Gamet BearingsExclusive North American distributor for Gamet Bearing.

Gamet Technical Information

This information is provided courtesy and permission of Gamet Bearing. All rights are reserved.

1. Preparation & mounting information of Gamet bearings

After inspection Gamet’s bearings are treated with a corrosion preventative oil, (except pre-greased bearings). Initial packaging is heavy gauge PVC bags, which are heat sealed, and boxed. Bearings can be stored for long periods providing packaging is not damaged and the storage area is dry and not subject to extremes of temperature.

Mounting should be undertaken in clean, dry, dust free conditions away from metal working or other operations producing swarf or dust. It is recommended that drawings and instructions are studied to determine the correct order of assembly. All necessary parts, tools and equipment should be available before commencing.

Each component of the spindle arrangement (housing, shaft etc.) must be carefully cleaned and checked for burrs. Dimensional and form accuracy of all components in contact with the bearings should be checked as optimum bearing performance can only be achieved if the prescribed tolerances are adhered to.

Bearings should remain in the original packaging for as long as possible prior to fitting to prevent the risk of contamination.

Whenever possible, bearings should be mounted onto the shaft in vertical position. It is very important that the correct method of mounting is chosen and that suitable equipment is used.

The inner races (cones) of the bearings must be preheated to expand sufficiently to assist mounting on shaft. Never attempt to fit cold as the amount of interference between cones and shaft will prevent sliding and any direct blows will cause damage to rolling elements and raceways. Heating can be achieved using induction heaters, ideal for grease lubricated bearings, or oil baths suitable for oil lubricated bearings. Under no circumstances should a pre-greased bearing be heated by submersing in oil as contamination of grease will occur. The temperature required to sufficiently expand cones to allow reasonable mounting time varies depending upon size and section, but 70ºC will suffice for the majority of applications. Care must be taken when locking bearings to ensure all rolling elements are seated properly, this is achieved by rotating at periodic intervals during locking. For specific advice contact Gamet Bearings.

2. Gamet lubrication

Bearings must be correctly lubricated to reduce friction between the rolling elements and raceways. Lubrication will minimize wear and protect bearing surfaces against corrosion. The choice of a suitable lubricant and method of lubrication is very important and depends upon the operating conditions (temperature, range, speeds, loads, environment). A wide variety of greases and oils is available offering solutions for all applications.

Oil

Oil lubrication is normally used where higher operating speeds are required as this offers more efficient heat dissipation.

The selection of a suitable viscosity grade is important to optimize the life and performance of bearings and adjacent components.

Filtration is strongly recommended as contaminated oil will have an adverse effect on bearing life and performance.

Regular inspection of oil and filters is advised and changes made when necessary.

Catalogue speed ratings are based on the use of oil lubrication

Grease

Grease lubrication offers a simplified and cost effective option as the lubricant is more easily retained within the bearing. It also eliminates the need for complicated and costly lubrication delivery and drainage systems.

Sealing of the bearings is important to eliminate the possibility of contaminant ingress and to retain the grease within the bearing structure.

Bearing speed ratings may reduce with grease lubrication. If you plan to use greased bearings, advice on maximum speeds can be obtained from Gamet’s engineering department.

Precision RPM offers a service of supplying bearings pre-greased to suit your requirements.

Running in

After installation bearings require a running-in phase to condition and match mating surfaces, this will ensure optimum performance.This is more critical when using grease lubrication as sufficient time is required to disperse and evenly distribute the lubricant within the bearing. If this is neglected, temperatures can rise rapidly causing localized overheating and lubricant break-down which can lead to premature bearing failure or inferior spindle performance.

Precision RPM offers advice relating to specific applications.

3. Component parts of a Gamet tapered roller bearing

Gamet bearings consist of four basic components – the inner race (cone), the outer race (cup), tapered rollers and cage. The cone, rollers and cage form an assembly which is separable from the cup

Principals of Gamet tapered roller bearings

The geometry of tapered roller bearings provides certain unique features: most importantly, the long line contact between roller and race gives high load carrying capacity and high bearing stiffness. The ‘on apex’ design ensures a true rolling motion of the rollers on the raceways, at every point along the roller body. See Fig 1. In addition, the tapered construction allows the bearing to carry combinations of radial and thrust load. The small seating force (x) produced at the rib aligns the rollers to prevent skewing. See Fig 2.

On-apex design results in true rolling motion at all points along the roller body

Fig 1: On-apex design results in true rolling motion at all points along the roller body.

Small seating force from the inner race rib keeps rollers aligned on the raceway

Fig 2: Small seating force from the inner race rib keeps rollers aligned on the raceway.

Other specific features of Gamet tapered roller bearings include:

Precision – Gamet bearings are manufactured only in a high precision class.

Hollow rollers – This assists the flow of lubricant through the bearing to provide cooling.

Roller roundness and calibration – A true roundness of rollers ensures equal load sharing within the bearing and contributes significantly to the overall precision of the bearings. Gamet Rollers are ground between centers to achieve near perfect roundness. Rollers are then calibrated precisely into matched sets.

Bearing cage – The cage has a low coefficient of friction. It is guided on the inner race to provide radial stability and is designed to pass sufficient oil across the races to maintain lubrication, the remainder being diverted through the center of the roller. Depending on rotational speed, grease lubrication may be used as an alternative to oil.

4. Gamet bearing tolerances

Shaft O.D. Tolerance
Bearing Bore (mm) from toBearing Bore Tolerance (µm)Shaft OD Tolerance (µm)Resultant Fit (µm) T = Tight
25
180
0
+5
+15
+10
15T
5T
+180
506
0
+10
+25
+15
25T
5T
Housing Bore Tolerance – Plain & C Type
Bearing OD (mm)
from
to
Bearing OD Tolerance (µm)Housing Bore Tolerance (µm)Resultant Fit (µm)
T = Tight
52
260
+5
0
-15
-5
20T
5T
+260
636
+10
0
-15
-5
25T
5T
Housing Bore Tolerance – H, G and P Type
Bearing OD (mm)
from
to
Bearing OD Tolerance (µm)Housing Bore Tolerance (µm)Resultant Fit (µm)
L = Loose
52
260
+5
0
+10
+20
5L
20L
+260
636
+10
0
+15
+25
5L
25L
Assembled Bearing Maximum Runouts
Bearing Bore (mm)
from
to
A Inner Ring (µm)B Outer Ring (µm)C Face Camming (µm)
25
180
1,53,03,0
+180
506
4,06,08,0

Fitting
Fig 3: Fitting