Learn more about Parker Hannifin seals, o-rings, polymer springs and much more in this collection of articles. Parker sealing products are used in a number of industries for a variety of applications, including hydraulic sealing systems.
Semiconductor FFKM Offers Low Particle Generation AND Extreme Etch Resistance
In the world of semiconductor manufacturing, performance requirements are driving circuit sizes smaller and smaller, causing increased sensitivity to wafer defects. In parallel, the number of manufacturing steps has also increased driving a need for improved tool utilization and leaving more opportunity for these defects to be introduced. Identifying and eliminating the sources of defects is a tedious but necessary process to improve wafer yield.
What impact does seal contamination make?
One very distinct source of defects are the seals within a fab’s tool. Plasmas involved in both deposition, etch and cleaning processes utilize aggressive chemistries that put even high-functioning perfluorinated sealing compounds to the test. Much room for improvement has been left in this industry with many seal materials still posing significant threats to defectivity or downtime despite being designed for low particle generation or etch resistance.
How can Parker ULTRA™ change the industry?
Parker’s UltraTM FF302 Perfluorelastomer has proven success in CVD and etch applications, putting this material at the top of its class. Typically, seal materials for semiconductor applications are optimized for low particulation or extreme etch resistance, however, Ultra FF302 provides both attributes in one material. Laboratory testing shows Ultra FF302 has lower erosion in aggressive plasma chemistries even when compared to today’s leading elastomeric materials (Figure 1 below shows comparison erosion levels of various etch resistant perfluoroelastmers after exposure to O2 plasma).
Custom Environmental Seal Solutions: When Unique Requirements Throw a Curveball
When it comes to the topic of utilizing elastomeric seals, it’s stereotypical to consider environmental sealing as one of the simpler categories of applications. Near-ambient pressure and temperature conditions and a lack of exotic or aggressive chemistries are the kinds of details that typically come to mind. However, throw in a curveball or two and suddenly the challenges posed can make finding a solution seem reasonably more intricate.
Unique conditions call for custom design expertise
For instance, consider the potential challenges of sealing off a battery enclosure or other kind of electrical component. While this may seem like a simple issue of finding a material that seals against moisture or fluids found in open-air conditions, manufacturability also needs to be taken into consideration. Many electrical enclosures have particular spatial requirements, including those which involve seal housings that require low closure force or those with sharp corners that could damage more conventional seal designs like solid-profile O-rings. These kinds of conditions are becoming more and more frequent, especially considering the automotive market and its increasing share of electric vehicles, which involve a larger proportion of electrical components in a more compact arrangement for reduced weight. Add to this the fact that these batteries and other electrical components are becoming more elaborate and more expensive as a result, and the need for highly-effective protective sealing design becomes imperative. This is where Parker engineers can design products like picture frames gaskets and hollow profiles that are customized to unique requirements.
A Guide to Proper Storage and Cleaning of Elastomer Seals
Elastomer seals from Parker Prädifa meet the most exacting demands in a wide range of applications. Aside from the appropriate seal designs, the material properties of the seal compounds are crucial to ensuring that seals deliver the desired performance.
A key criterion for the storage period of elastomers is the time at which the product was vulcanized. Parker indicates the date of manufacture on the packaging bags: “1Qxx” stands for parts produced in the first quarter of the year 20xx. The recommended maximum storage period depends on the type of elastomer.
Omega Seal Profile: A More Robust PSA-Backed Sealing Solution
Customers often call with various sealing challenges. But sometimes their dilemmas can be solved with more robust solutions instead of direct replacements. For example, when a customer is having issues with a PSA-backed hollow seal that keeps peeling away from the bottom surface.
If you need to seal a box with a lid, you may need a 4-corner gasket to seal the contents from dirt and moisture. If you use a solid gasket, the compression force may be too great to effectively close the lid. Using a hollow seal reduces the compression force by orders of magnitude, but it comes with its own set of challenges.
A hollow seal for a box will most often seal between two flat surfaces. The bottom surface will be flat for adhesion to the box, while the top surface is curved to engage the lid as it is seated on top of the seal. However, the disadvantage of this design is the tendency of the flat portion to lift off the bottom surface. Figure 1 illustrates this phenomenon with standard Parfab profile D015.
TetraSeal: An Alternate Sealing Solution When an O-Ring Isn’t Working
Our applications engineering team takes more than a few calls each month where the O-ring is leaking, either immediately or after just a short time in service. Once we drill down to the details, we learn the failure mode is an improperly sized groove and O-ring. It isn’t all that uncommon for a groove to be cut in a flange and a novice designer learns the hard way that standard O-rings cannot fit in just any groove geometry. For hardware that has already been machined, frustration ensues as the caller learns the O-ring solution requires tooling. Tooling can have a lead time of at least a month to cut and can cost thousands of dollars. Parker offers a TetraSeal® solution, which often does not require tooling and can be made of many of the same materials used for O-rings.
Benefits of TetraSeals
The TetraSeal is a circular precision-cut seal with a square cross-section. Unlike O-rings which require a unique mold for each material family and size, TetraSeals are extruded, cured and machine cut to the target thickness. Our manufacturing facilities in both Spartanburg, South Carolina and Goshen, Indiana are tooled in a variety of interchangeable extrusion dies, making this type of seal an easily sourced seal solution without the lead time and cost of a custom molded O-ring.
Avoid Leakage and Support a More Accurate System There are many applications in industrial settings where fluid must be sealed and released in calibrated quantities. Some examples include pressure regulators, relief values, fuel nozzles, or gas metering. Specifically a demand flow regulator is designed for use with various industrial instruments and uses a pump to draw the calibration of gas. It is crucial that there is no leakage of the fluid for the system to operate properly.
Parker Composite Sealing Systems Division designs different poppets to help control leakage in flow control applications. Our poppet is used to help keep the demand flow regulators in the “closed” position. And when the user “demands” gas flow, a diaphragm pushes down on the seat stem of the Poppet to help monitor the flow of gas.
We receive many requests from customers asking for recommendations on how to retain seals in an application. One of the most popular “quick fixes” is to apply liberal amounts of adhesive to a standard O-ring type product without respect to groove shape or sealing function. However, Parker OES provides a wide array of sealing technologies, offering innovative solutions to accommodate the challenging and vast sealing needs of our customers.
Replacing RTV with Pre-Applied PSA
A customer had been using a standard O-ring product on an outdoor electronic device. This part was sealing the external edge of the enclosure and meant to keep out water and dust. The enclosure was plastic injection molded so this extreme edge had irregular geometry to accommodate the molding process. The original proposal was to shove O-ring cord in place and adhere it down with RTV (Room Temperature Vulcanization) so that it did not fall out during assembly. This left a rust colored stripe exposed on a consumer device due to fitment issues. Parker’s proposal was to replace the O-ring cord with a custom hollow extrusion that fit the available space and allowed complete closure, thus not exposing the seal to be visible. The RTV process was replaced with PSA (Pressure Sensitive Adhesive) that was preassembled to the seal and allowed for quick and clean placement during assembly and retention for any maintenance needed.
O-Ring Selection Made Easy with the Parker O-Ring Selector
Two things are equally important for the reliable performance of an O-Ring seal: the right size and the right material. Parker’s new O-Ring Selector is an engineering tool that enables users to make the right material and size selections easily, quickly and reliably – in a single application. The accuracy of the results ensures the desired performance of the O-Ring in the subsequent application. This is primarily based on the fact that both functionalities – the material selection and the O-Ring size calculation – are closely interlinked. This achieves a new quality in calculating the total sealing system.
Overview of the O-Ring Selector
The Parker O-Ring Selector is divided into three main sections:
Service Conditions & Material Selector
The Service Conditions & Material Selector section is focused on mapping the material-related application conditions. Entering the operating temperature range, the desired polymer family and/or material hardness will take the user to the suitable material selection. The Advanced Material Selector enables experienced users to specify the operating conditions in even greater detail. Here the medium to be sealed can be selected from a database containing 2,500 media. In addition, a search for required approvals and conformities can be run.
The O-Ring & Engineered Seals Division is now offering a rapid prototype program for solid and hollow spliced O-rings that will reduce lead times on small orders to improve sample and trial testing on enclosure projects. The program provides spliced rings available in a variety of cross sections and can be purchased in either solid or hollow profiles.
Spliced ring sizes
In the event that enclosure tolerances are large or the available compressive force is low, Parker engineers can design a custom hollow seal to help absorb large tolerances while providing very low compressive force compared to solid cord. Spliced rings with large inside diameters up to 95” are available in silicone and nitrile materials. Rings with inside diameters up to 57” are available in fluorocarbon. Cross sections of .070”, .103”, .139”, .210” .250” are regularly stocked and available to splice to the ring ID needed. The chart below outlines the current compounds, cross sections, and diameters available under the program.
One of the decisions equipment designers need to make when installing O-ring seals in their applications is how much the O-ring will be squeezed by its mating hardware to create an effective seal.
What is O-ring squeeze
Squeeze is a ratio of the amount of deformation applied to the seal expressed as a percentage of the free-state cross-sectional thickness. Deforming the seal cross-section “energizes” the elastomer matrix much like compressing a spring; the inherent elasticity of the rubber material causes it to push back against the mating components. This contact force blocks the passage of liquids, gases and dry powders, preventing them from flowing between the rubber seal and the mating hardware.
The greater the squeeze, the more force is applied against the hardware and the tighter the seal. But that doesn’t necessarily mean that designers should always specify the most squeeze (assuming they knew what that level was or why it was “the most”). There are a number of factors to consider, which include: