Damage and Estimation of Industrial Bearing

Generally speaking, if the bearing is correctly used, it can reach fatigue life. But there is situation that incident premature damage happens on the beating and it can not endure. Opposite to fatigue life, the premature damage is called quality serve limits of failure or accident. Most of the damage is caused by inattention in mounting, usage and lubrication, intrusion of foreign body outside, and insufficient research on heat affecting on shaft and casing.

Bearing damage state, such as damage on ferrule and rib of rolling bearing, should be considered as causes. Other causes, say, insufficient and unsuitable lubricant, objection to oil supply and oil drain constitution, intrusion of foreign body, bearing alignment error and too much shaft flexing, can coincide with former causes.

Therefore, the true cause of damage can not be obtained by investigating bearing damage. However, if the service machine, the use condition and ambient constitution of the bearing is known, circumstances before and after accident are found out, inspect by combining with bearing damage state and several causes, similar accidents can be prevented reoccurring.

Bearing estimation:

Estimation on whether the bearing can be used is to estimate the damage degree, mechanical property, importance and running condition of the bearing. These can be determined by repair and examining period. If there are following defects, the bearing can not be used again, and it should be replaced with new bearing. The defects include crackle or notch on any of the components, namely inner race, outer race, rolling element and holder.

1. Rupture on either of ferrule or rolling element.

2. Evident damage on raceway face, rib or rolling body.

3. Evident holder wearing or rivet looseness.

4. Rust or damage on raceway face or rolling element.

5. Serious impress and scar on raceway face or rolling element.

6. Evident creep deformation on inner diameter face of inner race or outer diameter face of outer race.

7. Evident color change caused by heat

8. Evident disrepair on lock ring or dust cap of bearing enclosed in lubricating grease.