The words of an NTN-SNR expert:
For easier mounting and to avoid contact corrosion of the shaft or the housing, always use an anti-fretting paste. This thick lubricant helps preserve the quality of parts surfaces subjected to sliding forces. Without this paste, corrosion will gradually increase the play between the bearing and the shaft (or housing), ultimately causing vibration and even the premature deterioration of the bearing and its mounting surfaces. Avoid introducing contaminants when mounting (swarf, liquid, etc.).
What is cold mounting?
Cold mounting is the simplest method and is suitable for small and medium-sized bearings, completed with the normal adjustments.
The most frequently observed problems:
1st rule: The ring that rotates in relation to the load must be tightly mounted on its seat.
Load fixed in relation to the outer ring.
Load fixed in relation to the inner ring. Outer ring tightened into its housing.
2nd rule: Mounting is carried out using impact rings applied to the bearing ring which has the tightest fit. This avoids stressing the rotating body and damaging the bearing.
Special case of a long shaft for an assembly requiring a longitudinal adjustment of the bearing: it is preferable touse a mechanical coupling with a tapered seat joined to a bearing with a tapered bore.
What is hot mounting?
The words of an NTN-SNR expert
Use of anti-fretting paste facilitates insertion and protects the shaft or housing from contact corrosion
The wearing of heat insulating gloves is necessary for the safe and comfortable handling of the heated parts.
In the case of heavy bearings, help will be required for their handling.
Principle of heating by induction
The device comprises a steel framework surrounded by a coil with a large number of windings. When a current passes through it, this primary coil generates a magnetic field which itself induces an electric current in the bearing (or other steel part), substituted for the secondary coil of an electrical transformer. When a high-intensity, low-voltage AC current passes through it, the bearing heats up quickly while non-metallic parts and the device itself remain cool. Induction heating magnetises the bearing. It is therefore necessary for the heater to demagnetise it at the end of the heating cycle. This avoids steel particles being attracted into the bearing later on.
What is hydraulic mounting ?
The mounting of large bearings with a tapered bore requires considerable effort, difficult to achieve using mechanical screw tightening. The use of hydraulic technology is required in such cases.
Two types of mounting lend themselves to this method:
Tapered seat shafts
Disassemble cleanly: Look after your equipment and save time, safely!
By opting for the correct methods and tools, you reduce the risk of personal injury and damaging parts (shaft, housing, even the bearing, if it is to be re-used).
Find out the NTN-SNR maintenance tools offer:
What is mechanical dismounting?
So far as is possible, the best way is to extract the bearing with the ring held firm.
NTN-SNR offers a comprehensive range of extractors easy to use robust and safe to be chosen depending on the grip offered by the bearing, its accessibility and the extraction force required. Extractors equipped with a pump and hydraulic cylinder allow the operator to develop very high extraction efforts, using his own muscular strength. They are easy to use, due to the fact that their arms are self-centering. If hydraulic channels were originally provided in the shaft, the injection of a film of oil on the contact surface between the shaft and the inner ring greatly reduces the effort required.
The right questions to ask:
How do I grip the part? Selection of the type of grip: external, internal or special
What is the diameter of the part to be extracted? Enables the seat, spread and force to be defined.
How do I pull on the part? Choice of a support point: on the central shaft, on the outside of the part or using extraction accessories.
What is hydraulic dismounting?
When the dimensions of mechanical parts are large, and it is necessary to use high efforts for extraction, it is better to choose hydraulic techniques.
The NTN-SNR hydraulic nut is an ideal tool for a quick and easy dismounting of bearings mounted on the adapter or withdrawal sleeve.
Bearing Mounting Surfaces
Any burrs, cutting chips, rust or dirt should first be removed from the bearing mounting surfaces. Installation can then be simplified if the clean surfaces are lubricated with spindle oil.
Burrs, dirt, and other contaminants that infiltrate the bearing before and during mounting will cause noise and vibration during subsequent operation.
Ensure that all pressing blocks, driving plates, hammers and other mounting devices are clean, free of burrs, and of the correct size
Do not Unwrap Bearings until just prior to Mounting
Do not make any modifications to the products
Bearings are manufactured to very tight tolerances in order to meet extremely high accuracy requirements. Therefore, it is imperative to take special precautions with regard to their handling.
Mounting Procedures and Examples of Damage
Furthermore, the maximum static load that bearings can withstand is shown in the NTN catalog as the bearing's “basic static load rating.” This is the maximum amount of force which can be applied to the central contact area between rolling elements and raceway surfaces. If exceeded, total permanent deformation exceeding 1/10,000 of the bore diameter will result, and smooth bearing rotation will be impaired. This is the basis for establishing the basic static load ratings.
★ Mounting bearings using a hammer causes damage due to sharp impacts. Please mount press fit bearings using a pressing arbor or other designed to provide a uniform face.
Bearings are very susceptible to impacts and shock loads!
Bearings carry their loads along an extremely narrow contact surface between the rolling elements and the inner and outer raceway surfaces. If an excessive load or impact is applied to this narrow area of contact, brinelling and/or scarring will occur. This damage leads to objectionable noise and vibration levels and rough bearing rotation. (Even dropping bearings on the floor will cause this type of damage.
Bearings are very susceptible to foreign particle contamination!
If foreign particles infiltrate the bearing during rotation, denting and/or scarring will occur and this will lead to poor bearing rotation and excess noise.
Temperature Mounting (Heat expansion of inner ring to ease installation.
Commonly used for large bearings and bearings with a heavy interference fit.
Observe these precautions when heating bearings
Other heating methods