Shore A

Rubber materials come with a range of qualities that all play into the sealing process and its complexity. There are tolerances, environmental factors as well as compression set but also, the hardness is also a vital component. The hardness is measured by Durometer and this will measure the hardness in materials such as polymers, elastomers and rubbers. It can prove a difficult property to ascertain as it is dependent on geometry and this will require thorough testing.

The Shore A scale is utilised for measuring how hard, a material is. Therefore, if a material has a Shore A “0” then this will mean that it is soft and has a gel-like appearance to it such as silicone. However, any elastomers that are rigid will often be at the other end of the scale and so, they will have a rating of around 90-95A.

Polyurethanes are often used at the 80-95A hardness range as they have the right blend of mechanical properties. As a result, they have the ability to flex and absorb any impacts while they can handle pressure and keep their shape. Therefore, they are perfect for applications such as shock absorbers.

Shore D

Commonly, this scale is used for plastics. Those materials that have a hardness above 65D will be completely rigid and will not have the flexibility or surface flex that is commonly seen with A scale grades. These harder materials have a greater level of resistance to flex and that can mean that they are suitable for applications which includes impact protection or metal replacement. As a result, they are commonly used in mechanical products which can include gear wheels, castors and wheels.

So, the durometer scale is a way of measuring the hardness of a rubber material. The list below will provide you with an insight into the different hardnesses and where you can find them. As an overview, the majority of rubber materials will come under the scale of Shore A. However, with a variety of applications and requirements, material hardness can alter and measure on an alternative end of the scale. The list below will provide you with an idea of common materials are actively measured using the Shore Scale.

• Shore 20A – Elastic Band
• Shore 40A – Eraser
• Shore 60A – Car Tire Tread
• Shore 70A* – Sole of a running shoe
• Shore 80A – Leather Belt
• Shore 100A – Castor

In the basic sense, hardness relates to the way in which a material reacts to intrusion as well as permanent deformation from a harder body. When it comes to seals, it is a property that is a significant consideration, especially in relation to function and specification.

The hardness of seal materials such as rubbers, plastics and elastomers are measured in units of Shore or IRHD (International Rubber Hardness Degrees).

When comparing two materials, Shore hardness offers a reference point and there are 12 different scales that are used for measuring a range of substances. However, each scale will rank the hardness of a substance between 0 and 100. The higher the value, the harder the material.

The most common scales are the A and D scales, with the Shore A scale being used for elastomers and the Shore D scale is used to measure rigid plastics.

A durometer test instrument is used to measure shore hardness. The test method designation is ASTM D2240 while related methods include the like of ISO 7619.

So, the ASTM stipulates that the test method focuses on the penetration of a certain type of indentor when it is pushed into the chosen material under certain conditions. As a result, the indenter shape and the force that is applied will alter by scale and test.

The Shore Hardness gauge will have a needle mounted on a spring. This needle is then placed on the material before the pressure is applied. After the gauge has been placed against the material firmly and the needle has penetrated as much as possible, the needle will provide a measure of hardness that will relate to the Shore Hardness Scale

So, when it comes to seals, the Shore Hardness Scale will make it possible to determine which material should be used. The required hardness will be determined by the application

The Shore Durometer Hardness results are a great way of measuring the resistance of a number of materials. Despite this, the test is not used to predict a range of other property such as strength or resistance to scratches, abrasion or wear, and so, when it comes to design specifications, it should not be relied upon solely.

So, seal hardness is vital to fluid power system designers. The softer a seal is, the more easily it will stretch and that means that they will work their way into microfine surface imperfections while they will also provide a better seal on rough surfaces. This is ideal for lower system pressures. However, where pressures are higher, the hardness of a seal is important. A harder seal will have the ability to deal with abrasion and dynamic friction while it will also resist gap extrusion.

Therefore, the Shore Hardness Scale is imperative when it comes to ensuring the correct material is chosen for the application.

As far as manufacturing component goes, seals or o-rings are taken for granted. They have a history that dates back over a century but they are still needed in many industries. They are simple in how they look and the role that they play but despite this, they are extremely important.

While engineering, manufacturing and component design has altered significantly during this time, seals have pretty much remained unchanged. Despite this, they have altered in terms of their make up as technology and materials have improved throughout the years. However, seals are undoubtedly vital when it comes to the joining of two parts, as they will help to create a seal.

They can be used in a number of applications such as static and dynamic applications where there is movement behind the parts. Therefore, this enables the part to move and flex without the seal breaking. This is why the correct material has to be used when manufacturing the seal and choosing the seal.

They are required where the seal is needed to prevent the leakage of gases or liquids. Along with this, o-rings are especially suitable in high-pressure environments. Seals will sit in a groove or a channel between two surfaces that are pushed together. It then becomes compressed and that helps to form the tight seal. The more pressure that is applied internally, the more the seal will distort inside the groove and that will help to enhance the seal it creates.

These seals are often seen in pumps, connectors, valves and cylinders and they are seen in static, dynamic, hydraulic and pneumatic components. This makes them a versatile solution for a wide range of engineering problems.

In the same way as using any other form of gasket, a seal will be used in a similar way. It will sit across an engineered groove and this will bring with it a tight seal once it has been compressed. What’s more, many seals are simple to replace which makes them the ideal solution in a number of applications.

They also come in a variety of materials too. This makes them suitable for a wide range of requirement depending on a number of factors such as the industry and the equipment. Despite this, there is no doubt that seals have an important role to play regardless of the materials they are made of and the where they are used.

Northern Engineering (Sheffield) Ltd, as a responsible citizen of the business, local, and global community,  created an internal employee action plan based upon Public Health England recommendations :

1. Wash hands frequently with  soap and water for at least 20 seconds. An alcohol-based hand sanitizer is a viable option if soap and water is not available.
2. Avoid touching eyes, nose and mouth with unwashed hands.
3. Avoid close contact with people who are sick (ie, “6 foot rule”).
4. Stay at home when sick.

While we do not have direct suppliers in the impacted zones of China and Italy, we understand that the situation is dynamic and supply chains are complex.  If NES becomes aware of risk in our supply chain at any location, we will advise impacted customers and update our website accordingly.  At this time, we are not aware of risk to our internal operation  or delivery commitments.

Metal detectable O-rings are essential for companies that use machines fitted with rubber seals that come into contact with the product.

In industries which have highly-regulated hygiene standards such as pharmaceutical, food, dairy and beverage, metal detectable elastomer O-rings will save you a significant amount of time, money and hassle.

Fitted with components that are identifiable by inline metal detectors or X-ray machines that are commonly used for safety procedures in a wide range of industries, when fragments made from metal detectable O-rings fall into a product, they are easy to locate and recover.

As a result, your productivity does not suffer. Metal Detectable O-rings can be identified in a fraction of the time it takes to conduct visual inspections. Therefore, you won’t need to shut down the production line until the contaminant is located.

Detectable metal O-rings also give companies the opportunity to improve safety measures at each stage of the production line. By doing so you can prevent the possibility of having to recall an entire batch.

Why use Metal Detectable O-Rings

When rubber polymer applications are exposed to volatile temperatures, continuous vibration and corrosive chemicals, they naturally weaken and degrade. Eventually, fragments of rubber from seals and gaskets sheer-off and fall into the end product.

Whereas traditional O-rings are made entirely of elastomeric substances, such as natural rubber, Viton™, Nitrile or Silicone, metal detectable O-rings and seals are a new breed of sealing material that have been developed in order to meet strict regulations imposed on food and pharmaceutical industries.

Metal detectable sealing materials are detectable by standard in-line metal detector systems which are already in operation in the food, beverage, and pharmaceutical industries.

Fragments as small as 2mm can be identified and removed either manually or by magnetic separators. By reducing the risk of product contamination, metal detectable polymers meet the legal requirements for hygienic design of machinery and complies with FSA regulations to help protect product safety, and eliminate downtime and product recall.

Because metal detectable O-rings are such a straightforward approach and a low-cost investment, there are no better means to ensure product and package integrity is not compromised.

Types of Metal Detectable Polymers

There is a range of metal detectable materials available that have been tested to the highest quality standards and are proven to be suitable for the food, pharmaceutical, dairy, manufacturing and processing plants that use corrosive chemicals.

• Nitrile Rubber (NBR)
• Silicone (VMQ)
• Fluoroelastomer (FKM/ Viton®)

Metal detectable sealing materials are a simple and cost-effective solution to prevent the contamination of products intended for human consumption.

NES supply a range of premium quality metal detectable and x-ray detectable rubber seals and O-rings.

There is a wide variety of sizes, colours and material specifications available so contact our friendly Sales team and we will advise you of the best products to meet your needs.

Viton™ Rubber is a highly durable and versatile type of rubber that is ideal for a wide range of applications, and the strength of this rubber makes it an extremely useful material to have at your disposal. It is a form of fluoroelastomer, a type of fluorocarbon-based synthetic rubber, which has very high chemical resistance and is thus used in a wide range of applications.

There are four families of Viton™ Rubber, A, B, F and specialty, and these families vary by fluorine grade and can all be used for a wide range of purposes. The B family, for example, has a fluorine grade of around 68%, and is often used in seals and gaskets, while the specialty types are more commonly used in the automotive industry. The temperature resistance of this rubber paired with its high tolerance to a lot of chemicals and oils makes Viton™ Rubber a very useful material when mechanical stability and mobility is required under harsh conditions. This makes Viton™ Rubber extremely favourable in situations where hot oil may be of an issue, such as within the automotive or high-performance manufacturing industries.

The list of advantages continues, as the resistance to pressure of Viton™ Rubber also makes it useful in situations where other types of rubber would become brittle. If an O-ring is going to be subjected to high pressure for example, and if fuel is also going to be in contact with it over a long period of time, the importance of strength and durability becomes immediately clear. The high quality of Viton™ Rubber also makes it very useful in situations where acidic biodiesel is going to be used as fuel, as this would corrode most other types of rubber quite quickly.

When considering which material to use, it will be very useful to fully understand the specific range of capabilities of Viton™ Rubber. Viton™ can withstand temperatures between 40^oC and 250^oC, making it truly versatile for oil and gas refineries and the aerospace industry. The rubber can withstand a long list of chemicals, including many oils and acids, as well as halogenated and aromatic hydrocarbons, which makes this rubber an excellent choice for anything that involves fuel, from the automotive industry to large-scale manufacturing plants. In terms of weathering and wear and tear, Viton™ Rubber can hold up even under the most extreme of conditions.

It is clear that Viton™ Rubber has many uses, across many different disciplines and industries. You can take full advantage of the temperature, weather and chemical resistance of this material when it comes to choosing the right one for any job. It truly is a revolutionary material that will give you the power to handle tougher projects under more extreme conditions, and the reliability of Viton™ Rubber makes it extremely useful in projects or builds where there is a long-term plan involving plenty of use.

Fluorocarbon elastomers, commonly known as FKM, are a key component in industries that are exposed to harsh chemical conditions, ozone attacks and intense temperatures. FKM can handle environments from as low as -40°C and as high as 250°C – or higher for short periods.

FKM has been shown to contain a high ratio of fluorine to hydrogen content which gives them an extraordinarily strong resistance to a wide range of industrial chemicals including acids, steam, methanol, petroleum-based and silicone oils, diesel fuels and other highly polar fluids.

The strong carbon-fluorine bonds maintain their stability and help prevent chemical saturation even when exposed to high-temperature conditions.

As a general rule, the more carbon-fluorine content in the product, the more resistant it is to corrosive agents. Lower viscosity polymers are typically used for extrusions or to help mould flow for complex part configurations.

Applications for FKM

Fluoroelastomer was originally developed by DuPont in 1957 to meet the demands of the aerospace industry that required high-performance sealing applications.

Other industries subsequently found a need for FKM including national defence, automobile and other mechanical devices requiring maximum resistance to elevated temperatures and corrosive fluids.

Today’s FKM’s are manufactured with more fluorine atoms that shield the polymer backbone and provide products with a much broader solvent resistance and even greater thermal stability than standard fluoroelastomers.

Uses for FKM in Aerospace and Automobile 

Advancements in gas turbine engines are pushing fluoroelastomers to their thermal limits. As vehicles, aircraft and ships become more powerful and energy-efficient they require durable components that are more reliable, operate safely and last longer.

FKM polymers provide a solution to both the aerospace and automobile industries and are also used by the Ministry of Defence to build high-performance machinery that requires premium quality parts to provide stability in high endurance conditions. FKM compounds typically range from 55 to 90 durometer.

Typical uses for FKM in the aeronautical industry include O-rings, gaskets, shafts, fuel hoses, joints, and other electrical connector components that are subjected to intense temperatures and pressure changes during flights.

In the automotive industry, FKM synthetic rubbers help power high-performance engines that combine oil and chemicals with high temperatures.

Uses of FKM in Cold Conditions 

One of the issues with standard FKM rubber is their inability to withstand extremely low temperatures. Most polymer products can only be used down to -25°C. Low-temperature polymers can work down to -40°C.

Low-temperature flexibility refers to the temperature which an elastomer changes from an elastomeric to a hardened state. At this point, the polymer loses its flexibility and will not be able to recover its original condition after being deformed. As a result, leaks become a high risk.

Fluoroelastomers have low-temperature properties that improve the tolerance to extreme cold. Using standard low-temperature polymers can significantly increase the cost of production because you must replace the parts more often.

Because polymers differ in fluorine content, viscosity and curing method, there are many different FKM polymers to choose from. If you’re not sure what you need, contact a knowledgeable member of our team and we’ll guide you in the right direction.

There are two important organisations that play a key role in the regulation of elastomers and O-rings, these being the United States Pharmacopeia (USP) and the US Food and Drug Administration (FDA) as well as meeting European regulation EU1935. Any company wishing to produce USP Class O-rings for any kind of food and beverage, medical, pharmaceutical or other health care application must adhere to the strict rules and regulations set by these two organisations. There are several classes of USP, class VI being the highest grade and suitable for implantation in the human body with a test temperature of 121°C. The USP is a non-government organisation and is mainly concerned with pharmaceutical and bio-technology industries, and in order to adhere to these standards set by the organisation all O-rings must be extensively tested and assessed to ensure that they meet all expectations. The compliance by way of test report from a certified body confirming adherence to these standards is often requested by the companies or projects for which the O-rings are being manufactured.

There are two types of tests used by the USP for class VI O-rings, and these apply to all elastomers, plastics and polymeric materials. These tests are the in vitro testing procedure and the in vivo testing procedure. Some end-users may also require that the O-rings be free from animal derived ingredients (ADI free).

One key area where rigorous testing is required is the water processing industry. This is where an element of importance is placed upon the material’s resistance to bacterial build up rather than temperature or pressure, and cleanliness becomes a determining factor. The materials used for valves, pumps and other pieces of equipment must all have the ability to withstand a wide range of media, and they must also be able to endure rigorous cleaning and sterilising processes too.

The pharmaceutical and food industries also require their own set of strict standards to be adhered to, as these types of products are usually produced on large scales for mass consumption. With such a large scale of production, it is essential that every part of the processing equipment is able to not only withstand harsh conditions, but also must be resistant to bacterial build up and be able to cope with extensive and regular cleaning in order to maintain a high level of hygiene within the entire system. By adhering to the standards of the USP and the FDA, Class VI O-rings are much better suited for use in these industries for both the continued efficient operation of the plant and for the safety of the consumer or user of the products that are being made.

Overall, the importance of the standards imposed by the USP and the FDA cannot be overstated, and with such a large focus on health and safety it is essential that all class VI O-rings do adhere to these standards in order to be valid for use in a wide range of applications. Regardless of the industry or where the class VI O-Rings are used, there is always the safety implications that must be considered. Therefore, these standards form a crucial aspect of the entire process and procedures when it comes to using FDA and USP Class VI O-Rings.

It’s no surprise that rubber seals are among the most popular choices when it comes to ensuring an airtight and watertight fit in a wide variety of industries and applications. From aerospace to the automotive industry, from electronics to engineering, from medicine to mining; regardless of the sector, rubber seals are consistently preferred as a means of creating an impervious connection.

Why is this so? There are many reasons that rubber seals are a good fit (excuse the pun) for a range of situations and circumstances. Here are just a handful of the many benefits that rubber offers over other alternative materials when it comes to creating a gasket or O-ring between two component parts of equipment, machinery or other working apparatus:

• Even at very low temperatures, rubber (especially silicone rubber) retains a high degree of flexibility, meaning it will absorb any pressure placed upon it and mould itself to the contours of the groove (or gland) into which it is placed.
• Temperature resistance. Rubber is capable of withstanding extreme temperatures at both ends of the scale. In particular, silicone rubber can tolerate lows of up to -100°C and highs up to 310°C This makes rubber seals ideal in environments prone to massive swings in temperature.
• Rubber is an incredibly durable material which will absorb pressure applied on it and create an impervious seal that is increases in strength in direct proportion to the forces exerted upon it. It will also maintain this integrity for significant spells and although there are breaking points for both the amount of pressure it can withstand and the length of time that it can do so, its credentials are very impressive in both respects.
• Rubber is a highly malleable substance and can easily be moulded into all kinds of shapes and sizes, making it ideal for use in a variety of different applications and industries. Whether it’s a standard O-ring seal that’s needed or a more bespoke solution, rubber has the versatility to satisfy any situation.
• Depending on the type of rubber, many rubbers are non-toxic materials which won’t corrupt or compromise any substance with which it comes into contact or any environment into which it is placed. Thanks to the fact that it does not impart odours or flavours to surrounding mechanisms, it’s a highly popular choice for the food, pharmaceutical and medical industries.
• Silicone rubber is compatible with a wide range of different sterilisation techniques, including dry heat, electron beams, ethylene oxide, gamma radiation and steam autoclaving. This, coupled with the non-toxic properties mentioned above, allows us to offer medical grade materials.
• Compatibility with other materials. Rubber can easily be mixed with other substances to enhance certain aspects of the seal in question, including its tolerance to extreme temperatures, its compression capabilities and the length of its life.

Choosing the rubber seal that’s right for you

As you can see, there are any number of reasons why rubber seals offer a quality and comprehensive solution to sealing problems in a number of different industries. If you’d like to take advantage of the incredible properties of this versatile material, why not browse our range of rubber seals and gaskets suitable for all kinds of circumstances.

Alternatively, if you’d prefer to hear some advice on which type of seal would best benefit your unique situation, we’re on hand to dispense any guidance and answer any questions we can. Simply get in touch via our online form, give us a call on +44 1909 560 203 or drop us an email at sales@nes-ips.com and we’ll take things from there. We look forward to hearing from you soon

O-rings are an essential component in machinery across all kinds of industries and have been for well over a century. Despite their importance, the basic design of an O-ring has changed very little over the last 100 years – but the materials used to make them have undergone significant advances. Today, one of the most popular substances used in the manufacture of O-rings is silicone.

Silicone is the name applied to any synthetic compound in which siloxane is a repeating constituent part. When it comes to silicone O-rings, they are impervious to extremes of temperature. The same type of silicone rubber that is used to manufacture O-rings is also employed in a variety of other household items, from kitchen utensils to electronics and insulation to medical devices.

Strengths and weaknesses of silicone O-rings

Perhaps the biggest defining characteristic of silicone O-rings is their resistance to extreme temperatures. Capable of withstanding lows of -100°C and highs of up to 310°C, silicone O-rings can even tolerate even greater extremes for short periods of time.

As well as dealing with extremes, silicone O-rings are also extremely flexible, even in low ambient temperatures. They boast a low compression set as well, making them the perfect choice for compression force sealing and working among high temperatures and pressures. As well as being resistant to heat and cold, silicone O-rings boast tremendous resilience when exposed to ozone, acid, chemicals and oils. What’s more, the colour of the material used does not have any bearing on its effectiveness or capabilities, affording user greater aesthetic control when selecting the design of the O-ring. Silicone can be matched to any RAL or Pantone number.

On the other hand, their tensile strength is not as accomplished as certain other materials and they are prone to suffering damage from tears and abrasions. This makes them more suited to static applications than dynamic ones, since a moving part is more likely to rupture their surface. Similarly, they are not the best choice in situations exposed to naked flames and they do not offer as robust impermeability as some other O-ring materials.

Applications of Silicone O-rings

Thanks to their supreme resistance to extremes of temperature, their unparalleled flexibility and their ability to withstand exposure to all kinds of substances and gases, silicone O-rings are suitable for a wide range of applications in many different industries.

These applications include (but are not limited to) automotive manufacturing, aerospace, electronics, cooling systems, pressure cleaners and water processing equipment. Furthermore, the fact that they do not impart any discernible odour or taste to their immediate surroundings or the substances with which they come into contact makes silicone an ideal choice for O-rings in applications dealing with food production and processing, medical and pharmaceutical purposes and semiconductor systems.

In terms of specific environments, silicone O-rings are particularly useful in environments which experience dry heat, ozone exposure or contact with mineral oils with minimal additives. On the other hand, they do not perform so well in situations where they may encounter concentrated acids, ketones (such as acetone or methyl ethyl ketone [MEK]), fuels, gear lubricants or steam.

Advice from the experts

If you’re still unsure whether a silicone O-ring is the best solution to your particular conundrum, it’s always preferable to seek professional help rather than hazarding a guess and hoping for the best. Our dedicated team of experienced O-ring experts are on hand to answer any questions and offer any advice you might need – simply complete our online form, give us a call on +44 1909 560 203 or drop us an email at sales@nes-ips.com and we’ll get back to you as soon as we can.