Analysis of Laser Quenching Repair Processing Technology for Bearing Bush

As a key component in mechanical equipment for transmitting loads and reducing friction, bushings are prone to failure due to wear, fatigue spalling, and other issues after long-term operation. Traditional methods of replacing bushings are costly and time-consuming, while laser quenching repair technology has become the mainstream solution in the field of bushing repair due to its advantages of high precision, low damage, and high efficiency and energy savings. This article will comprehensively explain the application value of this technology from five dimensions: technical principles, processing procedures, core advantages, applicable scenarios, and precautions.

I. Technical Principles: The "Surface Strengthening Magic" of Precise Control

The core of laser quenching repair technology involves using a high-energy-density laser beam (typically CO₂ laser or fiber laser) to locally heat the worn or failed surface of the bushing. The principle can be divided into three key stages:

Rapid Heating Stage: The laser beam is focused on the area to be repaired, rapidly raising the surface temperature above the material's phase transformation critical point in an extremely short time without melting the base material, thereby avoiding thermal deformation.

Self-Quenching Stage: After the laser beam moves away, the high-temperature area rapidly cools through heat conduction from the bushing's base material, promoting the formation of fine martensite or bainite structures on the surface metal, significantly enhancing hardness and wear resistance.

Micro-Melting Repair Stage: For minor wear or scratches, the laser parameters can be finely adjusted to micro-melt an extremely thin layer of surface material, filling in minor defects and achieving integrated "repair + strengthening."

During this process, the laser energy can be precisely controlled through a CNC system to ensure uniform depth, range, and hardness of the heated area, avoiding any impact on the internal structure and dimensional accuracy of the bushing.

II. Standard Processing Procedure: Full Closed-Loop Control from Inspection to Acceptance

Laser quenching repair of bushings must follow strict procedural standards to ensure that the repaired performance meets or even exceeds that of new parts. The specific steps are as follows:

1. Preliminary Inspection and Evaluation

Appearance and Dimensional Inspection: Use calipers, micrometers, or coordinate measuring machines to measure the bushing's inner diameter, outer diameter, thickness, and wear amount to determine the scope of the repair area.

Material Analysis: Use a spectrometer to confirm the base material of the bushing to avoid cracking caused by mismatched laser parameters and material.

Defect Inspection: Use penetrant testing or ultrasonic testing to check for internal cracks, pores, or other defects in the bushing. If the defect depth exceeds the repair layer thickness, pre-treatment is required.

2. Pre-Treatment: "Clearing Obstacles" for Laser Processing

Surface Cleaning: Wipe the bushing surface with alcohol to remove oil stains and dust. If there is rust, use fine sandpaper to polish until the metal base is exposed, avoiding impurities that could affect quenching quality.

Fixture Setup: Secure the bushing on a CNC rotary worktable (for cylindrical bushings) or a平移 worktable (for irregularly shaped bushings) to ensure no displacement during processing and that the laser focus remains aligned with the repair area.

3. Laser Quenching Processing: Parameter Control in the Core Stage

Based on the bushing material and wear condition, set key parameters (using fiber laser as an example):

Laser Power: 500-1500W (lower power for Babbitt metal to avoid melting; higher power for copper alloys due to fast heat conduction).

Scanning Speed: 5-20mm/s (too fast may lead to insufficient heating and low hardness; too slow may cause an excessively large heat-affected zone).

Spot Diameter: 1-5mm (small spots for local scratch repair; large spots for large-area wear regions).

Overlap Rate: 10%-30% (ensures no gaps between adjacent quenching tracks, forming a continuous strengthening layer).

During processing, use an infrared thermometer to monitor surface temperature in real time, and automatically adjust parameters via the CNC system to avoid quality instability due to temperature fluctuations.

4. Post-Quenching Treatment and Acceptance: Ensuring Repair Effectiveness Meets Standards

Stress Relief Treatment: Perform low-temperature tempering on the quenched bushing to eliminate internal stresses generated during quenching and prevent cracking.

Precision Finishing: If minor protrusions exist on the surface after quenching, use a grinding wheel or honing machine for fine grinding to ensure the bushing's dimensional tolerance meets design requirements.

Performance Testing: Use a Vickers hardness tester to measure surface hardness and conduct friction wear tests to verify whether wear resistance meets operational needs.

Appearance Acceptance: Inspect the repair area for cracks, peeling,脱落, or other defects. A surface roughness of Ra≤1.6μm is considered qualified.

III. Summary

Laser quenching repair technology for bushings achieves efficient repair and performance enhancement through its core principle of "precise heating - rapid cooling - micro-melting repair." Compared to traditional methods, it offers advantages such as minimal deformation, strong wear resistance, and low cost. It is widely used in the maintenance of bushings in industries such as power generation, machine tools, metallurgy, and shipbuilding. In practical applications, strict preliminary inspections, parameter optimization, and post-treatment are necessary to ensure repair effectiveness meets standards. Combined with subsequent maintenance, this technology maximizes the service life of bushings, providing strong support for enterprises to reduce equipment operation and maintenance costs and minimize downtime losses.