The Technical Hub
O-Ring Calculator
This interactive calculator assists engineers with selection of O-ring and hardware dimensions, and to form the basis of an O-ring installation.
Chemical Compatibility Checker
This interactive guide will help you choose a seal material based on existing compatibility test results of known chemicals and elastomers.
Interactive Engineering Calculators
Click here for volume, mass and compression set values for O-rings and rotary seal and hydraulic cylinder calculations.
Unit Converter
Our interactive conversion tools allow engineers to switch between units of measurement when preparing engineering calculations.
Engineering Tables
Our reference tables provide cross reference information for surface finish, metal hardness and polymer hardness measurement units.
Surface finish requirements for static and dynamic sealingWhat is hardware surface finish? Any surface can look (and even feel) perfectly smooth. However, look closely enough with high magnification and all surfaces will have a degree of fluctuation and a topography that looks similar to a mountain range or the surface of the moon. The roughness of a surface is generally linked to the way a surface is produced or machined, and any subsequent processes such as coating or platings. Ra (metric) is the unit of measurement for surface hardware finish. Ra simply, is the mean roughness; the average calculated from the peak heights and valley depths. A surface that is mostly spiked can have the same Ra value as one that is mostly troughed, but each could have a very different impact on seal performance. Surface finish measuring equipment is capable of tracing a surface finish using a diamond tipped stylus or non-contact 3D laser scanning. Static and dynamic sealing applications will have different requirements for seal finish. Measuring and analysing the hardware surface finish is important to ensure the correct conditions and no leakage occurs. If a seal application is static, and is sealing a low molecular size gas such as helium, for example, then a very smooth surface is preferable. For some dynamic applications, it can be critical for either seal friction, or wear life, that the interface between the seal and the hardware is well lubricated. Specifying the right surface finish for the hardware components that contact a seal can be complex and daunting. Our expert team advise our customers on the relevant parameters, with consideration to what is important for the given application. We ensure the optimum finish is fully specified to achieve right-first-time seal performance. Find out how our expert quality engineers and inspectors ensure the highest level of quality assurance HERE
Are all elastomers the same?Elastomer rubbers look very similar - but are they all the same? With many different base groups and recipe formulations, there's a huge range of elastomer materials suitable for applications with varying temperature ranges and chemical media compatibility. It's critical to the seal performance to make the right choice. There are number of factors to consider, these include: Material hardness Elastomer material hardness can impact assembly loads, seal friction and extrusion resistance. Softer seal compounds can be used effectively against rough hardware surface finishes, as the softer rubber can better accommodate surface imperfections (especially when sealing low pressure gas). Harder compounds will have greater wear resistance in dynamic applications. Chemical compatibility Unlike PTFE seals (where there are very few chemicals that will attack and breakdown the material) elastomer seal materials have to be carefully selected. It's important to ensure properties are not affected by any fluids or gasses that the seals come into contact with. Temperature range Outwardly, elastomer rubbers seem straightforward, but the technology can be complex. Material groups often have well published temperature ranges. For example, the silicone family is able to reach -100°C (or even lower with special grades), and perfluoroelastomer (FFKM) grades are able to withstand 320°C (or even higher for short durations). Whilst guidance can be given on maximum temperature capability for any specific elastomer grade, this is often in a benign air environment. Therefore the chemical impact of being exposed to hot fluids in the sealing application should be considered. For information about our extensive product range, see HERE
The importance of engineering tolerancesTolerances are present in every man-made item. It is practically impossible to repeatedly manufacture something to an exact size or specification. In seal manufacturing, it's important to understand which tolerances impact performance and by how much. This will ensure a system is optimized for overall performance, and whole-life product cost. Considerations for tolerances include the seal material and the hardware for sealing installation.
Seal material, polymer and metal seals
Almost all polymer seal materials contain multiple ingredients. For PTFE and polyurethanes this is typically 2 or 3 different elements. Additionally, for an elastomer material, as many as 30 different ingredients can be used in the recipe. In machined seals, polymer seal materials tend to have high rates of thermal expansion. Together with their relative softness, this makes it difficult to maintain the same level of tolerance that can be achieved when machining metal components.
Hardware tolerances
When designing hardware for seal installation, engineering tolerances are sometimes more obvious, and certainly where engineers can focus some attention. A stack-up of tolerances for many applications should be considered. Together with tolerances of the assembly such as concentricity or misalignment (especially for dynamic sealing applications). Other considerations include bearing wear and the resulting increase in misalignment or runout as the equipment approaches the end of it’s target life.
Why are engineering tolerances important for sealing systems?
Every application starts from a nominal condition, and the maximum and minimum tolerance conditions should always be considered. Even in seemingly straightforward applications, it's important to ensure the seal is continuing to operate within it’s ideal set of conditions. Click on the link for information about our engineering, design and innovation service, click on this link HERE Use our interactive tools HERE
Elastomer manufacturing moulding processesHow is it manufactured? A question we get asked in the seal design process, but perhaps not considered often enough. How a rubber seal is produced can affect a number of things; the cost, the material choice...even how a part should be designed. All of these can have a significant impact on the performance of the seal in application. Let's take a look at the three main manufacturing methods for moulding elastomer seals. Compression Moulding This is the most simple method of converting a piece of rubber into a finished seal product. First, the rubber compound is mixed and prepared. The material has a stiff and non-elastic consistency (like thick dough). From this dough we produce a rubber blank (also known as a pre-form) by either cutting, punching or extruding cord. These blanks are normally a little bigger than the finished part (normally based on weight) will be placed into a metal moulding tool. The tool (in its simple form) is in two halves with the final product shape cut into the metal. This is known as the mould cavity. Injection Moulding This manufacturing process is often used to produce plastic components, but for rubbers, the temperatures are switched. A warmed rubber is injected into a hot tool, as the force required to inject uncured rubber is much greater than what’s required to push molten plastic into a chilled mould. Otherwise the equipment and principles remain similar. Transfer Moulding This is a variation on compression moulding. It uses the same hydraulic compression presses, but this tooling is a little more sophisticated (and consequently a little more expensive). Comparing the three most common methods of producing an elastomer seal, it's clear that evaluating how the part is going to be made, is key to ensuring the technical and commercial success of the seal in the application. Read more about our engineering, design and innovation service HERE
Polyurethane as a seal materialThe foam in your armchair. The strap on your wristwatch. The wheels on a supermarket shopping trolley and beyond; Polyurethane certainly has a diverse range of uses since its invention almost 85 years ago. Aside from day-to-day products; it is also a highly capable and versatile sealing material - and an option that is often overlooked.
What is Polyurethane?
This material is rubber, plastic, rigid and flexible. Polyurethane covers a group of materials; plastic polymers produced by the combination (or synthesis) of di-isocyanates with polyols and a chain extender. This makes Polyurethane an excellent seal material.
How are Polyurethane materials manufactured?
There is a one and two-step process to manufacturing polyurethane.
One-step process
This is when a compound containing multiple hydroxyl groups (called a polyol), is mixed with highly reactive low molecular weight chemicals (isocyanate), and a chain extender (low molecular weight diols or diamines). Consequently, the result is a random copolymer with a physically cross-linked irregular molecular structure.
Two-step process
In a two-step process, the polyol and isocyanate are mixed first to produce a pre-polymer. This is mixed with the chain extender to produce a block copolymer with more regular molecular structure. Although this often results in improved and more consistent material properties, there is a slightly higher production cost.
Why is Polyurethane a good seal material?
Evidently, when formulated appropriately, Polyurethane does produce an impressive set of material properties that make it an ideal material for sealing products. Consequently, its flexible, with very high abrasion resistance, tensile strength and stiffness. The tensile and tear strengths are typically 3-5 times higher compared to rubber seal materials. Although it lacks the chemical resistance and temperature capability of PTFE, it is compatible with mineral oils. There is more information on polyurethane as a seal material HERE You will learn more about our range of materials HERE
Why the focus on PFAS?PFAS is a blanket term used to describe Poly- and Per- fluoroalkyl substances. There are currently around 10,000 substances in existence that fit this description, with potentially more variants still yet to be produced. Some are already known to be harmful to human and animal health and the environment (such as PFOA and PFOS), and these specific PFAS are already controlled under legal restrictions. But in February 2023, The European Chemical Agency (ECHA) published a regulatory proposal to further restrict the manufacture, placing on the market, and use of all PFAS within the EU.
Seals for cryogenic applicationsCryogenic sealing means controlling or sealing a media at very low temperatures. This process can be complex and advanced, and spans a range of markets; from pharmaceutical, chemical and refrigeration, to automotive and electronics.
Why use 2-Shot moulded seals?2-Shot moulding is a manufacturing process that allows the co-polymerisation of hard (or soft) plastics and thermoplastic elastomers (TPE’s). We use the 2-Shot manufacturing approach to deliver engineered parts that perform a critical sealing function.
Why use PTFE seals?Polytetrafluoroethylene (PTFE) is a thermoplastic polymer that can be used in a variety of sealing applications; it is particularly suitable where the application conditions exceed the parameters of elastomeric seal use, but are not as highly demanding as applications that require the use of metal seals.
Why use metal seals?The use of metal seals as an engineered sealing solution is appropriate where it is not possible to use elastomeric or polymer seals due to extremely demanding application requirements. For example, these could include applications with extremely high temperatures (300°C upwards) and pressures, intense radiation, cryogenic conditions or highly aggressive chemicals.
Why use Push-in-Place gaskets?Where a seal groove follows an irregular path or profile, a common sealing solution is to design a custom Push-In-Place (PIP) gasket that has the same profile as the centre line of the groove, simply drops into place and is retained by the features of its own design.
Perfluoroelastomers in valvesIs it time to re-visit using perfluoroelastomer seals in your valves? First developed by DuPont™ in the late 1960s, perfluoroelastomers (or FFKMs), are now widely known and understood in a variety of markets. But for those that may be less familiar with these high performance materials, here is a quick recap...
Seals for valve applicationsValves are imperative for isolation and control functions, and can be found in a broad range of industries such as Oil & Gas, Water & Wastewater, Food & Beverage and Hydraulics & Pneumatics. We supply seal products into valve applications in a variety of styles including ball, gate, flap, plug, butterfly, spool, check and solenoid valves.
3D printing for seals3D printing has developed significantly and now performs a crucial role in many applications. 3D printed products vary from fully functional to purely aesthetic applications; with the most common application being for manufacturing. Here we discuss how our engineers use 3D printing to demonstrate a seal concept.
Tools
O-Ring Calculator
This interactive calculator assists engineers with selection of O-ring and hardware dimensions, and to form the basis of an O-ring installation.
Chemical Compatibility Checker
This interactive guide will help you choose a seal material based on existing compatibility test results of known chemicals and elastomers.
Interactive Engineering Calculators
Click here for volume, mass and compression set values for O-rings and rotary seal and hydraulic cylinder calculations.
Unit Converter
Our interactive conversion tools allow engineers to switch between units of measurement when preparing engineering calculations.
Engineering Tables
Our reference tables provide cross reference information for surface finish, metal hardness and polymer hardness measurement units.
Articles
Surface finish requirements for static and dynamic sealingWhat is hardware surface finish? Any surface can look (and even feel) perfectly smooth. However, look closely enough with high magnification and all surfaces will have a degree of fluctuation and a topography that looks similar to a mountain range or the surface of the moon. The roughness of a surface is generally linked to the way a surface is produced or machined, and any subsequent processes such as coating or platings. Ra (metric) is the unit of measurement for surface hardware finish. Ra simply, is the mean roughness; the average calculated from the peak heights and valley depths. A surface that is mostly spiked can have the same Ra value as one that is mostly troughed, but each could have a very different impact on seal performance. Surface finish measuring equipment is capable of tracing a surface finish using a diamond tipped stylus or non-contact 3D laser scanning. Static and dynamic sealing applications will have different requirements for seal finish. Measuring and analysing the hardware surface finish is important to ensure the correct conditions and no leakage occurs. If a seal application is static, and is sealing a low molecular size gas such as helium, for example, then a very smooth surface is preferable. For some dynamic applications, it can be critical for either seal friction, or wear life, that the interface between the seal and the hardware is well lubricated. Specifying the right surface finish for the hardware components that contact a seal can be complex and daunting. Our expert team advise our customers on the relevant parameters, with consideration to what is important for the given application. We ensure the optimum finish is fully specified to achieve right-first-time seal performance. Find out how our expert quality engineers and inspectors ensure the highest level of quality assurance HERE
Are all elastomers the same?Elastomer rubbers look very similar - but are they all the same? With many different base groups and recipe formulations, there's a huge range of elastomer materials suitable for applications with varying temperature ranges and chemical media compatibility. It's critical to the seal performance to make the right choice. There are number of factors to consider, these include: Material hardness Elastomer material hardness can impact assembly loads, seal friction and extrusion resistance. Softer seal compounds can be used effectively against rough hardware surface finishes, as the softer rubber can better accommodate surface imperfections (especially when sealing low pressure gas). Harder compounds will have greater wear resistance in dynamic applications. Chemical compatibility Unlike PTFE seals (where there are very few chemicals that will attack and breakdown the material) elastomer seal materials have to be carefully selected. It's important to ensure properties are not affected by any fluids or gasses that the seals come into contact with. Temperature range Outwardly, elastomer rubbers seem straightforward, but the technology can be complex. Material groups often have well published temperature ranges. For example, the silicone family is able to reach -100°C (or even lower with special grades), and perfluoroelastomer (FFKM) grades are able to withstand 320°C (or even higher for short durations). Whilst guidance can be given on maximum temperature capability for any specific elastomer grade, this is often in a benign air environment. Therefore the chemical impact of being exposed to hot fluids in the sealing application should be considered. For information about our extensive product range, see HERE
The importance of engineering tolerancesTolerances are present in every man-made item. It is practically impossible to repeatedly manufacture something to an exact size or specification. In seal manufacturing, it's important to understand which tolerances impact performance and by how much. This will ensure a system is optimized for overall performance, and whole-life product cost. Considerations for tolerances include the seal material and the hardware for sealing installation.
Seal material, polymer and metal seals
Almost all polymer seal materials contain multiple ingredients. For PTFE and polyurethanes this is typically 2 or 3 different elements. Additionally, for an elastomer material, as many as 30 different ingredients can be used in the recipe. In machined seals, polymer seal materials tend to have high rates of thermal expansion. Together with their relative softness, this makes it difficult to maintain the same level of tolerance that can be achieved when machining metal components.
Hardware tolerances
When designing hardware for seal installation, engineering tolerances are sometimes more obvious, and certainly where engineers can focus some attention. A stack-up of tolerances for many applications should be considered. Together with tolerances of the assembly such as concentricity or misalignment (especially for dynamic sealing applications). Other considerations include bearing wear and the resulting increase in misalignment or runout as the equipment approaches the end of it’s target life.
Why are engineering tolerances important for sealing systems?
Every application starts from a nominal condition, and the maximum and minimum tolerance conditions should always be considered. Even in seemingly straightforward applications, it's important to ensure the seal is continuing to operate within it’s ideal set of conditions. Click on the link for information about our engineering, design and innovation service, click on this link HERE Use our interactive tools HERE
Elastomer manufacturing moulding processesHow is it manufactured? A question we get asked in the seal design process, but perhaps not considered often enough. How a rubber seal is produced can affect a number of things; the cost, the material choice...even how a part should be designed. All of these can have a significant impact on the performance of the seal in application. Let's take a look at the three main manufacturing methods for moulding elastomer seals. Compression Moulding This is the most simple method of converting a piece of rubber into a finished seal product. First, the rubber compound is mixed and prepared. The material has a stiff and non-elastic consistency (like thick dough). From this dough we produce a rubber blank (also known as a pre-form) by either cutting, punching or extruding cord. These blanks are normally a little bigger than the finished part (normally based on weight) will be placed into a metal moulding tool. The tool (in its simple form) is in two halves with the final product shape cut into the metal. This is known as the mould cavity. Injection Moulding This manufacturing process is often used to produce plastic components, but for rubbers, the temperatures are switched. A warmed rubber is injected into a hot tool, as the force required to inject uncured rubber is much greater than what’s required to push molten plastic into a chilled mould. Otherwise the equipment and principles remain similar. Transfer Moulding This is a variation on compression moulding. It uses the same hydraulic compression presses, but this tooling is a little more sophisticated (and consequently a little more expensive). Comparing the three most common methods of producing an elastomer seal, it's clear that evaluating how the part is going to be made, is key to ensuring the technical and commercial success of the seal in the application. Read more about our engineering, design and innovation service HERE
Polyurethane as a seal materialThe foam in your armchair. The strap on your wristwatch. The wheels on a supermarket shopping trolley and beyond; Polyurethane certainly has a diverse range of uses since its invention almost 85 years ago. Aside from day-to-day products; it is also a highly capable and versatile sealing material - and an option that is often overlooked.
What is Polyurethane?
This material is rubber, plastic, rigid and flexible. Polyurethane covers a group of materials; plastic polymers produced by the combination (or synthesis) of di-isocyanates with polyols and a chain extender. This makes Polyurethane an excellent seal material.
How are Polyurethane materials manufactured?
There is a one and two-step process to manufacturing polyurethane.
One-step process
This is when a compound containing multiple hydroxyl groups (called a polyol), is mixed with highly reactive low molecular weight chemicals (isocyanate), and a chain extender (low molecular weight diols or diamines). Consequently, the result is a random copolymer with a physically cross-linked irregular molecular structure.
Two-step process
In a two-step process, the polyol and isocyanate are mixed first to produce a pre-polymer. This is mixed with the chain extender to produce a block copolymer with more regular molecular structure. Although this often results in improved and more consistent material properties, there is a slightly higher production cost.
Why is Polyurethane a good seal material?
Evidently, when formulated appropriately, Polyurethane does produce an impressive set of material properties that make it an ideal material for sealing products. Consequently, its flexible, with very high abrasion resistance, tensile strength and stiffness. The tensile and tear strengths are typically 3-5 times higher compared to rubber seal materials. Although it lacks the chemical resistance and temperature capability of PTFE, it is compatible with mineral oils. There is more information on polyurethane as a seal material HERE You will learn more about our range of materials HERE
Why the focus on PFAS?PFAS is a blanket term used to describe Poly- and Per- fluoroalkyl substances. There are currently around 10,000 substances in existence that fit this description, with potentially more variants still yet to be produced. Some are already known to be harmful to human and animal health and the environment (such as PFOA and PFOS), and these specific PFAS are already controlled under legal restrictions. But in February 2023, The European Chemical Agency (ECHA) published a regulatory proposal to further restrict the manufacture, placing on the market, and use of all PFAS within the EU.
Seals for cryogenic applicationsCryogenic sealing means controlling or sealing a media at very low temperatures. This process can be complex and advanced, and spans a range of markets; from pharmaceutical, chemical and refrigeration, to automotive and electronics.
Why use 2-Shot moulded seals?2-Shot moulding is a manufacturing process that allows the co-polymerisation of hard (or soft) plastics and thermoplastic elastomers (TPE’s). We use the 2-Shot manufacturing approach to deliver engineered parts that perform a critical sealing function.
Why use PTFE seals?Polytetrafluoroethylene (PTFE) is a thermoplastic polymer that can be used in a variety of sealing applications; it is particularly suitable where the application conditions exceed the parameters of elastomeric seal use, but are not as highly demanding as applications that require the use of metal seals.
Why use metal seals?The use of metal seals as an engineered sealing solution is appropriate where it is not possible to use elastomeric or polymer seals due to extremely demanding application requirements. For example, these could include applications with extremely high temperatures (300°C upwards) and pressures, intense radiation, cryogenic conditions or highly aggressive chemicals.
Why use Push-in-Place gaskets?Where a seal groove follows an irregular path or profile, a common sealing solution is to design a custom Push-In-Place (PIP) gasket that has the same profile as the centre line of the groove, simply drops into place and is retained by the features of its own design.
Perfluoroelastomers in valvesIs it time to re-visit using perfluoroelastomer seals in your valves? First developed by DuPont™ in the late 1960s, perfluoroelastomers (or FFKMs), are now widely known and understood in a variety of markets. But for those that may be less familiar with these high performance materials, here is a quick recap...
Seals for valve applicationsValves are imperative for isolation and control functions, and can be found in a broad range of industries such as Oil & Gas, Water & Wastewater, Food & Beverage and Hydraulics & Pneumatics. We supply seal products into valve applications in a variety of styles including ball, gate, flap, plug, butterfly, spool, check and solenoid valves.
3D printing for seals3D printing has developed significantly and now performs a crucial role in many applications. 3D printed products vary from fully functional to purely aesthetic applications; with the most common application being for manufacturing. Here we discuss how our engineers use 3D printing to demonstrate a seal concept.
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Product Range
Our seal products range from simple static O-rings to complex and bespoke seal designs in specialist materials. Whatever your application, we have the seal product for you.
