Use a structured approach to identify and define the problem.
To determine the root cause through analysis, and define an appropriate solution.
To describe how to use a range of root cause analysis techniques.
To Identify, evaluate and develop solutions that address the root cause of the problem.
You might know this sound all too well. But did you know that this problem could be caused by the smallest of components?
The component in question is called the O-Ring.
What are the characteristics of the O-Ring?
O-Rings are defined by their
O-shape. They are rotation-symmetric and have a circular cross section.
The inside diameter and the cross section are the functional dimensions of an O-Ring. These two measurements allow you to specify an O-Ring.
O-Rings are usually made out of various kinds of elastomers although other materials like Polytetrafluoroethylene (PTFE) or Polyurethane may also be used.
O-Rings are used for sealing which is core to keeping devices of all kinds functional and safe.
In which of these areas of application do you think that the absence or wrong choice of O-Rings has serious consequences?
.
O-Rings are suitable for a host of different applications and using or choosing the wrong O-Ring for any of these applications could have serious consequences, including machine malfunction and failure, loss of production and an increased risk of accidents.
It is always the small things that matter most.
Click on the reference documents icon for more detail information. Click on the Reference documents icon for more detailed information or click on the Next button to continue.
How do O-Rings work and how are they installed?
O-Rings are used between two components. They can be used as primary seals or energizing elements.
At first you are going to learn how an O-Ring works as a primary seal. Are you ready?
Click on the next button to continue.
If the O-Ring is used as the primary seal it has the main sealing function in the application.
As an O-Ring is self-acting it is functional immediately after installation. No system pressure or speed is required.
Furthermore the O-Ring is double-acting. That means the O-Ring can seal in two directions.
In order to achieve leak tightness an O-Ring always must be compressed. This is called the initial compression and results in the initial sealing force.
The initial compression enables the elastomeric O-Ring to adapt to the mating surface and compensates for production tolerances. Thus, it is essential for the sealing function of an O-Ring.
The leak tightness of the O-Ring increases when under system pressure which leads to the total sealing force.
Click on the buttons to see this principle in action.
The O-Ring is predominantly used in static sealing applications. Generally the direction of the sealing force defines the O-Ring’s mode of application - either axial or radial.
In this chapter you are going to learn about the different types of sealing applications O-Rings can be used for.
Are you ready? Click on the next button to continue.
If the O-Ring is used as an axial seal, the sealing surfaces are at the top and bottom of the O-Ring. The O-Ring seals in axial direction in flanges and cover plates, etc.
In axial sealing applications the direction of pressure is important for a proper O-Ring layout. Internal or external pressure is simply equivalent to a pressure difference between the inside and the outside of the axial seal housing.
Click on the tabs for detailed information about this differentiation.
External pressure
In this application the O-Ring works as an axial seal with external pressure.
Internal pressure
In this application the O-Ring works as an axial seal with internal pressure.
If the O-Ring is used as a radial seal, the sealing surfaces are on the inside and outside diameters of the O-Ring. The O-Ring is then used as a piston or rod seal.
For radial sealing applications we distinguish between the inner and the outer sealing.
Click on the tabs for detailed information on this differentiation.
Outer sealing
If the O-Ring is used as a piston seal the O-Ring is placed in a groove on the piston and the sealing area is at the outside diameter of the O-Ring.
Inner sealing
If the O-Ring is used as a rod seal the O-Ring is placed in a groove in the bore and the sealing area is at the inside diameter of the O-Ring.
Depending on whether the components are moving or not, the O-Ring works as a dynamic or static seal.
Click on the pictures to learn more about the differences between static and dynamic sealing.
Static sealing
Static sealing - as seen on the previous pages - is the most common field of application for O-Rings. Here the contact area of the O-Ring does not move.
Dynamic sealing
O-Rings in dynamic applications are recommended only for moderate service conditions. They are limited by the speed, the stroke and the pressure against which they are sealing. With dynamic sealing the contact area moves.
In the example the contact area moves in a linear direction.
O-Rings can also be used as energizing elements. In this case, the O-Ring has a static sealing function and provides the necessary initial tension to keep a non-elastic seal in its place.
The principal element is a PTFE seal. As PTFE is non elastic, the function of the O-Ring is to give the PTFE seal the necessary initial tension so that its sealing edge is pressed to the counterpart.
As you have learned before, O-Rings are used in a variety of different technical applications. Each sealing application puts specific requirements on the sealing elements.
It is essential to take into consideration both the advantages and disadvantages of the O-Rings when assessing its suitability as a sealing element. Click on the tabs for a brief summary of the advantages and disadvantages of elastomeric O-Rings.
Advantages
A main characteristic is the simple and compact design of the O-Ring. Due to the symmetric profile, the O-Ring requires a simple groove design and is relatively easy to be installed. In standard dimensions the O-Ring is an easily available and cost effective sealing element. Besides this a wide selection of elastomeric materials is available.
Disadvantages
In order to achieve optimal sealing results and prevent failure some limitations have to be considered. One aspect is the limited suitability in dynamic applications. The O-Ring is not fully recommendable for dynamic applications due to high friction and its tendency to twist. Furthermore the flash which results from molding may impair the sealing function of sensitive radial sealing applications. Besides possible media incompatibilities of elastomers have to be kept in mind.
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
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Confirm the entry by clicking on the “OK Button”.
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Thank you for participating in this lesson. Please also try the other e-Learning lessons for O-Rings.
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The O-Ring is perceived by many as a small black seal that may smell badly. It is therefore often treated with contempt. This perception though, could not be further from the truth.
For each area of application there is a different engineered O-Ring variant. Several important considerations need to be taken into account when choosing an O-Ring.
There are four aspects to consider when selecting an O-Ring, material, layout, quality and method of installation.
Choosing the right O-Ring and housing layout is important to maximize seal life and minimize maintenance costs.
Click on each aspect for further information.
Material
O-Rings are usually made of elastomers, also known as rubber, but they can also be made of other materials such as PTFE, polyurethane or metal to cope with even the harshest conditions.
The choice of material depends on its media compatibility, the application and the technical parameters, such as operating temperature and pressure, or whether the O-Ring will be used for static or dynamic sealing, etc.
Other important issues to be considered are required standards and approvals.
Layout
An O-Ring is defined by its inside diameter and cross-section dimensions.
Additionally, the layout of the housing needs to be considered regarding initial compression and system pressure. The surface finish of the groove diameter, its side walls and the mating surface also matter. To ensure correct installation you must ensure rounded edges or lead-in chamfers.
Quality
A set of standards has been established in order to guarantee the consistent quality of O-Rings. They define nominal sizes, permitted dimensional tolerances and surface finish and also give recommendations for the housing layout. These standards vary from one country to another. ISO 3601 is currently the most important international O-Ring standard. Wherever applicable we recommend using this international standard to benefit from globally standardized O-Ring dimensions and quality as well as easy availability.
Installation
You must take care when installing the O-Ring as the correct installation helps prevent O-Ring damage and malfunction. The factors to be considered are the level and speed of stretching, the twisting - which has to be avoided - and lubrication of the O-Ring as well as the use and design of assembly tools.
Use the O-Ring-Calculator on the Trelleborg Sealing Solution website to assist you with the layout of an O-Ring and its housing for your specific application.
Trelleborg Sealing Solutions also provides the "O-Ring selector" app that calculates ISO 3601 tolerances, recommends ISO 3601 O-Ring and housing dimensions for customer specific bore or rod sizes and provides chemical compatibility data for O-Ring materials.
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
In this section, you can take the chance to test your knowledge in a short test. You should be able to correctly answer 6 test questions which reflect the most important learning objectives of this lesson.
To qualify for a downloadable certificate you should answer 5 out of 6 questions correctly. You can repeat the test if you like.
Have fun answering the questions!
Lets look at the problem statement.
The skid fell over onto the operator injuring them on the leg. Please select the appropriate tool for solving the above problem statement.
Lets look at the problem statement.
The skid fell over onto the operator injuring them on the leg. Please select the appropriate tool for solving the above problem statement.