O-ring cord is a flexible sealing profile with a round cross-section that is used for various technical and industrial sealing applications. The material is particularly suitable for making O-rings in non-standard or large dimensions when a standard O-ring is not available. The cord can be cut to the required length and then joined to form a ring. This makes it a practical solution for maintenance, repairs and custom-made seals.
Techniparts supplies O-ring cord in various cord diameters, materials and hardnesses. These include NBR, EPDM, FKM/Viton and silicone. The correct version depends on the medium, temperature, pressure, required cord diameter and application.
In addition to custom-made seals, the material can also be used as a static seal or flexible construction element. O-ring cord is available in cut lengths or on rolls, making it easy to select the required quantity for an application. It can be particularly useful for large flanges, covers, machines and other connections with non-standard dimensions.
Looking for a specific cord diameter, material or hardness? View the available O-ring cord range.
O-ring cord is an extruded profile made from rubber or another elastomer with a round cross-section. Unlike a standard O-ring, the material is supplied as a straight length or on a roll. This allows you to determine how much material is required for the application. The profile is available in various diameters, generally referred to as the cord diameter.
The combination of cord diameter, material and hardness largely determines the properties of the seal. This makes it possible to select a suitable version for different operating conditions. Common materials include NBR, EPDM, FKM and VMQ/silicone.
The material can be used for static sealing applications where two components do not move relative to each other. Examples include covers, large flanges and other connections for which no standard sealing ring is available. The round profile is compressed between the sealing surfaces. This deformation creates contact with both surfaces and can prevent leakage of liquids or gases.
Whether a particular profile is suitable does not depend on the diameter alone. The groove, compression, pressure, temperature and medium must also be considered. Correct material selection is therefore important for reliable operation.
O-ring cord is used in technical applications where a flexible seal with a round cross-section is required. An important application is making sealing rings in dimensions that are not available as standard O-rings. The material is also used for large flanges, covers, machine components, pumps and industrial installations. It can also be practical to keep cord in stock for maintenance and repairs.
A technician can then cut a suitable length depending on the required dimensions. This eliminates the need to keep a separate sealing ring in stock for every possible diameter.
Cord material offers particular advantages for large or non-standard diameters. When a standard O-ring is not available, the required circumference can be determined and the material cut to the correct length. This makes it possible to produce seals for machines or installations with less common dimensions. The correct cord diameter must, however, match the groove and the required compression.
A profile that is too thin or too thick may result in insufficient compression or excessive loading of the seal.
Industrial systems can involve different media, temperatures and pressures. A sealing profile must therefore always be matched to the operating conditions. An application involving oil, for example, may require a different rubber compound than an application involving water or chemicals. The required hardness may also differ. By determining the medium, temperature, pressure, cord diameter and application in advance, a suitable version can be selected more effectively.
The material is one of the most important properties when selecting O-ring cord. Different elastomers react differently to oil, water, fuels, chemicals and temperature. A material suitable for one application may quickly deteriorate, swell or harden when exposed to another medium. The operating conditions must therefore be determined before selecting the sealing profile. Common materials include NBR, EPDM, FKM/Viton and silicone/VMQ.
Through the O-ring cord range, you can view different materials, cord diameters and hardnesses.
NBR, also known as nitrile rubber, is a widely used rubber compound for general technical and industrial seals. The material is commonly used where contact with many mineral oils and greases occurs. NBR is therefore widely used in hydraulic systems, machinery and other industrial applications. Exact resistance depends on the compound, temperature and medium.
For specific fluids, it is therefore important to always check whether the material is suitable for the operating conditions.
EPDM is widely used in applications involving water, hot water, weathering and ozone. This makes the material suitable for various technical installations and outdoor applications. EPDM can also be used with certain glycol-containing fluids. However, the material is not automatically suitable for every medium. For contact with oils or fuels, for example, it should be checked whether another rubber compound is more suitable.
FKM, also known as FPM and often referred to by the brand name Viton®, is used when higher temperature or chemical resistance is required. The material performs well with many oils, fuels and chemical media. FKM is therefore used in the automotive industry, mechanical engineering and process industries, among others. Actual suitability depends on the specific medium, temperature and compound.
Silicone / VMQ is used in applications where flexibility across a wide temperature range is important. The material is available in various versions and is used in technical and industrial systems. Silicone has different mechanical and chemical properties from NBR, EPDM or FKM. Always check whether VMQ is suitable for the medium and load of the application.
The cord diameter is the diameter of the round profile and is an important dimension when selecting O-ring cord. A cord diameter of 5 mm, for example, means that the round cross-section of the material has a diameter of 5 mm. The required size depends on the groove and the construction in which the material is used. The profile must be compressed sufficiently to create a reliable seal, but must not be so large that insufficient space remains for deformation.
When replacing an existing seal, the original cord diameter can be used as a starting point.
The diameter is best checked using a suitable caliper. Measure the profile at several points and avoid strongly compressing the rubber during measurement. If only the groove is available, the groove width and groove depth must be considered when determining a suitable size. The required compression is also important. A profile that approximately fits the groove is not automatically technically suitable for the application.
When making a ring from the material, the correct length must be determined in addition to the cord diameter. The required diameter of the finished seal is important for this calculation. Accurate calculation prevents excessive tension at the joint or the use of too much material. Measure the groove or required ring size beforehand and then determine the necessary length. If in doubt, check the dimensions and application before cutting the material.
An important advantage of O-ring cord is that it can be used to make an O-ring in a non-standard or large diameter. This is particularly practical when the required size is not available as a standard O-ring or when a custom-made seal is required. First, the required ring size is determined. The O-ring cord is then accurately cut to length and the two ends are joined together.
A precise connection is important. The ends should be cut straight and must align properly with each other. An uneven joint can create a weak point in the seal and increase the risk of leakage.
Start by selecting the correct elastomer for the application. The medium and operating temperature are particularly important. A material that performs well in contact with water may not be suitable for oil, fuel or aggressive chemicals. If you are unsure which material to use, consult our chemical resistance guide to compare different elastomers.
Next, determine the correct cord diameter and the length required to make the ring. The cord diameter must match the groove dimensions and the required compression of the seal. The required length can then be calculated based on the desired ring diameter. Accurate measurement is important, as too much or too little material can cause the finished O-ring to fit incorrectly in the groove.
Cut both ends of the cord as straight and cleanly as possible. The ends can then be bonded together using an adhesive suitable for the elastomer. Loctite 406 is commonly used for bonding suitable O-ring cord materials. A small amount of adhesive is applied to one end, after which both ends are carefully positioned against each other until the connection has set.
Always check whether the selected adhesive is compatible with the O-ring cord material and the conditions of the application. The bonding surface should be clean and free from oil, grease and contamination to achieve a reliable connection.
A bonded O-ring made from cord is primarily suitable for static sealing applications. For dynamic, high-pressure or safety-critical applications, a moulded endless O-ring or another sealing solution may be more suitable.
The resistance of O-ring cord is largely determined by the elastomer from which the profile is made. When exposed to water, oil, fuel, steam or chemicals, the same profile can react very differently depending on the material. Temperature also has a major influence on service life. A rubber that is suitable for a certain medium at room temperature does not necessarily retain the same properties at much higher temperatures.
For correct material selection, the medium, temperature, concentration, pressure and exposure time should therefore always be considered.
If the profile comes into contact with a specific medium, you can use the chemical resistance guide for O-rings. This allows you to compare different elastomers for their suitability with various chemical substances. Because O-ring cord is often produced from the same types of elastomers as O-rings, this information provides a useful starting point for material selection. For critical applications, always check the complete product specification.
The temperature range also varies considerably between materials. NBR, EPDM, FKM and silicone each have different properties at low and high temperatures. Consult our temperature resistance guide by material when temperature is an important factor. Consider both the normal operating temperature and any peak temperatures, as well as the influence of the medium.
Depending on the application, O-ring cord can be supplied on a roll or cut to length. A roll is practical when different seals are regularly produced or when the material is kept in stock. For a one-off application, a specific length may be more suitable. Techniparts can supply the material cut to size so that you do not have to purchase more material than necessary for the project.
When ordering, the cord diameter, material, hardness and required length are particularly important. For technically specific applications, also provide the medium, temperature and pressure.
Do you already know which version you need? Through O-Ring-Stocks you can search and order O-ring cord based on cord diameter, material and hardness. If you are unsure about the correct version, collect as much information as possible about the application. Consider the groove dimensions, required diameter, medium, temperature, pressure and any material requirements. This information can be used to determine which version is suitable.
O-ring cord is a flexible profile made from rubber or another elastomer with a round cross-section. It is supplied as a straight length or on a roll and can be used for various sealing applications. An important application is making O-rings in non-standard diameters. The material is cut to the correct length and the ends are joined using a suitable method. The profile is available in various cord diameters, materials and hardnesses.
The material is used for static seals, large flanges, covers, machines and industrial installations. It is also commonly used as the base material for making an O-ring when a standard size is unavailable. Because the cord can be cut to the required length, large or non-standard diameters can be produced relatively easily. The correct version depends on the cord diameter, material, temperature, pressure and medium.
Yes. One of the main applications is making a custom O-ring. First determine the correct cord diameter and required length. The material is then cut straight and the ends are joined using a suitable method. The joint must be made accurately because a poor connection can cause leakage. This can be a practical solution particularly for static applications and non-standard diameters.
The correct cord diameter depends on the groove and the construction in which the seal is installed. When replacing an existing seal, the diameter of the old profile can be measured. If only the groove dimensions are known, the groove width, groove depth and required compression must be considered. Do not select a size simply because it approximately fits the groove. An incorrect diameter can result in insufficient compression, excessive loading or leakage.
This mainly depends on the medium and temperature. NBR is widely used with mineral oils and greases, EPDM for many applications involving water and weathering, and FKM for higher temperatures and various oils, fuels and chemicals. Silicone can be useful when flexibility over a wide temperature range is required. If in doubt, use the chemical and temperature resistance guides.
Yes. Various versions can be supplied on rolls or cut to length. A roll can be useful when the cord is regularly used for maintenance, repairs or making different sealing rings. If only a specific length is required, a custom length may be more suitable. Available roll lengths and versions may differ depending on the material and cord diameter.
Through the O-Ring-Stocks O-ring cord webshop, you can view different versions and search by cord diameter, material and hardness. For the correct selection, determine the required dimensions and material properties in advance. For special technical applications, information about the medium, temperature, pressure and construction is also important.
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