How is oil analysis performed?
Oil analysis methods can cover a wide range of areas and tactics. Primary among them are
• Condition-Based Monitoring: As a form of condition-based maintenance, oil analysis is a vital element in keeping industrial equipment in optimal condition. Manufacturers depend on the information this process provides to monitor the condition of their machinery and identify potential problems before they have a chance to affect productivity.
• Visual inspection for contamination and viscosity: For maximum effectiveness, visual oil inspections should be performed at least daily. These simple inspections can detect the presence of debris, large contaminants, uneven viscosity, and other problems that, if caught early, can be resolved relatively easily (often by simply changing the oil). Visual inspections can also indicate larger equipment wear issues.
• Wear Particle Analysis: Since the oil is in direct contact with moving parts, this is where debris, no matter how small, is collected as these parts wear. The presence of debris or contaminants indicates the rate at which equipment is being worn and can alert maintenance personnel and equipment operators to early wear problems that indicate abnormal operation that can then be addressed.
Benefits of oil analysis
Oil analysis offers benefits including:
1. Early detection of unexpected equipment wear, indicating the presence of potential problems in equipment function
2. An accurate picture of when oil needs to be changed, so that oil does not continue to operate when it is no longer effective, while also ensuring that oil is not changed unnecessarily based on rigid time schedules, thus reducing costs.
3. An insight into equipment performance, as oil condition is closely related to equipment efficiency, wear and performance
4. A continuous and ever-expanding data set enables more informed maintenance scheduling and decision-making, ultimately improving maintenance efficiency and productivity, while reducing maintenance costs
5. Keep machinery in good working order to prevent the possibility of sudden breakdowns that could endanger the safety of employees
6. Ensure equipment operates at peak efficiency to reduce energy consumption and improve the manufacturer’s environmental sustainability
Hydraulic and gear oil analysis includes:
Kinematic viscosity – the oil’s resistance to flow under the influence of gravity at 40°C
Total Acid Number (TAN) – a measure of the acidity and oxidation of a lubricant. Oils with high TAN can lead to corrosion of machinery and clogging of oil filters
Metal corrosion – to see how well machinery and machine parts are wearing How
clean the oil is passing through the system: the oil must be clean to prevent filters from clogging Antifoam
and other additives – to determine if the antifoam properties are still working and if any additives have broken down and need to be replenished
Contaminants – to ensure the oil is free of various contaminants.
One of the main contaminants is dust. These fine particles, called silica, can get into hydraulic systems and act like diamonds on glass, scratching and causing wear that can cause equipment to stop working properly or fail.
Gears vary in size, but the largest are the open gears used in the cement industry. These large gears turn mills; their speed can be increased or decreased, and their torque can be increased to lift heavy loads, so it is important to consider the viscosity, wear metals, and remaining additives. Typically in gear oils, you will look for the presence of phosphorus, which is one of the extreme pressure (EP) additives. This can be measured to determine how much additive is left and to give an indication of when the oil needs to be changed.
Turbine oil:
Turbine oils used in power plants have a special set of tests similar to those used for hydraulic oils. In addition to tests for viscosity, wear metals, TAN, and cleanliness, a rotating pressure vessel oxidation test (RPVOT) is also performed. This test measures the oil’s oxidation stability and the amount of remaining antioxidants, which indicates how much life the oil has left.
Another test for turbine oil is the RULER (Remaining Useful Life Evaluation Procedure), which is also used to determine the amount of antioxidant additives in the oil. The patch filter test (MCP – Film Patch Colorimetry) is used to measure the amount of varnish in the oil, as oxidation can occur when the oil gets very hot. If the hydraulic control valve that controls the speed of the turbine is coated with varnish, the valve will not open and close properly, which can cause major problems in industries such as power generation.
Soluble cutting oil
Soluble cutting oils are used in metalworking, CNC machining and lathes. The concentration of the oil in the water emulsion must be checked regularly to ensure that it contains the correct coolant and anti-corrosion additives. If the cutting oil is not at the correct concentration, it will not perform as efficiently as expected and tools will need to be sharpened and replaced more frequently.
From a health and safety perspective, it is also important to test cutting fluids for biocides and bacteria. When cutting fluids are left unused, even for just a week, they can develop an unpleasant rotten egg smell due to the activity of anaerobic bacteria in the stagnant fluid.
The operator also needs to ensure that the pH level of the cutting fluid is within an acceptable range. If it is too low, it can cause corrosion of the workpiece, and if it is too high, it can cause skin and eye problems for the operator.
It is essential to maintain the quality of the coolant to ensure clean coolant, to keep the coolant lasting longer and to keep the machined parts produced in the best condition.
Water hardness should also be checked. Water hardness or softness can affect foam production or emulsion stability. For example, if there is too much foam, it can escape from the holding tank or tank onto the factory floor, creating safety issues.
Some of these tests, such as concentration and pH, can be performed on-site. Operators who value their machinery will perform this regularly as part of their expensive equipment maintenance.
Fat
Grease analysis is often performed reactively when a problem occurs, to help the operator understand the root cause of the problem. Observation of the grease will indicate whether or not wear metals are present, which can then be measured. Typically, very small samples are sent for analysis. The color and texture of the grease will indicate whether the grease has been overheated – that is, whether it is hard.
Oxidation can also be checked to ensure the grease is not oxidized. When grease oxidizes, there is a buildup of acids, which can lead to carbonization, where the grease hardens, reducing its effectiveness. The Gauge test can tell if all the antioxidants have been used up, and the Total Acid Number can tell if the grease is overheated.
For further investigation, scanning electron microscopy can be used to determine exactly which metals are present in the grease or wear metals can be identified using inductively coupled plasma (ICP).
Other techniques, along with pre-failure lubricant analysis, can also help build a picture of the cause of failure. These include vibration analysis and thermal imaging, although this is not always possible. Vibration analysis “listens” to the bearing to ensure it is operating properly and detects wear or misalignment.
Benefits of Lubricant Analysis
Reduces maintenance costs
Helps plan maintenance operations
Improves equipment reliability and performance
Minimizes downtime
Extends machine life
Extends oil change intervals.
Conclusion
The saying “prevention is better than cure” is true. The cost of analysis is small compared to the potential for failure and downtime, so you should consider condition monitoring and using a laboratory with the necessary test kits to ensure your lubricants are in good condition. If the results indicate that action is required, take note and implement the recommended corrective action.
Total’s ANAC INDUS industrial analysis service is designed to help manufacturing and industrial operations become more efficient and cost-effective.
Why choose our services?
With our team of experienced professionals and state-of-the-art equipment, our Oil Analysis results allow you to detect unwanted equipment wear, know when to change your oil, gain insight into your equipment’s performance, and make informed decisions when scheduling lubrication maintenance.
Let us help you improve machine performance and productivity, while reducing maintenance costs.