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Understanding the Different Types of Composite Bushings in Technology

In the world of technology, composite bushings play a crucial role in various applications. These bushings reduce friction and lubricate mechanical systems, ensuring smooth and efficient operation. However, “composite bushing” can be ambiguous as different manufacturers may use different product materials and designs. This article will explore the composite bushings commonly found in technology applications.

composite bushings

Composite Bushing Design 1: Steel Backed with Sintered Bronze Layer and Polymer Lining

One popular design for composite bushings involves combining a steel backing with a sintered bronze layer covered by a polymer lining such as polytetrafluoroethylene (PTFE). This design offers excellent load-bearing capabilities due to the steel backing while benefiting from the self-lubricating properties of PTFE.

The steel backing provides strength and structural support to withstand high loads and shock forces experienced during operation. It also acts as a solid foundation for the sintered bronze layer, which increases wear resistance and enhances load distribution across the surface area.

The sintered bronze layer compresses powdered bronze particles under high pressure and temperature. This process creates tiny interconnected pores that retain lubricants such as oil or grease, allowing continuous lubrication even under extreme conditions.

A polymer lining like PTFE is applied over the sintered bronze layer to optimize performance further. PTFE offers exceptional low-friction properties resulting in reduced wear on both mating surfaces. It also provides excellent chemical resistance against corrosive fluids or gases commonly encountered in technology applications.

Composite Bushing Design 2: Polymer Resin with Glass Fibers Filament Wound and PTFE Lining

 Another common type of composite bushing utilizes a combination of polymer resin reinforced with glass fibers that are filament wound followed by applying a PTFE lining. This design offers excellent mechanical strength, high wear resistance, and low friction characteristics.

The polymer resin acts as the primary load-bearing material in this design. It is chosen for its ability to withstand high loads while providing flexibility to absorb vibrations and shocks during operation. The resin is typically reinforced with glass fibers to enhance its mechanical properties further.

Glass fibers are known for their exceptional tensile strength and stiffness, making them ideal reinforcements for composite materials. These fibers are arranged in a specific pattern using filament winding techniques, creating a robust and durable structure that can withstand heavy loads without deformation.

A PTFE lining is applied over the filament wound composite structure to reduce friction and provide lubrication. PTFE’s self-lubricating properties ensure smooth operation by minimizing wear between moving parts. Additionally, it offers excellent thermal stability and chemical resistance, making it suitable for various technology applications subjected to harsh environments.

Applications of Composite Bushings

Composite bushings find wide-ranging applications in technology due to their unique properties. Some common examples include:

  1. Automotive Industry: Composite bushings are used in suspension systems, steering columns, engine components like connecting rods or camshafts, and gearbox assemblies.
  2. Aerospace Industry: Composite bushings are utilized in landing gear systems, control surfaces like flaps or rudders, engine mounts, actuator mechanisms, etc., where lightweight yet robust components are required.
  3. Industrial Machinery: Composite bushings find application in heavy machinery such as conveyor systems or hydraulic cylinders where high load capacity and reduced maintenance requirements are desired.
  4. Medical Equipment: Medical devices like surgical instruments or prosthetic limbs require smooth movement with minimal wear on joints or pivot points.

Benefits of Using Composite Bushings

The utilization of composite bushings offers several advantages over traditional bearing materials:

  1. Self-Lubricating Properties: Composite bushings eliminate the need for additional lubrication systems, reducing maintenance requirements and associated costs.
  2. Low Friction: The low-friction characteristics of composite bushings reduce wear on mating surfaces, resulting in extended service life and improved efficiency.
  3. Resistance to Corrosion: Composite bushings can withstand exposure to harsh chemicals or corrosive environments without degradation, making them suitable for various applications.
  4. High Load Capacity: Combining different materials in composite bushing designs provides excellent load-bearing capabilities, ensuring reliable operation even under heavy loads.

Composite bushings are essential in technology applications by providing friction reduction and lubrication properties. Manufacturers offer various designs based on the materials used, such as steel-backed with a sintered bronze layer and polymer lining or polymer resin reinforced with glass fibers filament wound and PTFE lining. Understanding the different types of composite bushings allows engineers to select the most suitable option for their specific application requirements. Whether it’s automotive suspension systems, aerospace components, industrial machinery, or medical equipment, the benefits offered by composite bushings make them an integral part of modern technological advancements.

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PEEK: A High-Temperature Material for Seals and Gaskets in Automotive Construction

The automotive industry constantly evolves by introducing new technologies designed to improve safety, comfort, and performance. One such technology that has garnered significant attention recently is using high-temperature materials for seals and gaskets. These materials play a critical role in ensuring that engines perform optimally by preventing leakage while providing excellent resistance to heat, wear, and creep. Polyetheretherketone (PEEK) has emerged as a leading choice among these high-temperature materials due to its superior properties.

PEEK

PEEK is a thermoplastic material with unique properties that make it suitable for automotive construction. The material exhibits excellent mechanical strength, dimensional stability at high temperatures, chemical resistance, and electrical insulation properties. PEEK also has remarkable resistance against wear and creep, making it an ideal material for applications where durability is essential.

PEEK Automotive Seals

One primary application of PEEK in automotive construction is the development of seals used in internal combustion engines. The sealing rings used in engines are critical as they prevent fluids from leaking out and keep contaminants from entering sensitive engine parts. Sealing rings must withstand extreme temperatures generated by combustion while maintaining their shape and sealing ability.

PEEK-based seals have been found to provide exceptional leakage stability at high temperatures, making them ideal candidates for sealing rings in internal combustion engines. In addition, PEEK-based seals exhibit low friction coefficients, which help reduce energy consumption during operation.

Automotive Cylinder Head Gasket

Another application is the development of cylinder head gaskets which require good heat resistance and wear behavior due to their proximity to hot engine components such as cylinders and exhaust systems. Cylinder head gaskets must withstand extreme temperatures without degrading or losing their ability to seal off different chambers within the engine block.

A compound based on PEEK combined with polytetrafluoroethylene (PTFE) has been developed specifically for cylinder head gasket applications, with good results recorded so far. This material has been found to have good resistance against heat, wear, and tear while also exhibiting excellent replaceability. Using the PEEK-PTFE compound in cylinder head gaskets eliminates the risk of contact corrosion which is a significant concern when using traditional metal gaskets that can cause damage when they come into contact with other engine components.

The benefits of using PEEK-based materials in automotive construction are numerous and significant. For instance, using seals and gaskets can help improve engine performance by reducing energy consumption due to their low friction coefficients. PEEK-based materials also require less maintenance than traditional metal seals and are prone to corrosion and wear.

In conclusion, using high-temperature materials such as PEEK in automotive construction represents a significant technological advancement with immense potential for improving vehicle performance and reliability. PEEK-based seals and gaskets have been found to provide exceptional leakage stability at high temperatures, making them ideal candidates for use in internal combustion engines. Cylinder head gaskets based on a compound consisting of PEEK and polytetrafluoroethylene (PTFE) have shown great promise as they offer good resistance against heat, wear, and tear while exhibiting excellent replaceability properties.

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The Versatile Use of PTFE Plastic in Technology and Food Industry

The world of technology and industry has been revolutionized by using PTFE plastic. This highly versatile material is known for its excellent chemical resistance, great thermal and electrical insulation properties, and low friction. PTFE is a soft fluoropolymer plastic that can easily withstand high temperatures, making it ideal for various applications.

PTFE Plastic

PTFE plastic is used in several industries, including electronics, aerospace, automotive, and medical equipment manufacturing. For instance, due to their low friction properties, PTFE is widely used to make bearings resistant to corrosion and wear. It also makes an excellent insulation material due to its thermal stability of up to 500°F.

PTFE Plastic in Food Industry

Another significant application of PTFE is in the food industry. Its non-stick properties make it ideal for cookware coating and other food processing equipment such as conveyor belts; this reduces the amount of oil required during cooking and prevents food from sticking onto surfaces.

Laboratories

One key benefit that sets PTFE apart from other plastics is its chemical inertness; it does not react with most chemicals or substances, making it safe for use in sensitive environments such as laboratories where purity levels are critical.

PTFE tubing also plays a vital role in many laboratory applications since it can resist harsh chemicals like acids without breaking down or reacting with them. This characteristic makes it invaluable when working with hazardous materials or conducting experiments where accuracy is paramount.

Electrical 

In addition to being chemically inert and thermally stable up to 500°F (260°C), PTFE has superior electrical insulating properties, making it useful for electronic applications. It resists moisture penetration better than most plastics while maintaining its insulating qualities over an extended period; this property makes parts made out of this material last longer than those made out of other materials like nylon or PVC.

Aerospace and Automotive PTFE Plastic

PTFE plastic is also used in the aerospace industry due to its light weight and ability to withstand high temperatures. It is often used as a coating for parts that experience friction or heat, such as engine components, gears, and bearings. This application of PTFE has helped reduce aircraft weight while increasing their durability.

In automotive manufacturing, PTFE plays a critical role, too; it helps make brake systems more effective by reducing wear on parts that would otherwise cause issues like brake squeal or vibration. This material also reduces fuel consumption by making engines run more efficiently with less friction between moving parts.

Medical Equipment

Medical equipment manufacturers have found PTFE plastic helpful in creating devices that require high levels of purity and chemical resistance. For instance, catheters made from this material can resist bacterial growth while maintaining flexibility; this makes them ideal for use in sensitive applications such as cardiac surgery, where contamination could lead to severe complications.

The versatility of PTFE plastic is enormous; it can be molded into different shapes suitable for various applications. It can also be blended with other materials, such as glass fibers, to increase its strength or pigments to give it color without affecting its properties significantly.

In conclusion, the versatile use of PTFE plastic in technology and food industries cannot be overstated. Its unique combination of thermal stability up to 500°F (260°C), excellent electrical insulating properties, and non-stick surface, which makes it ideal for cookware coating and chemical resistance, has made it an essential component in several sectors worldwide. As research continues into this unique material’s properties, more applications will undoubtedly emerge, making our lives easier and enhancing product performance across various fields.

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Selecting the Right Seals for Cold Temperature and Cryogenic Valves

Cold temperatures can cause materials to become brittle and lose elasticity, leading to seal failure. Additionally, thermal expansion and contraction can cause seals to break down over time. For these reasons, selecting the proper seals for cold temperature and cryogenic valves is crucial.

cryogenic valves

When selecting seals for cold temperature applications, it’s essential to consider the following factors:

  • Temperature range: The seal must withstand the extreme temperatures of cryogenic fluids.
  • Pressure range: The seal must withstand the pressure of the processed fluid.
  • Chemical compatibility: The seal material must be compatible with the processed fluid.
  • Wear resistance: The seal must withstand repeated valve cycling without breaking down.

 Factors to Consider When Selecting Cold Temperature Seals

When selecting the proper seal for your cold temperature application, there are several factors you need to consider:

Temperature Range

The first factor to consider is the temperature range your application will require. Cryogenic seals operate in temperatures ranging from -460°F (-273°C); you’ll want to choose a material specifically designed for these conditions. 

Pressure Range

You’ll also need to consider the pressure range your application will be operating under, as this will affect which type of seal you’ll need to use.

Chemical Compatibility

Another essential factor to consider is chemical compatibility with the fluid or gas your cryogenic valves system processes. Not all materials perform well with every substance they encounter over time.

Wear Resistance

Finally, wear resistance is an important consideration when selecting seal materials since repeated valve cycling and exposure to pressure can cause wear over time, eventually leading to breakdowns if not properly addressed beforehand.

Types of Cryogenic Valves Seals for Cold Temperature Applications

PTFE (Polytetrafluoroethylene), FEP (Fluorinated Ethylene Propylene), and UHMW (Ultra High Molecular Weight PE) are popular choices due to its exceptional chemical resistance and low coefficient of friction. It also has excellent thermal stability and can withstand temperatures as low as -460°F (-273°C). 

Another critical aspect of designing polymer seals for cryogenic applications is the seal geometry. The seal design must provide sufficient compression force to ensure proper sealing while compensating for any dimensional changes caused by temperature fluctuations or external forces. A common approach in these applications involves creating a labyrinth seal design where multiple grooves in the seal face interlock with corresponding ridges on the mating surface, creating various barriers between gasses while allowing relative movement between two mating surfaces.

Cryogenic valves’ sealing surfaces should be smooth and free of surface defects, as imperfections can compromise sealing integrity. Surface roughness is measured in Ra (arithmetic average deviation) or Rz (average peak to valley height). A typical Ra/Rz value for cryogenic seals should be less than 20/100 micro inch respectively.

Cryogenic applications often involve extreme pressure differentials, making it essential to select a polymer seal material that can handle high-pressure environments without extruding or deforming under load. In some cases, this requires designing the seal with an additional support element, such as a metal spring or an energizing lip that helps maintain proper compression force over time.

Proper installation procedures must be followed to ensure optimal performance and longevity of cryogenic seals, which includes ensuring that all mating surfaces are clean and free from debris or other contaminants that could compromise sealing integrity. The assembly process must also account for thermal expansion, which can cause dimensional changes in both components leading to reduced compression forces if not accounted for during installation.

Selecting the correct seals for cold temperature and cryogenic valves requires careful consideration based on multiple factors, including temperature range, pressure range, chemical compatibility, and wear resistance, among others discussed above. Choosing the proper seal can ensure that your valve system will function optimally and prevent leakages, which could be catastrophic in many processing applications. Be sure to work with a trusted supplier who can help you choose the proper seal for your needs and provide expert advice on installation and maintenance.

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Advanced Properties and Applications of PTFE in Sealing Technology

PTFE has a unique combination of properties that make it ideal for use in sealing technology. One of its most notable characteristics is its ability to withstand extremely high and low temperatures. PTFE can operate in temperatures ranging from as low as -200°C to as high as 260°C, making it an excellent choice for applications where sealing performance needs to be maintained at extreme temperatures.

PTFE

Another significant advantage of PTFE is its chemical resistance. It is highly resistant to various chemicals, including acids, alkalis, and organic solvents. This makes it an excellent choice for use in chemical processing plants or other facilities where exposure to harsh chemicals is common.

PTFE also has excellent non-stick properties, which make it ideal for use in applications where adhesion could compromise the effectiveness of the seal. Its low coefficient of friction means that even under heavy loads or with repeated cycles of movement, PTFE will not experience significant wear or degradation.

In addition to these properties, it has outstanding electrical insulation characteristics and acts as a barrier against moisture and dust.

Manufacturing PFE Gaskets

Pure PTFE gaskets are produced by molding directly from suspended material or cutting (turning) from PTFE sheets (rods). Molding plates have uneven density and poor flexibility while turning plates have a relatively uniform density. Still, their material is curved due to the influence of the processing technology, which is not conducive to installation and use.

Modified PTFE gaskets add a certain proportion of functional materials, such as glass fiber or graphite powder, during production. The resulting gasket provides improved strength and durability compared with pure PTFE gaskets while maintaining this advanced material’s desirable properties.

Despite its many advantages, however, some limitations are associated with using PTFE in sealing applications. For example:

  • It can be difficult to achieve consistent compression when using pure PTFE gaskets due to their poor flexibility
  • PTFE can be prone to creep under sustained pressure, which can result in a loss of sealing performance over time
  • PTFE is unsuitable for high-pressure applications as it has low tensile strength and may deform or fail under high loads.

Applications for PTFE 

Despite these limitations, PTFE remains one of the most advanced materials available in sealing technology. Its unique combination of properties makes it ideal for use in various applications where reliable sealing is essential.

One potential application area where PTFE could increase use is the automotive industry. As electric vehicles become more prevalent, there will be an increased demand for seals that withstand harsh operating conditions. Its excellent temperature resistance, chemical resistance, and non-stick properties make it an ideal choice for use in battery enclosures and other critical components.

Another potential application area is within the food processing industry. Many food products are highly acidic or alkaline, which can cause traditional seals to degrade over time. PTFE’s chemical resistance makes it an excellent choice for acidic or alkaline foods. At the same time, its non-stick properties mean that any residue left on the seal after cleaning can easily be removed.

In conclusion, Polytetrafluoroethylene (PTFE) has many advanced properties that make it ideal for use in sealing technology. Its ability to withstand extreme temperatures while maintaining effective sealing performance sets it apart from other materials commonly used in this field. While some limitations are associated with using the material in certain applications, such as those involving high-pressure loads, its unique combination of properties means it remains one of the most important materials currently available. Over time, we may see even greater advances made with this remarkable material with continued research and development into new formulations and manufacturing techniques.

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How Canted Coil Springs Provide EMI/RFI Protection

Canted coil springs

The rise of technology has brought about a new era of innovation and efficiency in the modern world. With the advancement of electronic devices, there has been an exponential increase in the number and type of gadgets we use daily. Electronics have become integral to our lives, from smartphones to computers, cars to airplanes. However, with this increase in usage comes a corresponding increase in electromagnetic interference (EMI) and radio frequency interference (RFI). EMI/RFI can cause significant harm to sensitive electronics resulting in malfunctioning or failure. Canted coil springs can be a way to protect equipment from EMI/RFI interference.

Canted Coil Springs as EMI Shielding

Shielding sensitive electronics from EMI/RFI is thus an essential requirement for any electronic device manufacturer. Various shielding solutions, like metal shields or coatings, often suffer from weight, thermal management problems, and low flexibility.

This is where canted coil springs come into play. These springs provide superior EMI/RFI shielding while being lightweight and flexible. The unique design features independent coils that serve as multiple contact points for optimal conductivity and/or grounding, ensuring consistent, reliable connection with mating surfaces under shock and vibration.

The precisely engineered coil angles ensure that these springs provide maximum surface area contact, resulting in efficient current transfer and decreasing contact resistance between mating surfaces. This feature leads to less energy loss due to heat dissipation than traditional designs, translating into better performance over time.

Canted coil springs are made using various materials, including stainless steel alloys capable of handling high temperatures without losing shape over time, ensuring longevity even under harsh operating conditions.

Applications as EMI Shielding

These unique springs can be used for applications ranging from medical equipment to aerospace systems, where reliability is paramount. One such example is their use as connectors between motherboard components on computers, where they reduce the noise created by signal transference between components leading to improved overall system performance.

Canted coil springs can also be used as cable shielding, providing flexible, lightweight, and low-resistance solutions for high-speed data transmission cables. They are especially useful in applications where weight is critical, like aerospace or automotive.

Advantages of Canted Coil Springs

An advantage of these springs is their ability to absorb shock and vibration, reducing the risk of damage to electronics due to mechanical stress over time. This feature makes them ideal for use in rugged environments such as military applications, industrial machinery, or heavy-duty vehicles.

In addition, canted coil springs are easy to install and require no additional hardware making them a cost-effective solution for manufacturers. They can be easily integrated into existing designs without redesigning entire systems, thus reducing development costs while still providing superior performance.

Overall, canted coil springs offer an excellent solution for EMI/RFI shielding needs with their superior conductivity, flexibility, and shock absorption capabilities, all while being lightweight and easy to install. Their versatility makes them an excellent choice for almost any application where reliable electronic performance is essential.

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Exploring the Benefits of Fluorolon PTFE in Industrial and Engineering Applications


Fluorolon PTFE (Polytetrafluoroethylene) is a unique synthetic polymer with many benefits for industrial and engineering applications. This versatile material can be used for a wide range of purposes, from chemical processing to cookware. In this article, we will explore some of the key benefits and uses of Fluorolon PTFE.

FEP encapsulated helical spring seals are approved for cryogenic and FDA use. Fluorolon PTFE

Chemical Resistance


One major benefit of using Fluorolon PTFE is its excellent chemical resistance properties. This material is highly resistant to acids, bases, solvents, and other corrosive substances. This makes it an ideal choice for use in applications such as chemical processing plants or food processing industries where harsh chemicals are often used. It can also be used as a protective coating on metal surfaces to protect them from corrosion or damage from exposure to corrosive materials.

High-Temperature Resistance


Another benefit associated with Fluorolon PTFE is its high-temperature resistance properties. This material can withstand temperatures up to 260°C (500°F) without losing its strength or shape – making it an excellent choice for use in insulation, gaskets, seals, and other high-temperature applications such as aerospace parts or engine components that require superior heat resistance capabilities. The thermal stability offered by this polymer also ensures that parts maintain their original dimensions even under extreme conditions making them ideal for precise manufacturing processes where dimensional accuracy is critical.

Low Friction Properties


Fluorolon PTFE also offers exceptionally low friction properties, making it suitable for use in various mechanical components such as bearings and slides where minimal friction between moving surfaces is desired. Its low coefficient of friction helps reduce wear on machinery parts resulting in increased operational life spans while simultaneously providing smoother operation with less vibration compared with traditional materials like steel or bronze alloys. Furthermore, since no lubricants are required, energy consumption costs due to frequent maintenance procedures associated with lubrication are significantly reduced compared to traditional metals.

Non-Stick Properties


In addition, Fluorolon PTFE has impressive non-stick properties, making it ideal for use in cookware, baking sheets, conveyor belts, and other industrial equipment. Its non-stick characteristics enable food products like cakes, cookies, etc., to slide easily off surfaces resulting in efficient production processes while maintaining product quality standards at the same time. Furthermore, these non-stick characteristics help reduce clean-up times after the production process, thereby saving both time & money.

Electrical Insulation Properties

Last but not least, one important benefit this polymer provides includes its electrical insulation capabilities making it perfect for use within high-voltage industrial equipment & electronic components alike. Its ability to prevent electricity from leaking out allows companies within the electronics industry to create safer products without having to worry about hazardous shocks occurring during usage, thus ensuring customer safety at all times, leading to higher customer satisfaction & loyalty levels over time.

At Advanced EMC Technologies we use Flourolon Virging PTFE primarily for seals, seats, bearings, and insulaotrs. All our Flourolon PTFE is FDA and dairy approved. We offfer both Virgin PTFE ASTM-D4894 and filled PTFE ASTM D4745-06.

PropertySpecifiedUnitsMethod
Specified Gravity (FEP) Only2.14 –2.19gr/ccASTM D792
Maximum Recommended  Stretch2 %N/AASTM D638
ES Seals Are For Type ServiceStatic N/A–
Coefficient of Friction (FEP)0.19StaticASTM D3702
Dielectric Constant (FEP)N/AN/AASTM D150
Dielectric Strength (FEP)N/AN/AASTM D257
Thermal Expansion No Spring8.3 x 10^5thin/in/°FASTM D696
Compressive StrengthN/AN/AASTM D695-57
FEP Seal Temperature Range-420 to 428°F–
PFA Seal Temperature Range-420 to 500°F–

To summarize, the many benefits associated with using Fluorolan PTE should not be overlooked, especially when considering various industrial & engineering-related applications that call out these specific attributes offered by this synthetic polymer beyond any other commonly available alternatives currently present in the market today. Its ability to resist chemicals and withstand higher temperatures than most polymers without losing shape/strength, alongside offering superior low friction/non-stick qualities coupled with excellent electrical insulation capabilities, clearly demonstrates why so many industries opt to choose Fluorolon PTFE over any other material available.

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The Effect Surface Finish Has on PTFE Seals

Surface finish plays an essential role in the effectiveness of PTFE seals. The different finishes provide different degrees of contact between the two components, which affects the seal’s strength and reliability. In this paper, we will discuss the effect of surface finish on PTFE seal performance and suggest ways to improve seal quality.

Surface finish on PTFE

The Influences of Surface Finish on Friction

The surface finish is critical for polymer-based seals. Despite being considered a soft plastic, PTFE is significantly harder than traditional o-ring materials. Because of this, if the mating surface is designed for other materials, it can cause the PTFE seals to leak.

As you can see in the graph below, the improvement in the surface finish has a favorable effect on the frictional force required.

The following specifications were used in the force test that resulted in the above data.

  • Stroke Speed: 4 in/min (102 mm/min)
  • Shaft Diameter: 0.1875in. (4.762mm)
  • Ambient Temperature: 73°F (23°C)
  • Mating Surface Material: 17 -4 PH S.S.
  • Mating Surface Hardness: -40 Rc

Surface Finish Influences on Wear

The finish of the mating surface is one of the main factors in the PTFE seal wear. Wear on the seal is generally proportional to frictional force. In other words, less friction reduces the wear on the seal. 

The following graph shows how a smoother surface finish reduces the PTFE seal wear rate.

To calculate the wear rate in microinches RMS, we used the formula IN3 -MIN/LB-FT-HR -10-9. For microinches Ra, we used the formula CM3 -MIN/KG-M-HR -10-9.

We used the following test parameters during our testing to ensure accuracy for each test.

  • Surface Speed: 55 fpm (17 m/min)
  • Loading Stress: 55 lb./in2 (4 bar)
  • Wear Rate in Air: @ PV 3025 lb./in2 x ft/min (7.5 N/mm x m/min)
  • Mating Surface Hardness: Rc 42
  • Matin Surface Maerial 17 -4 PH Stainless steal
  • Mating Surface Finish: 1.6 to 111.1 microinches RMS (1.4 to 100 microinches RA)
  • Ambient Temperature: 70°F (21°C)
  • Ambient Relative Humidity 75% RH
  • Duration 5 Hours
  • Seal material FP

Influences on Sealing Ability

Finally, we looked at how the surface finish affected PTFE’s sealing ability. In general, the sealing ability of PTFE is proportional to the fluid’s viscosity. If a media, like gas, has a reduced viscosity, it is more difficult to seal. In these situations, having a smoother finish on the mating surface can help ensure fewer leaks.

We’ve found that different mediums require not only different finish ranges between them but also different finish ranges when considering if the surface is dynamic or static. You can see our suggested finish in the table below.

MediaDynamic Surface Static Surface 
Gases and Liquids at Cryogenic Temperatures2 to 4 microinches RMS
(1.8 to 3.6 Microinches Ra)		4 to 8 Microinches RMS
(3.6 to 7.2 Microinches Ra)
Gas at Non-Cryogenic Temperatures6 to 12 Microinches RMS
(5.4 to 10.8 Microinches Ra)		12 to 32 Microinches RMS
(10.8 to 28.8 Microinches Ra)
Liquids8 to 16 Microinches RMS
(7.2 to 14.4 Microinches Ra)		16 to 32 Microinches RMS
(14.4 to 28.8 Microinches Ra)

As you can see, the mating surface finishes can profoundly affect PTFE seals. Because of this, if the mating surface is designed for other materials, it can cause the PTFE seals to leak. Finally, we examined how this affected PTFE’s sealing ability. In general, the sealing ability of PTFE is proportional to the fluid’s viscosity. 

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CNC Machining Basics

cnc machining

Computer Numerical Control (CNC) machining is a manufacturing process that uses pre-programmed computer software to dictate the movement of the tools and machines. It allows devices such as lathes, mills, and grinders to cut three-dimensional objects.

To understand CNC machining, we are going through a basic overview of CNC machining, including terminology, how they work, and the advantages and limitations of a CNC machine.

Terminology

Understanding the terminology associated with CNC machining is the first step to understanding CNC machining. CNC stands for computer numerical control. A computer and CAM software are used to animate, control, and observe the motions of the machine using digital data. 

CAM stands for computer-aided machine or manufacturing. It uses different software programs to generate tool paths and NC code for a CNC-operated machine based on data from 3D computer models. CAM only uses CAD to generate code for the device to follow. 

CNC machines could be robots, sheet metal stamping machines, lasers, grinders, lathes, water jet cutters, or welders. The computer controlling these machines is often an onboard controller. However,  the controller may also be an external PC.

How Do CNC Machines Work

CNC machines cut a desired piece based on what is programmed into the system. Therefore, it begins with designing the component. This step is necessary to establish the dimensions and features of the finished product.

Often the component design takes place in a CAD-CAM package. It allows the flow to continue through the program without going through file translation. Suppose they are not in the same package or software package. Then the CAD models will have to be imported into the CAM software.

Designing the component using CAD software allows you to construct the real piece and see what it looks like on the screen. The program is a code generator for the CNC machine that compiles coordinates to direct the cutting head during the manufacturing process. 

The final step in CNC machining is to choose the proper parameters. These include:

  • Voltage
  • Cutting speed
  • RPMS

The software will choose how the parts are arranged and oriented in relation to the raw materials. The part shape and tooling influence the configuration of the other parameters and equipment used.

Open and Closed Loop CNC Machining

CNC machining takes place in either an open-loop or closed-loop system. Open and closed-loop refer to the control process of the system. The position of the piece is determined by the type of system used.

The signal runs in a single direction between the CNC and the motor in an open-loop system. This system uses stepper motors, but the use of stepper motors doesn’t necessarily indicate an open system.  This system is commonly used when the forces and speeds are minimal.

In an open system, once the motor is in place, the controller has no feedback. That means unless a limit switch is tripped, the controller runs the operation as if there are no errors. 

A closed-loop system allows the controller to receive feedback. Because the controller can receive feedback, the controller can rectify irregularities and correct errors when necessary. There are two types of closed-loop systems. With the first type, the return signal feeds directly into the controller. The other type returns the signal feedback to the PC running the program.

A closed-loop system is necessary to ensure speed and consistency. It is the ideal choice for accuracy in creating a part. However, because there are more working parts, they have more components that can fail and be harder to tune.

CNC Machining Advantages

There are many advantages of using CNC machining for part manufacturing. For one, it is an excellent method for producing multiple parts that are identical to one another. If you need upwards of 100 parts, CNC-machined parts are more cost-effective than 3D printing.

CNC machining creates precision pieces. With a tolerance of +/- 0.127mm, machined parts come down to +/- 0.005mm. The equipment can produce them quickly. 

CNC machines can be used with various materials. Alloys such as zinc and magnesium are standard materials. In addition, aluminum, steel, brass, and titanium are common choices.

Limitations

While CNC machining has many advantages, the process has several limitations. One of them is using older machines to perform this process. CNC machines require a system that can perform demanding tasks. As a result, older computers and devices may not be able to handle the tasks.

Another limitation is that most CNC controllers may be constrained by only comprehending circular arcs and straight-line motions. Archs are often allowed on the main XYZ planes. However, some parts require a five-plane rotation that some controllers can’t comprehend. 

Conclusion

CNC machining is a significant advancement in manufacturing with the aid of computer technology that will give you accurate parts. It is a quicker and more efficient way to produce parts. 

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Expanded PTFE vs. PTFE

expanded PTFE

Polytetrafluoroethylene (PTFE) is one of the most common materials used for seals. Expanded PTFE, or ePTFE, is a soft material with many of the same properties as PTFE. However, ePTFE is more flexible, making it a better choice for specific applications.

How does ePTFE compare to PFE? For better clarification, let’s look at some of the aspects of the two.

What is Expanded PTFE

Expanded Polytetrafluoroethylene (ePTFE) is a PTFE resin created through a unique processing method that includes stretching, making it flexible. Expanded PTFE has a mesh structure ideal for medical equipment, food processing, oil and gas, and any other industry requiring tight seals.

Like its counterpart PTFE, ePTFE is non-toxic, hygienic, and chemically inert. In addition, its flexible nature allows it to seal tightly over surfaces where traditional seals won’t work. 

Advantages of ePTFE 

Expanded PTFE has high sealability, especially at low stress. It can compensate for irregularities in the surface to create a steadfast seal. The ePTFE gasket sheets have superior resistance to creep and cold flow and adapt well to sealing surfaces.

Applications ePTFE 

The ePTFE gasket sheets have a porous nature making them ideal for use in medical devices. For example, it is found in dental implants and barrier membranes in medical equipment. It is also found in electronic insulators and high-performance filters.

The oil and gas industries use ePTFE sheets to even out bumps and ridges in chemical pipe flanges. Smoothing out the bumps helps to provide a tighter seal between the flanges for better leak control.

Other applications for ePTFE include:

  • Pumps
  • Glass-lined flanges, reactors
  • Heat exchangers
  • Apparatus constructions

Properties of ePTFE 

ePTFE is 100% multidirectional and is physiologically inert for all recommended applications. Other technical properties of ePTFE sheets include the following:

  • Chemical resistance in the entire pH range (except for molten alkali metals)
  • Temperature Range: -268°C to 270°C (-450°F to 518°F).
  • Density of 0.85g/cm3 +/- 0.10g/cm3 
  • Pressure range of vacuum up to 200bar (3000psi)

What is PTFE

Polytetrafluoroethylene (PTFE), also known by its trade name Teflon®, was discovered in the 1950s by Dupont Chemist Roy J. Plunkett. It is a non-wetting, high-density material that is resistant to high temperatures.

Because of its high melting point and insolubility in most solvents, PTFE is the ideal choice for most sealing applications. In addition, PTFE can be unfilled (virgin) or filled with various compounds, such as glass or carbon. 

Advantages of PTFE 

Using PTFE as a seal or gasket has many incredible advantages. These benefits make it the ideal choice for applications across many fields. Let’s take a look at some of those advantages. 

PTFE has a high-temperature resistance. PTFE can withstand temperatures of up to 500°F or 260°C. In addition, PTFE is chemically resistant to aggressive chemicals such as solvents, acids, and bases. 

Along with its temperature and chemical resistance, PTFE has non-corrosive properties and can be used as electrical and thermal insulation. This versatile material comes in a wide range of thicknesses, fillers, and compressed sheets.

Applications PTFE 

There are several applications in which PTFE is the ideal sealing solution. Industrial plants use PTFE as envelope gaskets to contain leakages of the substances being managed. The substance’s water resistance makes it suitable for industrial plants, the food industry, and medical laboratories.

PTFE is also used in construction because of its low frictional quality, which extends the life of the PTFE. The sheets are also used in industries where highly reactive substances because of the sheet’s resistance to acids. 

Properties of PTFE 

PTFE’s low coefficient of friction is not the only property that makes it ideal for many sealing applications. Other properties include:

  • A density of 2.10e3 – 2.2e3 kg/m3
  • Tensile strength is 2.07e7 – 3.45e7 Pa
  • Max Temperature 250°C to 271°C (482°F – 520°F)
  • Melting Temperature 215°C – 339°C ( 599°F to 642°F)
  • Chemical resistance to the entire pH range (except for molten alkali metals)

Conclusion

Both ePTFE and PTFE are suitable for most sealing applications. Determining which product is necessary depends on the application. Contact us today to learn more about our PTFE sealing options.