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

The limiting speeds for all-ceramic bearings 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 but generally, shock loads should be avoided. Using ceramic bearings on steel shafts at high temperature can cause bearing damage due to the large difference in expansion coefficient. For more information see Shaft/Housing Fit


WARNING: Hybrid bearings can offer very low frictional torque 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 lower quality hybrid bearing can have much higher friction levels and a lower maximum speed than a good quality all-steel bearing... 

Any questions?  Please feel free to contact us for further assistance!



SMB Bearings review from Aaron Skippings, downhill skater...

Thanks so much to Aaron Skippings for his fantastic review of our products - it's always great to hear that our bearings are a real help to competitive skaters, gravity sports exponents, cyclists & more.  Here's what Aaron had to say:




Skate Bearing



Ceramic hybrid skate bearing



"SMB Bearings are an awesome bearing company from Brize Norton in the UK , these guys have been hooking me up with bearings for skating use , in the picture above on the left is a standard skate bearing from smb and on the right is the ceramic version . As soon as i used these i knew i liked them , they run super smooth and dont make noises or rattles . The bearings are also pretty good at holding the water out if you decide to ride in wet conditions.  I took a few sets of these bearings away with me on the euro tour, i wanted something decent for the world cup races and smb showed me the way. The ceramic versions i especially love as the smoothness of the bearing is at a super high level , no noises and no nonsense from smb again. its hard to say if there is a speed difference between the ceramic and the standard either way i couldnt tell but you know the quality is much higher in ceramics.There super kool bunch of guys have definatly created a brilliant bearing and i hope that other skaters from the uk and even global try these bad boys out , because i gurantee once these bearings are in your wheels ,you'll be riding faster!
Aaron"


Thanks so much for the high praise Aaron - we've put a lot of work into finding the best quality, genuine skate bearings around - we've lots of technical info on them at our website & we also tell you how to care & maintain your bearings for the best performance.

To keep up-to-date with Aaron, check out his blog & of course we'll update you when we have news of his latest exploits to share :0)

Downhill Skateboarding, Street Luge & "Team For Ride"...

Meet "Team For Ride"

We are delighted to be involved with this awesomely diverse French downhill skateboarding & street luge team & would like to introduce them, & gravity sports, to you.  The team compete in a broad range of gravity sports, which we try & explain to the dazed & confused amongst you below...

The team members are:

Fabien Prual - riding streetluge and classic luge in competition but also riding skate in slalom, cruising carving ... (2009: #11 in streetluge / #16 in classic luge)

Thibaut Meline - riding streetluge and classic luge in competition and riding skate in cruising (2009: #15 in streetluge / #17 in classic luge)

Quentin Drouault riding - downhill skateboard in competition and also riding in carving and cruising (2009: #146 in stand up)

Phillipe Dupuy - riding downhill skateboard in competition for the first year and also riding in carving and cruising.

Marie Bougourd - the lady of the team, riding downhill skateboard and classic luge and also riding in slalom, carving and cruising. She is a serious opponent on the girl's competitions...

What is Downhill Skateboarding?

Downhill Skateboard riders stand on long skateboards designed for stability and speed, and assume an aerodynamic position to achieve great speeds. Probably the most spectacular of the sports, it offers great spectating especially through corners.

What is Slalom Skateboard?

Slalom Skateboard involves being the fastest to skate through a set course of cones. The cones are set up in a straight line at a set distance (tight slalom) or spread across the width of the road at random intervals (giant slalom). Knocking down cones results in penalties or disqualification.

What is Classic Luge?

The Classic Luge, or Buttboard, is the low-tech brother to Street Luge. Still a form of skateboard on which you lie, the Buttboard is shorter, narrower, uses smaller wheels and has to be made from a single piece of plywood. While not as fast or high performance as Street Luge the Classic is great fun, requires a lot of skill and due to very low costs is a great entry point for beginners.

What is Street Luge?
 
Street luge was born in Southern California as downhill skateboarders found they could reach faster speeds by lying down on their skateboards. This early form of the sport is now referred to as "classic style" or "butt boarding."

In 1975, the first professional race was held at Signal Hill, California and hosted by the U.S. Skateboard Association. The race winner was based on top speed. The boards used in this race varied from basic skateboards to complex skate cars in which the rider was completely enclosed by plastic or fiberglass. The sport was not commonly referred to as street luge at this time but the term luge was used to describe some participants riding position, lying supine on their boards.  many riders chose to stand & injuries were commonplace so safety rules & equipment continued to be implemented throughout the 1980's - 1990's.  In the early 1990s, some Austrian skateboarders started sitting down on their skateboards on the way back from teaching skiing in the Alps. This activity lead to a classic style street luge race in Austria, riding wooden boards closer to large skateboards than the usual street luge, which is heavier, longer, has larger wheels and more trucks than a skateboard or classic luge. There is now a healthy street luge riding and racing presence in many European countries & over 1200+ active street luge riders in the world. Current street luge stretchers are made from many materials including steel, aluminum, wood, and carbon fibre.

The majority of the street luge stretchers in the world are custom made although commercial models are now available. Actual stretchers designs can vary as the construction rules are very open and allow for numerous design considerations.

Competing in Downhill & Streetluge...

Riders participating in sanctioned racing events are required to wear safety equipment including:

1.Hard shell helmet with chin strap and face shield or goggles

2.Leather or Kevlar racing suit

3.Leather or Kevlar gloves

4.Sturdy Shoes

Race courses are usually held on mountain roads but have been held on city streets as well. Courses can range in length from 0.5 to 3 miles (1 to 5 km) and vary in layout (number and severity of turns). Racing can take the following formats:

1.Single elimination with 2, 4, or 6 racers at a time

2.Double elimination with 2, 4, or 6 racers at a time

3.Timed trials

4.No elimination points system (points for each finishing position in several heats)

5.Mass runs, with up to 20 racers at a time (positions are decided by the order they cross the finish line)

For more information on streetluge, downhill skateboarding & an impressive range of other (slightly madcap) sports in the UK, visit http://www.ukgsa.org/ UK Gravity Sports Association.

****

Team For Ride are using our ceramic hybrid bearings (metal rings, ceramic balls & a high-speed plastic cage) & have found them, to quote Fabien "My feeling: GREAT!

No sensation of resistive torque while I was pushing, great acceleration... I didn't test it on the fastest spot I know, but just on this one I was around 85km/h and feeling great, I don't think that will be this bearing that will slow me down...to give you some idea of the speed we are going and the efforts the bearings are subject to, Phillipe had been officialy recorded over 94 km/h but the three skaters of the team had rode over 95km/h

and the two lugers, Thibaut and me had rode over 125 km/h and I'd like to break the 125 on classic luge wich has never been done officialy."

Quentin is pictured above, competing in a downhill race.  He won the Boarder X race at Lyon last weekend with the aid of our bearings - congratulations Quentin & to all in Team For Ride!

Full Ceramic Bearings are here...

We are very excited... We've been talking about it for ages, but now they're actually here...

Our first two sizes of full ceramic bearings have just been delivered - HOORAY!!!!!!!!!

We are now the proud owners of 608 (8x22x7mm) & 626 (6x19x6mm) bearings - they're ideal for situations where you need amazing resistance to chemical corrosion, marine applications (salt-water can't touch these puppies!), applications that require completely non-magnetic bearings or electrically insulated bearings. They are composed of Zirconia rings & balls & have a hardwearing PEEK cage, see below:



They're not so good for high speeds or loads, any kind of shock loads (they're too brittle) or any temperature over 260 degrees centigrade - but that's high enough for most of us to get a decent tan ;0) . For those of your who need additional temperature ranges, we can order in full-complement bearings to cope with temperatures in excess of 800 degrees centigrade. We'll hopefully be introducing a wider range in the next few months, together with some hybrid ceramic bearings (steel rings & ceramic ball) for applications requiring higher speeds & loads.

Watch this space!

****

Mach1 Team - F1 in Schools Regional Champions...

Our hearty congratulations to Mach1 Team from Lutterworth College, who at yesterday's regional finals qualified for the National F1 in Schools Championship final being held at Birmingham's NEC, during the Autosport International Show, in January 2010.


Mach1 celebrated a trio of trophies, taking overall victory in the Formula 1 class, as well as taking awards for the Fastest F1 car(1.289 seconds) and Best Engineered car.

Pictured below are Johnny, Elliot, our very own Chris in the middle, Alex & Ricky. Chris joined the talented quartet for race-day at the NEC, to offer whatever technical assistance & general encouragement he could (& to get to play with lots of cars...).

The cars, designed by students aged between 9-19 race along a 20 metre track, shown below, at speeds in excess of 60Kph...

Teams are judged on car speed, as well as supporting evidence of their design, verbal presentation and marketing display stand in ‘‘the pits”. The Mach1 team's pit was very impressive & made great use of all the materials they had gleaned from their sponsors, including SMB Bearings.

The victorious Mach1 can't rest easy though, as preparation must begin in earnest for the national finals, now only 8 weeks away.

We'll be working hard for the team too & are looking for ways to improve our bearing performance as much as possible to achieve an ultra free-running, high speed finish. We've already treated previous bearings with Diamond Nanolube & are now looking again at this option, compared to results achieved by coating bearings with a Molybdenum disulfide suspension. Both substances act as thousands of tiny particles, suspended in a carrier oil, coat the surfaces of the bearing & float between the metal parts of the bearing to keep surfaces apart (it will still work even if the carrier oil is gone):

• preventing metal to metal contact
• prolonging bearing life
• reducing friction
• preventing galling, gouging & scoring
• preventing heat build-up

We're not sure ourselves yet whether there will be any advantage between the two different methods for this application, but we'll do our best to find out very soon.

We'll also be investigating the benefits provided by ceramic hybrid bearings (ceramic balls, metal cage, rings & shields). The speed increase for hybrid bearings is, on paper at least, approximately 30 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.

A word or two of caution - ceramic hybrids have become something of a fashion "fad" in recent times, with many Chinese hybrids flooding the market. These bearings are often of a poor quality & do not deliver on a theoretical promise to reduce friction & increase speed. For Mach1, we'll be trying to deliver on the theoretical promise by sourcing Japanese ceramic balls for their bearings... watch this space ;0).

Online store in development...

In response to your demands for an online store, we're currently in the process of building one for you! We plan to make available online a range of our hobby bearings & also a new range of ceramic hybrid bearings, for those of you wanting to go to the next level in performance terms.

We'd love to hear from you, to let us know exactly what you'd like to see for sale online, so please do get in touch. For example, as well as our range of hobby bearings we're also thinking of including a range of lubricants (that you'd normally have to buy by the barrel-load) to help you maintain your bearings, skate t-shirts & decals etc...

Never fear! For those of you who need a bit of extra help, technical information or something listed in our catalogue that you can't see for sale online, we'll still be available via ye olde telephone or email ;0).

We have over 2000 different items in stock in our UK warehouse at any one time & we only plan to list about 200-250 sizes at this stage, to see how you like them. We look forward to hearing what you think about it all & what you'd like to see online.

Watch this space for updates!

***

RC Helicopter Fishing

Yes really! This guy manages to combine two of our favourite activities in one!

Watch in wonder & awe...

We are in the process of sourcing some top-notch Japanese ceramic hybrid bearings, for our RC model & hobby nuts, so watch this space & we'll let you know when the lovelies arrive...

RC Model Bearings

We can offer high precision, smooth-running, noise & vibration tested replacement bearings for all type of RC models.




We can also offer a bespoke re-lubrication service, to get the absolute maximum RPM from your RC model bearings.



We are currently researching ceramic hybrid bearings (ceramic balls held in a steel bearing) for RC models; we'd be interested to know what you think of hybrid bearings' performance in your model - are they living up to the hype? Do let us know, we'd love to hear your comments.

RC enthusiasts, check out this video on YouTube:
http://www.youtube.com/watch?v=aCByYDwt5vE
We've not seen one that big before, ooh-er missus!!

Bearing materials

What materials are used for our bearings?


SAE52100 Chrome Steel (no prefix)

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 a protective oil coating on the exterior surfaces 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.

AISI440 and KS440/ACD34/X65Cr13 Martensitic Stainless Steel (prefix "S")
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. The load capacity of 440 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 and superior low noise qualities to the standard AISI440C grade. Corrosion resistance can be increased by passivation (see section below). The 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")
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 main problem here is that 316 grade stainless steel is non hardenable, therefore as a softer steel, it 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.

Plastic - acetal resin (prefix "AC") Bearings made from acetal resin with balls made from 316 stainless steel or glass are more corrosion resistant. They will however, corrode in the prescence of certain chemicals for which made-to-order polyethylene or polypropylene bearings with glass balls may be a better choice. These are generally termed as "plastic" bearings and like 316 stainless steel bearings, are not suitable for anything other than low loads and low speeds and should not be used in temperatures of greater than 90C. These types are also low precision so not suitable for instrument use. The smaller bearings are not usually available in these synthetic materials.

Ceramics - Silicon Nitride (prefix "CB" or "CC")
Some types may be available with steel rings and ceramic balls (hybrid) or "all ceramic" bearings with ceramic rings and balls. These types may not be stock items and could be subject to minimum order quantities. There are many advantages to silicon nitride such as a lower friction coefficient, much greater hardness and temperature resistance. Silicon nitride has 40 percent of the density of bearing steel but is about twice as hard. The lower density means that the balls exert less force on the outer raceways reducing wear while the extra hardness means greater wear resistance. Some ceramic materials such as Zirconia or Alumina are heavier and not as suitable for hybrid bearings although they can be used in full ceramic bearings. Hybrid bearings are also capable of higher speeds (usually up to 30 percent) and can also operate better with limited lubrication as the lower friction material generates less heat. However, ceramic bearings can be significantly more expensive, particularly "all ceramic" bearings partly due to the material and partly due to very low production quantities. The cost may be prohibitive for some sizes or quantities.
WARNING: Ceramics are often overrated particularly hybrid bearings.It is often thought that they will provide incredibly high speeds which is not correct unless you use special retainers or no retainer and the bearing still needs to be high quality. Customers often expect very low frictional torque with low noise and vibration levels. 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. There are many cheap hybrid bearings on the market that do a worse job than a good quality bearing with steel balls. Good hybrid bearings often prove too expensive for an application. Most sizes are made to order.

For further information, see cerbec's comments at
http://www.cerbec.saint-gobain.com/HybridBearing/Hybrid.asp
Click on the following for a compatibility check for several different materials and chemicals:
http://www.coleparmer.com/techinfo/ChemComp.asp