Did you know that ...
10 ppm of water in a bearing lubricant will half the bearings lifetime?
This is the relative amount of two drops of water in a glass of beer.
CONTAMINATION is the cause of more than 30 % of lubrication related bearing failures?
NEW OILS have commonly a higher contamination level than recommended by the machine supplier?
The number one problem with lubrication today is contamination and this can be particle contamination or chemical contamination or both. A Lubrication Reliability strategy consistently uses three words. These are Cleanliness, Contamination and Control and when combined they are generally used as cleanliness control and contamination control.
Cleanliness control is the processes and tools to ensure only clean lubricants are added to the equipment whereas Contamination Control is the processes and tools to ensure only clean lubricants are operating in the equipment .
So why the difference?
In lubrication management we spend a lot of time, effort and money to ensure the lubricants operating in our equipment are kept very clean, so why would we add dirty oil to an already clean system, it makes our work even harder, not to mention more costly.
The effects of particle contamination on bearing life is supported by a research project conducted by Doctor MacPhearson, which looked at the relationship between filter ratings and millions of bearing cycles to fatigue failure. This research and others conducted on the effect of contamination, conclude the same basic fact – the cleaner the lubricant the longer the machine life.
The International Organization for Standardization created the cleanliness code ISO 4406 to quantify particulate contamination levels per milliliter of fluid at three sizes: 4 micron, 6 micron and 14 micron. It is this code that is used by most companies to set their targets for lubrication cleanliness. This ISO code is expressed in 3 numbers, for example 22/18/13. Each number represents a contaminant level code for the correlating particle size.
Companies that are managing their lubrication contamination have ISO 4406 targets for different applications and set targets accordingly, depending on the criticality of the machine in their processes. Below are some examples of recommended target levels.
Others have overall target levels set for the whole plants. In any case the key is to have a target level and then employ the actions to ensure the target is reached and maintained.
Organisations that are at Best Practice levels in managing their lubrication activities understand that oil can be contaminated in the process from when it is received at the store and when it is running in the machine. The following are some examples of how the lubricant can become contaminated along the way.
There are 5 steps we need to consider in managing our oil cleanliness and contamination levels. These are:
1. Receipt of new oil.
2. Storage and conditioning of new oil.
3. Dispensing of the oil to the machines.
4. Stopping contaminants entering the machine.
5. Removing contaminants generated in the machine from wear.
In step 1 it is important to remember that new oil is not necessarily as clean as we would like and if we are serious about our cleanliness standards then we should make sure it is conditioned before use to acceptable standards.
If we store oils before use then this needs to occur in a dry and clean location. The drums should be preferably stored horizontally with the two entrances at 9 and 3 o'clock and to ensure they are not kept too long in storage. Then the First In First Out (FIFO) process should also be employed.
Best Practice lube storage, is that all new oil is not only kept clean and dry, but the oil is also filtered before it enters the machine. Systems like the one shown below filter the oil in three ways, when emptying oil from Drums into the storage tanks, over the storage containers and when transferring the oil to the dispensing container. High quality desiccant breathers prevent subsequent contamination to the fluid and flow meters measure and track the amount of oil dispensed.
a) Portable filter carts are effective tools for lubricant transfers and decontamination.
Dispensing containers should meet certain criteria:
In addition to stopping contaminants entering the oil we also need to ensure that the right lube gets into the right machine and the standard practice is to use a colour coded system of one colour for one type of oil. The storage facility, the dispensing containers and the fill points all need to be labeled.
All oil reservoirs need to breathe, and unless they are protected this breathing process is a source of airborne contaminants entering the system. The fitting of Air Breathers on the systems preventing water, dust and dirt from entering the system.
Air Sentry introduced the Guardian desiccant type breather, manufactured with both particulate filters and desiccant, which is designed to help improve filter performance.
And the fifth step in the process is to filter the system in order to remove any contaminants generated from within, like wear debris for example.
A well structured lubrication strategy will require some investments. The costs are generally associated with the following activities:
Lubrication practices within a plant have a direct effect on plant and equipment reliability. When the lubrication is working effectively, wear will be reduced and equipment reliability will be improved.
Assessment
Plan, Manage, Organise
Identification and Inspection
Lube storage by cleanliness control
Oil dispensing is an Art..?
Grease Lubrication
Contamination Control
Measure Quality by oil analysis
Environmental control
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