Removing FAG and SKF Bearings Without Damage

Most bearing failures blamed on "fake products" actually originate from the removal step.

The correct way to remove FAG and SKF bearings depends on bearing type, interference fit level, and seal material: mechanical pullers for small sizes, hydraulic pullers for medium sizes, and induction heating combined with pullers for large spherical roller bearings. Puller tonnage must match the calculated interference force, and induction heating temperature must stay within material-safe limits — otherwise raceway spalling, shaft scoring, or microstructural damage will follow, leading to premature failure of the replacement bearing.

I still remember the first time I opened a return crate from a West African port. Inside were several FAG 22320 spherical roller bearings, pulled out with a hammer and a steel chisel. The raceways were full of brinell marks. The customer swore we had shipped counterfeits. In reality, the bearings had been destroyed during disassembly. That shipment triggered a long investigation into field removal practices, and since then I have attached a removal instruction sheet to every order going to overseas maintenance teams. The return rate dropped noticeably after that. [NEED_CITE: root cause distribution of premature bearing failures per ISO 15243]

Let us walk through the tools, temperature limits, and step-by-step methods that keep FAG and SKF bearings intact during removal.

Why Proper Bearing Removal Matters for FAG and SKF?

Improper removal is the single largest hidden cause of "phantom failures" in rotating equipment.

When a bearing is hammered off a shaft, the impact force travels through the rolling elements and into the raceways. Even if the bearing appears undamaged on the outside, subsurface micro-cracks may have already formed. Once the new bearing is installed and the machine starts, these cracks propagate quickly, and the bearing fails within weeks. Maintenance teams then blame the supplier, the brand, or even the lubricant — never the removal method. [NEED_CITE: relationship between impact damage during disassembly and subsurface fatigue initiation]

In my experience shipping to ports across West Africa and the Middle East, the pattern repeats:

• A machine goes down for scheduled maintenance.
• The old bearing is stuck on the shaft due to corrosion or heavy interference fit.
• Workers grab a hammer, a pipe, or an oversized puller.
• The bearing comes off — but the shaft journal is scored, or the bearing seat in the housing is bell-mouthed.
• The new bearing is installed, runs hot, and fails within a few months.

The real cost is not the bearing itself. It is the downtime, the freight for a replacement, and the lost trust. Proper removal preserves the shaft, the housing, and — when the bearing is to be reused — the bearing itself. [NEED_CITE: SKF maintenance handbook guidance on bearing disassembly and reuse criteria]

For both FAG and SKF product lines, the core principle is the same: force must be applied only to the ring that is being removed, and only on its interference-fit surface*ng from the housing. Never transmit force through the rolling elements.

What Tools Do You Need to Remove FAG Bearings Safely?

Tool selection is driven by bearing bore diameter, interference fit class, and available clearance around the shaft end.

The puller tonnage required for a given bearing is not a guess. It follows a straightforward engineering relationship: the pull force equals the interference amount multiplied by the contact area between the inner ring and the shaft, multiplied by the friction coefficient of the mating surfaces. [NEED_CITE: bearing puller tonnage calculation formula based on interference fit and friction coefficient]

In practice, the field selection follows a tiered approach:

For FAG spherical roller bearings such as the popular 22320 series, an extra factor must be considered: internal clearance class. A C3 clearance bearing and a C4 clearance bearing of the same nominal size have different internal geometries, which affects how the rolling elements distribute load during pull-off. If the puller jaws grip the outer ring while the inner ring is being pulled from the shaft, the load path goes through the rollers — and that is exactly what must be avoided. [NEED_CITE: FAG technical documentation on clearance classes C3 and C4 and their impact on disassembly load paths]

A distributor in Lagos once reported that SKF and FAG bearings of the same nominal size felt "different" during removal. The SKF 22320 came off with noticeably less puller effort than the FAG 22320. The reason was not quality — it was the default clearance class shipped to that market. FAG often ships C4 clearance for vibrating screens and crushers, while SKF may ship C3 for the same application envelope. The puller setup and jaw positioning must be adjusted accordingly.

How to Use Induction Heating for SKF Bearing Removal?

Induction heating is the most efficient way to break a heavy interference fit — but temperature control is non-negotiable.

The principle is simple: an induction coil generates an alternating magnetic field that heats the steel inner ring by eddy currents. As the ring expands, the interference fit loosens, and the puller can slide the bearing off with minimal force. However, if the temperature is too high, the steel microstructure changes. Tempering temperatures for through-hardened bearing steels are typically in the range of 150–200 °C depending on the grade. Heating beyond this range during removal will reduce the surface hardness and destroy the load-carrying capacity of the ring. [NEED_CITE: SKF general maintenance guidelines on induction heating temperature limits for bearing拆卸]

The safe temperature windows are:

• Standard through-hardened steel bearings (open or with steel cages): heat to a maximum of 120 °C. This is sufficient to generate the thermal expansion needed to break most interference fits on shafts up to large sizes.
• Bearings with rubber seals, plastic cages, or pre-packed grease: heat to a maximum of 80 °C. Beyond this, the seal material degrades, the plastic cage softens, and the grease oxidizes — rendering the bearing unusable even if it is to be reinstalled.

A maintenance team at a cement plant in the Middle East learned this the hard way. They were removing a set of SKF cylindrical roller bearings from a fan shaft. The bearings were heavily corroded onto the shaft, and the team decided to "speed things up" by heating the inner ring with an oxy-acetylene torch until it glowed. The bearings came off easily — but the inner rings were dimensionally distorted, and the raceway hardness had dropped below the acceptable threshold. The bearings could not be reused, and the shaft journal had to be re-machined. [NEED_CITE: induction heating vs open-flame heating effects on bearing steel microstructure and dimensional stability]

The correct induction heating procedure is:

1. Select an induction heater with a yoke or coil sized to encircle the inner ring.
2. Place the coil around the inner ring, ensuring even contact.
3. Set the target temperature on the controller — 110 °C is a safe working point for most standard bearings.
4. Heat until the target temperature is reached; the heater will auto-cut or hold.
5. Immediately mount the puller and apply steady force. The ring will contract quickly once heating stops, so speed matters.
6. If the bearing does not move within a reasonable time, stop. Do not increase temperature. Re-evaluate the puller alignment or consider injecting a penetrating oil at the interface.

Step-by-Step Removal Process for Spherical Roller Bearings

Spherical roller bearings require a disciplined sequence — outer ring first, then inner ring — to avoid偏载 and cage distortion.

Spherical roller bearings, whether FAG or SKF, are commonly found in heavy-duty applications: vibrating screens, conveyors, crushers, and paper machines. Their size and the heavy interference fits used in these applications make removal a critical operation.

The step-by-step process is as follows:

1. Lock out and prepare. Isolate the machine, release all stored energy, and clean the external surfaces of the bearing housing. Mark the orientation of the bearing and any spacers or shims.
2. Remove the outer ring from the housing. If the outer ring is a light interference fit or a slip fit, use a brass drift and a soft-faced hammer to tap it out evenly from alternating sides. If it is a heavy interference fit in the housing, use a hydraulic press or a puller with a backing plate against the outer ring face. For split housings, remove the cap and lift the outer ring out.
3. Expose the inner ring on the shaft. Once the outer ring is removed, the inner ring remains on the shaft. Clean the exposed shaft area and inspect for corrosion or burrs.
4. Position the puller on the inner ring. Use a puller with jaws that reach behind the inner ring. If the inner ring has a tight shoulder and no groove for puller jaws, use a backing plate or a puller with thin jaws designed for bearing inner ring removal. [NEED_CITE: SKF and FAG technical guides on puller jaw positioning for inner ring removal]
5. Apply steady, aligned pull force. The puller screw must be centered on the shaft axis. Off-center pulling will tilt the inner ring, score the shaft, and potentially crack the inner ring.
6. Use heat if needed. If the inner ring does not move under hydraulic pressure, apply induction heating to the inner ring as described in the previous section. Do not heat the shaft — heat the ring.
7. Remove and inspect. Once the inner ring is off, inspect the shaft journal for scoring, the housing bore for bell-mouthing, and the bearing for any signs of cage distortion or roller damage.

A critical detail that many field teams overlook: when removing the inner ring of a FAG spherical roller bearing, the cage type matters. FAG uses both steel cages and polyamide cages in the 223-series. A polyamide cage (suffix TVPB or similar) must never be heated above 80 °C, even during removal. If the bearing is to be discarded, this is less critical — but if there is any chance of reuse or forensic failure analysis, the cage must be preserved.

Common Mistakes That Damage Bearings During Removal

Three mistakes account for the vast majority of removal-related bearing and shaft damage: hammering, oversized pullers, and overheating.

Mistake one: hammering the bearing off. This is still the most common method in many field locations, especially where pullers are not available or where the culture of maintenance has not caught up with the precision of modern bearings. The impact force from a hammer is transmitted through the rolling elements to the opposite ring. The result is brinelling — permanent indentations in the raceway — which will cause vibration, noise, and early fatigue in the next installation. Even if the bearing is being scrapped, the shaft and housing may be damaged in the process.

Mistake two: using a puller with excessive tonnage. A common belief is that "bigger is better" — a 50-ton puller will always work where a 10-ton puller fails. In reality, an oversized puller applies force beyond what the inner ring cross-section can withstand. The inner ring can crack, or the shaft thread can be stripped. The correct puller tonnage is the one that matches the calculated interference force, plus a modest safety margin. [NEED_CITE: engineering guidelines on puller tonnage selection relative to bearing interference fit]

Mistake three: overheating during induction or flame heating. As discussed, exceeding the material-safe temperature destroys the heat treatment of the bearing steel. A bearing that has been overheated will look normal to the naked eye, but its hardness will be reduced, and its fatigue life will be a fraction of the original. There is no field test to verify this — the damage is invisible until the bearing fails in service.

How to judge whether a removed bearing can be reused:

• Visually inspect the raceways under good light. Any brinell marks, spalling, or discoloration (blue or straw temper colors) indicate damage.
• Measure the inner ring bore and outer ring OD. Any deviation from the original tolerance means the ring has been distorted.
• Rotate the bearing by hand. It should turn smoothly with no tight spots or grinding feel.
• Check the cage for cracks, deformation, or missing rivets.

If any of these checks fail, the bearing must be scrapped — regardless of its brand or original cost.

Conclusion

Removing FAG and SKF bearings without damage is not about strength — it is about discipline, correct tooling, and temperature control.

Every step of the removal process must be planned before the first tool touches the bearing. The puller must match the interference fit, the heat must stay within material limits, and the force must be applied only to the ring being removed. When these principles are followed, shafts and housings remain intact, reusable bearings survive, and the root cause of future failures can be accurately diagnosed — instead of being misattributed to the bearing brand.