Archive for the ‘Seals’ Category

5 Fun Ways To Use O-Rings

Friday, July 8th, 2016

O-rings are gaskets in the form of a ring or an ‘O’ with a circular cross section usually made of pliable material. They are used for sealing joints and connections in pipe, tubes, etc.

Common uses of O-rings include hydraulic and pneumatic systems. However, there are some surprising and uncommon uses for O-rings. For fun, let’s take a look at some of these…

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5 Types Of Materials Commonly Used To Make O-Rings

Friday, May 6th, 2016

O-rings are a common type of seal used in various manufacturing industries.

Due to their simple production, cost, pressure resistance, and easy installation, they have found their way into many common products including engines and vehicles. The aerospace industry has also put them to good use in different types of rockets.

O-rings work in many different applications since they have a diverse range of materials used in their fabrication.

What Are They Made Of?

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Use SKF Speedi-Sleeve for Worn Shafts

Friday, April 17th, 2015

The Speedi-Sleeve is a thin-walled sleeve developed by manufacturer SKF, that is simply pushed into position over the worn area. This provides a surface that is then optimized for radial shaft seals, reducing costly downtime. And, there is no need to disassemble the shaft, or search for other seals since the same sized seal as the original can still be used. The only installation tool needed is supplied along with the shaft, so no special equipment is needed either. All you’ll need is a mallet and pair of pliers.

SKF Speedi-Sleeve Features: Through the stainless steel and manufacturing process, the speedi-sleeve provides an optimized seal that minimizes wear on the sleeve and the sealing lip, and increases strength and ductility. Its surface is wear resistant and made to minimize directionality – traits that are better than most counterface surfaces achievable on a shaft. It is complete with imperceptible lubricant pockets that allow the lubricant to sit on the sleeve, and prevent running of the sealing lip while it is dry, which would create excessive wear.

Installing SKF Speedi-Sleeve: The seal counterface surface of the shaft should be carefully cleaned, and any burrs or rough spots filed down before installation is attempted. If not properly cleaned, due to the thin-walled sleeve’s interference fit, any disturbances on the shaft surface may create a similar pattern on the sleeve surface and cause the seal to leak. If there are deep wear grooves, scratches or very rough surfaces, treat first with a suitable powdered metal filler, and position the sleeve before the filler has hardened. Take care the sleeve is not installed over keyways, cross holes, splines, or threads since this will result in deformation of the sleeve and will make it difficult to follow its new counterface surface as it rotates.

To simplify installation, the SKF Speedi-Sleeve has a removable flange, as well. The flange should be removed in applications where it may reduce the supply of lubricant to the seal, or in applications where it would interfere with other system components, but otherwise it can be left intact.

Also, the SKF Speedi-Sleeve should not be heated prior to installation. Using heat will cause the sleeve to expand, but when it cools, it may not contract back to its original size, resulting in a loose fit on the shaft.

Removing the SKF Speedi-Sleeve: Note that upon removal, the SKF Speedi-Sleeve cannot be reused. If needed, the sleeve can be removed by applying heat, which will expand it enough to let it slide off the shaft without causing damage to the shaft. In addition, the sleeve can be removed by relieving the press-fit tension using a small hammer to peel across the width of the sleeve, or using a cold chisel to cut through the sleeve, or a pair of wire cutters starting at the flange and twisting.

SKF Speedi-Sleeve Gold: There is also an enhanced version of the SKF Speedi-Sleeve, that has increased durability and resistance to abrasive wear. A thin, metallic coating is applied to the base stainless steel of the SKF Speedi-Sleeve, and imparts a gold color along with enhanced features. It was designed for applications where extended sealing system life is required, and to essentially bridge the performance gap between the standard sleeve, and acquiring an expensive custom shaft treatment. The SKF Speedi-Sleeve Gold is especially effective in environments where there are abrasive contaminants. Note that the installation procedure is the same as for the standard Speedi-Sleeve, and the original seal size can still be used.

Test results: To ensure optimal performance, the SKF Speedi-Sleeve Gold has been extensively tested in order to establish its level of abrasion resistance in severely contaminated environments. Tested using both coarse and fine sand, and at temperatures up to 225 °F and shaft speeds up to 1 700 ft/min. Under these conditions, seals on SKF Speedi-Sleeve Gold ran for an average of 2500 hours. Just another reason SKF is among the largest, and most reliable bearings manufacturers on the market today.

Labyrinth Seals and Contaminant Ingression

Friday, August 1st, 2014

Keeping contaminants away from machines comes down to managing potential entry points including where oils are added and where air is exchanged.

It can help to make simple modifications to breathers and sight glasses. However, including shaft seals are just as beneficial. Labyrinth-type seals are typically used in contaminant exclusion. Given that you properly maintain them, they can have a great impact on the reliability of the components they are installed in.

A seal’s purpose has different facets. Not only does it keep contaminants out, it also keeps what’s inside the machine where it belongs – inside. The standard lips seals can keep certain contaminants from entering and prevent leakage, but when operating in high pressure or extreme ambient conditions, they don’t deliver very well.

On the other hand, labyrinth seals can lower contaminant ingression by blocking the clearance where particles get through. Also, they produce areas of turbulent flow to exclude contaminants.

Every contaminant that tries to get in the bearing housing should pass through the seal’s maze of turns and angles for it to get to the bearing. These contaminants are incessantly subject to centrifugal forces due to the rotational motion of the shaft while on their way, though. Thus, only very little make it through the entire length of the seal.

When you’re on the hunt for something that would help you increase reliability and lower bearing failures, take into consideration the seals that are used. In high airborne particulate matter or heavy washdown areas, go for a labyrinth-style seal as it could aid in limiting the ingress of contaminants, as well as add years to the machine’s life while at it.

With the right lubrication and proper contaminant-exclusion devices, a lot of bearings are able to achieve their design life.

Seal Selection Tips

Friday, May 9th, 2014

Bearing Seals must be able to offer a bare minimum amount of friction and wear while at the same time be able to give maximum protection even under the most extreme conditions. A plethora of factors must be taken into consideration when choosing the most suitable seal type for a certain bearing arrangement. These factors are as follows:

  • the type of lubrication: oil or grease
  • the peripheral (circumferential) speed at the sealing surface
  • the shaft arrangement: horizontal or vertical
  • possible shaft misalignment
  • available space
  • seal friction and the end temperature increase
  • environmental effects
  • cost

Choosing the right seal is of the essence when it comes to the performance of a bearing. That said, it’s only fitting that you accurately determine the requirements as well as precisely define the external conditions. There are two types of external sealing devices typically used with roller bearings: non-contact and contact seals.

Non-contact seals

The efficiency of an external non-contact seal will rely largely upon the sealing action of the narrow gap between the rotating and stationary components. The gap could be arranged radially, axially, or in combination.

Such seals could be as simple as a gap-type seal or more intricate such as a labyrinth seal. In either case, considering there is no contact, such seals produce practically no friction and do not wear. For the most part, they’re not easily damaged by solid contaminants and are pretty fitting for high speeds and high temperatures. So as to improve their sealing efficiency, grease can be pressed into the gap(s) formed by the labyrinth.

Contact seals

The efficiency of a contact seal relies upon the ability of the seal to exert a minimum pressure on its counterface by a fairly narrow sealing lip or surface.

More often than not, contact seals are quite reliable, especially when wear is kept to a minimum through making an appropriate surface finish for the counterface and by means of lubricating the seal lip/counterface contact area. They are, however, susceptible to mechanical damage like improper mounting, or by solid contaminants. In order to avoid damage by solid contaminants, it is a must to put a non-contact seal in front of a contact seal for protection purposes.

The New Design For A Turbine Bearing Seal

Friday, March 14th, 2014

An engineering firm that’s known for designing seals used in wind turbine bearings used finite-element analysis software in simulating the performance of a gasket or seal. Then they ran through a wide array of design and material potentials so as to pin down the best fit for a wind turbine’s wide operating range.

All wind turbines have at least 4 big diameter bearings, all of which to pitch every blade as well as the yaw bearing. Each requires 2 seals. These seals, at some point, might act up. And it could be for several reasons, namely load variations, temperatures, as well as small variations while being manufactured — which are, quite honestly, inevitable.

Variations in manufacturing tolerances as well as other loads could introduce deformation of a bearing. It could then alter the width of the gap between the inner and outer bearing rings. An axial offset of the two rings can lead to further issues. Furthermore, the gasket’s coefficient of friction may have a massive impact on the sealing function.

The search for solutions called for tradeoffs. Case in point: how rigid should the gasket be in order to hold its shape under load? The daily performance and maintenance needed tradeoffs, too. The gasket must not take rocket science to install and should be able to remain in place while running. Lastly, there is the unavoidable conflict between controlling cost and maximizing capability.

To come up with an answer, Schoenberg’s team utilized Abaqus finite element analysis (FEA) software, and Isight optimization software—the two being from Dassault Systèmes 3DEXPERIENCE SIMULIA application. These allowed analysts to simulate a sizable amount of variations and determine the ones that are best fitting for design goals.

The gasket’s main functions include safeguarding large bearings from environmental perils as well as seal the lubricating grease inside. Moreover, the gasket is anticipated to still be performing for 20 years even in extremely demanding environments.

The first analysis task involved making a meshed model that would run in Abaqus. The setup of its characteristics was pretty basic: Bearing metal is defined as obstinate as compared to the elastomer gasket, which had nonlinear elements.

The analysts selected 14 parameters, geometric dimensions and material properties, for optimization. And the number was cut down to six crucial parameters. They claim that through determining effects, they were able to get rid of unnecessary factors. They regularly update the design to cater to ever-changing client specs and deployment locations. Thus, it brings about a design that is not a one-size-fits-all seal.

They were able to play with design concepts which yielded excellent outcome. The gasket they were able to formulate had superior features and was less sensitive to processing and manufacturing variations, and to operating conditions for the wind turbine.

What are the Uses of Oil Seals?

Friday, February 14th, 2014

The job of oil seals, otherwise dubbed as grease, fluid, or dirt seals, is to close gaps between stationary and moving components found in mechanical equipment, and keep lubricant from escaping. Oil seals also prevent contaminants from getting into machinery, especially in severe environments.

As important parts of pretty much all types of machines and running vehicles, oil seals can protect every type of precision-constructed, close-fitting ball, sleeve, as well as roller bearings.

When it comes to precision bearings, oil seals keep lubricants from escaping the bearings or a certain area. While in machine components, oil seals can help keep out abrasives, corrosive moisture, as well as other harmful contaminants. Oil seals also aid in stopping intermixture of two different mediums, specifically lubricating oil and water.

The seals are helpful in a full range of equipment in a wide array of applications, namely automotive, manufacturing, off-highway, oil refineries, as well as power transmission. It’s a must that grease seals match the aftermarket applications or original equipment. By doing so, you can rest assured that your machine’s performance will be optimal and consistent.

Typically, a dirt seal is installed adjacent to the bearing.  It could be sealed in or sealed out, as per requirement of the machinery which relies upon the different kinds of solids, gases, or liquids that come across a specific mechanism.  Therefore, keep in mind that before you choose the lip material or sealing element, determine beforehand the environment that the oil seal will be operating in.

Fluid seals are also made out of several compounds and materials.  It could be from PTFE, tetrafluoro-ethylene propylene, fluoro-elastomer, silicone, polyacrylic or ethylene-acrylic, polyacrylate, nitrile, urethane, leather, as well as felt compounds.

You can avail of industrial type of seals that come in different sizes. You can stumble upon small-bore, ranging from zero to 13 inches.  You can also find high-temperature and metric varieties of grease seals. That said, it’s crucial to know which seal to use for your machinery.