Laser Cladding Repair of Bearing Inner Holes: Practical Sharing from Parameters to Effects

In the maintenance of industrial equipment, wear and corrosion of the inner holes of bearings are common faults – especially for bearings under heavy-load and high-speed working conditions (such as rolling mill bearings and wind turbine main shaft bearings), when the inner hole size exceeds the tolerance, they often face the problem of scrapping and replacement. Laser cladding technology, with its advantages of “precise temperature control, low thermal deformation, and strong coating adhesion”, can achieve efficient repair and performance enhancement of the inner holes of bearings. Today, we will discuss the application details of this technology in combination with actual case data.

Why Choose Laser Cladding?

First, let’s look at the repair pain points of the inner hole of the bearing. The core requirements for the inner hole of a bearing are “dimensional accuracy + surface hardness + wear resistance”, and traditional repair methods (such as electroplating and arc welding) have obvious limitations:

• The thickness of the electroplating layer is limited (usually ≤0.1mm), and its adhesion is weak (about 10-20MPa), making it prone to peeling off under heavy loads.
• The high heat input of arc welding (≥1000J/mm) can cause deformation of the bearing base (the deformation can reach 0.2-0.5mm), and it is difficult to restore the accuracy in subsequent processing.

The advantages of laser cladding precisely match these pain points:

• The heat input is low (typical value 50-200J/mm), the heat-affected zone (HAZ) of the bearing base is only 0.1-0.3mm, and the deformation can be controlled within 0.02mm.
• The coating has a strong adhesion force (≥50MPa), which is equivalent to more than 80% of the substrate’s own strength.
• The coating thickness is controllable (0.1-2mm), and can be flexibly adjusted according to the amount of wear, easily restoring the inner hole size.

How to Determine Key Parameters?

Taking the common inner hole of 45# steel bearing (specification φ100mm× length 150mm, wear rate 0.3-0.5mm) as an example, we adopt the “fiber laser cladding machine + iron-based alloy powder” solution. The specific parameters are as follows:

Parameter category	Specific value	Selection basis
Laser power	3000-6000W	Too low power can cause the powder to not melt, while too high power can burn out the matrix
Processing speed	300-500mm/min	Matching power forms a “narrow heat-affected zone + dense coating”
Powder feeding amount	8-12g/min	Ensure uniform coating thickness (increase thickness by 0.05-0.1mm per circle)
Spot diameter	2-3mm (ring-shaped spot)	The ring-shaped light spot can prevent overheating at the center and make the coating more uniform
Protective gas flow rate	8-10L/min (argon)	Prevent the oxidation of the molten pool and ensure the purity of the coating
Powder composition	Fe-Cr-Ni-B-Si (Iron-based alloy)	The hardness reaches HRC 55-60, and its wear resistance is 3 to 5 times that of 45# steel

Key points of operation: The inner hole of the bearing needs to be pre-treated first – use sandpaper to remove rust, then clean the oil stains with acetone, and finally pre-turn 0.1-0.2mm on a lathe to expose the fresh substrate (improve the adhesion of the coating). When cladding, a “spiral scanning path” is adopted, with the overlap rate of each circle controlled at 30%-50% to avoid coating lap gaps.

How effective is the repair?

We conducted a comprehensive inspection of the inner hole of the repaired bearing. The key indicators are as follows:

• Dimensional accuracy: Inner hole roundness ≤0.005mm, cylindricity ≤0.01mm, fully restored to the original design tolerance (IT6 grade).
• Coating performance: Hardness HRC 58±2, porosity ≤0.5% (no obvious pores or cracks), no coating peeling after 1 million fatigue tests.
• Service life: Installation tests show that the repaired bearings have a service life of 8,000 hours under heavy load (200kN) and a rotational speed of 1500r/min, approaching the level of new bearings (about 10,000 hours), and far exceeding the 3,000 hours of electroplated repair.

Actual Case Presentation

In which scenarios is laser cladding more suitable?

Not all inner holes of bearings are suitable for laser cladding. The following situations are recommended first:

• Bearings with wear ranging from 0.1 to 2mm (those that are too small are not cost-effective; those that are too large require multiple cladding).
• Bearings made of medium carbon steel or alloy steel (such as 45# steel, 40Cr, GCr15);
• High-value bearings (such as wind power bearings and large rolling mill bearings, with a single set value exceeding 10,000 yuan and high repair cost-effectiveness).

If it is a light-load, low-value small bearing (such as a motor bearing), it is recommended to replace it directly – after all, the single processing cost of laser cladding (about 500- 1,000 US dollars) may be close to the price of a new bearing, and the economic efficiency needs to be comprehensively evaluated.