By installing pneumatic seals and pneumatic cylinder seals in your machinery, more control is gained over the system and thus your process runs smoothly and efficiently. Pneumatic seals are just one component of pneumatic automation. Pneumatic Tips helps you stay up to date on the latest pneumatic seals and automation news.

Sanitary Gaskets from Trelleborg

Trelleborg Sealing Solutions launches a complete line of sanitary gaskets, broadening its offering to the food, beverage, pharmaceutical and biotech industries. These gaskets are compatible with the temperature extremes, steam and aggressive chemicals associated with Steam-in-Place (SIP) and Clean-in-Place (CIP) regimes in process industries.

The range of sanitary gaskets comes in a variety of sizes, including mini, standard, larger and metric, and are available in many different materials. Materials include NBR, EPDM, FKM, PTFE, VMQ, FFKM, PTFE filled with Stainless Steel and sometimes special configurations such as bonded envelope gaskets.

Sanitary gaskets from Trelleborg Sealing Solutions include:

•Bonded Envelope Gasket- PTFE bonded to an EPDM rubber inner core

•Validation Gasket- Allows the capture of real-time validation data: thermal mapping, meter fluids, withdraw fluid samples and facilitate validation using spore trap challenge test strips

•Biological Gasket- Enables the use of a self-contained biological indicator in a sanitary process
line

•Gauge Guard- Isolates hot or caustic media from instrumentation

•ANSI Flange 150#- Ideal for applications where low seating stress is required.

•Smart Tracker- Miniature, battery-powered, stand-alone precision temperature recorder

•Torque Nuts- Control clamp and gasket compression, eliminating over- or under-tightening

•Others Including: standard gaskets, engraved gaskets, John Perry gaskets, clamps, APC fittings, Schedule 5 gaskets, I-Line and Q-Line gaskets, bevel seat gaskets, V²B vent gaskets, sanitary diffuser gaskets, perforated metal gaskets, orifice plate gaskets, sock screen and screen gaskets and controlled compression gaskets

The primary functions of sanitary gaskets are to seal pipe unions and joints in a sanitary fashion so that there is no dead space, but additional functions are also performed. These include process validation, filtration, fluid conditioning, flow control and instrumentation protection.

www.trelleborg.com

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Flexcoat™ Coatings and Surface Treatments from Trelleborg

FORT WAYNE, IN - Trelleborg Sealing Solutions offers Flexcoat™ coatings and surface treatments to improve friction characteristics of elastomer seals, especially important in automated assembly.

Trelleborg Sealing Solutions developed the Flexcoat™ range of coatings and surface treatments to give optimum friction characteristics and enhance the performance of elastomer seals. Benefits are also provided when seals are fitted in plug fit and quick release couplings and allow elastomer seals, usually recommended for static applications, to be used in low-speed and short stroke length dynamic situations.

The way seals perform depends on more than just the material they are made of. What’s on the surface matters as well. The tendency of elastomer seals to stick to mating counterparts makes them less suitable for dynamic situations and assembly operations where insertion is required. Seals are also inclined to adhere to one another, making automated assembly difficult. To solve these problems, Flexcoat™ can be applied to seals, improving their friction characteristics.

The performance characteristics of surface treatments are evaluated in the Trelleborg Sealing Solutions research and development laboratories in Europe and the Americas. They undergo assembly, endurance and friction tests. In all cases, results for a variety of commonly used elastomers are recorded.

www.trelleborg.com

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Ductorseal® Hermetic Feedthroughs

RANDOLPH, N.J.– Douglas Electrical Components, Inc. now offers Ductorseal® sealed wire and cable assemblies to solve through-bulkhead conductor sealing problems in small engine fuel delivery modules. Ductorseal feedthroughs provide an interconnecting harness in a fully sealed, pre-wired, pre-tested and ready-to-install hermetic unit.

Ductorseal feedthroughs for small engine in-tank fuel delivery module applications feature a precision-machined, chemical-resistant epoxy housing with no mold parting line that can compromise O-rings and cause potential leak paths. They are available in a wide range of standard housing sizes and configurations, and with any number and type of conductors. Aluminum, titanium, steel, brass, and plastic housings are also available. Like all Ductorseal feedthroughs, the units are epoxy-sealed to provide leak-free performance. Connector configurations on both atmospheric and vacuum/pressure sides can be mixed and matched as needed.

DECo designs and manufactures feedthroughs, sealed cables, hermetic seals, sealed connectors, fiber optic seals, bulkhead connectors, coaxial connectors, ceramic feedthroughs, hermetically sealed connectors, electrical feedthroughs, vacuum feedthroughs and waterproof connectors. DECo can hermetically seal any conductor, including wires, cables, harnesses and fiber optics, through any housing, and to any leak rate and sealing level standard, including IP, NEMA and Military MTD-STD-810.

Using customer-furnished or sourced materials, the company also supplies pre-tested, documented and ready-to-install subassemblies, including transducers, sensors, switches, heaters, connectors, flex circuits, ribbon cables, thermocouples, fiber optics and other discreet components.

www.douglaselectrical.com

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Trelleborg Sealing Solutions Adds to its Online Tools

Trelleborg Sealing Solutions has on its website a number of best-in-class tools aimed at making it easier for engineers to specify seals for their applications. New additions are a material search and chemical compatibility check. These join the already well-established O-Ring calculator, electronic catalog and CAD service. All are available free of charge. With these additions, Trelleborg Sealing Solutions believes that it now provides more widely available online services than any other sealing supplier.

Details of the new services are as follows:


Material search

•Find material properties searching by material type or trade names quickly and easily

•Identify compounds that meet specific property requirements such as operating temperatures or hardness

•Identify formulations that comply to specific approvals or standards
Chemical compatibility check

•Quick and user-friendly way of finding the level of resistance of material groups to a broad range of media, both fluids or gases

•Simple symbols indicate resistance

•One or multiple media can be selected in a single search

All online services are available free of charge on the Trelleborg Sealing Solutions website at www.tss.trelleborg.com/us through the registration area. The site is accessible in 22 different country specific versions in 18 languages.

www.trelleborg.com

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Bal Seal Launches Global Website

Foothill Ranch, CA — Bal Seal Engineering recently rolled out a comprehensive re-design of their website. The purpose of this re-design is to create a website that allows users to obtain information about  products and engineering solutions in a more efficient and user-friendly manner.

Enhanced new areas include solutions by industry, product menu selections, and a user firendly technical library including technical reports and updated product news.

About Bal Seal Engineering
For over 40 years, Bal Seal has specialized in applying advanced designs, materials, and manufacturing capabilities to specific sealing, connection, or energizing needs. Their high performance, custom engineered designs provide critical solutions for companies throughout many industries including aerospace, advanced medical device innovation, scientific development, deep-sea oil and gas exploration, and advanced automotive electrical systems

www.balseal.com

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Steel-Disk Seals

NILOS steel-disk seals for grease-lubricated roller bearings contribute to bearing service life.  They protect against contaminants in mining equipment exposed to dirt, dust, and debris and minimize bearing friction loss and heat build-up.  They also prevent lubricants from leaking.

Their non-contact, grease-filled labyrinth sealing elements comprise laminated steel-seal disks and steel cores.  The seals resist axial pressure and do not slip when secured in the axial direction on the inner and outer edge of a roller-bearing ring.  They come in a range of shaft and casing diameters and are ready to install for quick and easy mounting.

SKF Linear Motion & Precision Technologies
www.linearmotion.skf.com

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Micro Miniature Metal Bellows

Cedar Grove, NJ- Servometer / Precision Manufacturing Group, LLC presents micro miniature electrodeposited nickel bellows manufactured with diameters as small as 0.020 in. (0.5 mm) that are dynamically flexible. Servometer micro bellows can bend, compress, cycle, and are helium leak-tight.

Servometer’s custom designed products serve a variety of needs in Aerospace, Medical, Semiconductor, Instrumentation, and related technologies. Key attributes are extreme sensitivity and long fatigue life.

Servometer micro miniature metal bellows can be used as miniature flexible micro-couplings, pressure responsive devices, aneroids, electrical contacts, precision micro-springs, and flexible micro-hermetic seals that will survive multiple autoclave cycles.

Electrodeposited nickel bellows are ideal for dynamic applications where precision, repeatability, reliability and long life capability are critical requirements. Servometer bellows can be designed for a variety of stroke and pressure combinations.

Custom precision components and assemblies can be designed to exacting specifications and requirements.

About Servometer
Servometer’s tradition and history are built on a fundamental philosophy of hard work, honesty, and teamwork. Dedicated people providing innovative solutions to serve ever-changing times have built the company. From the early 1960′s when the company’s products were part of NASA’s Telstar Satellite Program, until today, providing precision parts for the United States Air Force air combat missiles and the Space Shuttle Program, Servometer has remained the benchmark of the industry. Today, Servometer provides products and services to a growing global market.

For more information, visit: www.servometer.com.

Servometer
Precision Manufacturing Group, LLC
501 Little Falls Rd. Cedar Grove, NJ 07009-1291
Tel: 973-785-4630
Fax: 973-785-0756
E-mail: info@servometer.com

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Silicone Seals & Parts For Medical Applications

Simple to complex silicone seals and parts, including O-rings, gaskets, face seals, housing seals, filter seals, custom shapes, and more are available. Made from several technologies, including LIM, they are for microminiature medical applications. Silicone seals come from 0.990 mm (0.09 in.) I.D. or C. S. down to 0.305 mm (0.012 in.) I.D.

Apple Rubber Products, Inc.
www.applerubber.com

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Seals meet aerospace requirements

The Turcon® Variseal® uses a PTFE-based material that directly replaces slipper seals and O-rings in standard grooves in aerospace applications. It resists extreme temperatures, aggressive aerospace fluids, such as synthetic hydrocarbon, petroleum base, phosphate ester, and all types of aviation jet fuels. Additionally, its low coefficient of friction increases sealing load. The seal is specially designed for closed glands. It fits in even the smallest diameter Mil-G-5514F glands.

Trelleborg Sealing Solutions 
www.tss.trelleborg.com/us

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Proper Seal Design Ensures Optimal Cylinder Operation

Larry J. Castleman is Technical Director, Product Development for Trelleborg Sealing Solutions Americas

While pneumatic cylinders are often a preferred option for linear actuation in many applications, all portions of the cylinder design must be balanced and work together for efficient and reliable function. One of the more critical components that rely on good design is the sealing system. To achieve the necessary sealing system effectiveness, several engineering disciplines need to work together to reach the right balance for each application. A good place to start is to take a closer look at linear actuator output.

Good linear actuator design includes many performance measures. Past practices are well defined for identifying such variables as load capacity, stroke length, positional accuracy, and cylinder life. Today’s technology actuation choices are wider, with subsequently more variables to manage during the design process. Application parameters now typically include such features as:
• Acceleration and deceleration requirements
• Vibration of the linear actuator load
• Impact of environment variables around the linear actuator such as thermal effects, contamination, noise, and hardware growth or distortion
• Linear actuator repair and reuse
• End of life disposal requirements
• Initial and sustaining system costs

For efficient and reliable function, pneumatic cylinders rely on a well designed sealing system. To achieve the necessary sealing system effectiveness, several engineering disciplines must work together to reach the right balance for an application.

All of these factors require examination of all components to insure the necessary balance for maximum system operation. To understand how to achieve this balance, let’s look at the role of the sealing system in cylinder function.

The role of the sealing system
The sealing system is a critical element of cylinder design. All of its performance measurements can be grouped in one of the following four areas:
1. Excessive leakage of the internal fluid out or the external fluid in
2. Friction levels that fall outside the desired specifications
3. Total system cost that exceeds the maximum levels
4. Too short a working life for the sealing system, which can  result from any one or more of the above factors falling outside acceptable limits in less than the desired time frame.

These areas are mutually dependent, and often require careful examination and balance. Good system design requires tradeoffs where improvement in one area often means a sacrifice in one or more of other three areas.

Failure of the sealing system often masks or hides larger system issues, as seals tend to be one of the areas that fail most often in a pneumatic cylinder. The sealing function involves a few basic critical elements – a seal material(s), a seal surface, and internal and external fluids.
The basis mechanics of a seal are to:
• use the position of the sealing material to create the necessary clearance with the mating surface to reduce the flow of the internal fluid outward and the flow of the external fluid inward.
• to keep the clearances to a low enough level to appropriately keep the fluids separated and generate required pressure differential.

In many cases, seal design includes an initial stress placed on the seal material through interference and compression of elastomeric materials, springs, and other loading elements.
Positioning the seal material for tight clearances controls leakage, while using designs that use available sources of energy like system fluid pressure, thermal effects, and motion help assist in loading the seal material.

The seal material(s), seal surface, and internal and external fluids are critical elements to the sealing function.

How environmental factors affect effectiveness 
For the required clearances to be effective at sealing, it isimportant to consider many environmental variables as they affect the basic seal function. Some of these environmental factors include:
• Fluid flow and pressure profiles
• Thermal changes
• Media changes
• Hardware motions
• Assembly processes
• Time

All of the above factors eventually affect the clearances required for desired pneumatic cylinder performance, especially where there is a significant pressure differential between the internal and external fluids.

There are four main measures of sealing system performance: leakage, friction, life, and system cost. There are also three main areas to adjust when working with other engineering disciplines to optimize sealing systems: materials, geometries, and processes.

To better understand how materials, geometries, and processes are selected in the design process, an overview of the impact of the environmental factors involved is helpful. Note that these factors are not independent, and there are many different dependencies between each of these factors.

Fluid flow and pressure profile
The fluids involved in sealing influence final system design. Several phenomena can occur when designing pneumatic cylinders for various pressures using different internal fluids to control the entrance of external fluids:
• The seal material can degrade chemically (swell, hardening, cracking, and so on.)
• Foreign material or fluid will permeate through the seal
• Leakage can occur through the mating surfaces’ microstructure

Other behavior is related to the pressure rate and path of the gases involved. Some examples include:
• Explosive decompression, which is a cracking and blistering of the material caused by rapid release of pressure and subsequent tearing of the permeated gas as it escapes out of the seal materials
• Extrusion of seal materials accelerated by high pressure or pressure spikes
• Erosion of materials by fluid jetting
• Directional sealing performance dependent on whether the sealing system is pressurized from one side or both sides

Thermal changes
Because seals are contact elements that control clearances for good fluid flow control, they are subject to a natural increase in temperature associated with the frictional heating from any
dynamic contact of the seal material with the mating surface. This frictional heating, in combination with other environmental changes like external temperature, fluid temperatures, and mating surface heat flow, all combine to affect the necessary clearance levels required to maintain an effective seal. Here are some common behaviors associated with thermal changes:
• Softening or hardening of the seal material and mating surface materials, which affects the depth of penetration of the seal material into the mating surface and ultimately the friction, wear, and leakage control
• Softening or hardening of bearing materials near the seal that impact seal position
• Accelerated chemical degradation
• Growth or shrinking of components from thermal contraction or expansion

Material changes
As discussed previously, fluid composition and the resulting chemical degradation of the seal material alter all four critical elements in the basic sealing process. Other factors are introduced during cylinder operation that involve one or more of these materials, including:
• Wear or corrosion of the seal material or mating surface
• Contaminates within the internal or external fluids
• Degradation of the lubricating qualities of the internal or external fluids

Hardware motions
The dynamics of moving pressurized components always affects sealing clearances. Some hardware motions that affect the sealing function include:
• Offset, side loading, angular misalignment, or cocking
• Excessive tolerance stackups
• Ballooning, which is the growth of hardware under pressure
• Vibrations or dithering, which is high frequency cycles at a short stroke

Assembly processes
Proper assembly assures the sealing system begins life in the best possible condition. Some common issues involving assembly include:
• Appropriate hardware design (radii, chamfers, removing burrs, and so on) for good installation
• Use of integrated piston/wear ring assemblies, rod cartridges, and other designs which easily assemble
• Use of mandrels, loading cones, and other tools to facilitate manual or automatic assembly

Time
All systems change over time, so it’s no surprise that time based activities influence sealing system performance. Some examples of time-related factors include:
• Creep, stress relaxation, compression set, breakdown or chemical degradation of materials
• Increased variation of hardware dynamics caused by wear
• Fatigue, stress softening, and other duty cycle related phenomena
• Various special events like storage or long term holding and positioning operations
These factors are often overlooked, so it’s good practice for all parties to understand the various steps of the duty cycle and the timing involved.

Tips for addressing environmental factors
Because the basic function of a seal is influenced by a range of environmental factors, it’s imperative for the design team to communicate to insure the proper balance of measurables. The following process will achieve that goal:
• Identify all parties involved in the design of the components of a pneumatic cylinder
• Address leakage, friction, system cost, and life, and assure that all parties know how these measures are calculated
• Identify various design options and determine the best for design, test and validation areas. Some examples include: 3D assembly, process mapping, Finite Element Analysis (FEA), surface finish analysis, materials testing, product validation, Failure Mode Effects Analysis (FMEA)

This approach allows a robust, speedy design process. Effective pneumatic cylinder function requires proper sealing system function, which necessitates close examination of the basic sealing function so one can examine all of the environmental factors in conjunction with other pneumatic cylinder engineering functions.

A closer look at designing a new range of pneumatic sealing systems

Trelleborg Sealing Solutions has been working with customers to develop a new line of pneumatic sealing systems. Demands in the market indicated the need for a more robust, longer life, and more cost effective sealing system for pneumatic cylinders. After gathering market data, the best value for cylinder performance turned out to be a sealing system that would work well in the following environment:
• in oil-free compressed air with minimal lubrication at startup
• compressed air conditions of 100 psi, with 230 psi maximum pressure
• a working speed range of 100 fpm, with maximum short term excursions to 400 fpm
• low friction and no stick slip during operation
• lifetime travel of 4000 miles
To achieve this balance, the design team addressed
materials, designs, and process improvements concurrently. The result was a focus on three areas:
• Develop suitable Zurcon® polyurethane materials that would offer excellent wear and abrasion resistance with the right strength, chemical compatibility, and friction characteristics required to achieve long life, excellent sealing, low friction, and appropriate total system cost.
• Develop appropriate geometries with rounded contact area at the seal lip to maintain grease film, small lip thickness for low radial force and friction, air channels to allow proper pressure activation, and other features available through the use of the low hardness Zurcon material. FEA and product testing validated and confirmed the performance of these features.
• Develop and validate the use of an injection molding process that limits cost and provides the required material properties.

Tests were done to ensure that proper balance was achieved between leakage, friction, system cost, and lifetime measurables. The graph on the right shows an
endurance test conducted to determine the rod seal leakage during the course to see trends related to leakage at 29 psi and 145 psi. Other validation tests included breakout friction, low temperature performance, high-pressure tests, and bursting pressure tests.

To study the effects of leakage, friction, and wear on the geometry and material, this FEA analysis shows a sealing profile at 29 psi and 145 psi.

An endurance test for rod seal leakage showed leakage trends at 29 psi and 145 psi.

 

Trelleborg Sealing Solutions R&D
www.trelleborg.com

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