Bearing grease: application methods

Relubricating the bearing grease is of great importance to ensure the longevity of your ball- and roller bearings. Bearing grease provides a smooth process with as little friction as possible. Bearing grease is also necessary to avoid direct contact between the rolling elements and their treads.

CONTENTS

Regular grease lubrication

Most applications require that you relubricate or replenish your bearing grease. Though the bearing grease stays put and barely leaks, old grease can dry out eventually and therefore be less effective. This is ecause the base oil spreads out over the moving parts of the bearing and the thickener vaporises through the heat.

How you replenish or renew your bearing grease depends on the application it is used for. Occasionally a machine has a built-in ‘replenishing mechanism’ which makes lubrication quick and easy.

Assortment bearing grease

Discover the assortment of bearing grease and find the right product for your application.
View the assortment

2. Tools and resources for your application

If you wish to manually apply your bearing grease, there are certain tools available. These tools ensure that you work cleanly and can distribute the bearing grease precisely and evenly.

These are widely-used tools to distribute bearing grease manually:

• Grease gunAdvantage: a grease gun prevents contamination in a machine. The gun makes it easy to accurately apply the grease onto the bearings. Uses: agriculture, industry, automotive industry and in construction.
• Volt grease gunAdvantage: a volt grease gun prevents you from using too much or too little bearing grease. This gun comes with a grease meter, so you can measure your doses accurately. Uses: agricultural vehicles, bearings and (high-speed) machines in an industrial or production setting.
• Bearing packerAdvantage: a bearing packer fills open bearings completely with bearing grease without risk of contamination. Uses: e.g. tapered roller bearings.
• Grease filler pumpAdvantage: you can quickly and hygienically clean your grease gun or bearing packer with a grease filler pump. Uses: in combination with a grease gun or bearing packer.
• Grease pumpAdvantage: the grease pump should be used if you must use large quantities of grease. Uses: large bearing casings, applications with several lubricating points and containers of central lubrication systems.
• Grease meterAdvantage: Instantly check how much grease needs to be applied with a grease meter. You will not have to calculate your grease use and avoids either an excess or lack of grease used. Uses: use in combination with a grease gun..

Together with these tools, there are also accessories that can make applying or replenishing grease easier, cleaner and more precise. Accessories include connecting pieces, couplings, nozzles, head caps and grease-resistant disposable gloves.

3. Application methods for bearing grease

There are two methods available for lubricating or replenishing bearing grease. These are then divided by different methods.

Manually

1. With a (volt) grease gun
2. With a grease pump (large volumes)
3. With a bearing packer (open bearings)

Automatically

1. With an automatic single-point lubrication unit.
2. With an automatic multi-point lubrication unit

Perma is an A-brand with ready-to-use automatic systems for lubrication.

How much bearing grease do you use?

The amount of grease you should use is indicated through a percentage. The percentage indicates the grease volume in relation to the internal space of the bearing. If the bearing needs to be filled up entirely, the percentage will be 100 percent. The manufacturer of your bearing usually designates the standard percentage for your bearings. Usually this is between 20 and 40 percent.

Establish the quantity

The percentage is largely determined through the rotational speed of the bearing. We recommend a 50% to 65% bearing grease when the rotational speed is less than 50% (of the maximum speed). For a rotational speed that is higher than 50 per cent, the recommendation is a bearing grease percentage of 30% to 50%.

The percentage is also dependent on these factors:

• The design of the housing
• The available space
• The specifications of the bearing grease
• The ambient temperature

Where to apply the bearing grease

Most bearings come with a handy opening for relubrication. This opening also ensures that the grease reaches the core of the bearing. If you relubricate the bearing here the old grease will be pushed outside, and the new grease will not staple on top of the old

If it is not possible to relubricate at the core, then you should relubricate on one side of the bearing. Then the old grease has a chance to pushed out from the other end. Some machines typically come with either an opening or a way for the old bearing grease to find its way out through sealing lips.

For applications that are being used in industries with abrasive particles, the bearing grease also serves as a filter to collect these particles. By consistently relubricating these bearings you also purge them of the contaminated grease from the bearing housings. Please note that you must relubricate the bearings in time before the grease has become completely contaminated.

Assortment bearing lubrication systems

Discover the assortment of lubrication systens and find the right product for your application.
View the assortment

4. What method works best for you?

Usually, the manual method is chosen in applying bearing lubrication. When there several lubricating points or when lubricating is complex, one typically chooses the automatic method. It is best to choose a specific method when it comes to certain applications or industries.

Application / Industry	Lubrication method
Machines and mechanisms with closed bearings	Manual lubrication with a (volt) grease gun
Machines and mechanisms with open bearings	Manual lubrication with a bearing packer
Machines and mechanisms with a large number of bearings	Manual lubrication with a grease pump
Torque sensitive applications where the grease must remain in place	Manual lubrication with grease plating
Minuscule bearings or bearings from instruments	Manual lubrication in a clean environment
Machines and mechanisms with difficult to reach lubricating points (e.g.: pumps, ventilators, blowers, transport tires and chains)	Automatic lubrication
Factories and other industries with a lot of lubricating points (which could have different lubrication frequencies and needs)	Automatic lubrication
Machines and mechanisms where lubricating points may be behind safety cages	Automatic lubrication
Machines and mechanisms where lubricating points are at a high altitude	Automatic lubrication

5. Manual vs. automatic lubrication

Manual lubrication knows a few drawbacks. First, most applications must be brought to a halt which requires employees. When the lubrication isn’t done properly, either by smearing too much or too little, this may lead to problems in the future.

Too much grease can contaminate the product whereas too little grease increases the chance of abrasion, premature repairs and high repair costs. Automatic smearing minimises the grease use, waste, the threat of contamination, human error and defects. It also optimises the bearing performance, grease amounts- and frequency, the accuracy, safety and use per time unit.

That said, manual lubrication is a good choice for many applications. Please keep in mind that you must work accurately and sterilely for which you can use tools and accessories like a grease gun and disposable gloves. There are also lubrication management tools available that stipulate the right amount of lubrication necessary.

Crucial: using bearing grease on time

Using bearing grease on time is crucial in ensuring an optimal lifespan of your bearings because it prevents the chance of contamination and defects. ‘Timely’ lubrication can be tricky to predict. You need to account for these variables:

• The bearing temperature when the machine is in use
• The number of daily hours that a machine is in use
• The bearing size
• The rotational speed of the bearing

Sometimes one machine will have bearings with different intervals, some will require daily lubrication whilst others only require a monthly lubrication check. In that case it’s wise to also do a thorough check of your machine once a year: wash off the old bearing grease and relubricate the machine from scratch.

One tip: send used bearing grease to a lab for further analysis to establish which bearing grease is right for your application.

Advantages of relubricating in time (and the risks if not)

Bearing grease is necessary to prevent bearing defects and is vital for the lifespan and functioning of your bearings.

Advantages of timely lubrication	Risks of not properly lubricating
Higher productivity of the machine	Higher energy consumption of the machine
Higher operating reliability (through a higher reliability of the machine)	Machine downtime (through friction)
Durable machines	Abrasion, noise pollution, heat development (through friction)
Better operational capacity	Product contamination
Bigger maintenance intervals	Higher company-, maintenance- and reparation costs
Higher level of safety	Bigger chance of work accidents

6. Common mistakes and guidelines

During lubrication, many of the mistakes are usually repeated offences. Please make sure that you prevent the two most common mistakes by following the guidelines below.

Mistake 1: lubrication is only based on time
Lubricating a machine once or twice per month is consistent. But if the machine hasn’t been making enough hours to require new bearing grease, this means that there is too much grease in the bearing. If a machine clocks too many hours or if the grease evaporates due to a high temperature, it will create friction before (re)lubrication. This is exactly what a bearing grease should prevent from happening.

Guideline: Monitor, measure and map the friction with ultrasonic waves.. You will know exactly when you need to relubricate your bearing grease.

Mistake 2: too much or too little bearing grease
Using the right amount of bearing grease is crucial for the efficiency of the bearing and minimising the amount of friction. If you use too much grease, this will cause an excess amount of pressure in the bearing that will press the rolling elements towards the outer ring. In short: the bearing has to work much harder, causing a temperature increase, which then decreases the effectiveness of the grease.

When the heat increases, the base oil separates from the thickening agent. Too little grease has an adversary effect on the longevity of the bearing.

Guideline: Check the friction level with ultrasonic waves when you apply the grease. Carefully apply the grease and measure before you apply more. Stop applying grease as soon as you notice an increase in the decibel level.

Requirements of measuring instruments for the friction level

• The instrument provides measuring feedback
• The instrument has a digital decibel scale
• Preferably, the instrument has multiple condition indicators in order to measure which bearings need bearing grease and which bearings need to be replaced

Practical lubrication management tools

For the optimal lubrication of all bearings in your machines or industry, you can use lubrication management tools. Think of software like the LubeSelect for SKF-greases (software for lubricant selection and when to lubricate), the SKF lubrication planner (tool for lubrication planning) and the SKF Dialset (provides you with information for re-lubrication intervals and quantity calculations).

With thousands of variations available, it’s no wonder the deep groove ball bearing is the most widely used of all ball bearings.  These bearings have low friction and are optimized for low noise and low vibration, which enables them to run at high rotational speeds. They can accommodate radial and axial loads in both directions and are easy to mount, whilst requiring less maintenance than other bearing types.

What are the features and applications of deep groove ball bearings?

Features & Benefits

• Capable of very high speeds
• Can carry relatively high radial load
• Ability to carry some axial load in both directions
• Quiet running
• Low maintenance
• High running accuracy

​Applications

Deep Groove Ball Bearings have limitless possibilities. They are the most widely used bearing on the market today and are used in everything from Gearboxes & Electric Motors to Textile machines and Hand tools.

Bearing product manager Andy Fletcher has been asked hundreds of questions about bearings during his career. In this series of articles, Andy shares some of the most common questions and provides in-depth answers to help you select the best bearing for your application. 

WHAT DO I NEED TO CONSIDER WHEN SELECTING A BEARING? 

Bearings are one of the most critical components for any piece of industrial machinery. These high-precision components are essential for reducing friction and carrying load during rotational motion. You won’t find many industrial applications which don’t have at least one bearing.  

There are thousands of bearings on the market, including ball bearings, cylindrical roller bearings, tapered roller bearings, needle bearings and bearing units. Whilst ball bearings are the most common type of bearing, each type has its own features and benefits, making it suitable for certain usages and applications and unsuitable for other operating environments.  

Order the perfect bearing for your application today 

Selecting and installing the right bearing is crucial for ensuring optimal machine performance. Not only will the right bearing increase the performance of your machinery, but it will also extend its service life whilst reducing your downtime and maintenance costs. 

Choose the wrong bearing and you risk reducing your efficiency, increasing your maintenance requirements and potentially even causing expensive downtime.  

However, it’s not always easy to choose the right bearing for your application. There are many different factors you need to consider when selecting a bearing, such as speed, load and operating conditions.  

If you’re unsure, it’s always best to consult a bearing specialist for advice on the best bearing for your application.  

Here are some of the factors you should take into consideration when choosing a bearing for your application.  

AVAILABLE SPACE 

The first thing to consider when you’re selecting your bearing is the installation space available. No matter how suitable a bearing is for your application requirements, it can’t be fitted if there isn’t space available.  

Some types of bearing take up more axial space than others, so there are always alternative options if the most suitable bearing is too large for your application.  

The space available will determine the bore size and outer diameter of the bearing you select, so it’s important that you find out this information before choosing your bearing.  

LOAD RATING 

There are two different types of load that we talk about when we’re looking at bearing specification: radial load and axial load. Radial load is perpendicular to the shaft, whilst axial load, also known as thrust load, is parallel to the shaft.  

Different bearings are able to support different types, directions and magnitudes of load. For example, a cylindrical roller bearing can withstand a high radial load whilst the thrust bearing supports a predominantly axial load.  

When a bearing is subjected to both radial and axial load at the same time, this is known as a combined load. Bearings, such as the tapered roller bearing, have been specifically designed to accommodate combined loads.  

In some applications, bearings may need to be paired to balance variable load conditions, or to address complex load conditions. In this situation it’s best to consult a bearing specialist to receive expert advice on the best bearing arrangement for your application.  

ROTATIONAL SPEED 

Every bearing will have a speed at which it performs optimally, along with a maximum operating speed. An application which operates at high speeds will need a different type of bearing to an application which operates at slow speeds.  

Certain bearings such as the deep groove ball bearing and angular contact bearing are designed to be able to withstand high speeds. However, this is often at the expense of some load carrying capacity. Cylindrical roller bearings and needle bearings are often available with a cage which allows for higher operating speeds. Again, this typically reduces the load carrying capacity of the bearing.   

If you choose a bearing which does not have a high enough speed rating, it’s likely that your bearing will quickly fail due to fatigue, causing expensive downtime and requiring replacement.  

RIGIDITY 

Applying load to a bearing causes elastic deformation. This begins with the areas of contact between the rolling elements and the raceway. The rigidity of a bearing describes the relationship between the bearing load and the resulting elastic deformation. The higher the rigidity, the lower the deformation.  

In many cases, the elastic deformation of bearings is minimal and can be ignored. However, in some applications such as machine tools, the rigidity of the bearing is critical. 

Roller bearings are often the bearing of choice where high levels of bearing rigidity are required. The rigidity of other bearings such as angular contact bearings and tapered roller bearings can often be increased through preloading.  

MISALIGNMENT  

Misalignment can be caused by a number of things including load, inaccuracy of the shaft and housing and mounting errors. Whilst some bearings are able to tolerate misalignment, others may become damaged as a result, leading to premature bearing failure. For this reason, it’s important to consider the level of misalignment within the application before bearing selection takes place.  

Bearings which have self-aligning capability are typically chosen for applications where misalignment is present. This may include the spherical roller bearing and self-aligning bearing which are able to absorb misalignment and help to prevent damage to surrounding machinery.  

RUNNING NOISE 

In some operating environments, low levels of running noise may be important. The majority of rolling bearings generate minimal levels of running noise. However, some electric motors and measuring instruments may demand further reduced noise levels during operation.  

Deep groove ball bearings are typically the bearing of choice where low noise levels are critical. Adjustments can also be made to bearings such as cylindrical roller bearings to further reduce the noise levels during operation.  

OPERATING ENVIRONMENT 

Every application will have a different operating environment. It’s critical to understand the conditions in which your bearing will be operating before selection is made. This includes contamination, temperature, impact and vibration. 

Some bearings are available in materials which are resistant to corrosion or are certified as food-safe, making them ideal for industries such as chemicals, food and pharmaceuticals. Others have been specifically designed for operating at high temperatures or withstanding heavy shock loads and high levels of vibration.  

Understanding the operating environment of your machinery will help you to choose the right bearing for your application, along with the most appropriate sealing solution and lubricant to support it. This will give your bearing the best possible chance of achieving a long service life, keeping your downtime to a minimum and optimising your productivity.  

BEARING INSTALLATION 

How you’ll install and remove your bearing will depend on the type of bearing, your operating environment and your individual preferences. However, it may also be influenced by the space available.  

Bearings which can be taken apart are generally easier to install and remove. This typically includes cylindrical roller bearings, tapered roller bearings and needle roller bearings. These bearings are ideal for applications where regular inspections are required.  

Bearings with tapered bores are more difficult to mount as the internal clearance needs to be adjusted during the installation process.  

For applications where regular inspection or maintenance is required, or where the bearing is surrounded by heavy machinery, a split bearing may be a good choice. These bearings are simple to install without the need for dismantling surrounding equipment.  

LUBRICANT 

The choice of lubricant is critical when it comes to reliable and efficient bearing performance. Lubricants help to reduce friction which leads to a reduction in wear and an increase in service life for your bearings. For this reason, it’s essential to consider your choice of lubricant at the same time as specifying your bearing.  

Choosing the right lubricant is just as important as choosing the right bearing. The lubricant you’ll choose will depend on the operating conditions of the bearing including load, speed, temperature and contamination.  

NSK has made a vital contribution to the growth and advancement of the various industries that rely on machinery. As a comprehensive bearing manufacturer, NSK responds to needs in a wide variety of fields.

A surprisingly large number of bearings can be found all around us. Take automobiles, for example: there are 100 to 150 bearings in a typical car. Without bearings, the wheels would rattle, the transmission gear teeth wouldn’t be able to mesh, and the car wouldn’t run smoothly.

Bearings are not used only in cars, but in all kinds of machinery such as:

• trains
• airplanes
• washing machines
• refrigerators
• air conditioners
• vacuum cleaners
• photocopy machines
• computers
• satellites

Bearings enhance the functionality of machinery and help to save energy. Bearings do their work silently, in tough environments, hidden in machinery where we can’t see them. Nevertheless, bearings are crucial for the stable operation of machinery and for ensuring its top performance.

The word “bearing” incorporates the meaning of “to bear,” in the sense of “to support,” and “to carry a burden.” This refers to the fact that bearings support and carry the burden of revolving axles.

The two pictures below show the most basic bearings, known as rolling bearings.

Rolling bearing

(Ball bearing)

Rolling bearing

(Roller bearing)

Rolling bearings are made up of four elements and have an extremely simple basic structure.

Outer ring:

The large ring of the outer race

Inner ring:

The small ring of the inner race

Rolling elements:

Several balls or rollers that are contained in the space between the outer race and inner race

Cage:

Used to fix the position of the rolling elements

The basic function of bearings is principally to reduce mechanical friction. Reducing friction means:

1. machinery will run more efficiently
2. there will be less frictional wear, extending the operating life of the machinery
3. preventing abrasion burn, avoiding mechanical breakdown

Bearings also contribute to lower energy consumption by reducing friction and allowing the efficient transmission of power. This is just one way in which bearings are environmentally friendly.