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Different elastomers for o rings and various applications

An elastomer is a primary raw material used for most o rings. They are typically manufactured as gum rubber or manufactured synthetically, and surprisingly today, there are approximately over 32 different synthetic rubbers now available.  Elastomer compounds will...

Spiral wound gasket thickness – what’s best?

It is often recommended that using a thinner gasket type/material will result in better sealing performance.  Why?  Because thinner gaskets tend to require much less gasket stress to provide applications with the perfect seal, they also have an excellent response to...

Choosing the correct oil seal application

Choosing and using the proper sealing devices within oil and gas applications can be vital when preventing dirt, dust, water, and other debris from potentially getting inside and contaminating products.  Of course, all rubber materials and seals will provide a range...

Nitrile rubber, NBR, and Buna-N – how well do you know your o ring materials?

A widely used elastomer, Nitrile, Buna-N, or NBR rubber, are all oil and fuel resistant and provide a great level of strength, making them a popular material for seals across various industries.  Suitable for a range of applications, this versatile rubber material,...

Optimum squeezing force for an o ring

It is true that the more squeeze you place on an o ring, the tighter the seal it will provide. In essence, the more squeeze (compression) you apply, the greater the force between the o ring and its mating hardware.  And ensuring you have the perfect seal is all...

O Ring Squeeze

The squeeze and shrinkage on an o ring are vital to understanding as these factors stand in the way of your application either experiencing a perfect seal or your application suffering from leaks.  You can measure the shrinkage of an o ring during...

The importance of mechanical seals when reducing water consumption in mining

Environmental considerations are at the top of most industry's agendas in the 21st century as companies evaluate and improve operations, processes, and systems.  Conserving water in mining is one such area that is now being investigated further with the rotation of...

How choosing the correct gasket reduces risks

Health and Safety across any industry are vital, especially so in industrial facilities and settings.  Why?  Because harmful leaks and emissions must be avoided at all costs to avoid serious accidents or injury to your teams and property.  That’s why having the right...

How to tighten your bolts perfectly

How to tighten your bolts and which tools you should use to achieve the perfect seal is not as seamless and straightforward as we would like. Various factors come into play in these situations, such as bolt grade, size, and even application type.  Tightening torques...

Static and Dynamic o rings

A range of factors and application dynamics come into play when choosing a particular type of o ring.  You need to understand the type of seal exert you require, the dimensions, and even compounds.  Due to the nature of an o ring and its overall design, o rings use...

Keeping your o rings bonded

Keeping your o rings bondedEMI o rings. Those seal ring gaskets are made of silicone compounds, combining environmental sealing with electromagnetic interference protection. 

Consisting of metal or metal-coated particles, silicone o rings are filled with silver, silver aluminium, or nickel graphite. 

Experienced o ring suppliers UK will be able to advise you on the best type of o ring for your specific application, with EMI o rings, in particular, being highly effective for the automotive, aerospace, industrial, medical, and military sectors. 

O ring adhesive 

Manufactured from EMI elastomers and solid cords, bonded o rings are designed to provide EMI shielding and environmental sealing capabilities to a range of industries. 

The benefits of using EMI shielded o rings are that they provide reliable protection against electromagnetic interference, radio frequency interference, and environmental sealing and electrical conductivity. 

Cut by gasket manufacturers, silicone o ring cord ends are bonded together to form a tight seal. This bonding process is carried out via cold bonding or vulcanisation. 

Of course, like with anything, there are both pros and cons to each process which we will explore in a little more detail below. 

Cold bonding 

As the bonding name suggests, cold bonding doesn’t use any heat. Instead, a non-conductive adhesive is placed on the cord ends. Due to not using a compression moulding technique, customers wanting these o rings will experience shorter lead times, and due to the production volume of these rings, cold bonding also helps limit your cost per part. 

However, it is important to be aware and note that during the o ring splicing process, if the o ring is spliced incorrectly, the non-conductive adhesive will no longer be effective when the two ends are bonded together. 

Providing a reliable shielding for most applications, for you to get the maximum benefit from these o rings, they must be bonded together by experienced gasket fabricators to ensure speed and precision. 

Vulcanisation 

The vulcanisation process uses heat to join the cut lengths’ ends, using conductive adhesives, creating single, solid o rings from EMI cords or extrusions. 

Applied to the ends, the adhesives are then pressed together in a vulcanising press or hot mould. 

These o rings can also match the reliability of conductive shielding elastomers, i.e., vulcanised EMI o rings provide reliability and typically meet or exceed the strength of the material it is used alongside. 

Vulcanised o rings offer consistency and dependability and should be used in static, non-pressurised environments. 

However, compared to cold bonding, lead times are longer, and sometimes costs are slightly higher as this particular process requires compression moulding techniques. 

Ultimately you need to select the most appropriate o ring glue and joining method for your application. 

Binding agents 

We know that EMI o rings are more economical compared to moulded o rings, and they do not compromise performance. 

And when a vulcanised o ring uses an EMI bonding agent with the same characteristic as the extruded cord, then EMI penetration or leakage can be prevented. 

This is why EMI o rings should be bonded using silicone-based adhesives containing EMI filler as non-silicone glues without EMI filler can create a weaker seal which makes the application more susceptible to leaks. 

(Finding the right gasket seal for your application is vital. To support your decision-making you might also be interested in o ring shrinkage and the shrink rate calculation, which you can find more about in our latest post, O ring squeeze.”) 

It’s also important to note that acrylics and other non-silicone glues tend to dry much harder than EMI silicone cord. This means you will often find a `hard spot` in the finished gasket as the acrylic adhesives can’t match the temperature range of the EMI cord material, making them easily breakable. 

To prevent these issues and risks of leaks, the vulcanised o ring should use the same EMI bonding agent as the extruded cord, with the bond strength and elongation checked against standard o rings to ensure the highest of standards. 

At Specialist Sealing Products, we supply o ring stock to cut and bond using the various methods mentioned above. With a range of options available call us today on xxx to find out more and to see how we can help you. 

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