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9 Dec 2017
Electric vehicles are developing fast in line with growing demand. However, only by selecting proven, reliable, high-quality products for the effective thermal management and EMI shielding of batteries, is it possible to maximize performance.
Although electric vehicles represent a greener and cleaner future, they come with a number of technology challenges, including within the battery pack. When large batteries need to provide as much power as possible to supply energy to the car, they generate a considerable amount of heat that must be dissipated. Left unchecked, excessive heat can cause faster battery wear, reduced performance and reduced charge efficiency, not to mention the obvious safety hazards associated with thermal runaway of the battery packs.
Effective thermal management is therefore critical to optimize battery performance and longevity with improved safety and reliability, allowing vehicles to travel greater distances and increasing the achievable run-time on a single charge.
In addition to effective thermal management, another technology challenge presented by the growing demand for electric vehicles is the need to shield against electromagnetic interference (EMI). The cables that travel between the battery and engine, as well as the battery and charger, see high current produced at low frequency. This produces a large magnetic field that can negatively affect other electronics within the vehicle. High shielding attenuation is also required to protect the battery and its circuits from any incoming EMI.
Conductive elastomers can be used to overcome these issues. These elastomers, such as the CHO-SEAL family of elastomer gaskets, are filled with conductive particles and connect interfacing components to reduce the air gap and create a Faraday Cage that blocks EMI fields. Oftentimes, batteries also need to be sealed against environmental dust/fluids. Here, it is possible to deploy combined solutions to support EMI and environmental shielding/sealing.
Form-in-place (FIP) conductive gaskets can be used for battery applications which require shielding of the electric traction elements. FIP can be robotically dispensed directly onto castings making it a low cost option.
Electrically conductive paints, which can replace the metal housing of the battery ECU, can eliminate 35% of the housing weight, and provide cost reductions of up to 65% by eliminating secondary operations. PREMIER PBT-225 is a single pellet electrically conductive polybutylene terephthalate that offers many comparable properties to those of aluminum, along with weight reduction which helps improve the performance of electric vehicles.
Learn more about Parker Chomerics' EMI shielding and thermal management technologies for electric and hybrid vehicles.
This article was contributed by:
Tiberius Recean - sales manager, automotive
David Beresford, marketing and technology manager, Chomerics Division Europe.
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16 Nov 2017
The utilization of suitable materials based on specialized engineering and manufacturing know-how makes it possible to integrate several parts and/or functions in a single assembly component. In many cases, this can shorten the process chain and reduce logistics and assembly requirements. In the case of hygienically sensitive applications such as those in the food industry, a reduction of the number of components enhances hygiene and ease of use, as the number of interfaces and joints decreases as well. As a result, the need for long and costly cleaning cycles is eliminated and the frequently necessary partial dismantling of equipment for maintenance and cleaning can be accomplished with much greater ease and in less time.
The brew unit is the centerpiece of any fully automatic coffee machine. This is where the key parameters of the coffee’s quality are determined, such as the compaction level of the grounds, water pressure and filtering of the coffee product.
The brewing chamber, the metallic micro-strainer and, last but not least, the brewing piston with the associated sealing and wiping system are the key components of the brew unit.
Conventional brewing piston systems in professional fully automatic coffee machines frequently consist of complex, metallic brewing pistons with sophisticated geometries and failure-prone sealing systems with an average expected lifetime of approximately 50,000 brewing cycles. Afterwards, the brewing piston and the related sealing system have to be exchanged in a time-consuming and costly process.
The sealing system not only has to withstand a pressure of up to 20 bar at temperatures of 95 °C, but also resist the highly abrasive coffee powder and the acidic coffee extract.
The newly developed brewing piston system features two major components: the brewing piston and the portafilter with integrated sealing, wiping and filtering function. Easy connection of the components can optionally be achieved by a threaded connection or snap fitting for ease of assembly and servicing.
The fully integrated design of the nobrox® brewing piston reduces the geometric complexity and number of single componens while increasing ease of assembly and servicing.
The piston attachment combines various functions, which helps reduce the complexity and component diversity of the brew unit. This where the non-reinforced nobrox® material can display its advantages. Its high wear resistance makes it possible to combine the sealing and wiping function in a dynamic sealing system. The sealing/wiping lip is preloaded by a TPU O-Ring and ensures consistently good sealing performance between the brewing piston and the brewing chamber across the entire lifetime.
Service life extended on average by 50 to 100 % or to an average expected life of > 100,000 brewing cycles.
Lower heat loss compared with metallic pistons saves heating elements.
Manufacturing cost benefits due to injection molding technology compared with machining of metallic brew pistons.
Unlike solution concepts that enclose the seals in a groove on the outer piston diameter the fully integrated system permits absolutely no dead space. This avoids coffee deposits that impair functionality or flavor. Due to the outstanding tribological properties of the nobrox® material, there is no need for additional lubrication.
Article contributed by
Market Unit Manager Industry
Engineered Materials Group Europe, Prädifa Technology Division
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6 Nov 2017
Frequently, our team in Applications Engineering receives a question along these lines: “Is your compound E0740 peroxide cured?” Usually, these questions are asked because an end customer specifies cure system as a requirement on the drawing for the part. Parker considers the ingredients used in our manufacturing process as a trade secret and are not at liberty to directly disclose what cure system is used for any given compound. However, there is a valid and scientific basis behind why customers are concerned with the cure systems of the O-ring material, but is it as critical as it seems?
When uncured rubber is subjected to high temperature and pressure, the polymer chains that make up the rubber material are being locked into place due to cross-linking. Cross-linking is when chemical bonds are formed between individual polymer chains and is what allows rubber to go from a sticky, soft playdough-like material to a solid, sturdy seal. To facilitate this reaction, cure agents are added into the raw compound. These substances form the cross-links while the parts are being molded. The key result of curing the rubber is that curing drastically affects the material properties for a given compound. Two compounds could theoretically be the same up until the point of curing, but once the rubber is cured, these two compounds would have very different material properties.
Depending on the base polymer, there are different options for what cure system can be used during manufacturing. In general, each polymer family has at least two options for cure, each providing a different set of finished material properties. In addition to final material properties, cure systems can also differ in cost, with the costlier cure system typically resulting in a more desirable set of final properties for seal applications. Often when customers are specifying a cure system, their intended end-result is to obtain a material with a particular set of properties. A common example of this was laid out above, when a customer may ask whether “E0740 is peroxide cured.” In practicality, what they likely want to know is “Does E0740 have a high resistance to compression set, high tensile strength, and better-than-average high temperature resistance?” These are the properties that result from an EPDM material being peroxide cured. If, in some crazy advancement of science, we discovered that barbecue sauce provided EPDMs with material properties superior to that of peroxide while being less expensive, specifying a “peroxide cure” would no longer be beneficial, as the finished material properties of a peroxide-cured-compound would be inferior and more expensive than those obtained through barbecue-sauce-curing. While that is certainly a silly example, one day in the future, a new technology will be developed and rubber materials will be cured with different substances than what is currently considered to be “mainstream” technology.
When someone asks about the cure systems of a compound, our protocol is to understand more about the customer’s application. Each option for cure system of a rubber family has its advantages and disadvantages. Understanding each customer’s specific application tells us what properties are going to be critical in the material selected for their application. For nitrile compounds, many customers prefer peroxide curing, which typically provides increased compression set resistance, higher temperature performance, higher ultimate tensile strength, and increased chemical resistance. However, there are other customers who, maybe in the case of dynamic sealing, would prefer sulfur cure, which would provide better wear resistance, is more cost effective, provides higher ultimate elongation, and improves the ability to withstand repetitive bending. When it comes to sealing, it’s not always about how you got there, but whether or not you get the right material that gets the job done!
For more information or to speak with an engineer about your specific application, use our Live Chat tool or give us a call.
This article was contributed by Tyler Karnes, applications engineer, Parker O-Ring & Engineered Seals Division.
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2 Nov 2017
Mobile cranes perform a wide variety of tasks, typically of the heavy-duty kind. The work they do and the locations at which they operate are frequently exposed to harsh climatic conditions in places with insufficient infrastructure. This means that the sites at which the cranes are positioned and the environment in which they move is often not entirely suitable for this kind of heavy construction equipment. Accordingly, there are high loads acting on the components, which often wear out prematurely as a result. A new sealing solution for swivel joints in cranes subjected to high loads, which combines a polyurethane O-ring with a nobrox® back-up ring, has effectively remedied this issue.
Swivel joints are generally used for swiveling and/or rotating hydraulic connectors. The type of ball bearing mounted swivel joint from Parker Ermeto, which specializes in a wide range of industrial components, is unique in this form and features a particularly robust design. In addition to applications in booms or cranes, these swivel joints can essentially be installed in excavators, drill units or diverse stationary applications as well.
Aside from a ball bearing mounted race made of bearing steel, which transmits rotary movements even under extremely high interior pressure loads of up to 420 bar with nearly no losses, such high-performance swivel joints require a seal that encloses the hydraulic fluid while permitting relative rotary movements in its seat under maximum contact pressure without abrasion or extrusion. Drag-in of the hydraulic fluid into the ball guide must be prevented – even after an extremely cold night when the mobile crane after an eight-hour period of rest with unheated units is set up, i.e. started up again. Furthermore, a sealing ring as atmospheric protection is provided against external dirt and drag-in of dust or condensate.
The ball bearing mounted swivel joints utilized in mobile cranes posed the problem that the NBR O-rings and back-up rings used for sealing could extrude into the gap between the ball bearing mounted pivot and the surrounding housing after a relatively short period of time. Consequently, the back-up ring was practically pulverized, resulting in wear of the O-ring. The extremely high contact pressures and the simultaneous slow rotating movement were identified as the causes. As a result, the sealing elements were pushed into the gaps induced by the manufacturing process, which ultimately led to seal wear. This effect can be observed during the controlled lowering of the jib under high operating pressures and simultaneous occurrence of extreme flow velocities, i.e. above those established by the engineering design criteria.
Thanks to its excellent wear resistance and good anti-frictional properties, Parker Prädifa’s new thermoplastic sealing material nobrox® (PK) was taken into consideration as a material for the back-up ring at an early stage. Another objective was to enhance the robustness of the O-ring as well by utilizing a material with higher wear resistance. Therefore, instead of the previously used NBR material, an Ultrathan® (TPU) compound from Parker Prädifa’s portfolio was selected.
In the physical laboratory, the swivel joint with the new sealing set was tested in a wide range of extreme operating conditions exceeding those of the application and simulating the operating parameters actually prevailing on the vehicle with maximum realism. These tests run over 10,000 cycles were successfully passed, revealing that the maintenance-free operating period of the swivel joint far exceeds the typical frequency and operation sequences of a jib.
O-ring Praedifa series V1, Ultrathan®
Ermeto DIN Ball Bearing Rotary Fittings
Michael Dillmann, Account Manager,
Engineered Materials Group Europe
Carsten Schippers, Research & Development,
Fluid Connectors Group, Tube Fittings Division Europe
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25 Oct 2017
Reducing the environmental impact of operating a passenger car has long been a request from the environmental community, and that demand continues to spread. But how can something as small as a seal influence vehicle emissions?
The most obvious way to reduce the environmental impact of a vehicle is to burn less fuel while doing the same job, and to burn it more completely. In a previous blog, I mentioned several ways in which state of the art seal materials help improve overall vehicle efficiency. These include VG286-80 and VG109-90 used in gasoline direct injection fuel systems and VG292-75, VG310-75, and FF400-80 used in turbocharger coolant applications. But these are not the only ways that seals impact vehicle emissions.
Another critical source of emissions – and one that is directly impacted by seal material – is fuel vapor escaping from the vehicle’s fuel system. This happens whether the car is running or not, and it’s much worse in hot weather. Gasoline evaporates quickly, and that fuel vapor can be hard to control. Not only are vapor leaks much harder to prevent than liquid leaks, but fuel vapor can permeate through most rubber and plastic materials and escape into the environment When it does, those unburned hydrocarbons contribute to smog and ground-level ozone pollution.
Fortunately, Parker has decades of experience in solving these types of sealing challenges.
Fuel vapor permeation rates can be measured directly through fuel vapor permeation tests such as the Thwing-Albert method, but this is a very slow process and it takes weeks to reach equilibrium. As a result, it’s not a good screening test for quick comparison. It’s much easier and faster to measure the volume swell with a liquid fuel immersion. While it’s not a perfect, it does provide a quick, “down and dirty” evaluation of different types of seal materials.
Table 1 shows the volume swell of various fuel-resistant materials after being fully immersed in two laboratory reference fuels. Using reference fuels eliminates the variability inherent in using actual pump gasoline from different manufacturers, refined at different times of the year, and from different batches. Fuel C is a little more aggressive to seal materials than regular American gasoline. CE-10 is a blend of 10% ethanol and 90% Fuel C, which makes it similar to most gasoline sold in the US. As you can see, there is a significant difference among different types of seal materials. Clearly, high fluorine fluorocarbon materials offer the best resistance to both fuels.
Table 1: Volume swell of various seal materials in fuel, 70 hours at 23 C per ASTM D471.
High ACN nitrile
Low temp fluorocarbon
High fluorine fluorocarbon
Because reducing the weight of a vehicle also helps with fuel economy, many fuel system components have changed from metal to plastic over the years. Not only does this increase the opportunities for fuel to permeate out of the fuel system, but it also increases the sealing challenges. Sealing plastic components brings three challenges not seen when working with metal components: parting lines, rigidity, and creep. Plastic components are almost always molded, meaning they have mold parting lines. Those parting lines frequently pass through the seal groove, and the seal must be able to conform around that imperfection to form a vapor-tight seal. Second, plastic components aren’t rigid like metal components; they move when a seal is pushed against them, so the amount of seal load force that can be applied is limited. Third, plastic components move over time in response to these load forces in a process called creep, which means the amount of squeeze applied to a seal reduces over time.
To get the best performance when sealing against plastic components, softer materials are key. Compounds in the normal 70 to 75 Shore A range generate so much load force that they deform the plastic and dramatically increase the creep rate of the plastic. In addition, harder compounds don’t seal well around plastic parting lines, so softer compounds are preferred over harder ones.
However, there’s a limit to how soft a compound can be. Hardness is controlled by the use of reinforcing fillers, and these fillers also help to reduce the fuel vapor permeation through the elastomer. Softer compounds usually have higher permeation rates. Also, extremely soft rubber compounds with no fillers tend to have poor resistance to compression set and compressive stress relaxation, which reduces the effective service life. The ideal balance tends to be in the 60 to 65 Shore A range.
Based on these two design criteria, the ideal compound for minimizing fuel vapor loss is a 60 to 65 Shore A, high fluorine fluorocarbon elastomer. For nearly 20 years, that exact solution, Parker’s VW252-65 compound, has sealed the fuel tank of almost every passenger car assembled in North America.
Now, Parker has taken another evolutionary step forward by improving the compression set resistance, low temperature performance, and fuel vapor permeation resistance with VW313-65, our next generation fuel system seal material. A comparison is shown in Table 2. Still a high fluorine fluorocarbon compound in the ideal 60 to 65 Shore A range, VW313-65 was also designed to be manufactured in all corners of the globe. This means seals can be made locally to best suit our customers’ needs to localize manufacturing and optimize logistics.
Table 2: Comparison of VW313-65 and VW252-65.
Hardness, Shore A
Compression Set, 336 hours at 200°C
Compressive Stress Relaxation, 1500 hours at 150 C
CE-10 volume swell
CE-10 fuel vapor permeation
VW252-65 has long been the preferred material for minimizing fuel vapor loss from a vehicle fuel system, and VW313-65 offers further performance enhancements to provide for the next generation of vehicles.
For more information, please contact our Applications Engineers via our live chat service on Parker O-Ring & Engineered Seals Division's website.
This article contributed by Dan Ewing, senior chemical engineer,
Parker Hannifin O-Ring & Engineered Seals Division.
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