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The competitive landscape, combined with government regulations, are driving technology in today's automotive market for improved efficiency and fuel economy. Any incremental improvement in fuel economy is strongly considered. Just a half mile per gallon may seem to be insignificant, but these projects are all taken very seriously. The entire vehicle is being examined for efficiency improvements; not just the engine. Anything that reduces weight or eliminates friction is a prime target for investigation.
Recently, technological advances in the automatic transmission have been a big step in improving fuel economy. The "old" 5 and 6 speed transmissions are being replaced with more efficient 8, 9, and even 10 speed transmissions. The theory behind these new designs is providing the optimum gear ratio for the current acceleration condition.
Increasing the number of speeds, however, also increases the number of clutches, components, fluid circuits, and potential friction locations within the transmission. Combined with the fact that the available space under the vehicle does not change, means all this has to be done within the same size transmission case. This has resulted in packaging challenges for the additional clutch packages within the transmission.
One critical component within the clutch assembly is the clutch piston itself. These pistons are energized by hydraulic fluid pressure with the assistance of elastomeric sealing elements. In addition to being a critical component in the function of the unit, each of these sealing elements is a source of friction in the transmission, thus directly impacting the overall efficiency of the vehicle.
As important to the application of the clutch when needed, is the ability of the clutch to release when not in use. Return springs are used to retract these pistons. Lower force springs are being implemented to reduce the energy needed to apply the clutch, therefore lower drag seals are required to assure smooth, quick response time for the apply and retract cycles of the piston. These smaller springs also reduce weight and the space utilized.
Automatic transmission clutch pistons are typically made from either steel stampings or cast aluminum. The configuration of these pistons and corresponding sealing elements are dictated by the available space within the mating components:
O-Rings
D-Rings
Low Drag D-Rings
Lip Seal
Bonded Piston Seal
Parker Hannifin has the engineering design and manufacturing expertise to supply all clutch sealing configuration. Please contact one of our Applications Engineers to evaluate your specific needs and provide the optimal sealing solution for your application needs.
This blog was contributed by Scott Van Luvender, applications engineering manager, Automotive.
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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.
Recommended maximum storage period
Elastomer seals should preferably be used within the statutory liability period of 24 months.
The properties profile of an elastomer seal typically remains constant for years if the seal is properly stored. Improper storage conditions, on the other hand, can drastically reduce a seal’s potential shelf life due to a large number of influencing factors (see Figure). Ultimately, the seal will no longer be fit for use due to hardening, softening, permanent deformation, cracks, surface damage, etc.
To avoid this, Parker Prädifa, based on the DIN 7716 and ISO 2230 standards, recommends that the following information is observed for storage, storage periods and cleaning of elastomer seals:
The preferred storage temperature for elastomer products is +15 °C and should not exceed +25 °C. Accordingly, sources of heat such as radiators, boilers (minimum distance: 1 meter) or direct sunlight should be avoided. Temperatures should not drop below a maximum of -10 °C. As in this case, a stiffening of elastomer products occurs the seals should be handled with special care to prevent deformation. Chloroprene materials should not be stored below -12 °C.
It is important to ensure that the relative humidity in storage facilities is below 65%. Storage in humid rooms and condensation must be avoided. Neither should elastomer seals be stored in extremely dry conditions.
Elastomer seals must be protected against sources of light with a high UV content as they might be able to damage the products. Examples of light sources with a high UV content include intense artificial light or direct sunlight. Light-induced (photo) damage can be avoided by adequate application of UV filters to the window panes in the storage room. All types of radiation such as gamma or radioactive radiation must be avoided.
Generally, elastomer seals should be protected against circulating air by suitable packaging such as airtight containers. This is particularly important for very small seals with a large surface-to-volume ratio. Mercury vapor lamps, fluorescent light sources, electric motors – generally any device that is capable of producing ozone through sparks, electrical discharges or high-voltage fields – must urgently be avoided. Ozone is harmful to many elastomers so that storage rooms must be ozone-free. This also applies to organic gases as well as combustion gases as they are capable of producing ozone via a photochemical process.
Greases, oils and solvents may cause damage to elastomer seals. Therefore, it should be ensured that the seals cannot come into contact with these media in storage (unless packaged this way by the manufacturer).
Elastomer seals which are exposed to tensile or compressive strain, or other types of deformation, may be damaged. Cracking may occur. Therefore, the seals must be stored without being exposed to strain and deformation.
In addition to these recommendations, there are a few other aspects to be observed when storing elastomer seals:
Generally, elastomer products should be checked to ensure their proper condition prior to installation. Negative changes due to improper storage can usually be detected by visual inspection. The main characteristics discernible in a visual inspection are:
Elastomer seals should be cleaned swiftly using a clean cloth and lukewarm water. Exceptions are fabric-reinforced elastomer seals. In this case, contact with water must be avoided. Gasoline, benzene, turpentine and similar substances are not suitable for use as cleaning fluids.
Elastomer products must not come into contact with sharp-edged or pointed objects such as steel brushes, sanding paper, etc. Drying near radiators is not recommended.
Additional information: Brochure: Storage and Cleaning of Elastomer Seals
www.parker.com/praedifa
Posted by Dr. Heinz-Christian Rost, technology & innovation manager, Prädifa Technology Division
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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.
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.
There are also industry standards for electrical enclosures that help ensure a seal material meets relevant requirements that might not be taken into consideration or well-understood by those outside the elastomer industry. For instance, the UL 50E standard evaluates the physical properties and volume swell requirements deemed necessary for a seal material to withstand the conditions in these applications. Parker has materials from the EPDM, nitrile, and silicone compound families that are certified under this standard.
Another set of industry standards that reveal the specialization of environmental sealing requirements are Ingress Protection (IP) Ratings, which rate sealing performance against both solid contaminates and various forms of water (the most strenuous ratings for sealing against solid contaminates - those most relevant for elastomeric seals - indicate prevention of dust contamination). These ratings apply to the effectiveness of an entire assembly and not the material of a component specifically – this means each assembly must be assigned a rating on a case-by-case basis.
One example of an IP rating is IP65, which uses a special set of test requirements to evaluate designs for resistance to blasts from standard-pressure water jets. Another example is IP67, which rates sealing performance under water submersion conditions. Parker engineers can provide the design support necessary to ensure a system earns either of these two ratings in particular, as well as those that verify an assembly’s ability to prevent dust contamination from inhibiting performance.
To see how Parker engineers can provide environmental sealing solutions involving standards like these and many others, consult our Application Engineers or chat with us online.
This article was contributed by Nathaniel Reis, applications engineer, Parker O-Ring & Engineered Seals Division.
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As consumers demand faster processing speeds, high resolution pictures, and a longer battery life, mobile electronic devices such as smartphones and tablets require highly-populated PCBs to support their functionality and performance requirements, in an ever-increasingly competitive market space. So how do designers fit all those components on there, with zero (yes, read ZERO) tolerance for electromagnetic interference (EMI) issues? This is where your Tetris® high score finally becomes useful!
To eliminate potential EMI issues caused by densely-populated boards, PCB and semiconductor designers are investigating new ways of shielding semiconductor devices and PCBs. Traditional metal EMI shields are no longer an option, as they take up too much board space and therefore reduce the overall competitive functionality of the mobile electronic device.
In contrast, advanced conductive organic coatings such as Parker Chomerics CHO-SHIELD 604 can be applied to semiconductor devices with minimal capital equipment investment. All the while still achieving a continuous high volume application process.
Another approach to tackling EMI issues at the package or board level in electronic mobile devices is by applying an organic absorber coating to the semiconductor package or PCB to absorb extraneous electromagnetic waves. Absorber coatings, such as the Parker Chomerics Absorber Coating 9101, are formulated to absorb electromagnetic waves at customer specific frequencies, and - because they are non-conductive - can be applied directly to PCBs already populated with semiconductor packages. These absorber coatings can be applied to the PCBs or sections of the PCBs to reduce unwanted EMI noise after board assembly.
Like conductive EMI shielding coatings, absorber coatings can be applied in a continuous high volume manufacturing environment with minimal capital equipment investment, making them a low cost, low risk solution for board or component level EMI issues. Learn more about Parker Chomerics Package Level EMI Shielding Coatings here and click here for additional product information.
This article was contributed by Jarrod Cohen, marketing communications manager, Chomerics Division.
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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.
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.
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).
Figure 1
Not only has Parker’s Ultra FF302 shown promising results in the laboratory, but it has also had major success within the fab. In one field use, a fabricator was experiencing notable etching of industry-leading seals during a High Density Plasma Chemical Vapor Deposition (HDP-CVD) process involving SiH4 deposition with NF3 and O2 plasma cleans. Use of competitive materials (Competitor I, Figure 2) resulted in severe degradation with roughly 20% of the seal volume eroding; after the same period, FF302 O-rings experienced no erosion even in the most aggressive locations of the tool. (Figure 2 below shows the cross-sectional view of various FFKM O-rings after a full PM (60k wafers) on an HDP-CVD process).
Figure 2
If you are an equipment owner, you know this type of erosion is not unique to this fab alone. As a matter of fact, Parker has seen this type of erosion across various fabs and various companies.
Resistance to any variety of etching of the sealing material is imperative. Physical and chemical etch often wears away the polymeric components of the elastomer, leaving behind organic or mineral fillers in a rough, abraded manner and dislodging larger particles. The successes of FF302-75 show its ability to resist the most aggressive etching and cleaning chemistries. For this very reason, more and more tool owners see Parker’s Ultra FF302 as a great solution for reducing the cost of ownership on the tools for which they are responsible.
For more information, visit Parker O-Ring & Engineered Seals Division online and chat with our experienced applications engineers.
This article was contributed by Nathanael Reis, applications engineer, Parker O-Ring & Engineered Seals Division.
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Increased emission restrictions are requiring engine manufacturers to conform to Euro 6 and Tier IV regulations to reduce exhaust leakage 80% or more. In order to achieve these new standards, engines with extreme temperatures coupled with a high amount of vibrational movement, need to have highly engineered sealing solutions. Applications with predetermined mating components cannot always be changed, so the need for a sealing solution with a similar coefficient of thermal expansion is needed.
Most heavy duty diesel engines can reach exhaust gas temperatures upwards of 1292°F(700°C) while subjected to constant vibrations. These engine vibrations can cause havoc when a seal needs to be maintained on the exhaust line. Vibrations from the engine cause rotation, cavity offsets, pivoting, and reciprocation which become difficult to seal against. Movement, pressure cycling and thermal cycling require an engineered solution to maintain a seal under extreme application conditions. With the use of custom engineering and advanced analysis techniques, Parker is able to create custom solutions for our customers’ most difficult applications.
Parker’s Air Duct Seals for Heavy Duty Engines are a single piece, easy to install metal design, providing lower leak rates than traditional labyrinth piston ring seals.
The continuous single-piece metal seal design is enhanced with the use of TriCom-HT™, Parker’s proprietary high-temperature, anti-wear coating. TriCom-HT™ provides superior wear resistance, protecting the Air Duct Seal from the detrimental effects of engine vibration and thermal cycling, resulting in 80% less leakage and extended seal life.
Our Air Duct Seal design fits tightly into the mating hardware, greatly reducing leak paths. Machined grooves are not required in the mating hardware, thereby lowering your manufacturing cost.
Parker has been able to incorporate its design experience and knowledge of metal sealing technology and material science technology to create this solution. The Parker Air Duct Seal was designed with cost savings in mind and the patented design allows for value added one-piece out of the box installation, virtually eliminating complex sealing needs. Installation of the Air Duct Seal is simple, and requires only a press fit for both sides of the seal. Some key benefits are:
For more information on this technology, available sizes or additional questions, please contact our applications engineering team at Composite Sealing Systems Advanced Products Business Unit at 203 239 3341.
This article was contributed by Vivek Sarasam, heavy duty mobile senior applications engineer, Engineered Materials Group.
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