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Why You Should Use Custom Seals
While you could buy seals made with the size and materials of industry standards, its performance simply won’t hold up. Whether you have a static or a dynamic application, each one has its own unique needs and circumstances. Wouldn’t you rather create the perfect solution to your problem, rather than finding a product that only approximately fills the needs of your application?
That’s why you should have your seals custom built: you’ll be able to go through each step of the production with your application in mind.
Size
No matter how big or large your application, Real Seal has the solution. We can produce parts anywhere between 0.50” to 27” in diameter. Our state-of-the-art machinery will produce parts with the exact dimensions you need.
Manufacturing Processes
Each manufacturing process has its own advantages and disadvantages, depending on the needs of the application. Real Seal’s manufacturing process balances injection molding and compression or transfer molding.
By combining the three manufacturing processes above, Real Seal can produce just about any seal for any application:
- Injection molding is considered the most cost-effective molding process, suitable for high-volume productions of small products that require tight tolerances and little finishing. The process involves feeding material into a press, which is warmed and injected into a mold. The process is extremely precise, since the pressure temperature and speed at which the material enters the mold can all be controlled. This cost-effective process can produce parts quickly.
- Compression molding is best suited for low-to-medium production volumes and larger parts which do not require the tightest tolerances or perfect finishes. The rubber is pre-heated, and then inserted into a mold by a press where it is held until it is cured. It produces more intricate products with fewer knit lines. Other benefits include: fast production, low tooling costs, and the ability to produce high durometer materials.
- Transfer molding uses a press and mold much like compression molding. But unlike compression molding, transfer molding uses a piston to force a material through a passage into the mold cavity. This method can produce very complex components with tight tolerances at a high production rate. It can also handle larger products. Unfortunately, these benefits come with a much higher production cost.
Material
One of the most important choices you will make for your seal is the material it is made of. There are a wide variety of materials to choose from, each with their own unique properties. If you haven’t determined the right material for your application, the performance of your application and the seals themselves have likely been suffering as a result. In some applications, the performance of the seal material can make or break the entire system.
Some of the materials you will have to choose from include the following:
- Nitrile is the most widely used elastomer in the seal industry due to its ability to resist petroleum products and is compounded for use in temperatures ranging from -22°F to 212°F. Since it is a copolymer consisting of butadiene and acrylonitrile, they can be added in different proportions in order to give the product the properties needed for the application. For example, it may result in improved performance within a specified temperature range.
- Ethylene-propylene compounds are typically combined with a third monomer to produce EPDM. They are often found as seals in brake systems, as well as applications with hot water or steam. It is resistant to mild acids, detergents, alkalis, silicone oils and greases, ketones, and alcohols. They do not perform well with petroleum oils, mineral oil, di-ester lubricants or fuel.
Other common materials include:
- Hydrogenated Nitrile (HNBR)
- Fluorocarbon (FKM)
- Neoprene/Chloroprene (CR)
- Polyacrylate (ACM)
- Polyurethane (AU) (EU)
Helping You Produce the Seals You Need
There are so many different factors to consider in seal production, and just one misstep with any of them can negatively impact the performance and longevity of your seal. That’s why Real Seal has its own full-time chemist and support staff to analyze your situation, and produce a seal that meets your needs. With our experience producing thousands of seals, you can be sure that you’ll have a seal that performs to your standards. Give us a call to get started today.
The Perfect O-Ring for Any Application
O-rings are among the most versatile, dependable, and inexpensive seals available. O-Rings provide a number of unique advantages over other seals, including:
- A circular cross-section with a minimal surface area, enhancing their resistance to abrasion, fluids, adverse environments, and mechanical damage.
- This cross-section also makes them adaptable to various types of squeeze, including axial, radial, and angular.
- They seal in both directions.
- They fit into confined spaces without bulky, adjustable, or expensive support structures.
- Easy to maintain: there are no bolts to re-tighten.
For these reasons, O-rings are the best choice for a wide variety of applications.
Static Seal
A static seal application refers to a gland in which there is very little motion between the parts of the gland which come in contact with the O-ring. Small amounts of motion – such as thermal expansion, vibration, bolt stretch, and O-ring response to fluid pressure – do not change the definition of a static application. Static applications are divided into two types based on the direction of squeeze applied to the O-ring cross-section: axial and radial. In some cases, both types of squeeze are present, though this is not recommended since it prevents the O-ring from expanding.
Static Axial Seals
A static axial seal applies pressure on the top and bottom of an O-ring. Static axial seals are most often used in face seal applications. Another common type of application in this category involves an O-ring on the face of one part of a structure, which closes on another structure. As the structures close on each another, a sealing action compresses the O-ring between the mating surfaces.
Static Radial Seals
In a static radial seal, there is squeeze between the inside diameter and outside diameter of the O-ring. Common static radial seals include cap seals and plug seals. Although seals are best left on one side of the seal, O-rings are versatile enough to work in grooves of many different shapes and directions of squeeze. One example is a crush seal, in which the O-ring is installed on a triangular gland with very little space surrounding it.
Due to potential damage during installation, as well as the potential for warping in the metal gland, this application is only used where cost and ease of machining are the most important factors.
Dynamic Seals
Dynamic sealing applications involve relative movement between the parts of the gland. O-rings in these applications must be able to withstand the friction caused by the sliding action against the gland. This factor makes dynamic seal applications somewhat more difficult to design. In many dynamic sealing applications, O-rings are subjected to radical squeeze, reciprocating intermittent or continuous motion, or intermittent rotary or oscillating motion.
Reciprocating Seals
In a reciprocating seal application, a back and forth motion along the shaft axis between the inner and outer elements of the gland occurs in what is called a piston and rod seal.
Oscillating Seals
The inner and outer members of a gland move in an arc around the axis of a shaft in alternating directions (typically at an intermittent rate). They are most often found in faucet valves, but may be found in any other types of valves since they are simple to design and reduce costs.
Other Dynamic Seals
O-rings can be used in any application where data used for reciprocating or oscillating seals do not apply. Their versatility allows them to be used in many rotary applications where either the inner and outer members of the gland continuously turn around the axis of the shaft.
Rotary Applications
Rotary seals involve an inner and outer member of a sealing element turning around a shaft axis in one direction. The name applies to any application where the rotation is reversible, but not when the motion is intermittent (such an application is an oscillating seal). In such an application, heat from friction is continuously generated in one place. Thus, the main concern in a rotary application is using a seal which can withstand high temperatures and to reduce heat buildup as much as possible.
Other Applications
Rubber seals can be used in many other applications not listed here, including seat seals, pneumatic seals, and vacuum seals.
Whether you need a seal for a simple static application, or a more durable seal for a rotary application, Real Seal will have a rubber seal suitable for your application. We are also one of the few seal suppliers that have a full-time chemist to answer any questions you might have, and ensure that you have the perfect seal for your application. Don’t hesitate to give us a call today.
The Benefits of a Backup Ring
No matter what type of application you have or who you work for, having a system that will run well for as long as possible should be one of your top concerns.
A backup ring is just one of the many little things you can do to help keep your system running smoothly for as long as possible, along with these other methods. But you might be wondering, just how does it work? There are a few ways a backup ring could improve your system performance and longevity.
Extrusion
O-Rings experience a lot of stress, causing them to wear down in various ways. One of the biggest causes of an O-Ring failure is extrusion, particularly in hydraulic rod and piston seals. Extrusion occurs when the internal pressure of an application becomes too great, causing the O-Ring to extrude – or stick out – into the clearance gap. This extruded or extended portion of the O-Ring will wear down quickly, reducing the amount of material in the O-Ring. After a short period, extrusion results in seal failure.
According to Daemar, some of the common causes of extrusion include:
- Excessive clearances.
- Pressure exceeding system design.
- An O-Ring with an insufficient durometer for the application.
- Degradation of the O-ring due to system fluid.
- Irregular clearance gaps caused by eccentricity.
- Increased clearance gaps due to excessive system pressure.
- Improper machining of O-ring gland.
- Wrong O-ring size installed, resulting in an excessively filled groove.
You should inspect your O-rings for signs of extrusion. Examine the edges of your O-rings on the low pressure or downstream side to see if it appears chewed or chipped. If extrusion has caused your O-ring to fail, you should see small pieces missing from the low pressure or downstream side. In some cases, 50% of the O-ring may have been lost already before the leakage has been found.
Preventing Extrusion
There are three ways to combat extrusion. The first is to reduce the clearances in order to lower the extrusion gap. Unfortunately, this is not practical due to the high expenses involved.
It would be much cheaper to instead raise the durometer of the O-ring. An O-ring with a higher durometer would have a much higher resistance to extrusion, but would also bring two other problems with it: namely, the limited availability of higher durometer materials, and that these materials are not as effective in low pressure applications.
Backup Ring
This brings us to the third option: backup rings. Rather than acting as a replacement for your installed O-rings (as its name suggests), a backup ring is actually meant to work in tandem with the O-Rings you have already installed. Backup rings are typically made of materials with high durometers and resistance to extrusion, including nitrile, Viton (FFKM), or PTFE.
The backup ring is installed between the O-ring and the extrusion gap. The addition of a backup ring will improve the pressure resistance of the O-ring, and prevent it from being forced into the clearance gap, reducing the chances of extrusion and premature seal failure. Depending on the direction of the pressure, you may even be able to install two backup rings. This will provide added protection against extrusion and O-ring failure.
Choosing a Backup Ring
You will have a number of options to choose from to cater an O-ring for your application. They come in two styles: a flat, washer-like style, or a contoured face which provides greater grip and support on the O-ring.
They may also have a solid or spiraled construction. A spiraled construction is made of overlapping rings, providing several different contact levels against the shaft. They provide greater support over solid construction backup rings.
Buy Your Backup Rings From an Industry Leader
From humble beginnings as an O-ring distributor in 1970, Real Seal has grown to become a full-service O-ring supplier and industry leader. Real Seal is not only one of the most technologically advanced O-ring suppliers today; we are also one of the few organizations with a fully-equipped laboratory as well as a full-time chemist and technical staff. This allows Real Seal to meet design challenges special material formulations in a way that no other company can. Don’t wait: give us a call and we’ll provide you with backup rings made to your exact specifications as soon as possible.
How To Maintain Hydraulic Components
Proper maintenance of a hydraulic pump is crucial for reaching maximum pump efficiency. Every component is reliant on another, so if just one component is damaged, the others will be damaged as well. Regular maintenance is necessary to prevent damage from occurring or getting worse.
Contaminants and Moisture
Prevention is the best way to properly maintain a hydraulic system. This means taking the steps necessary to keep contaminants out of the system (…if not, the performance of your system will suffer due to a number of factors):
- Clean the area around dipsticks, fill plugs, and hydraulic filters before removing them to check or change hydraulic fluid. Make sure that hydraulic fluid containers are tightly sealed when stored. Pour the fluid directly into the system.
- Change the fluid and filter after the first 50 hours of use. The manufacturing process may allow contaminants to enter the hydraulic system. Changing the fluid after 50 hours will eliminate these contaminants. From there, change the hydraulic fluid and filter at regular intervals according to the directions in the owner’s manual.
- Check the oil before each use. Ensure that the fluid is in good condition, and that fluid levels are at a sufficient level. If the fluid is foamy or milky, there could be a leak where air is entering your system, causing jerky and slow hydraulic operation. Insufficient levels of oil will cause severe damage to the pumps.
Air within the system carries moisture. When the system cools down following an operation, the moisture will condense and mix with the hydraulic fluid, resulting in the milky appearance mentioned previously. Test for water by pouring a 1/8 cup of hydraulic fluid into a metal can, then heat it with a propane torch. If you hear popping or crackling, the fluid has water and must be changed immediately.
Check the temperature of the hydraulic fluid often, for signs like the oil being too hot to touch, or a burning smell. These symptoms point to a problem with the cooling system or pressure level. Inspect the hydraulic oil cooler or reservoir, making sure that they are clean. Remove dirt and other debris inhibiting airflow surrounding them. If the fluid is too hot for an extended period, the fluid will break down and won’t be able to lubricate properly.
Pumps
Pumps should be inspected for obvious external wear and damage, as well as cavitation. Cavitation occurs when the the pump does not receive the necessary amount of fluid from the reservoir. Follow these steps every 50 hours:
- Listen to the pump while the hydraulics are in operation. Rattling or a sound similar to marbles or rocks bouncing around the pump is a sign of cavitation. Shut the system down immediately if you hear either of these sounds.
- Check the fluid level and filter if they are limiting or restricting the flow.
- Examine for previous modifications to the reservoir, inlet lines, or pump. Alterations to these components will affect the pump inlet flow.
- Leaks, bends, pinching, and other discontinuities will restrict the flow. Regularly clean your system’s strainer if you have one.
Cylinders and Motors
Cylinders have seals and rings which may be damaged by excess pressure and contaminants in the fluid. Check that your hydraulic fluid is clean, and inspect where the cylinder rods move in and out of their housing for leaks. Cylinders should not have dings, dents, and other kinds of damage, which will allow fluid and pressure to escape.
An attitude of prevention is essential for protecting your O-rings. Learn more about four ways to prevent seal failure here.
O-rings are susceptible to a variety of elements, including UV rays, temperature, and humidity, so they must be stored in a very particular way. Real Seal has covered proper O-ring storage here.
Valves
Valves may be abraded or may leak internally, which will result in low hydraulic pressure. Contaminants may become lodged in the valves and restrict the flow. Maintain clean hydraulic fluid to ensure properly-functioning valves.
Other Components
Hoses, lines, fittings, and couplers must be inspected for damage. Hoses and lines may be dented from falling tools, contact with other equipment, and a number of other factors. Lines should be inspected for cracking, cuts, or dents, which will restrict the flow or leak pressure. Hoses may be damaged in the same ways, in addition to overheating, extended wear, and defective manufacturing. Hoses may also be internally damaged, causing pieces to contaminate the system.
Buy Your Hose Components From an Industry Leader
Purchasing quality components will help prevent damage and the need for repairs. Contact Real Seal, and our team of experts—including an in-house chemist and technical staff—will help you purchase the right seals and components to keep your hydraulic system running smoothly.
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