FAG Bearing Mounting and Dismounting: Tools, Steps, and Mistakes That Shorten Service Life

Before mounting an FAG bearing, check that the shaft and housing are clean, free of burrs and marks. Any foreign particle can damage the raceways or rolling elements. Also verify that the seat dimensions are correct according to the manufacturer's catalog. A fit that is too tight or too loose compromises operation.

Check the condition of the new bearing: no impacts, corrosion, or dirt. If it comes pre-greased from the factory, do not wash it unless expressly indicated. For bearings with a tapered bore, such as those mounted on adapter sleeves, prepare the sleeve and the lock nut. Have the appropriate mounting tools at hand.

The work environment also matters: avoid drafts with dust and keep the area tidy. If you are going to heat the bearing for mounting, use an induction heater or an oil bath with controlled temperature. Never heat with a direct torch, because you can alter the heat treatment of the steel.

To mount FAG bearings without damaging them, use tools that apply force only on the ring with the fit. If the fit is on the shaft, push the inner ring; if it is in the housing, push the outer ring. Mounting sleeves and impact tubes are useful for small bearings. For medium and large bearings, a press or an induction heater is preferable.

For bearings with a tapered bore mounted on an adapter sleeve, you need a lock nut wrench and a gauge to measure radial clearance. Mounting is done by advancing the bearing onto the sleeve until the specified clearance reduction is achieved. For this, feeler gauges and a radial clearance gauge are used.

Hydraulic pullers are the best option for dismounting large bearings without damaging the shaft. There are also heating plates and infrared thermometers to control temperature. At MR we advise you on which tool is suitable for each FAG bearing.

Cold mounting is used for small bearings with a not very tight fit. A uniform mounting force is applied to the ring with the fit, using an impact tube or a press. Never hit the bearing directly with a hammer, because you can mark the raceways and generate premature vibrations.

For deep groove ball bearings such as 6003 or 6020, cold mounting is usually sufficient if the fit is light. If the fit is firmer, it is better to heat the bearing to expand it so it fits easily. Remember that the inner ring must be well seated against the shaft shoulder.

A common mistake is applying force to the wrong ring: if you push the outer ring when the fit is on the shaft, the balls get marked against the raceways. That reduces bearing service life. Therefore, always identify which ring has the fit and use the appropriate tool to push it.

Hot mounting is used when the fit is tighter or the bearing is large. The bearing is heated to a controlled temperature so that the bore expands and fits onto the shaft without effort. The safest way is with an induction heater, which heats evenly and without flame.

You can also use an oil bath with a thermometer, making sure the bearing does not touch the hot bottom. Never use a direct torch, because uneven heating can deform the bearing. The maximum temperature depends on the heat treatment of the steel, so it is advisable to consult the manufacturer's data sheet.

After heating, mount the bearing quickly and let it cool before applying load. Verify that it is well seated against the shoulder. For bearings with a tapered bore, heating is not used; they are mounted cold by advancing onto the sleeve and measuring radial clearance.

To dismount an FAG bearing without damaging the shaft or housing, use mechanical or hydraulic pullers. Two- or three-leg pullers are useful for small and medium bearings. For large bearings, such as spherical roller bearings, a hydraulic puller with sufficient capacity is preferable.

If the bearing is to be reused, the extraction force must be applied to the ring with the fit. If it is to be discarded, it can be applied to the other ring, but always careful not to scratch the shaft. For bearings with a tapered bore, first loosen the nut and remove the sleeve with a special puller.

Never hit the bearing to remove it, because you can damage the shaft seat. If it is very rusty or stuck, use a penetrating liquid and let it act. At MR we advise you on the appropriate puller for each FAG bearing and provide a quote.

One of the most common mistakes is mounting the bearing by hitting it directly with a hammer. That generates marks on the raceways that later translate into noise and vibration. Another mistake is not cleaning the shaft or housing well before mounting. Dirt acts as an abrasive and wears prematurely.

Using an incorrect fit also shortens service life: if the fit is too loose, the ring rotates on the seat and wears the shaft; if it is too tight, internal clearance is reduced and the bearing overheats. Therefore, it is key to respect the tolerances indicated by the manufacturer. For bearings with a tapered bore, not measuring radial clearance during mounting is a serious mistake.

Another frequent mistake is not lubricating correctly after mounting. Lack of grease or excess can cause failures. Mixing incompatible greases is also a mistake. Before starting the equipment, turn the bearing by hand to verify that there are no hard spots or abnormal noises.

To get a quote for an FAG bearing, send the complete code that appears on the part, for example 32326 or 32920. If you do not have the code, send the main dimensions: inner diameter, outer diameter, and width. A photo of the bearing and the equipment where it is mounted also helps.

At MR we sell FAG bearings, including deep groove ball, angular contact, tapered roller, cylindrical roller, and spherical roller bearings, and we help you identify the correct reference if you have doubts. We also advise you on how to mount and dismount them.

Write to us via WhatsApp or email with your inquiry. We will respond promptly with the quote and the technical information you need. We are in Buenos Aires, Argentina.