7 Possible lubrication failure scenarios of industrial gear boxes due to prolonged stoppage
July 29, 2020
Effective lubrication practices for smooth operation of chains
July 29, 2020Avoid bearing failure while restarting machines after prolonged stoppage
Machine Restart Guideline for Bearing
Restarting machines without priming after prolonged stoppage can have adverse effect on the components and land you in further downtime. While there is a vast range of bearings suited for every application based on speed, load and alignment, optimal lubrication is a common yet critical requirement for efficient performance. Here is a list of possible scenarios that can adversely affect bearing performance due to lubricant starvation and remedies to ideally prep the machine before restart.
Bearing Exposed To Water
Possible affects due to prolonged stoppage
- Absorption of water in the grease
- Reaction of water with grease creating change in consistency
- Oxidation of grease
- Additives in the grease (For example, Corrosion protection additives) getting consumed due to prolonged idle time
- Grease film rupture in the load zone of the bearings during prolonged idle time
Restarting after prolonged stoppage
- Clear traces of water and corrosion present in housing and grease nipple. Scales and chemical deposits to be removed
- Check condition of grease nipple for chocking/ corrosion on nipple spring etc. If found faulty replace the nipple with new one
- Flush bearings free of the old grease by pumping grease through nipple. Grease pumping to be done until such time the fresh grease comes out
Bearing Operating At High Temperature
Possible affects due to prolonged stoppage
- Grease oxidation due to exposure to temperature of around 180ºC
- Grease film break down from the load zone due to static load
- Corrosion on bearings
- Base oil evaporation and grease hardening due to exposure to high temperature
- Reduction in base oil viscosity due to high temperature exposure resulting in grease bleeding
- Grease hardening due to thermal stress
- Hard residue formation of the grease on bearing which may prevent fresh grease from reaching contact zone
Restarting after prolonged stoppage
- Check the condition of existing grease in bearing. Physically feel the grease in comparison with fresh grease for oil content.
- If oil content is 50 % lower than fresh grease, flush the bearing with fresh grease until such time old grease is completely purged out
- If excess grease bleeding/ run down from the housing is noticed, follow flushing procedure as mentioned in the above point
- While applying fresh grease, if resistance is encountered in grease pump, open the housing and manually clean the old grease residues
Motor Bearing
Possible affects due to prolonged stoppage
- Oxidation of grease due to presence of catalysts like bearing steel, housing, end cover etc.
- Reduction on base oil properties due to oxidation and shear.
- Cake formation of grease in the bearing. External contamination like dust, process residue etc.
- Chocking of grease nipples and hardening of grease in tubes used for applying fresh grease.
Restarting after prolonged stoppage
- Since relubrication quantity recommended for motor bearings is only a few grams, it is recommended to re-grease all motors before restarting. Care to be taken to apply only the recommended grease quantity
- Check for grease hardening in the grease nipple, pathway and exit port. Remove hardened grease before relubrication
- Check for grease hardening in the tubes used for relubrication. Flush out hardened grease before applying fresh grease
- Keep grease exit port open for one hour so that excess grease (if any) in the bearing or housing will bleed out. Remove the bledout grease and re-assemble the exit port nut after one hour
Machine Restart Guideline
General guideline to check condition of lubricant (greases and oils) in machines after prolonged stoppage to ensure maximum performance and avoid wear damage
- Do not start any bearing in full load and maximum speed condition immediately after extended stoppage period. If possible, run the bearings under no load condition for one hour, before increasing the load and speed in steps
- Where ever dynamic or static seals are provided in the equipment, check them for hardening and brittleness. Change the seals if they have become too hard or brittle
- Equipments which are prone for mis-alignment as per maintenance records, should be checked for alignment before restarting them
- All grease guns and grease pumping equipments need to be recalibrated, before being put to use. Grease in containers to be checked for oil separation and stirred with a clean rod wherever necessary
- All oil storage drums should be checked for sedimentation and cleanliness. Thoroughly shake oil drums/ oil cans before taking oil for lubrication
- For rust removal of machine parts such as housing, bearings, gears etc, Beruclean 3849 is recommended.
The recommendations are based on our books of experience and available knowledge at the time of release. The general guidelines are to check condition of lubricant (greases and oils) in machines due to unplanned stoppage that can be affected due to a combination of known and unknown factors including natural ageing, environmental impact or contamination by external impurities. For further reference and practices specific to the equipment, we suggest you to follow the machine manual or contact the Service team. This information is intended as a guide and does not necessarily represent a marketing specification. To address your concerns, please contact our Engineering Team on +91 80 66900800 / +91 9379917484.
Machine Restart Guideline for Chains
Chain links running dry is sure way to wear, noisy operation and breakdown. Cause for worry if you are restarting chain drives after prolonged downtime. Chain drives are used to transmit force and motion between parallel shafts. Many varieties of chains are in use like heavy duty roller chains, precision roller chains, flat top crate conveyors, duplex or triplex roller chains, inverted tooth or silent chains. While friction characteristics of these types of chains vary depending on construction and mounting position, there are common challenges in ensuring effective lubrication of drive chains. And special care should be taken while restarting chain drives after prolonged stoppage.
Machine Restart Guideline for Industrial Gearbox
7 Possible lubrication failure scenarios of industrial gear boxes due to prolonged stoppage. Condition of the oil prior to restarting a gearbox after a prolonged or unplanned stoppage would make the difference between smooth operation and unwanted wear as well as surge in temperature. Here is a list of possible scenarios that can adversely affect performance output of the gear box due to lubricant starvation and remedies to ideally prep the gearbox before restart. Condition of the oil is an indicator of the long-term reliability of the gear box.
