Bearing are precision parts and in order to preserve their accuracy and reliability it must be ensured that the bearings gets mounted in a proper manner. Depending on the mounting procedure, it is recommended that the handling procedures must be thoroughly understood before implementation.
Handling of the Bearing Unit
- In some cases, improper fits may lead to damage and shorten bearing life, therefore it is necessary to make a careful analysis in selecting a proper fit. Some of the negative conditions caused by improper fits are :
- 1) Raceway cracking, early peeling and displacement of raceway.
- 2) Raceway and shafts or housing abrasion caused by creeping or fretting corrosion.
- 3) Seizing caused by loss of internal clearances.
- 4) Increased noise and lowered rotational accuracy due to raceway groove deformation.
- Periodic inspections are necessary to ensure safe operation’s of the unit’s most important parts. While the interval between inspections varies from case to case, according to the degree of importance and the rate of operation, it is usually some time between two weeks and a month.
- Since the inside of the bearing can be examined only by removing the slinger, seal, etc. The condition of the bearing should be judged by checking for the presence of vibration, noise, overheating of the housing, etc., while the machine is running.
Bearing Internal Clearance
- Bearing internal clearance is the amount of internal clearance a bearing has before being installed on a shaft or in a housing. The internal clearance of a bearing under operating conditions is usually smaller than the same bearing’s initial clearance before being installed and operated. This is due to several factors including bearing fit, the difference in temperature between the inner and outer rings etc.
- As a bearing’s operating clearance has an effect on bearing life, heat generation, vibration, noise, etc. Proper care must be taken in selecting the most suitable operating clearance.
- The purpose of bearing lubrication is to prevent direct metallic contact between the various rolling and sliding elements. This is accomplished through the formation of a thin oil (or grease) film on the contact surfaces. For rolling bearings, lubrication also has the following advantages:
- 1) Friction and wear reduction.
- 2) Friction heat dissipation.
- 3) Prolonged bearing life.
- 4) Prevention of rust.
- 5) Protection against harmful elements.