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There are several different methods of industrial lubrication. It can be difficult to choose the one that best suits your applications and processes, and to ensure that your chosen method results in efficient lubrication and long term cost-savings.
Lubrication methods can vary in both cost and efficiency, but familiarising yourself with the different types of lubrication method can offer significant improvements to your industrial maintenance, long term reduction of lubrication cost, and dramatic reductions in breakdown and repairs.
Some companies employ one lubrication technique across their entire operation, others use a variety of lubrication methods for different applications in the plant. There is no magic formula for the right industrial lubrication programme, but knowledge and research is the best way to ensure you run at optimal performance.
Often, companies select a lubrication method based on what they’ve done historically. Chances are there’s a better way, read on to learn the benefits of different lubrication methods.
Each lubrication method has different benefits, some more than others. They key to selecting the correct technique is choosing the one which will offer you the most reliability, convenience, and cost savings, once you factor in maintenance hours, system costs, and repair costs.
Manual lubrication is certainly the cheapest lubrication method, and requires the least equipment – at its simplest just a grease gun and some grease. It’s the traditional method of lubrication, grease has been smeared on by hand since Roman times, and companies have been giving machinery a few strokes of the grease gun for around one hundred years.
Naturally, as with most industrial processes, the oldest technique is rarely the easiest or most efficient! Manual lubrication can be effective, but it is by far the hardest technique to get right, and therefore the most susceptible to human error and machinery failure.
Manual lubrication is often carried out on a time-schedule, to fit in with the maintenance team’s busy work schedule. For example the maintenance crew might go round the plant every Wednesday afternoon, applying 4 shots of grease to every bearing.
This is the opposite to how a lubrication program should be executed. Each bearing or lubrication point should have its own lubrication plan, with highly speciailised frequency and volume specifications to be rigorously followed.
Employing an effective manual lubrication program is very difficult, and requires serious commitment, but it can work if well managed. However, not only does it introduce the potential for human error, it is incredibly time consuming. Manual lubrication of a large industrial plant can cost hundreds of maintenance hours per year. Contrast this to some other techniques which can take just a few hours per year, and the expense saved on system installation is lost several times over in maintenance hours.
Furthermore, manual lubrication can result in a detrimental cycle of over-lubrication followed by under-lubrication. Many operatives simply pump grease into a bearing until they see it seeping out. This leads to severe over-lubrication, leaving the grease no room to move when the bearing starts moving. This results in churning of the grease, which leads to increased temperatures, and eventual solidification of lubricant. This renders the existing grease useless, and blocks the ingress of new grease.
Single point lubricators are compact little lubrication units, that are commonly fitted directly into a bearing or lubrication point. As the name suggests they are only designed to service one lubrication point, generally because they don’t generate enough pressure to reliably service more than one.
There are different types of single-point lubricators, classified by the source that powers them. Knowing the strengths and weaknesses of each type is necessary to ensure you spend your lubrication budget wisely.
Spring lubricators are an old style of automatic lubricator. Whilst you will still find them available to buy, the technology has been superceded by lubrication methods which produce a more reliable method of lubrication, such as gas-driven or motor-driven lubricators.
As with all single point units, spring lubricators are easy to install. The main advantage is that they are cheap. They can also be refillable, which means that they offer a low-cost lubrication technique. Unfortunately, the benefits of spring lubrication are hugely outweighed by the disadvantages. They offer a crude method to lubrication, which is generally outdated in modern lubrication practices.
Spring lubers don’t generate a consistent pressure, and therefore changes in backpressure from the bearing or machinery can dramatically affect the flow of lubricant from the unit. The variation in pressure can be as much as 10 bar from full to empty, which highlights the dramatic difference in lubrication.
they tend to over-lubricate for the first third of the dispense cycle, again leading to churning, overheating and caking of lubricant. This is followed by under-lubrication and excessive wear on the components. So although spring-driven lubricators are cheap to install, they offer false economy when considering the long term effects of inefficient lubrication.
The lubricant flow rate will also be significantly affected by temperature, as well as the age and the grade of lubricant. This makes even vaguely precise control of lubrication incredibly difficult. Also, because of the variation in pressure, a spring-powered lubricator will introduce a cycle of over/under-lubrication during the course of its dispense cycle.
Electro-chemical lubricators are driven by gas pressure. An electric charge is delivered to a chemical, causing a chemical reaction. Gas is produced as a byproduct of this reaction. As the reaction progresses the increasing volume of gas inside the lubrication unit exerts pressure on a piston, which drives grease out of the lubricant reservoir and into the bearing or machinery.
Unlike spring lubricators electro-chemical units build up constant pressure. This helps to eradicate the over/under-lubrication cycle, by delivering a consistent, controlled flow of grease or oil.
In any chemical reaction temperature plays a role in the speed of the reaction, and therefore gas production. it is essential to invest in a quality gas-driven lubricator, to ensure that the unit delivers lubricant relaibly at the rate prescried in the manufacturers program literature. Some electro-chemical lubers are prone to wider variation in lubricant flow, making them less reliable.
You should ensure that the automatic lubricator you choose has a well documented dispense programme table, which shows dispense according to temperature, and should also ensure the unit you choose has a wide operating temperature range. Those units with a narrow temperature range, eg. 0°C to +60°C, will tend to experience an almost total shut down of lubrication at cold temperatures, whilst in warmer conditions flow rate will increase and the lubricator will empty far before its expected life cycle.
Therefore it’s wise to avoid cheaply made electro-chemical lubricators. A cheap unit might seem like a sensible way to save money, but in reality it will probably be far more expensive if reliability issues lead to costly downtime and repair bills. The difference in reliability between a quality unit and a cheap unit can be huge, with failure rates being less than 1 in 1000 on a well made unit, and as awful as 1 in 5 on cheaply-produced units!
Another important aspect to consider is the safety of your chosen electro-chemical lubricator. Despite the obvious dangers, some gas-driven lubricators still in use today produce potentially explosive hydrogen gas. Ensure you choose a lubricator which produces inert nitrogen gas to avoid potentially life-threatening accidents.
Electro-mechanical lubricators commonly use a motor as the means of lubricant delivery. The are different ways in which the motor converts this mechanical power to hydraulic power.
A good quality motor-driven lubrication unit produces significantly more pressure than a gas-driven unit. So it can be used either to overcome higher backpressure from machinery, or to run long feed lines to the bearing or lube point.
Electro-mechanical lubricators naturally cost more than gas-powered lubricators. They are much more complex, containing circuit boards, motors, pumps etc, and therefore cost more to build, They are often re-usable though, the motor housing can be retained and the lubricant reservoir either refilled or replaced. So despite larger initial investment, a high quality and durable electro-mechanical unit does offer long-term economy.
Lubricant flow rates do not vary with a motor-driven lubricator. There are no temperature or pressure fluctuations, so a quality unit will deliver a precise dose of lubricant as specified in the manufacturers programme table. For example, most electro-mechanical units dispense a set volume of lubricant on each dispense cycle, say 1.2ml. If your bearing requires 10ml of grease per day, the lubricator will dispense a 1.2ml shot of lube every 2.85 minutes.
Motor-driven units are not suitable for all applications. Nothing with a motor will ever be certified for an ATEX/UL zone with a persistent presence of flammable gas or dust particulates Similarly you can’t submerge a motor-driven unit like you could with a quality electro-chemical lubricator, so in these applications opt for a gas-driven unit.
Good quality electro-mechanical lubricators can also be used for multi-point installations, providing the unit generates enough pressure. This offers huge savings over using a motor-driven unit for single-point lubrication.
Always check the product specs, as some ‘well-known’ motor-driven units can only service one lubrication point, due to inadequate pressure. A unit such as the Jack Luber, which can feed between 1 and 12 points, costs the same as many motor-driven single-point lubricators, offering huge savings over similar lower quality alternatives.
An automatic lubricator should generate a minimum of around 15 bar to service multiple bearings effectively. The most powerful automatic lubricator on the market generates over 100 bar. These automatic lubrication systems offer a very economical alternative to centralised lubrication systems. They can be used to dispense grease or oil, and can service up to 12 lubrication points, depending on the pressure they generate.
As mentioned, some motor-driven units serve as both single-point and multi-point lubricators, so the cost of the unit is no more expensive – they can cost between €60-300, depending on pressure, reliability, technology, quality etc. In a single-point installation no other equipment is necessary, simply fit the luber into the bearing or lube point. A multi-point installation requires the distribution block, tubing, fittings etc, so the initial cost is higher.
But remember, you’ll only be installing a single lubricator, instead of say 4, 6 , or even 12. The additional installation equipment only needs to be purchased in the initial order, and should last years. So this type of system gives you significant long term cost savings, with only the cost of grease refilling in the future.
Multi-point installations can often be filled by your maintenance team on site. Therefore a high quality, durable automatic lubrication system provides years of lubrication for your machinery, and is cheaply and easily refilled. Some systems even employ a standard grease cartridge, meaning grease refills take seconds with absolutely no tools required!
Centralised Lubrication Systems
Centralised lubrication systems are the most expensive lubrication method available. Depending on the size of the system they can range in price up to many thousands.
For most applications a multi-point automatic lubrication system offers a compact and cost-effective alternative to centralised systems. However, there are applications and circumstances when a centralised system provides the most practical and economic solution.
Despite the vastly higher installation costs, there are applications where there will be no practical option other than a centralised system. When very high volumes of grease are required a centralised system offers the most economical maintenance solution.
How Do Centralised Lubrication Systems Work
Centralised systems can pressure to several hundred bar. This means that they can service a high number of lubrication points. Some very large bearings can have 50 or more lubrication points, so a centralised system can service this type of application more economically than smaller systems.
This type of lubrication system also tends to have a larger lubricant reservoir, and some may even use a 180kg drum of grease. In factories and plant this can be an inconvenience, but in applications requiring high volumes of grease it is an advantage. A larger reservoir means less frequent servicing, which in hard-to-access applications can be a bonus.
For example, a large main bearing on offshore equipment could be 6m in diameter, with 80 lubrication points, each requiring 100ml of grease per week. Because this is such a high demand application this bearing needs a large grease reservoir to feed it. Firstly, the sheer volume of lubricant required demands a large amount of stored lubricant, and secondly the inaccessibility and expense of offshore maintenance means that frequency of servicing needs to be reduced as much as possible.
Centralised systems involve many components, not only driving up the installation cost but also increasing the potential for component failure. Unlike an automatic lubrication system, where not much can go wrong, a centralised system requires constant monitoring and adjustment. They can take up a lot of space, making them impractical for many businesses and applications. Reservoir fills can be difficult and messy, and changing lubricant type requires a lot of line purging.
Centralised systems are therefore much more complex than an automatic lubrication system. They can also require filters & strainers, monitoring devices, alarms, and lots of other components unnecessary in smaller systems. Aside from the obvious cost factor, this makes maintenance much more complicated than an automatic lubrication system, which has a much lower potential for failure. It can also be very difficult to know where faults or blockages have occurred in a centralised system.
How Do Spring Lubricators Work?
A spring lubricator – fairly obviously – uses spring pressure to drive lubricant into a bearing. A plunger-style piston is used in the grease reservoir, and the spring sits behind this piston plate. the spring may be single use or re-usable depending on the manufacturer. The lubricant reservoir is filled, pushing the plate to the top of the unit. The setting is selected, and the pressure of the spring then gradually moves the piston plate, driving grease from the reservoir into the bearing.
Pros & Cons Of Spring Lubricators
Gas-driven lubricators offer by far the most versatile automatic lubricators on the market. A high quality unit can be used in virtually any application. The better ones on the market can even be used underwater, or in explosive zones such as underground mines or metro applications. The most reliable gas-driven lubricator available can even be used for cold temperature lubrication, right down to -40°C.
How Do Electro-Chemical Lubricators Work?
Pros & Cons of Electro-Chemical Lubricators
Electro-mechanical automatic lubricators use a motor to drive the equipment. The price can vary considerably, depending upon a number of factors, and especially the quality.
How Do Electro-Mechanical Lubricators Work?
Some electro-mechanical units employ a small internal pump. The motor drives the pump, which takes lubricant from the reservoir, and forces it into the bearing or lubrication line. Units employing pump style delivery tend to be the most powerful.
Other electro-chemical lubricators use the motor to directly drive a piston.This can be done in different ways, but essentially mechanical power forces the piston towards the bottom of the reservoir, driving lubricant out as it advances. This method is less powerful than using a pump, but it’s also cheaper, so both have advantages depending on the application.
Pros & Cons Of Electro-Mechanical Lubricators
How Do Multi-Point Lubrication Systems Work
The simplest kind of multi-point lubrication system uses an electro-mechanical lubricator in conjunction with other components, to build a network of lubrication lines. The operation of the lubricator itself is identical to the methods described in the previous section, but instead of fitting the lubricator directly to a bearing or machinery, a grease line from the lubricator is fed into a lubricant distribution block.
Grease or oil is delivered from the lubrication unit to this distribution block. The distribution block then has the job of delivering lubricant to each individual bearing or lubrication point within that system. This is usually done in a cycle, to ensure that each lubrication point receives the precise desired amount. If the distribution block fed all the points at the same time each point would receive a percentage of the desired lubricant.
For example, in a 4 point system, the distribution block cycles through points in order, 1, 2, 3, 4, then back to the beginning, 1, 2, 3 and so on. Each point therefore receives say 1.2ml of grease every cycle. If the block fed all the lubrication points simultaneously, each point would only receive 0.3ml per cycle.
Pros & Cons Of Multi-Point Automatic Lubrication Systems
There are numerous different types of centralised lubrication systems. They can be quite confusing, so we won’t go in to excessive details.
A direct centralised system employs a pump to pressure and control the flow of the lubricant, whilst an indirect system just uses the pump to pressure the grease, with metering valves along the lubrication lines to control flow. Things get more confusing here! The indirect system can then be either a progressive (non-parallel) or non-progressive (parallel) system. In a non-progressive system all the metering valves operate at the same time, in a progressive system they operate in sequence. Furthermore, parallel & non-parallel can then be either single-line, dual-line, or multi-line systems.
Centralised systems can also use a variety of pumping methods. Either a pump with separate sealed lubricant reservoir, a pumping station which combines the two, or even simply a grease pump plonked into a barrel of grease.
In essence, each type of system uses a pump to pressurise the grease, which is then distributed throughout the system. At some point the grease will reach a manifold, which will take smaller grease lines to individual lubrication points.
The Pros & Cons Of Centralised Lubrication Systems
Dual line barrel & grease pump system