Tuesday, May 22, 2018

PTFE WIRE APPLICATIONS

PTFE APPLICATIONS
PTFE’s significant chemical, temperature, moisture, and electrical resistances make it an ideal material whenever products, tools, and components need to be durable and reliable in even the most strenuous applications. On top of this, teflon coated wire boasts unique low- temperature durability and fire resistance that make it a good choice for a constantly growing list of products, components, and applications.
These qualities have allowed PWI to provide insulated PTFE wire for an extensive range of high tech industries across the country. While PTFE coated wire is often referred to by it's most popular brand-name, Phoenix Wire has made it our specialty to start where most other companies stop, and provide PTFE insulated wire not only in all standard sizes, but in a range of micro and miniature sizes that continue to enable innovation in even the most advanced industries.
Coated Wire for Medical Applications
PTFE coated wires provide ideal coverage and protection when medical devices require a smooth coatings that’s thin, smooth, precise, chemically inert, and capable of withstanding a wide variety of conditions. It’s non-flaking finish makes it a coating of choice when finish quality is paramount for both aesthetics and regulatory specifications. At PWI, our specialty is insulating the kind of micro PTFE coated wire that is frequently used in medical instrumentation, implants, and other devices.
PTFE Insulated Wire for Automotive Applications
The electrical demands placed on wiring in automotive applications continue to demand more. With the presence of corrosive chemicals, extreme temperatures, and friction - durable automotive wiring is relied on for a growing list of applications including air conditioning systems, navigation,power steering,battery applications, heated seats, and more.
With micro miniature teflon coated automotive wires, PWI gives automotive manufacturers the ability to continually innovate with wiring that meets their exact performance specifications, no matter how limited they may be on space.
PTFE Coated Cable and Wire for Oil and Gas Applications
One of the greatest engineering challenges for the Oil and Gas industry is the ability to protect important instrumentation from temperature extremes, corrosive chemicals, and pressure. Fortunately, the low footprint and outstanding qualities of PTFE have allowed PWI to address the oil and gas industry’s complex wiring needs for drilling operations and instrumentation in even the toughest conditions.
On top of insulation, teflon coated wires not only offer the electrical, temperature, and corrosion resistance needed by the gas and oil industries, but they also provide essential protection against the gas diffusion, pressure, and corrosion typically encountered in downhole drilling.
PTFE Coated Wires for General Electrical Applications
As one of the best known insulators, PTFE is frequently used in electrical components around the world for its ability to insulate to 500 volts per mil with unyielding reliability in even the most strenuous applications.
From mobile devices to advanced, high-tech machinery -- PTFE coated wires can be found in virtually every industry. It is often used as wire and cable wrap, as a separator on the conductive surfaces in capacitors, and in a limitless range of electrical applications where components are expected to withstand the elements.
With modern electronic manufacturers continually creating smaller, more portable advanced electronics, a cost efficient and reliable source for teflon coated wire has never been more important.
Other Applications for PTFE Insulated Wire
The qualities of PTFE lend our products to an almost infinite list of uses. Other industries and applications PWI works with include retail, computers, veterinary medicine, the food industry, communications, the art community, robotics, marine sciences, space exploration, bioengineering, chemical sciences, and more.

Tags:teflon,teflon ptfe,teflon wire

Sunday, May 20, 2018

PFA and TFM PTFE Excellent Material Choice for Bellows and Diaphragms

Polymer Bellows and Diaphragms
PTFE (polytetrafluoroethylene), aka Teflon, is typically the first choice polymer for bellows and diaphragms, but did you know that PTFE isn’t the only polymer you can choose from?  In this article we are going to compare two other polymers – PFA and TFM – to PTFE as a material choice for bellows and diaphragms. 
PFA
PFA, or Perfluoroalkoxy, is sometimes referred to as Teflon PFA.  It has properties that are similar to PTFE, including outstanding chemical resistivity and has extremely low gas permeability.  It is not hydrophobic like PTFE, however, and absorbs slightly more water.  One reason it might be chosen over PTFE is its ability to maintain its mechanical strength at high temperatures, even when combined with caustic chemicals.  It also possesses both excellent creep, fatigue properties and thermal stability.  Its maximum continuous service in temperature is 260°C.
PFA is also more versatile when it comes to how parts can be manufactured; for example, it lends itself well to extrusion, injection molding, transfer molding, blow molding, and compression molding. You will often see PFA used for plastic lab equipment because of its outstanding chemical inertness, and its flexibility had made it a popular choice for tubing in many chemical applications.  It’s also popular for semiconductor and pharmaceutical applications.
TFM
You may have heard of TFM, or PTFE-TFM.  TFM is a second generation PTFE that includes an additional modifier called Perfluoro(propyl vinyl ether).  This modifier makes its polymer structure denser than PTFE, lowering its gas permeability below that of PTFE but not quite as low as PFA.  The same wall thickness of TFM has twice the barrier effect as PTFE.  Its water absorption is comparable to that of PTFE, which is very good. Like PFA, it performs well at high temperatures and is very chemically inert.  TFM is also well adapted to applications that combine high temperatures with vacuums.  Like PFA, it works well for pharmaceutical and semiconductor applications.
Compared to PTFE, it has an even better surface characteristics, is stiffer, and is less susceptible to creep and has improved fatigue properties.  Compared to PTFE, it also exhibits better stress recovery.  Its maximum continuous service temperature is 250°C, which is slightly below PFA. 
Polymer Options
Both of these polymer options are excellent choices for high purity applications, including medical, pharma, semiconductor bellows.  So, the next time you are selecting polymer bellows or diaphragm, don’t forget that PTFE isn’t your only material option.
Tags:Polymer Bellows,Diaphragms

Friday, May 18, 2018

6 Key Reasons PEEK Works Well for High-Performance Bushings

PEEK, which stands for polyetheretherketone, is a well-known engineering thermoplastic. It has become a popular choice for bushings that must operate in demanding high-speed, high-temperature environments.
In this post, we will look at 6 reasons why PEEK actually works well in such hostile environments.

1. PEEK Can Take the Heat
PEEK bushings can operate continuously in temperatures up to 480°F without loss of their key tensile and flexural properties. In addition, when exposed to flames, PEEK bushings exhibit low smoke and have a very low toxicity rating, and it even has a V-0 flammability rating.

2. PEEK Has Good Chemical Resistance
PEEK has very good resistance to a variety of aggressive chemicals and is also compatible for use with steam and hot water. It is inert to common solvents and can resist many chemicals, both organic and inorganic.

3. PEEK Is a Good Replacement for Metals
PEEK an excellent replacement option for metal bushings because of its chemical resistance, strength properties, and the fact that it is up to 70% lighter than the metal parts it can replace. In fact, it’s light weight has made it a popular choice for aerospace applications, where weight and fuels savings are key design factors.

4. PEEK Has High Strength
PEEK is considered the high-strength alternative when it comes to hostile environments where other polymer bushings simply can’t perform. It’s high tensile strength and impact strength make it an excellent choice for aggressive applications.

5. PEEK Is Durable
Another key benefit of PEEK bushings is their durability and excellent fatigue life. In fact, some PEEK parts have been shown to exhibit up to 100 times better fatigue performance than their metal counterparts.

6. PEEK Can Be Improved by Additives
There are a variety of additives that can further enhance PEEK’s already outstanding properties, including glass and carbon fiber. Carbon and glass can enhance PEEK’s tensile, compressive, and flexural strength, reduces its coefficient of thermal expansion, increase its thermal conductivity, slightly increase its hardness, and significantly increase its deflection temperature.

Conclusion
The combined strength, thermal, and chemical properties of polyetheretherketone make it an excellent choice for high temperature, environments in need of bushings. Add to that its ability to serve as an excellent replacement for metal bushings, and its ability to have its properties further enhanced by additives like glass and carbon, and PEEK quickly stands out as a top choice for high-performance polymer bushings.

Tags:PEEK,High-Performance Bushings

Tuesday, May 15, 2018

Five Ways that PTFE Rotary Seals Differ from ElaomstericSeals

The PTFE Rotary Seal Difference 

PTFE rotary seals are often the answer when elastomeric seals just can’t handle the demands.  In this article we are going to look at just five ways that PTFE seals differ in performance and behavior from elastomeric seals.

Here are some additional blog posts from the Advanced EMC Technologies Blog:

•Out of Whack: Eccentricity and Runout in PTFE Rotary Seals

•PTFE Rotary Lip Seals - 6 Feature Competitors Don't Want You to Know!

•Rotary Seals for Dummies: Four Questions about Shaft Surfaces for PTFE Rotary Seals

Low Friction

Because of the incredibly low coefficient of friction that PTFE has, it can be used in applications where lubricant cannot be used.  This is referred to as “dry running,” and PTFE seals excel in these types of applications where elastomeric seals fail.

Speed

Because of the low friction and excellent wear capabilities of PTFE, most PTFE seals can withstand running speeds of up to 5,900 feet per minute, or 30 m/s.  This makes them ideal for speed-intensive applications where reliable sealing is vital.

Chemical Compatibility and FDA Approval

PTFE is known for its incredible compatibility with a variety of chemicals, which sets it apart from the elastomeric materials typically used in sealing applications. Many PTFE compounds already FDA approval and are commonly used in pharmaceutical, food, and dairy applications
.
Operating Temperatures

Another benefit of PTFE rotary seals over traditional elastomeric rotary seals is the temperature range over which they can operate.  Most PTFE seals can perform in the cryogenic temperatures all the way down to -95°F up and up to extremely high temperatures of 480°F.

Relationship between Speed and Friction

The hydrodynamic film all the separates the seal lip from the movie.How much friction exists between the seal and the sealing surface is a function of the thickness of the hydrodynamic film.  The film pulled into the gap between the seal and the surface by viscous drag.  When the shaft is at rest, this layer will be at its minimum thickness and a certain amount of torque will be required to overcome the initial resistance to motion. Friction decreases as the velocity increases up to a point; after that speed is reached, friction will again begin to rise and the seal may begin to experience wear.  However, PTFE has a very low coefficient of friction to begin with, and may often be an exception to this rule.

PTFE Seals Alternative

The next time you are choosing a dynamic seal for an application that involves high speeds, extreme temperatures, a need for low friction, FDA approval, or chemical resistance, don't forget to look intoPTFE seals as an alternative to the traditional elastomeric dynamic seals.
For more detailed information on PTFE Rotary Shaft Seals download Advanced EMC Technologies resource guide.

Tags:rotary seal,ElaomstericSeals,ptfe

Sunday, May 13, 2018

Custom Spring Energized PTFE Seals for Medical Devices

The medical device industry faces continually evolving challenges when it comes to finding the right sealing solutions for new and improved designs. Issues such as sterilization, wide ranges of expected pressure, potentially aggressive environments, and FDA and USP approval make the design and specification process quite challenging. In this article, we are going to look at custom spring energized PTFE seals as a potential solution for sealing challenges in the medical industry.

Why PTFE Seals?
PTFE is a popular choice for spring energized seals for medical applications for several reasons. One is the fact that certain grades of PTFE have been approved by the FDA as USP Class VImaterials. It is resistant to a variety of aggressive chemicals, has extremely low friction, and retains its key characteristics – including strength – over a wide range of temperatures and pressures. It can be sterilized using methods such as steam and EtO (ethylene oxide), and is both hydrophobic and oleophobic.

Why Spring Energized Seals?
As you probably already know, spring energized seals are able to achieve a seal at low pressures because the spring applies outward pressure to the lip of the seal against the shaft or bore. As pressures increase, the pressure itself takes over from the energizing spring and achieves a tight seal. The result is an effective sealing solution.

Where Are Energized PTFE Seals Used in the Medical Device Industry?
PTFE seals are a common sight in the medical device industry, found in everything from dialysis equipment and infusion pumps to oxygen therapy, implanted electronic devices, trochars, and IV systems. Spring-energized PTFE seals are used in medical instruments, drug delivery systems, and orthopedic applications, just to name a few.

Custom Seals
Custom seal designs are available to meet the complex needs of the medical device industry. This includes custom engineering of the polymer (including fillers), unusual sizes or geometries, special spring materials, and more. In addition, PTFE lends itself to manufacturing processes such as machining that offer a high degree of accuracy and precision.

Conclusion
PTFE seals are popular in the medical device industry for a variety of reasons, including their low friction, chemical resistance, and excellent performance in a variety of pressure, temperature, and speed situations. Spring-energized PTFE seals provide a reliable sealing solution that is effective even in low-pressure environments. Even if an off-the-shelf energized PTFE seal won’t meet your needs, you can look into a custom-designed energized Teflon seal tailored to your requirements and specifications.

Tags:seal,custom,ptfe,medical

Monday, May 7, 2018

Comparison Between PTFE and PFA Processing

For a number of years fluoropolymers have played a significant role in the chemical and similar industries to protect plants and equipment against chemical attack by a broad range of aggressive media. This is because they offer substantially better chemical resistance and thermal stability than other plastics or elastomeric materials.

Following the development of PTFE, the introduction of melt-processable fluorinated ethylene-propylene (FEP) in 1960 opened up entirely new application areas. PFA, a perfluoro-alkoxy polymer which has been in successful use for 20 years as a lining material, is now a thermoplastic successor to PTFE, with equivalent thermal and chemical resistance and superior properties with respect to processability, translucency, permeation resistance and mechanical strength.

In the chemical industry, both fluoropolymers - PTFE and PFA - are used mainly in the form of linings (fig. 1, 2). For simple shapes, such as pipes, bends, T-pieces or reduction joints, PTFE is generally used; it is applied by means of paste extrusion, ram extrusion or tape wind-ing (fig. 3). In these processes a pre-form is made of the PTFE; this is then sintered and inserted into the metal workpiece. Using PTFE for lining of metal parts of complicated shape, such as valves and pumps, is more difficult. Isostatic molding is then the preferred method. In this PTFE powder is filled into the space created between the metal work-piece and a rubber bag which is specially made to fit into the shape of the area to be lined. The powder is pre-compressed, then cold-pressed into the desired shape. Finally, the rubber bag is removed and the lined part is sintered in an oven at over 360?C (680?F).

PFA, a thermoplastic material with a well-defined melting point, can be processed by means of transfer molding or injection molding. The granulate is melted in a melt pot or in the extruder and then forced into the hot tool by a hydraulic press.

This method enables very precise wall-thicknesses to be achieved, with tolerances of ? 0,5 mm, even at tight radii and in undercuts. Practically no mechanical finishing is needed, except to remove the sprue and to smooth the mating faces of flanges.

When using isostatic molding, however, a considerable amount of mechanical finishing is needed - depending on the degree of complication of the shape to be filled - to achieve the desired dimensions with precision.

The evenness of the wall-thickness may vary more, especially in the case of more complicated shapes such as valve housings.

Absorption and Permeation

Unlike metals, plastics and elastomers absorb varying amounts of the media with which they come in contact. This is often the case with organic compounds. Absorption may be followed by permeation through the wall lining. Though this is rarely observed with fluoropolymers, it can be counteracted by an increased wall-thickness or by installing devices to exhaust the space between the fluoropolymer lining and the metal wall. It has been clearly shown that in respect of permeation and absorption, melt-processed fluoropolymers such as PFA show better barrier properties than PTFE.

Vacuum Resistance

Vacuum resistance is needed because, in closed systems of the kind widely used in chemical processing, a drop in temperature creates a vacuum in the system, unless it is already operating below atmospheric pressure. When using PFA it is relatively simple to achieve adequate vacuum resistance for the lining. Usually the lining is ?anchored? to the metal wall by means of ?dove-tail? grooves or channels in the
latter.
With PTFE granulate that has been cold- formed, it is more difficult to achieve a sound anchoring of the lining in the metal wall as relatively large channels would be needed in order to allow the PTFE powder to flow into the grooves. More typically, therefore, bonding agents are used between the PTFE lining and the metal housing. However, due to the anti-adhesive characteristics of fluoropolymers and the limited thermal resistance of the bonding agents, PTFE shows only limited vacuum resistance.

Quality Control prevents Cracks and Voids

With PTFE and PFA linings, the dielectric strength is measured in order to identify faults. This method reliably pinpoints cracks and voids which go all the way through the material but, due to the well-known high resistivity of fluoropolymers, it does not indicate any faults which start 1,5 mm or more under the surface (fig. 5).

For this reason further tests using ultrasonic methods can also be applied. This test measures the distance from the surface of the lining to the metal housing. However, it is unreliable because it does not provide the true lining thickness when a void or porosity is present. In addition, this method is impractical to employ on small parts or small complicated shapes with undercuts and tight radii.
Another method to check for surface defects such as cracks and voids is with the so called ?Met-L-Check? dye penetrant method. But this method is limited to detecting surface defects only.
Chemical Structure
PFA, which is translucent, can reliably be checked optically. Cracks and voids under the surface can be made visible with suitable light sources. Hardly accessible locations in the lining can be examined using cold light lamps and flexible fibre light guides.

Cost Comparisons for Linings

In terms of raw material prices, PFA costs roughly three times as much as PTFE.

This disadvantage can, however, be compensated or greatly reduced, as a function of factors such as the shape to be lined, its size, the number of workpieces to be lined and the processing method adopted. This is possible because PFA neither requires manual process preparation nor finish machining with corresponding material losses.

The use of PFA for lining very large parts is not recommended, because the high material cost would make the part too expensive. Another point to be kept in mind is the cost of tools, which are not amortized
when only small numbers of parts are to be lined. Furthermore, there are practical limits to the weight of injected material that molding machines are capable of handling.

Conclusions

More than 20 years of experience with linings for various parts, e.g. valve and pump housings, have shown that PFA has numerous advantages when high thermal and chemical resistance are the main requirements.

The accurate and even wall-thickness that can be achieved with PFA is a major advantage, especially when working with media which have a strong tendency to diffuse.

Practical experience has also shown that PFA gives better barrier properties than PTFE.

Bromine manufacturers report, for example, that the penetration depth of bromine in PFA is about one third less than in PTFE, when operating conditions such as time, temperature and pressure are the same.

PTFE, on the other hand, is still widely used for components of chem- ical valves and other chemical processing equipment where flex fatigue resistance is required.

Typical examples of such applications are bellows, as well as diaphragms in valves and pumps.

For seat rings, plugs, seals and similar parts, PTFE is a suitable and economical material.

A recent trend for parts such as these is to use modified PTFE, as its dimensional stability and hardness are superior to those of standard PTFE.
Tags:PTFE,PFA,PTFE vs PFA

Sunday, May 6, 2018

Why use a PTFE (Polytetrafluoroethylene) instead of Rubber in a Rotary Shaft Seal?

PTFE Rotary Shaft Seals Outperform Rubber Shaft Seals

Elastomeric seals performed well for many years, but as the applications and environments became more demanding, elastomers had a hard time keeping up.  If the application pressure is above 30 psi or the operating temperature goes above 275°F, elastomers simply don’t perform as well as, say, PTFE. (polytetrafluoroethylene).  In this article, we are going to look at 3 areas where PTFE rotary shaft seals outperform rubber shaft seals.

Need more information on PTFE Rotary Shaft Seals? Check out these additional articles from the popular Advanced EMC Technologies Blog:
•Four Most Popular Rotary Shaft Seals Material Options and How They Compare
•Five Ways that PTFE Rotary Seals Differ from Elastomeric Seals
•Rotary Seals for Dummies: Four Questions about Shaft Surfaces for PTFE Rotary Seals

Wider Temperature Range
A major area that PTFE outpaces elastomeric seals is in its operating temperature range.  As seen in the chart below, PTFE can function between -95°F to 480°F, far beyond any of its competitors in both cryogenic and high temperature applications.
Lower Friction
Friction generates heat, and heat buildup can be catastrophic to seals – resulting in unpleasant things like cracks or melting.  PTFE has the lowest coefficient of friction of any solid material currently known, which is much lower than that of the elastomers typically used for seals.  PTFE can also be used for dry running (i.e., without needing a lubricant), which elastomers cannot.

Better Chemical Resistance
PTFE is known for its chemical compatibility and excellent performance even in the presence of some of the most caustic chemicals out there.  Rubber, however, has some limitations.
For example, Viton (FKM) is susceptible to ketones and acetones.  EPDMdoesn’t perform well many oils and fuels, as well as hydrocarbons and concentrated acids.  Nitrile (NBR) doesn’t do well in the presence of ozone, acetone, esters and ethers, or methyl ethyl ketone.  Polyacrylatedoesn’t get along well with alkalines.  In addition, elastomers aren’t really compatible with water, either.

Higher Speed Applications
As shown in the chart below, PTFE is the number one choice for high speed seal applications.  In order or performance from low speed to high speed, we see Nitrile, Polyacrylate, and FKM (Viton).

Conclusion: PTFE Outforms in Four Areas
PTFE outperforms rubber seals in four distinct areas:  
•lower friction
•wider temperature range
•better chemical resistance
•higher speed applications
The next time you need seal for an aggressive environment, don’t forget to check out PTFE (polytetrafluoroethylene) seals.

Tags:PTFE,Rubber,Rubber Shaft Seals