Consult Standard 20 for bearing failure

It is important to be able to identify or fail a bearing in operation without passing a disassembly inspection, which is important for improving productivity and economy.

The main identification methods are as follows:

1) Recognition by sound.

Recognition through sound requires a lot of experience. It must be trained to recognize bearing sounds from non-bearing sounds.

To this end, this work should be carried out by a dedicated person as much as possible. The sound of the bearing can be clearly heard by attaching a listening device or listening stick to the housing.

2) Identification by operating temperature.

This method is a comparative identification method and is limited to occasions where the operating state does not change much. For this purpose, continuous recording of the temperature is necessary.

In the event of a malfunction, not only does the temperature rise, but also changes irregularly.

This method should be used in conjunction with the sound recognition method.

3) Identification by the condition of the lubricant.

Lubricants are sampled and analyzed by the degree of fouling, whether they are mixed with foreign substances or metal powder, etc.

This method is particularly effective for bearings that cannot be observed in close proximity or for large bearings.

In the process of analyzing bearing failure, we often encounter many intricate and intricate phenomena, and various experimental results may be contradictory or unclear, which requires repeated experiments and demonstrations to obtain sufficient evidence or counter-evidence. Only by using the correct analysis methods, procedures, and steps of the state of knowledge can we find the real cause of failure.

Different bearing failure types correspond to different characteristics of bearing vibration trapping. The service life of the moving parts of the bearing depends on the fatigue and wear of the material on the contact surface of the moving parts. There are many reasons for early bearing failure, the most common of which include:

Fatigue, wear, plastic deformation, corrosion, localized hardening, poor lubrication, assembly defects, and design defects. Often, the failure of a bearing is the result of a combination of factors, or at first one factor, which gradually leads to multiple failures as the failure increases.

Figure 1 Profile of the bearing.

Let's explain it to you.

The main forms of failure of rolling bearings:

1. Wear and tear failure.

2. Fatigue failure.

3. Corrosion failure.

4. Fracture failure.

5. Indentation failure.

6. Gluing failure.

Rolling bearing wear is a common equipment problem in the process of shaft use, which is mainly caused by the metal characteristics of the shaft: although the metal has high hardness, it has poor concession (cannot be restored after deformation), poor impact resistance, and poor fatigue resistance, so it is easy to cause adhesive wear, abrasive wear, fatigue wear, fretting wear, etc.

Most of the shaft wear is not easy to detect, only when the machine has high temperature, large beating amplitude, abnormal noise, etc., it will be noticed, but by the time people notice, most of the rolling shafts have been worn, resulting in machine shutdown.

There are three main failure modes of rolling bearings:

1) Under the load of fatigue pitting rolling bearings, contact stress will be generated between the rolling elements and the inner and outer raceways. When the bearing rotates, the contact stress is cyclically changed, and when the working time is over, the local surface metal of the rolling element or raceway falls off, causing the bearing to produce vibration and noise and fail.

2) Plastic deformation When the speed of the bearing is very low or intermittent oscillation, the bearing will not be fatigue pitting, at this time the bearing failure is due to excessive load (called static load) or impact load, so that the rolling element or the inner and outer ring raceways appear large plastic deformation, forming uneven pits, thereby increasing the frictional torque of the bearing, increasing vibration and noise, and reducing the motion accuracy.

3) Abrasive wear and adhesive wear are provided with sealing devices at the bearings when the bearing is designed in combination. However, for bearings working under dusty conditions, external dust and impurities will still invade the bearing, causing abrasive wear on the rolling elements and raceway surfaces. If the lubrication is poor, there is a sliding friction surface in the rolling bearing, and adhesive wear will also occur, and the higher the bearing speed, the more serious the adhesive wear.

After wear, the bearing clearance increases, the motion accuracy decreases, and the vibration and noise increase.

Spalling and breaking.

Indentation rubbing. Scratches, stains, rust, and corrosion.

Creep discoloration. The cage is damaged.

Burns other (electric erosion, rough surfaces, scratches, etc.).

Common failure modes of rolling bearings: contact fatigue failure, wear failure, fracture failure, corrosion failure.

Under normal conditions, the main failure modes of rolling bearings are:

Pitting damage on rolling elements or inner and outer ring raceways.

3 types: 1fatigue pitting; 2.abrasive or adhesive wear; 3.Plastic deformation.