The success of oil mist lubrication on a scale ranging from just one machine to 30 plant-wide oil mist systems serving 2,000 or more machines at a single site has been a matter of record since the mid-1960s.

Oil mist lubrication is a fully proven and superbly reliable technology.

Oil mist experts with access to many plants and reliability professionals with decades of applicable experience consider oil mist lubrication a fully proven and superbly reliable technology. They have become experts by learning from others, being inquisitive, and considering it their obligation to read books, articles, and conference proceedings on the subject matter.

None of these experts would find requesting or endorsing field trials plausible. Even today, field trials would add nothing to the existing knowledge on the subject. We mention this because the issue arises when uninformed persons call for field trials to prove that oil-mist lubrication is not just wishful thinking.

There was no justification for such demonstrations on the two known occasions when field trials were requested in the 35 years from 1986 until 2021. Perhaps a subcontractor attempted to turn experience-based technical advice into a “make work” project. Or it could have been a matter of “seeing is believing,” and the individuals making the “show me” request hoped they would not need to spend time reading.

Mature technologies like oil mist don’t require prototyping or proof of concept.

Whatever the case, it is inappropriate and wasteful to demand proof of concept and/or selection of beta sites for mature technologies such as oil-mist lubrication and oil-mist preservation. Hundreds of full-scale installations attest to its effectiveness and reliability. Mature technologies are the exact opposite of ideas or pursuits that warrant prototyping.

Storage Preservation: Where Field Trials Still Apply

The conventional methods of equipment preservation using several products discussed in Chapter 13 of our book, Optimized Equipment Lubrication, 2nd Edition (2021), and the suitability of utilizing those protection methods from a technical point of view is undisputed.

Competent manufacturers and vendors have continually improved such products. Their product-summary books and applicable brochures are informative and helpful. All available brochures have been carefully reviewed and, where needed, updated. These updates occasionally include clarifying or amplifying some of the recommendations issued by lube marketers when they align with the field experience of experts.

Today, lubricant technology is accessible worldwide. Accordingly, the recommendations and summaries of major U.S. providers of industrial lubrication could probably be joined by similar summaries available in electronic form from providers in other parts of the world.

Clarifying Deliverables in Lubrication Projects

Expert providers of oil-mist lubrication and other preservation technologies usually have access to transparent polycarbonate or plexiglass (acrylic) demonstration models. For example, a transparent bearing housing replica equipped with ball bearings and a steel shaft is an ideal visualization tool. Mechanics, operators, supervisors, and managers can readily observe oil mist in operation.

Generally, expert providers agree to develop, sign, and adhere to contract clauses showing machine interiors in the “as-received” versus the “as removed from storage” condition.

The provider would have a service contract with the client and be able to monitor the storage yard, quality of instrument air supply, adequacy of lubricant, and so forth. The contract terms may include corrosion-monitoring details and an up-front definition of remedies.

Takeaways for Smarter Lubrication Practices

What have we learned here? Best practices do not involve reinventing the wheel. However, they require familiarization with the steps and procedures that have allowed the competition to prosper.

Best practices don’t reinvent the wheel—they use proven solutions.

Demonstrations, videos, and/or scale models may facilitate familiarization with best practices. Such items are often available at minimal cost. Some can be purchased, others rented or leased.

However, when it comes to oil-mist technology, which has been successful for decades at well over 3,000 plant sites worldwide, field trials proving that it works (in-plant “proof of concept”) are never justified.

On the other hand, in-plant demonstrations showing operators how oil mist works are part of an intelligent training routine that makes sense.

In most industrial facilities, many lubricant application tasks are performed manually using either a grease gun, an oil can, an oil top-off container, or an aerosol spray.

Done correctly, manual lubrication can be an efficient and effective way to keep smaller equipment running reliably while also allowing us to inspect the asset easily at the same time.

But is there a better way? Sometimes, the answer is a resounding “yes” using single or multipoint automatic lubrication systems.

Automatic Lubrication Overview

Automatic lubrication systems range from simple single-point lubricators to large, complex multiline systems that lubricate hundreds of individual lubrication points. While some are designed just for grease, others can be used with either oil or grease, offering flexibility to accommodate various scenarios.

Automatic lubrication systems vary widely in design and layout. However, they all offer similar positives while having some very real negatives if they are not properly selected, installed, and maintained.

Perhaps the most significant benefit of automatic lubrication is ensuring that a bearing or other lubricated point receives the optimum amount of lubricant.

With manual lubrication, there is always a tendency to add too much initially, creating a period of oversupply.

Conversely, the bearing may be under-lubricated as we reach the prescribed relubrication interval. With automatic lubrication, we can add a smaller amount of lubricant over a shorter time interval, helping always to maintain an amount closer to the ideal quantity (Figure 1).

Aside from optimizing lubricant volume, automatic lubrication can also help in applications where it is difficult to access the lubricated component safely during normal operation.

In mobile applications, using a central greasing system to lubricate pins and bushing can also help to purge contaminants out of the bushing. This is particularly useful in off-highway applications where high dust and dirt ingression can cause significant wear problems.

 Perhaps the biggest downside to automatic lubrication is the false sense of security or a so-called “set-it-and-forget-it” mentality. Left unattended and uninspected, automatic lubrication systems can stop working, become plugged, or run empty.

Often, automatic lubrication systems need just as much and sometimes more maintenance to ensure proper operation.

Single-Point Automatic Lubricators

The simplest type of automatic lubricator is the single-point auto-luber (Figure 2). As the name implies, the automatic lubricator is connected to a single point, often a pillow block or other bearing housing. Single-point auto-lubers are commonly used with grease and are a good option where safety concerns preclude manual lubrication.

Most units can be adjusted to vary the quantity and frequency of lubricant and come in different designs that use either a prefilled cartridge of grease or a grease zerk for refilling.

The simplest form of single-point lubricator uses a spring and plate design. By filling the reservoir, the plate compresses a spring. Over time, as the bearing rotates, the force created by the compressed spring in conjunction with the centrifugal force of the rotating bearing causes grease to be injected into the housing.

Spring-type auto-lubers are probably the most unreliable. Over time, the spring may weaken or break, or the force generated may be too low to inject grease into the housing effectively.

Likewise, changes in ambient temperatures can affect both the lubricant viscosity and grease consistency, resulting in under or over-lubrication.

In some applications, such as explosion-proof atmospheres, some auto-lubers use a chemical reaction to generate gas.

As the gas expands, the force causes a diaphragm to push grease into the housing. Like spring-activated auto-lubers, ambient conditions greatly influence how effective gas-activated auto-lubers work.

In cold climates, the reaction rate may be too slow to generate enough pressure, while in warmer temperatures, the reaction may work too well, injecting too much grease into the housing.

The most reliable single-point lubricators use a motor and positive displacement pump to inject the lubricant. These can be hardwired or battery-activated and generate hundreds of PSI of pressure. In some cases, they can also be connected to the plant’s PLC and DCS system to stop pumping if production shuts down.

Some single-point lubricators can be used with divider blocks to distribute lubricant to as many as sixteen lubrication points nearby. These can be particularly helpful in applications such as conveying systems where many grease-lubricated pillow block bearings can be found at the head or tail of the conveyor.

Multipoint Automatic Lubricators

Multipoint automatic lubrication systems are used for distribution across a wider area. Multipoint systems can be divided into two general categories: parallel (non-progressive) or series (progressive).

In non-progressive systems, a pump pressurizes a supply line with lubricant. Divider blocks connect the grease supply line to individual application points, which can be uniquely adjusted to dispense different quantities of oil or grease (Figure 3).

While parallel systems are inexpensive, they have some drawbacks, most notably a limited distance range, particularly in cold climates. At the same time, each injector needs to be periodically inspected and tested using a grease gun to ensure both the supply line and injector are functioning.

Progressive Multipoint Automatic Lubrication Systems

Single-line series or progressive systems are slightly more complex and use injectors that are connected in series.

The supply line is pressurized and primes and fires the first valve. This, in turn, primes and pressurizes the second valve, and so on Figure 4). Series systems can be used over a slightly longer distance since they carry more pressure to a single lubrication point.

The valve blocks are often automatically monitored for pressure and alarmed to ensure the system is still functioning. The biggest drawback for any series system is the progressive nature of the system, whereby any valve failure early in the series will result in no lubricant being dispensed further down the line.

In applications where oil or grease has to be dispensed over large distances or where high-viscosity oils or thicker greases are in use, it is common to use a dual-line parallel system.

Like the single-line parallel system, a dual-line system has two lines that pressurize and de-pressurize the system to feed multiple lubrication points through adjustable injectors.

Automatic lubrication systems are not foolproof. They must be inspected, topped up, tested for obstructions or failed injectors, and properly maintained. Likewise, we need to consider the viscosity of the oil or thickness of grease to be used, particularly at very high or low ambient operating temperatures.

So, too, thickener type should be considered. Some thickeners have a higher bleed rate than others, causing grease to separate in a multipoint lubrication system. This can result in plugged lines and a lack of lubrication.

Used judiciously, the case of automatic lubrication is clear. Whether to ensure that just the right amount of lubricant is supplied at the right time or to help ensure that we don’t expose our lube techs to unnecessary safety risks, automatic lubricators can play an essential role in any lubrication program.

But they are not and never will be, an excuse for laziness or no maintenance. Choose them carefully, inspect them regularly, and never “set it and forget it.”

This presentation was presented at the Lubrication Reliability Virtual Summit on September 20, 2023 by Blair Fraser, with UE Systems.  Discover how UE Systems cutting-edge technologies are revolutionizing maintenance practices, enhancing equipment performance and operational efficiency.

Blair explores the latest advancements in wireless ultrasound, vibration, and temperature sensors, specifically focusing on bearing monitoring and lubrication. He uncovers the power of advanced sensors and data analytics that enable real-time monitoring and condition-based lubrication.