Bearing lubrication is the act of applying a lubricant on the surface between the rolling bearings parts ant the metal surface. Lubrication seeks to reduce direct contact between the rolling and the sliding surfaces. When applied, the lubricant separates the two surfaces, reducing friction.
In some cases, the sliding surfaces are not totally separated by the lubricant; as a result, there are some small cases of wear and tear between the metal surfaces. Friction between the metallic parts generates high temperature thus causing tribal chemical reactions. As a result, a tribochemical layer forms that acts as a lubricant hence are reducing friction.
Lubrication condition dictates friction wear and tear. The following are the main lubrication conditions.
1. Full fluid film lubrication
This is a lubrication condition where the lubricating surface continually separates the lubricating fluid. Fluid lubrication is the other name of full fluid film lubrication. The friction experienced is normally between the fluids.
2. Mixed lubrication
Sometimes the lubrication fluid layer may become too thin. As a result metal, to metal contact occurs hence causing mixed friction.
3. Boundary lubrication
Boundary lubrication occurs when the lubricating materials contains additives that enhances lubrication. Due to friction the temperature of the lubricating service increases.as a result, lubricating additives in the lubricants causes some chemical reaction. After the chemical reaction a chemical lubrication layer is formed that prevents friction. Prevention of friction due to the chemical layer is the one referred to as boundary lubrication
All types of lubrication occurs when using both oil and grease lubricants. The strength of a lubricating material depends on the viscosity of the lubricating fluid.
Inadequate bearing lubrication
Proper bearing lubrication is essential. The following are the main symptoms of poor bearing lubrication and the resultant side effects.
Noise is one of the major symptoms of inadequate lubrication. Noise can be caused by three things namely starved lubrication, contamination of the lubricant and unsuitable lubricants. Starved lubrication results to one on one contact between metal services which causes the wear. The viscosity of the lubricating material determines the suitability of the lubricating material. Use of an unsuitable lubricating fluid will result to a thinner layer of the lubricant. Local metal contact formed will result to noise production. The last cause of noise is contamination contained in the lubricant. Dirt particles and other impurities in the lubricant disrupt the lubricating film and hence producing noise.
2. Cage wear
Cage wear is another symptom of inadequate lubrication. Cage wear result from starved lubrication and poor choice of lubricating materials which result to local metal contact.
3. Wear on rolling elements, raceways and lip surfaces
The other symptom of poor lubrication is wear, on the rolling services. Similarly to the other symptoms, starved lubrication, unsuitable lubricants use and impurities in contained in the lubricants are the major causes. Starved lubrication causes chemical corrosion due to oscillating relative motion and slip marks. Unsuitable lubricants may not contain the anti-wear also known as the EP additives hence causing wear on the rolling parts. Contamination in the lubricants may contain solid hard particles which are corrosive.
Poor bearing lubrication will cause fatigue. Starved lubrication result to a thinner lubricating fluid layer hence causing direct contact between the lubricating fluids, as a result, fatigue will obviously occur. Unsuitable lubricants may also contain may contain substances whose viscosity increases slightly under pressure, as a result the bearing will experience some fatigue.
5. High temperature and discoloring bearing parts.
Due to friction, the temperature of the system increases causing some of the colored substances to melt. Bearing discoloring occurs. High temperature results from starved lubrication and use of unsuitable lubricants.
6. Damaged lubricant
Another symptom of poor lubrication is damaged lubricant. The lubricants may solidify, discolor or lose the lubricating ability. This result from starved lubrication and the use of unsuitable lubricant. Other possible cause of this includes excessive operating time of the system.
Importance of proper lubrication
1. Saves cost
Lubrication saves the costs of replacing bearing balls and installing new equipment. This is because, the use a lubricant, eliminates friction hence reducing the wear on rolling surfaces.as A result the surfaces life spun increases hence reducing the cost of replacing them. Apart from the cost of buying new equipment’s, lubrication also saves the maintenance costs.
Lubrication improves the efficiency of a bearing. When one uses suitable lubricants, friction between the rolling parts is minimized this in turn eliminates fatigue. A fatigue free machine provides maximum performance and works according to the required standards.
3. Saves time
Non lubricated bearings are slow in their operation. When using a lubricated bearing, the bearing moves faster provide the needed services at a higher speed hence having a positive impact on the productivity. Also, bearing lubrication saves time spent repairing the rolling parts in a system.
4. Reduces noise pollution
One of the most irritating things about friction is the noise produced. Noise has a negative implication on the working environment and may influence other workers performance. When done, bearing lubrication reduces one to one metal contact hence reducing the noise produced.
5. Reduces wear and discoloring
Lubrication reduces wear of the rolling material and also reduces discoloring of the operation surfaces.
6. Increases the life of the bearings
As a result of reduced wear and tear, the life of a bearing increases with a considerable margin
Over-lubrication is one of the main culprits behind electric motor failure.it Occurs when due to excessive use of a lubricant on rolling surfaces. Over-lubrication result to pressure building .pressure causes temperature increase which can result to bearing failure. Also over lubrication can result to lubricant spill which result to the lubricant going to unexpected areas.As a result the oil spill may cause damage to sensitive parts and result to system breakdown. So when doing bearing lubrication, it is advisable to avoid over lubrication.
Bearing lubrication is essential mechanical maintenance activity. Bearing lubrication should be carried out by expert in the field to maintain high standards. The above article enlightens about bearing lubrication and symptoms of ineffective lubrication.