NBR O-ring Cord 8.00 mm 70 Shore A

NBR O-ring Cord 8.00 mm 70 Shore A

NBR O-ring Cord 8.00 mm 70 Shore A is an extruded elastomer sealing cord with a round 8.00 mm cross-section, manufactured from nitrile rubber with a hardness of 70 Shore A. It is designed for making custom-length seals and joined O-rings, particularly for large or non-standard diameters where a ready-made moulded O-ring is unavailable or impractical.

Technical Specifications - NBR O-ring Cord 8.00 mm

What Does NBR O-ring Cord 8.00 mm 70 Shore A Mean?

The product designation identifies its essential technical characteristics:

O-ring Cord - a continuous elastomer profile with a round cross-section used as sealing material.

NBR - Nitrile Butadiene Rubber, commonly known as nitrile rubber.

8.00 mm - the nominal diameter of the round cord cross-section.

70 Shore A - the hardness of the elastomer measured on the Shore A scale.

Unlike a ready-made O-ring, O-ring cord does not have a predefined inside diameter. The required length is selected according to the dimensions of the seal being produced.

Construction of 8.00 mm O-ring Cord

The product is manufactured as a continuous extruded elastomer profile with a solid, round cross-section.

Its primary dimensional parameter is:

Cross-section diameter: 8.00 mm

O-ring cord is not a ready-made seamless O-ring. A suitable length can be cut from the cord and its ends can then be joined using an appropriate method to produce a closed sealing ring.

This makes it possible to manufacture O-rings of different diameters from one 8.00 mm cord size.

NBR 70 Shore A - Material Characteristics

NBR, or Nitrile Butadiene Rubber, is one of the most widely used elastomers in sealing technology.

NBR is commonly used with many:

• mineral-based oils,
• mineral lubricating greases,
• hydraulic oils compatible with NBR,
• vegetable and animal oils,
• compatible technical fluids.

NBR is not a universally resistant elastomer. Material suitability must always be assessed against the actual operating medium, temperature and service conditions.

What Does 70 Shore A Mean?

70 Shore A specifies the hardness of the nitrile rubber.

This is a commonly used hardness for technical NBR sealing elements and provides a practical balance between elasticity and mechanical stability.

When installed in a correctly designed groove, the elastomer can deform under compression to establish sealing contact with the mating surfaces.

Hardness is an important technical parameter. A cord with the same 8.00 mm diameter but a different hardness should not automatically be considered interchangeable.

What Is 8.00 mm NBR O-ring Cord Used For?

O-ring cord is particularly useful where a seal of a specific length or diameter is required and a standard moulded O-ring is unavailable, difficult to obtain or impractical.

It can be used to produce:

joined O-rings

large-diameter sealing rings

custom-size seals

seals for large covers

seals for flanges

sealing elements for maintenance and repair

The ability to cut the material to length is especially useful in maintenance operations where several O-ring diameters with the same cross-section may be required.

O-ring Cord vs Moulded O-ring

O-ring cord and a ready-made moulded O-ring are not structurally identical products.

A moulded O-ring is manufactured as a closed ring with a defined inside diameter and cross-section.

An O-ring cord is a continuous profile with a defined cross-section but no predefined inside diameter.

With 8.00 mm O-ring cord, the value 8.00 mm refers to the cross-section diameter, not the inside diameter of the finished ring.

Another important difference is the joint. A standard moulded O-ring is seamless, whereas a ring made from cord has a connection between its two ends.

For this reason, a joined O-ring should not automatically be considered technically equivalent to a moulded O-ring in every application.

Making Custom O-rings from 8.00 mm NBR Cord

One of the principal uses of O-ring cord is the production of sealing rings with a required circumference.

This can be particularly useful for:

very large O-ring diameters

non-standard dimensions

older machinery and equipment

on-site maintenance and repairs

prototypes and special-purpose equipment

maintenance inventories

Instead of keeping every possible inside diameter of moulded O-ring in stock, a maintenance department can hold selected cord cross-sections and prepare the required ring length when needed.

How to Make an O-ring from 8.00 mm NBR Cord

The cord must first be measured and cut accurately according to the required sealing geometry.

The ends should be prepared so that they can be joined accurately.

Important factors include:

• accurate length measurement,
• precise cutting,
• correct alignment of the ends,
• avoiding twisting of the cord,
• appropriate joining technique,
• compatibility of the joining system with NBR.

The joint becomes an integral part of the finished sealing ring. Its quality can therefore directly affect sealing performance.

Static Sealing Applications

O-ring cord is particularly useful for producing simple static seals.

Typical applications for this product group include sealing:

large covers

housings

flanges

stationary joints

For each application, the cord cross-section, groove geometry, compression and elastomer material must be appropriate for the specific sealing arrangement.

Can O-ring Cord Be Used in Dynamic Applications?

O-ring cord should not automatically be treated as a direct substitute for a moulded O-ring in demanding dynamic applications.

A ring manufactured from cord contains a joint, which distinguishes its construction from a seamless moulded O-ring.

For reciprocating, rotary or other dynamic sealing applications, the sealing design and suitability of a joined ring should therefore be verified before use.

NBR O-ring Cord vs FKM, EPDM and VMQ Cord

O-ring cord with the same cross-section can be manufactured from different elastomers.

NBR is widely used with many mineral oils and lubricating greases.

FKM/FPM, EPDM and VMQ have different material properties and different areas of chemical and temperature resistance.

Therefore, FKM 8 mm, EPDM 8 mm or VMQ 8 mm cord should not automatically be considered a replacement for NBR 8 mm cord.

The same cross-section does not mean the materials have the same operating properties.

How to Select 8.00 mm NBR O-ring Cord

Before using the product, verify:

• required cross-section diameter of 8.00 mm,
• NBR material,
• 70 Shore A hardness,
• groove dimensions,
• required compression,
• required seal length,
• operating medium,
• operating temperature,
• pressure,
• static or dynamic operating conditions,
• method used to join the cord ends.

Selection should be based on the requirements of the specific sealing arrangement.

Alternative Designations and Search References

Natural technical variants of the product name include:

NBR O-ring Cord 8 mm 70 Shore A

O-ring Cord NBR 8.00 mm 70 ShA

NBR Sealing Cord 8 mm

Nitrile Rubber Cord 8 mm 70 Shore A

O-ring Cord 8 mm NBR 70 ShA

These are descriptive variants of the product name, not manufacturer part numbers or OEM references.

Installation and Seal Preparation

The groove and mating surfaces should be clean before installation.

During preparation and installation, protect the cord against:

sharp edges

burrs

surface cuts

excessive stretching

twisting

contamination

After making a closed ring, the alignment and quality of the joint should also be inspected.

If an assembly aid or joining product is used, its compatibility with NBR and the operating medium should be confirmed.

NBR O-ring Cord for Maintenance and Industrial Service

O-ring cord is a practical maintenance material for industrial facilities and service departments working with seals of many different diameters.

Keeping selected cord cross-sections in technical inventory allows custom-size sealing rings to be prepared without stocking every possible diameter of moulded O-ring.

This is particularly useful for large diameters, non-standard dimensions and repair work on machinery and industrial equipment.

FAQ - NBR O-ring Cord 8.00 mm 70 Shore A

What does 8.00 mm mean?

The 8.00 mm dimension is the nominal diameter of the round cord cross-section. It is not the inside diameter of a finished O-ring.

What does NBR mean?

NBR stands for Nitrile Butadiene Rubber, an elastomer widely used for O-rings, sealing cords and other technical sealing components.

What does 70 Shore A mean?

It specifies the hardness of the elastomer on the Shore A scale. The abbreviated technical notation is 70 ShA.

Can an O-ring be made from 8 mm NBR cord?

Yes. The cord can be cut to the required length and its ends appropriately joined to produce a sealing ring with the required circumference.

Is 8 mm O-ring cord the same as an 8 mm O-ring?

No. For O-ring cord, 8 mm specifies the cross-section diameter. A finished O-ring is normally identified by at least its inside diameter and cross-section.

Is NBR suitable for oil?

NBR has good compatibility with many mineral-based oils and greases. Suitability should nevertheless be verified for the specific fluid and actual operating conditions.

When should O-ring cord be used instead of a moulded O-ring?

O-ring cord is particularly useful for large or non-standard diameters, on-site maintenance and applications where the required moulded O-ring is difficult to obtain.

Can NBR 8 mm cord be replaced by FKM 8 mm cord?

Not automatically. Although the cross-section is identical, NBR and FKM/FPM have different material properties and chemical compatibility.

NBR O-ring Cord 8.00 mm 70 Shore A - Key Information

NBR O-ring Cord 8.00 mm 70 Shore A is an extruded nitrile rubber sealing profile with a round 8.00 mm cross-section and 70 Shore A hardness. It is used to make custom-size seals and joined O-rings, particularly for large or non-standard diameters, static sealing applications, industrial maintenance and repair work.

Available from simmering.pl, stock in Poland with worldwide shipping.