Rubber Round Cords

What is O-ring cord?

O-ring cord, also known as round cord, is a rubber cord with a round cross-section that can be used to create a sealing ring in almost any required diameter. Unlike a standard preformed O-ring, this round cord is supplied on a roll in continuous lengths, allowing you to cut it precisely to size. The ends can then be joined together to form a custom O-ring that fits your specific application perfectly. This makes O-ring cord an ideal solution when you need a non-standard size or when a replacement seal has to be made quickly. Instead of waiting for the delivery of a specific O-ring, you can produce an accurately fitting rubber sealing ring on site, ensuring minimal downtime and maximum flexibility.

When do you use O-ring cord instead of a standard O-ring?

O-ring cord is a practical alternative to a standard O-ring in situations where flexibility, availability or installation limitations play a role. Although preformed O-rings are often the preferred sealing solution, they are not always immediately available in the required size. In addition, some applications require unusual diameters or configurations that fall outside standard dimensions. In these cases, round cord allows you to create a suitable seal without delay. Because the cord can be cut and adjusted on site, O-ring cord offers a versatile solution for maintenance, repair and custom seals where speed and adaptability are essential.

When a standard O-ring is not available

If a standard O-ring is not in stock and a replacement is urgently needed, O-ring cord offers a fast and efficient solution. Instead of waiting for delivery, you can cut the round cord to the correct length and immediately assemble a functional seal. This is especially useful during maintenance work or unexpected breakdowns, where minimizing downtime is crucial. O-ring cord helps keep processes running when time is limited.

For special or non-standard dimensions

Not every application matches standard O-ring dimensions. Equipment with non-standard groove dimensions, very large diameters or specially built components may require a seal that is not available as standard. With O-ring cord, you can create a custom sealing ring that matches your requirements exactly. Because the round cord is supplied in continuous lengths, it offers a flexible solution for both small and very large diameters.

When installation is difficult

In certain constructions, installing a closed O-ring can be difficult due to limited accessibility or complex component geometry. O-ring cord, supplied as an open length, can be positioned more easily in tight or hard-to-reach spaces before it is joined. This simplifies installation in applications where fitting a preformed O-ring would be difficult or impractical, making round cord a practical choice for specific sealing situations.

How do you join O-ring cord?

Correctly joining O-ring cord is essential to create a reliable and durable custom O-ring. After the round cord has been cut to the required length, the ends must be carefully prepared before bonding. For the best result, it is recommended to cut the O-ring cord at a 45° angle. This angled cut increases the bonding surface and creates a stronger and more secure joint. Make sure the cut surfaces are clean, dry and free from grease or dust before applying the adhesive. Accurate alignment of both ends is also important to maintain a consistent diameter and ensure good sealing performance in static applications.

Instant adhesive for most materials

For most rubber materials, a high-quality cyanoacrylate adhesive, such as Loctite 406, is suitable for bonding O-ring cord. This type of instant adhesive works well with materials such as NBR, EPDM, FKM and CR. Apply a small amount of adhesive evenly to one cut surface, press the ends firmly together and hold them in place for the recommended curing time. Correct bonding ensures a tight and consistent seal.

Silicone adhesive for VMQ

VMQ (silicone) O-ring cord requires a special silicone adhesive, such as Elastosil E41. Standard instant adhesive is not suitable for silicone materials, as it does not provide sufficient adhesion. Apply the silicone adhesive evenly to the prepared 45° cut surfaces and carefully align the ends before pressing them together. Allow sufficient curing time according to the manufacturer’s instructions to obtain a flexible and durable joint.

Precision O-ring cord (according to ISO 3302-1)

For applications where dimensional accuracy is crucial, precision O-ring cord produced according to ISO 3302-1 offers a reliable solution. Tolerances play an important role in sealing performance, especially in grooves with minimal clearance or where consistent compression is required. O-ring cord with controlled tolerances ensures a predictable fit, improved sealing reliability and a reduced risk of leakage.

Our NBR, FKM and EPDM O-ring cord is supplied with E1 tolerances in accordance with ISO 3302-1, making it suitable for demanding industrial applications. Our silicone (VMQ) O-ring cord is produced with E2 tolerances. By choosing a precision cord with the correct tolerance specification, you are assured of optimal performance in applications where strict dimensional accuracy is required.