What are Oil Seals - Guide to what an Oil Seal is used for

What are Oil Seals - Guide to what an Oil Seal is used for

What are Oil Seals – A guide to Oil and Rotary Shaft Seals

Also known as a Rotary Shaft Seal, Shaft Seal, Lip Seal, Elastomeric Lip Seal or any variation of these. It is a simple device for excluding dust, dirt, water or any other contaminant whilst retaining lubricant in rotary shaft equipment. Generally, it has been developed as a means of protecting the bearings of rotating shafts.

In this blog, we attempt to highlight what are Oil Seals and the various Rotary Shaft Seals including Mechanical Face Seals, Water Pump Seals, Gland Packings, and V-Seals that are readily available.

 

What are Oil Seals and how do they work?

The basic principle of sealing is straightforward – the flexible lip is held against the rotating part (usually the shaft) whilst the casing (or O.D.) is pressed into the housing or bore and holds the seal in place. The sealing lip needs some form of lubrication to avoid overheating and is usually energized by means of a garter spring.

What are Oil Seals and the different types?

Many – too numerous to list, covering a vast range of designs, sizes, and materials suitable for a never-ending range of applications. Some designs conform to International Standards such as BS1399 and DIN 3760 for metric sizes and seal types, but the majority have been manufactured to suit particular applications – hence the enormous selection available. This blog is intended to assist in this selection and will consider seal type, materials, and sizes.

What are Oil Seals and how should they be ordered?

The simplest way is to know either the preferred manufacturers part number, the overall sizes of shaft diameter, housing diameter and bore depth, or use our brochure to establish the M Barnwell Services ordering reference. Many of the old traditional names of seal manufacturers have either changed or disappeared in this age of “acquisitions”. If no longer available, we will advise you and offer a suitable alternative seal, from stock whenever possible. If your concern is getting the right seals for the job, you will need to know something about the application as well as the overall sizes. If you have any doubts – contact us, we will help in your seal selection.

What materials are available?

Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile (NBR) is still by far the most common elastomer for “normal” use, whilst Viton® (FKM/FPM) is rapidly replacing Polyacrylate (ACM) and Silicone (VMQ) for high-temperature applications. Viton® also has high resistance to abrasion and chemical attack making it a preferred elastomer. Recent developments in the use of PTFE for Rotary shaft seals has caused widespread interest particularly for high-speed shaft rotation or poor lubrication applications.

How are they used?

Once you have selected the most suitable seal available, considering the environment, temperature, shaft speed, pressure, lubrication availability, as well as the size, of course, the seal should be stored adequately and then fitted properly. Here are a few suggestions that could help:-

Storage and Handling

There is a British Standard laid down for the control of synthetic rubbers. BS 3574 (1989) helps to determine shelf life – for instance, Nitrile (NBR) and Polyacrylic (ACM) are Group ‘B’ rubbers and have a 7-year life, whilst Silicone (VMQ) and Fluoroelastomers (Viton®) are Group ‘C’ rubbers and have a 10-year shelf life. PTFE and Leather do not come into this category but like the others should be kept in the original packing for as long as possible away from direct light, dust, and humidity. Ozone, which can also be produced by battery-driven forklift trucks has a very bad effect on synthetic rubbers. Finally, protect the sealing lip – DO NOT hang the seals on nails, wire etc.

Installation

If the seal is being fitted to original equipment you may have some influence over the shaft and housing bore finish, but if you are replacing a worn seal you still need to take into account the condition of these 2 essential parts. Check for sharp edges and burrs – particularly on the shaft and housing chamfers or you could ruin the seal before you start up. If the shaft is too worn consider using an M Barnwell Services Shaft Repair Kit.

Require More Knowledge?

For more information on the characteristics of Oil Seals click on some of the links below:

For more information visit our Oil Seals page, download the brochure or contact us today.

Oil seal: get to know all the details about this component

 

Fundamental things and its importance 

 

An oil seal, also known as crankshaft retainer, is a small device, but essential to ensure the proper engine operation. It plays a key role in all moving parts of an engine, acting as a physical barrier. This mechanical seal fulfils the dual purpose of sealing a rotary shaft to maintain the necessary lubrication (avoiding leaks) and preventing other foreign matter from contaminating shafts and bearings in the rotary shaft equipment.

It is generally used in the union of two lubricated parts, so that it hermetically seals both sides. Therefore, it guarantees the proper engine operation and helps to maintain the vehicle’s distribution system in better condition.

 

 

 

Oil seal characteristics

 

Several variables must be considered when selecting oil seals. The physical dimensions and materials will vary depending on the environment of use. In addition, oil seals must remain lightweight, compact, and exhibit high self-lubrication performance.

Most oil seals consist of some basic elements that configure their structure, such as the sealing element, the metal case, and the spring:

 

 

 

Dust lip

: prevents particles from reaching the sealing lip.

Sealing lip

: guarantees dynamic and static sealing.

Metal case

: the metal case supports the rotary shaft seal, ensuring the structural stability.

Spring

: spiral shaped, ensures constant pressure and maintains the optimal force to the shaft.

 

 

 

Aspects to consider when selecting oil seals

 

Operating conditions such as the engine’s temperature, position, size, pressure and shaft speed largely determine which individual oil seal composition is most suitable for every individual application.

Some aspects to consider when selecting this component are:

Temperature:

The temperature within the oil seal environment is the main factor that dictates the composition of an oil seal. Generally, there is a range of set temperatures that are optimal for that material. If the operating environment is too cold, the seal may become brittle and, at high temperatures, the seal material may show increased elasticity and become leaky.

Pressure:

As the pressure increases, the radial load and the friction of the sealing lip increase in contact with the shaft. As with temperature, each oil seal has a recommended pressure for optimum performance. Excessive pressure causes the seals to wear more quickly and consequently have a shorter life.

Shaft Speed:

The speed at which an oil seal can operate effectively depends on the previously outlined conditions together with the design of the seal itself. Some designs allow for a range of maximum peripheral speeds and are therefore more suitable for larger shaft diameters. Speeds below and above the recommended range can cause friction and thus impact the sealing material.

 

 

 

Common causes of oil seal failure

 

Like any element of the engine, oil seals are subject to wear. Over time they can lead to possible leaks of lubricating liquid.

Among the most common causes of oil seal failure are:

Installation inaccuracies

, such as placing the seal in the wrong position in its housing or handling it incorrectly.

Improper

use of sealants

.

Imperfections on the shaft

(burr, corrosion, etc.), which will directly affect the service life of the oil seal.

Cracks or swelling

of the component due to extreme temperatures, causing premature deterioration of the oil seal material.

Other maintenance factors, such as

insufficient lubrication

inside the engine.

 

 

 

Oil leak: the most frequent failure of the oil seal

 

Finding oil spots under a parked vehicle can be both worrying and stressful for any vehicle owner. If the seal’s leak is small, oil may start to accumulate on the underside of the engine. But as the leak gets bigger, the oil leak will become visible in the front side of the engine.  

Wear and oil loss remains two of the most frequent signs of engine seal failure and, if not paid attention to, it can give rise to a breakdown in the vehicle’s system. Regular maintenance and routine oil changes minimize the issues associated with oil seals and potential oil loss. 

 

 

 

 

 

Dolz, your safety choice

 

Oil seals included in the Dolz timing chain kits are lightweight, high-precision seals with wear resistance and made from the highest quality materials.

It is recommended to replace all timing elements in a single operation, ensuring an optimal coupling of the components and thus avoiding premature aging and possible future engine failure.

At Dolz we put our almost 90 years of knowledge and experience at your service to provide you with an optimal replacement of your components.

Are you looking for the best solutions for the distribution of your vehicle?

Contact us to learn more about our full range of products!

 

 

 

Oil Seal Buying Guide

Different Types of Oil Seals

Are you looking to keep your machinery free from any unwanted leakages but aren’t sure which rotary shaft seal is right for your needs? This guide will provide you with everything you need to know in order to select the right one for your application.

Oil seals, which are also known as rotary shaft seals, fluid seals or grease seals, play an important role in closing down the gaps between moving and stationary elements of mechanical equipment.

By preventing lubricants from escaping, they protect key components of machinery from being damaged by leaks of various fluids. Everything from car engines to assembly machines use these oil seals to remain free from any harmful interactions that can cause serious and expensive damage to any of their critical parts.

There are a wide range of oil seals to select from for any number of uses, so this guide will break down the most common seals to help you choose the right one for whatever piece of machinery you are working on.

What are rotary shaft seals?

Rotary shaft or oil seals are placed between moving and stationary pieces of machinery to ensure that contaminants, moisture, corrosive materials and abrasives do not damage the various components. They can also prevent unwanted mixing of fluids, including water and oil combining within a machine.

How are Oil Seals made?

First, an elastomer, most often nitrile, is vulcanised to a metal ring. This creates a stiffening effect that includes a specialised metal tension spring directly behind the sealing lip, keeping the oil seal firmly in place against the moving part.

Oil Seal Materials

There are many different materials used to manufacture oil seals.

Leather Oil Seals - Leather Seals, also known as Type L Oil Seals, are most common in components that are subject to dirt and poor lubrication. Since they come pre-lubricated and are able to absorb fluids, leather oil seals are able to provide sealing properties in conditions that synthetic rubber is unable to.

Synthetic Rubber Oil Seals - Styrene Butadiene Rubber oil seals, or just SBR oil seals, offer strong resistance to abrasions and lesions, making them an ideal seal for fast-moving machinery. With the ability to withstand extreme temperatures with its heat-aging qualities, they can be used in outdoor components. They are also seen as more cost-effective oil seals than natural rubber.

Nitrile Oil Seals - Nitrile oil seals, which is the commonly used term for acrylonitrile-butadiene rubber seals, is a very good general-purpose option due to the flexibility of use across a variety of components. The resistance is strong against fats, hot water, gasoline, mineral oils, grease and animal oils, making them the most often-used oil seals. They do not have a wide temperature range, making them a poor choice for machinery that can see extreme changes in temperature.

Viton Oil Seals - A synthetic rubber and fluoropolymer elastomer, Viton is used to make oil seals that provide resistance in both high temperature, up to 250°C and low compression set components. They also offer a high resistance to chemicals and abrasions, so they can be used in elements that regularly interact with petroleum and solvents.

Polyacrylate Oil Seals - Mostly selected for automotive and transmission uses, polyacrylate seals are able to withstand fuel, oil, ozone, sunlight and weather when used. With cars exposed to all these different fluids and elements, they are the perfect choice. However, they should not be used in low temperatures, as their flexibility weakens when cold.

Silicone Oil Seals - Designed to absorb lubricants in order to lessen wear and friction, silicone rotary shafts also offer high thermal resistance and a large temperature range. But, they do not handle abrasions well or interact with oxidized oils.

PTFE Oil Seals - A relatively new and exciting oil seal, the use of polytetrafluoroethylene means that they can withstand dry or unlubricated operations. With a massive thermal range of  -130ºC to +200ºC and a strong resistance to chemicals, they are considered to be the future of rotary shaft seals.

How to Choose the Right Oil Seal

There are several key factors to consider when you are selecting the oil seals for your next project to ensure that you protect your machinery from immediate and long-term damage.

Pressure - Many oil seals can only withstand low-pressure applications, so understanding the compression set of your components is key.

Temperature - Just like pressure, the temperature that your oil seal will be operating in must be known so that you can choose one that can withstand the heat or cold. PTFE have the widest range of temperature, making them useful for machines who can see usage in extreme weather or elements.

Shaft Speed - Considering the speed that the shaft will be moving, the runout, the housing bore and the type of oil being sealed is vital to making sure you select an oil seal that will not suffer from abrasions or spiralling.

Fluid Types - Various oil seals are able to withstand interactions with oils, fuels, grease, water and more. Knowing what type of fluid the rotary shaft seal will be in constant contact with will ensure the longevity of the seal and surrounding components.

Lubricant Amount - Seals will always perform best when lubricated, however in some machines there are more likely to be dry spells. For these cases, selecting a leather or PTFE seal will be beneficial, as both can operate with less lubrication than others.

If you require any assistance in discovering the factors that lead to the right oil seal choices, the Simply Seals Team is happy to assist you!

Find the right Oil Seal for your needs with Simply Seals!

With dozens of specifically-designed oil seals made from a variety of materials, it can be very difficult to understand the best choice for their machinery.

That is why the Totally Seals team is always available to assist you with choosing the correct style, material, and size of oil seal for everything from commercial machinery to hobby car building.

Contact us today to make sure that you select the proper rotary shaft seal that will protect your components and lead to a long, healthy life for all of your machines!