Ring types & materials

• a.
  Flanged Outer Rings: It is always desirable to produce a through bore which ensures good bearing alignment and reduces production time. A flanged outer ring enables the bearings to be located on the face of the housing.
• b.
  Extending the inner ring width allows the bearing to be located axially using the inner ring faces while giving clearance for the outer ring to rotate.
• c.
  Unless specified generally SAE 52100 chrome steel is used.
• d.
  If the designation “SS” is used then X65 Cr13 is supplied as good corrosion resistant steel.
• e.
  X30 Cr Mo N15-1 is suggested for applications where high corrosion resistance is required. With GRW’s extensive experience they have developed their own heat treatment methods to ensure the optimum benefits of this material. Due to it’s fine grain structure a better surface finish is achieved which ensures quieter running.

Ball materials

In almost all cases the balls are made from X65Cr13 stainless steel, when a hybrid bearing is required Si3N4 silicon nitride balls are used in conjunction with steel rings.

Shields & seals

• a.
  Shields are non-contacting covers, usually stamped from thin sheet corrosion resistant steel or moulded from rubber with the addition of a metal stiffener; they are either pressed into the outer ring or fixed by a circlip. There is a small amount of clearance between the inner ring of the bearing and the bore of the shield, thus contaminants are prevented from entering the bearing and lubrication is retained. Shields neither increase the torque nor influence the maximum speed in comparison to an unshielded bearing.
• b.
  To produce an effective seal contact must be made between the seal edge and the inner ring. Seals are generally manufactured from rubber or Teflon, there are limits on temperature range and speed, torque will also be increased.
• c.
  GRW have the ability to design and manufacture special closures should the need arise.

Retainer types & materials

Retainers or cages perform a number of functions:

• Ball separation.
• Ball retention.
• Lubrication reservoir.

The “J” two-piece, clinched ribbon retainer is the most popular and is suitable in most applications. If your application requires something more, give us the details and we will suggest the optimal design for you.

Lubrications

In most cases, open bearings are oiled and shielded or sealed bearings are greased with a standard lubrication such as:

• Aeroshell Fluid 12    -40 to 100C
• Longtime PD2         -35 to 140C

It is very important to select the correct lubrication for the application, as the life of the lubrication may also be the life of the bearing. The operating criteria for the application must be considered to ensure that the best lubricant is used. We have an extensive list of over 250 oils and greases to choose from.

Our ball bearings when lubricated at the manufacturer have a tightly controlled dose according to the bearing size; in some cases the amount of oil or grease is reduced to lower the torque or to lower the risk of contamination.

What is ‘GPR’?

You may have seen this in the bearing reference and wondered what it means. This is a noise test which all GRW bearings and a selection of their associate supplier’s bearings are subjected to, it analyses the quality of the balls rolling in the raceway and the data produced can show issues such as poor raceway finish and geometrical errors, this ensures your bearings are to the exacting standards that you deserve.

Bearing assemblies

Around 30 to 40% of GRW’s business is ball bearing assemblies manufactured to their customer’s specific needs, this means that the customer only gets assemblies and sub-assemblies that are to specification. Goodbye to the hassle from sub-suppliers and hello to assemblies that are consistent and work every time.

GRW take the care to select the right sub-suppliers so that their parts are manufactured with the same precision as their bearings, they have the quality procedures to ensure that components for assemblies are up to the highest standard. Their vast experience with adhesives and assembly techniques is second to none.

Special bearings

• High temperature or very low temperature.
• High corrosion resistance, for instanceagainst blood, salt, or chemicals.
• High speed.
• High sensitivity, possibly at low speed.
• Vacuum or space applications.
• Special profiles.
• What else do you require?

GRW has many years of experience in all these areas. High quality Application Engineering and careful design with attention to detail is the key to success. Give us a try.

Duplex bearings

If you require little or zero play in your bearing assembly then duplexing could be the solution. To create a duplexed pair of bearings; each individual bearing is axially loaded to a desired pre-load, the offset of the ring face is measured, the bearings are dismantled and the ring faces are ground to remove the offset.

Back to Back
Stiffer assembly

Face to Face
Allows slight
miss-alignment

Tandem
Almost double axial load

The benefits:

• Accurate positioning, without play.
• Controlled rigidity of the assembly.
• Higher load capacity.
• Overall better performance and longer life.

Quality

• GRW have an ultra modern manufacturing facility that ensures the highest quality and consistency that is needed to produce the very best precision bearings.
• Qualified to EN ISO 9001/2000.
• Full traceability that can include material certification if required.
• Bearings are offered from ABEC1 (P0) through to ABEC9 (P2) and in some special cases better.

Bearing types

Deep groove radial ball bearings:

• Mostly miniature and instrument sizes though larger sizes are available.
• Both in metric and imperial sizes:
  Standard production range with bores from 1mm to 25mm and outside diameters of 3mm to 40mm in some cases larger.
• A wide range of shields and seals.
• In most cases available with a flange.
• Lubrication to meet the most arduous conditions.

Angular Contact / Spindle Bearings:

• Metric sizes from 3mm to 20mm bore. Possibly larger upon request.
• Full compliment cageless options for high speed / high loads.

Thin Section Bearings:

These are also available from an associate company up to 12 inches in diameter in radial, angular contact and 4-point contact options.

Handling precision bearings

A ball race is a precision instrument that has been manufactured under highly controlled conditions. To ensure you get the maximum benefit from your bearings please follow the simple procedures below:

1. Keep bearings in a CLEAN, DRY sealed container in their original packing until ready for use.
2. Work in a CLEAN, DRY dust free environment i.e. sweep the bench and work on a CLEAN sheet of plastic or dust free non-absorbent paper as a minimum.
3. Avoid contamination from fingers; latex gloves should be used when handling bearings or their mating parts.
4. Mating components and tools should be clean and burr free, your bearings are only as good as the mating components, out of round or high interference fits will deform the bearing rings.
5. Sub-assemblies should be kept in a clean environment and covered when not in use.
6. When fitting bearings with an interference fit ensure the load is applied to the mating ring NOT THROUGH THE BALLS.
7. ADHESIVES HAVE CAUSED THE PREMATURE FAILURE OF MANY BEARINGS. Keep the quantity to a minimum, wipe away any excess with a LINT FREE cloth or “bud”, remember the adhesive will be pushed towards the face of the bearing when inserting into the housing or onto the shaft.
8. EXTRA CARE WITH OPEN UNSHIELDED BEARINGS as contamination such as hair and skin can fall directly into the raceways.

We at Principle Engineering understand that it is not always possible to work in perfect conditions, that is why we hope these minimum standards will help you get the best results every time. If we can be of further assistance in the design or application please give us a call or contact us.