Optimizing Lubricant Reliability: Strategies to combat Contaminations and enhance
Operational Excellence

Introduction:

The right Operational and Maintenance Skills help manufacturing industries live up to their vision of an ever-flourishing organization with an attempt to achieve “Better than Before” results in terms of Profitability, Safety, and Environmental Sustainability. Zero Waste, Net Zero and Sustainability are the buzzwords today in almost every industry. Lubricants (oil and grease) and hydraulic oil are precious resources. Judicious application of lubricants and nullifying the associated wastages will reduce lubricant consumption and save great cost to the company. Every industry is vying desperately to optimize its available resources. The thought process and strategies may differ but the focus is Business Excellence in terms of reduced input Costs and optimum Throughput. One of the most effective strategies is to focus on lubricants and work on an action plan to be lean in its usage, to be proactive in its preservation; and to be cautious in preventing its contact with foreign material and environment dust (solid contaminants).

Lubricant Functional Reliability (RLubricant): Depends on many factors

Detection of lubricant issues in their budding phase followed by prompt corrective actions could be a game-changer. This is a simple approach yet the most effective one. It is a known fact that moisture and solid contaminants hinder the normal working of lubricants and decrease their lubricating properties. Somehow, the environment dusts in the metal and mining industries; cement and power units find their way into the lubricants. Lubricant Functional Reliability (RLubricant) depends upon the Reliability (Success) of a series of activities of lubricant management. Each activity has its own failure chances. Success rate has equal probability yet it can be assured through established proactive measures in place. All the activities of lubricant management are equally important. Do All or Do None if they are in a series. (Fig. 1)

RLubricant = R1 x R2 x R3 x R4 x R5 x R6

(If any activity of the series has a negative outcome, Lubricant Reliability becomes Null and Void)

RLubricant = 1 x 1 x 1 x 1 x 1 x 0 = 0 (Costliest if we fail in any one or two activities in series)
RLubricant = 0 x 0 x 0 x 0 x 0 x 0 = 0 (Cheapest as nothing has to be done)
RLubricant = 1 x 1 x 1 x 1 x 1 x 1 = 1 (Ideal/ desired where all the activities in series must be a success)

Fig.1: Series of Activities for Lubricant Reliability

Contaminants in Lubricants: Oil and Grease

Lubricant contaminants could be metallic or non-metallic. Metallic with a normal wear pattern is desirable but non-metallic in any amount in lubricant is a point of concern. Contaminant types have been elaborated here. (Fig.2)

Contaminants Detection Techniques and Methods:

Contaminant visualization is the key. There are many techniques and methods available to know the presence of contaminants in the lubricant. All of these help in the detection and assessment of the potential role of these contaminants in negating the overall lubricant's Functional Reliability. (Fig.3)

Fig.3: Few contaminant detection techniques

Lubricant Contaminants: Common Reason of Most of the Failures of Industrial Machines

More than 80% failures of the hydraulics and lubricant systems are linked to contaminants. Contaminants damage the equipment components in 3 ways: Abrasion, Erosion, and Fatigue.

Defect and Failure Total Cost to Company: An illustration

Contaminated lubricants are technically useless for machines. In fact, they are the worst enemies to the engineering components they touch or interact with. Some dusts are abrasive in nature. If they are used then they will damage the vital components leading to premature failures and costly breakdowns. As a result, contaminated lubricants become just a waste which increases the

input cost to company. The lubricant consumption increases which is a natural resource loss and additional cost to company. Prevention is always better than cure. So, the lubricant must be prevented from dust ingression into it.

Contaminant lubricant can result in a potentially high loss to the company. An illustration (Fig.4) is given below to show how seal damage due to lubricant contaminant could lead to a potential high loss to the company. The damaged seal if not attended can cascade into a total asset failure resulting in various losses – Production,Safety ,Environment , Asset Integrity and Morale of People.

Suggested Contamination Codes: NAS 1638 and ISO Codes

A guide for Contamination Code for hydraulics and lubricating oil is given below. This serves as a reference to assess the contamination level in a lubricant. This also serves as a basis for taking precautionary measures of lubricant filtration; replacement or flushing out the contaminated lubricant. This also provides a clue regarding the contaminant ingression points or contaminant generation points. Knowing the source of contaminants helps in developing countermeasures.

Knowing Contaminants in Lubricants: Step towards Lubricant Functional Reliability

A Lubricant Manager must understand the source of contamination. Knowing the contaminants may be easy yet sometimes very complex and may involve the microscopic studies of the wear debris.

Once the source of contaminants is known then counter-measures become easy. Controlling entry of contaminants into the lubricant or filtering out contaminants from lubricants helps to achieve a Reliable Lubricant Program.

Physical Interpretation of NAS Class: Through Photograph

Contaminants can be quantified in various size ranges which suggests which particle size range is a concern and can have a high potential of lubricant deterioration or have a damaging effect on engineering components. Too small particles in large quantities may lead to sludge formation making lubricant properties ineffective. Large particles will cut down the lubricant film thickness and may reduce the working clearances. Each size range has a limit of acceptance as per NAS 1638. A typical case is shown here to have a physical understanding of what the NAS value denotes. Size-wise particles have been counted and NAS level determined.

The NAS level is displayed in the form of dust concentration and distribution with possible size ranges. This is just a reference to and may not exactly imitate the NAS level and physical particles shown. But it will be very similar to the one shown here. (Fig.5)

Fig.5:            Reference             image            for            showing            particles            and            NAS            level

Visualization of Contaminants: Some Microscopic Images are shown here

A few high-resolution microscopic images are shown here (Fig.6) to show what contaminants look like. This gives a clear understanding of the internally generated contaminants and the ingressed foreign particles into the lubricants. Visualization helps to point out the causes of contaminants in the lubricants. This also suggests the extent of damages that occurred to the engineering components which are crucial for maintenance decisions and avoiding costly failures.

Conclusion:

The flow path of lubricants inside company premises must be known to any Reliability Manager. This allows an understanding of the possibilities of contaminants entry into the lubricants. The skill of lubricant technicians is equally important when they handle lubricants. The tools and containers used for lubricants must be contamination-free. Transferring lubricants to usage points is very critical as there is every possibility of environmental dust or moisture finding entry into the lubricant circuit. Scheduled inspection and monitoring will be of great help in restricting the entry of foreign contaminants or checking the cascading effects of the internally generated wear particles. Basic knowledge of contaminants will definitely help to save the precious resource called Lubricant (oil and grease). Contaminant-free lubricant will reduce the breakdowns of production-critical industrial assets. This will help the industries to produce more and more products safely to exceed their production targets, and increase their profitability ratios.