PTFE Pricing Update – The Impact of Anti-dumping Duties

For anyone connected to the PTFE industry, the last 18 months have been fraught with anxiety. The shutting down of a few PTFE resin manufacturers in China in early 2017 caused a supply crunch that has yet to ease out, driving prices up as much as 60%.

Many believed that the imbalance between demand and supply of PTFE raw materials would spur a capacity expansion from those manufacturers still operational. However – as we earlier saw in 2011 – resin manufacturers opted instead to maintain capacity and allow prices to increase. From the point of view of companies like Gujarat Fluorochemicals (India) and Shangdong Dongyue (China), this appears to be a sensible strategy. Until early 2017, the price of PTFE resins had been steadily declining due to fierce competition between resin suppliers. The shutting down of Chinese plants would have come as a blessing for these companies, who have since seen their realizations increase.

But while a rational observer may argue that an upward price correction was certainly due in early 2017, pinpointing the “fair” price for PTFE has always been tricky. Not only is the PTFE industry minuscule in comparison to more familiar polymers such as PVC, Polypropylene and Polyethylene, but its irreplaceable properties as an engineering plastic allows resin manufacturers a lot of leeway to test the extent to which higher prices would be accommodated by processors such as ourselves. Considering the price increase has been a worldwide phenomenon, it has not been impossible to convince clients regarding the upward revision of rates. What has been taxing, is the instability. A client may be willing to revise rates once or twice, but when it becomes a monthly affair, one can expect some backlash.

Amid all the uncertainty, it appears processors may have found some solace in the protectionist tendencies of the current US government. When the US announced in October 2017 that they would be reviewing the anti-dumping policy in relation to PTFE resin supplies, no one took much notice. This administration has highlighted multiple instances where the competitiveness of the US economy was threatened by low-cost-countries. We never believed that much attention would be paid to a niche industry like PTFE.

Over the past week, however, tariffs of 69% to 208% were announced on Chinese manufacturers, while Gujarat Fluorochemicals (India’s only manufacturer) was slapped with an 18.5% anti-dumping duty. The resulting impact of this measure is something we would like to extrapolate.

1. Demand realignment
   
   
   The first and most obvious effect of a tariff such as this is to curb demand from the US for Indian and Chinese resins. Globally, North America is said to contribute to about 25% of PTFE demand, with the bulk of this coming from the US.
   Our understanding of the price of Chemours resins (the erstwhile DuPont and the company that has lobbied to get the anti-dumping duties imposed) is that they lie between 1.25-1.6 times the price of resins from India. Hence, even with freight and other duties, Indian suppliers may still find some takers in the US market. It should however be noted that given the superior quality of Chemours’ material, processors cannot be expected to choose Indian resins, should the price differential be small.
   
   With regards to China, the pricing is a little more opaque. There are several manufacturers, and each has their own rate contracts with their respective clients. Whether a 208% tariff is warranted or is merely the result of effective lobbying on the part of Chemours, we cannot really tell.
   In a twist of undeniable irony, Russian manufacturers have been omitted from this tariff. When Gujarat Fluorochemicals successfully lobbied for anti-dumping duties into India, they made it a point to include both China and Russia in their report. The absence of Russia from the US’ anti-dumping measures means that they are well poised to benefit from the demand shift – assuming the US does not penalize them with any other general trade tariffs.
   
2. Supply realignment
   
   Considering what a large share of the world’s demand the US commands, their focus inward will leave a lot of Indian and Chinese resin manufacturers in the cold. The move is likely to cause the capacities of Asian firms to come in line (if not even exceed) local demand. There is still a significant amount of demand within Asia Pacific – which accounts for more than 50% of the global market. However, the price points are lower and the fact that the US has practically shut its doors mean that competition will drive prices down again.
   This may be particularly harsh for Indian resin manufacturers, as Chinese resins – which have been hard to come by locally due to the supply crunch – will undoubtedly flood the market. Interestingly, the anti-dumping duty on Russian resins into India has expired recently, implying that here too, they have a good opportunity to enter the market.
   
3. Value realignment
   
   
   When India imposed anti-dumping duties on China and Russia back in 2010-2011, the effect was not as beneficial to Indian resin manufacturers as initially assumed. This was because processors shifted their demand from buying raw materials from China to buy semi-finished goods. Traders who were earlier importing resins, now began dealing in rods and sheets.
   It is therefore equally likely that in the US too, the market will shift such that semi-finished and finished components get imported, rather than resins. Ultimately, the US has a significant appetite, and this needs to be met one way or another. One cannot imagine a processor in the US agreeing to pay a 200% duty, when they can just as well import finished products with no such penalty.
   
   It should also be noted that while Chemours may certainly want to monopolize the North American market as it once did, it simply may not have the capacity to satisfy the local demand. As a result, shortages will push clients to look further up the value chain for their requirements. In protecting the interest of a few large companies, the US may have just killed of a large portion of its processing industry, which was no doubt dependent on Indian and Chinese resins for staying competitive.

PEEK in India – A Growing Market with Many Challenges

At Poly Fluoro Ltd. we started our journey with PTFE and gradually expanded into other polymers. Initially, this was at the behest of existing customers, but over time our expertise in machining plastics meant that we were comfortable offering a variety of options to our clients, rather than try and force fit PTFE into their application.
We discovered the benefits of PEEK in one such exercise. Although we have already blogged extensively on the benefits and properties of PEEK, our own experience in dealing with this material serves to explain much of the commercial and technical queries surrounding this material.

PEEK in India is a small market in terms of volumes. The total consumption is only about 35 Tonnes. Of this, most of the material is imported as semi-finished rods and sheet, with only 12-15 Tonnes being processed from resin indigenously. Small as these numbers are, keep in mind that semi-finished PEEK sells at anywhere between US$275-US$400 per Kg – so in value terms, the market is not as small as the volumes suggest. Nonetheless, it is very much a niche market – even among speciality polymers.

Being present in the PEEK market as a processor poses many challenges. Some of these are technical in nature, while others relate to the commercial issue (PEEK is very expensive) and how clients respond to PEEK. Again, we have touched on some of these points in our earlier article – but as we have delved deeper into PEEK processing, many new findings have arisen.

Compression moulding PEEK not a simple affair

There are many challenges in compression moulding PEEK and most of these do not get explicitly highlighted in manuals and guidebooks. In most manuals, the process is outlined in 5-6 basic steps, which at first glance make PEEK appear a very friendly material to deal with.

In reality, the process is time-consuming, highly sensitive to the exact process needed and very specific in the type of tooling required.

The benefit of compression moulding PEEK over, say extrusion is that we are able to make customized dimensions based on the customer drawings. The stock piece for a part measuring 70mm in diameter can be moulded as 72mm, rather than using a 75mm rod. Over a 50mm length, this saves almost 25 Grams per part – which is significant when we consider the cost per Kg. Furthermore, if the part has an internal diameter the saving is even more, as the same cannot be attained in extrusion for large diameters.

However, against this saving, the time consumed to make a 50mm part would be many times what extrusion would take. Compression moulding is known for low productivity and even a large processor is only able to consume 20-25 Kgs per day of production. In India, however, where labour is inexpensive, this is not a huge cost factor – it only limits volumes. And since PEEK is still a low volume polymer – even processing 4-5 Kgs a day can be significant.

The actual process of compression moulding PEEK is also not straightforward. The 5-6 steps mentioned in the manuals each contain nuances that need to be fine tuned until you reach a process that most suits the equipment available. In our own experience, we have found that over 25-30 trials had to be taken, each using up between 250-800 Grams of resin. After each trial, some parameters were changed before taking another trial. Parameters such as pressure, peak temperature and soak time all need to be varied to control issue such as porosity, cracking, black spots and cold spots.

In addition to this, the selection of dies is critical. PEEK, in its molten form can be a very aggressive material and we have had many steel dies get corroded during moulding. Again – finding a balance between a strong die metal and the correct process is critical in obtaining a final process that is both economical and productive and which yields a high quality final product.

Variants and substitutes do exist for the price conscious

We have had some success in blending PTFE with PEEK ratios of 5%, 10% and 15% by weight (ie: PTFE+5/10/15% PEEK). Again – the process of blending is not straightforward and the PTFE itself needs to be processed slightly differently owing to the fact that PEEK melts at a higher temperature than PTFE. However, the final blend has proven to be useful in applications involving sealing and needing high wear resistance, with a low coefficient of friction.

Another alternative to PEEK is PEK. PEK is very similar to PEEK and is processed in much the same way. As far as properties go, some have even suggested it is slightly superior on some parameters. Commercially, it is roughly half the price of PEEK – which makes it a very tempting alternative. However, PEK is still being proven in OEM applications, whereas PEEK has been around long enough to give any OEM designer confidence in its properties.

Marketing PEEK is a challenge

In a market like India – which is highly price sensitive – PEEK is a difficult product to win customers over with.

PEEK is usually the last choice of any OEM due to its price, and if someone has not come across the material before, it takes some educating before they are convinced that any polymer exists at such a price. And while PEEK is well established in the West – in India, it is still very nascent in comparison and clients do not always see the long-term benefits of using it.

Furthermore, the relatively recent introduction of PEK into India is threatening to take some of the long-term market share from PEEK, as in a price sensitive market, people may be willing to make the gamble on a cheaper substitute.

Mapping the PTFE Price Increase - An Update

 We have been receiving many mails asking us to map or at least project the PTFE price trend going forward. Since our last post on PTFE pricing was about a year ago (Feb 2012), it is a valid question to ask whether there has been any further volatility in this market and what that implies for prices as a whole.

To lay any suspense to rest right away – we can firmly say that prices have indeed been stable this past year and it is due to this stability that our own interest in analyzing the prices has dimmed somewhat. However, that is not to say that things would continue along this vein indefinitely. PTFE is a complex material and the dynamics involving its manufacture and sale are constantly in flux – meaning that the next shock may just be around the corner at any time. So we would like to look at some of the buzz surrounding the industry in a hope to at least demystify the future to some extent.

Prices are expected to remain stable throughout 2013

This is the general consensus as of now and is due to two primary factors:

1. There is a general slowdown in global demand (much in line with most other industries) that makes it risky for resin manufactures to experiment with pricing like was done early in the price escalation of 2010-11
2. There was a significant over supply of resins when prices were high and this led to huge inventories which manufacturers are still offloading

In some areas it is believed that there is still some scope for prices to fall further. However, it is most widely accepted that the current rates are stable and should be for the foreseeable future

China still a key player – but not the only price maker

Back in 2010, it was largely a price war between manufacturers that led to very low PTFE prices. Much of this was driven by China – where the abundance of fluorspar and the support from their government allowed Chinese PTFE manufacturers to scale up very quickly.

Although China remains a key player still, a few factors are affecting their economics and scale right now:

1. The government support has reduced for PTFE resin manufacturers in China. With the clamping down of R22 within China (for environmental reasons), there is a subsidy of US$0.5 per Kg of R22, which is no longer being offered by the Chinese government.  Owing to this, Chinese manufacturers have had to pass on this cost increase of about US$2 per Kg on to PTFE processors.
   
2. Due to quality issues with Chinese resins, many OEMs have started specifying that their parts be made from resins such as DuPont, Daikin or AGC. Many semi-finished PTFE processors have also shifted away from Chinese resins due to the instability of the material. It was long believed that China reserved the good quality resin for their domestic manufacture and preferred to dump the off spec grades into other countries (one of the reasons why the anti-dumping duty on Chinese resins was upheld by the Indian government). This has hit the volumes of Chinese resin manufacturers
   
3. Another key issue is repro material. While India earlier had significant imports of Chinese semi-finished PTFE materials, most of this was repro material but was being passed off as 100% pure virgin PTFE in the local market. This high intake of semi-finished PTFE was affecting the local semi-finished manufacturers as well as local resin suppliers. However – owing to the major quality issues with repro and the lack of accountability and transparency in the percentage of repro being incorporated, many companies have had to stop procuring semi-finished PTFE from China and have started buying domestically – where it is easier to monitor quality and also return material if found defective. This has led to a resurgence in domestic PTFE semi-finished goods production and also an increased off-take from local resin manufacturers.

With China on the back foot due to the reasons listed above, it may be safe to say that price manipulation and/or competition is for the time being not a threat – since it is usually with China that most of these issue do arise. Hence, the current view is that of stability – and we should enjoy that while it lasts.

The Many Chemical Applications of PTFE

PTFE is known to be among the most chemically resistant materials known to man. While this property is well known and often quoted in manuals and our own blog articles, we would like to touch upon some of the common applications that this property leads to.

PTFE Labwares

PTFE has been a mainstay in lab-ware items for a number of years. Lab-ware items include stopcocks, beakers, pipes, test tubes, stirrers, petri dishes and stands. In most labs, glass is the commonly used material for these items, but as we know, glass has a tendency to break. Furthermore, when dealing with harsh chemicals at elevated temperatures and pressures, PTFE becomes a viable option for a number of reasons.

1. PTFE is chemically inert – barring certain alkalis at elevated temperatures
2. PTFE does not break easily: Under loads, virgin PTFE would tend to deform rather than break. This makes it useful in applications involving high centrifugal forces – where a glass test tube might break under extreme loads
3. PTFE is stable across temperature fluctuations: Even toughened glass would have a limit on how suddenly it can be cooled down when under high temperatures. PTFE is able to cool down rapidly from elevated temperatures without cracking
4. PTFE is a great sealing material: Especially for stopcocks, PTFE forms a much better seal than glass equipment owing to the fact that it is soft and will easily seal gaps which may arise due to minor variations in taper between the pipe and the stopcock.
5. PTFE is flexible: PTFE tubes can be used in place of glass and be bent to accommodate the layout of the apparatus
6. PTFE can be moulded with a magnetic core: PTFE stirrers are used because they can be moulded with a magnet at the core and used in magnetic mixers

PTFE Stirrers and Shafts

Stirrers and shafts are used primarily in highly corrosive applications including biotech, pharma and refineries. The ability of the PTFE to be constantly immersed in a chemical and neither modify nor be modified by the chemical makes it an invaluable component in many mixing arrangement.

More often than not, the shaft or stirrer needs to be custom moulded and machined to suit the mixing assembly. This makes it an expensive component and therefore only sparingly used. In some cases, a stainless steel core can be used over which the PTFE is moulded/ lined. In other cases, the stainless steel shaft can simply be coated with PTFE. However, this latter case only works where there is little or no abrasion expected on the shaft – since PTFE coating will peel off if the shaft is subjected to wear.

PTFE umbilical cords

Although the name sounds strange – the umbilical cord is a well-known arrangement of PTFE tubes used in the refinery industry. The purpose is simple – the refinery process yields a number of different gasses, which need to be analysed in a lab to gauge whether the right chemical reactions are taking place in the chamber. Taking these gasses to the lab (which needs to be a minimum of 200-250 meters from the reaction chamber) is a difficult process, as the gasses are corrosive and highly reactive – which may mean that they change composition during transit if not kept in a chemically inert environment.

An assembly of 12-15 tubes is bunched together using a PVC coating and each tube has a length of 250 meters and transports a single gas to the lab, where it is collected and analysed.

The complication in this design is that the PTFE tube needs to be continuous for the entire length of 250 meters. Any bonding or jointing leads to a foreign chemical in the tube and this affects the gas passing through it. After extensive trials, we find that using a welded joint comprised of PTFE is able to create an effective solution for the tubes.

Filtration

Many chemical applications involve multiple substances, which often need to be separated from one another. In such cases, PTFE becomes the preferred medium for filtration.

PTFE is used in 2 forms here:

1. Porous PTFE sheet: This is a standard PTFE sheet skived from a porous PTFE billet. The billet is made porous by adding certain substances in the PTFE compound, which sublimate during the sinter cycle, leaving voids. These voids form the pores which aid in filtration. This type of membrane is not used extensively due to the inexact nature of the pores. However, the membrane can be made as thick as 5mm – which makes it useful in corrosive applications where a liquid needs to be separated from large solid particles.
2. Expanded PTFE membrane: This is also called breathable PTFE membrane owing to the fact that you can pass gas through it, but not liquids. Expanded PTFE is more commonly used that porous PTFE as the pore size can be easily defined to within a few microns. It finds multiple applications in automotives, pharma and biotech.

PTFE Valves and Ball Valve Seats

Although valves and ball valves form an industry unto themselves and use a variety of materials other than PTFE, certain applications involving the flow of chemicals need PTFE valves to withstand the corrosion otherwise caused to non-PTFE valves.

Our own experience with PTFE valves sees it being used in piping systems in chemical plants and in equipments such as paint dispersion machines.

In paint dispersion, the equipment is used by retailers to mix different colours of paint to form a batch of a new colour as chosen by the customer. The paint passing through the PTFE valve needs to remain un-changed. Any reaction due to, say, using a nylon or PVC valve can alter the colour to the extent that the colour being chosen by the customer does not match the actual colour of the final paint. Thus PTFE is an invaluable component within this assembly.

Reprocessed PTFE and chemical applications

We had earlier done an article on reprocessed PTFE and the various issues it presents with regards to the base properties of the material. One of the issues we have observed is that when using reprocessed PTFE, the scrap is seen to change colour when using a coolant during machining. This came as a huge shock to us – as common opinion suggests that it is only in mechanical properties that the material suffers when reprocessed.

The finding leads us to believe that a number of things may be happening to cause this:

1. There may be foreign substances used in making the reprocessed PTFE. Titanium Di-Oxide for example is a known additive in making PTFE appear whiter. Similarly – cheaper, un-tested additives may be added to improve appearance, which may not have the chemical inertness that PTFE has.
2. Micro-impurities may be present in the material that cannot be seen by the naked eye. These may be reacting with the coolant causing the colour change
3. The basic chemical structure may be altered on a microscopic level. PTFE is chemically inert because of its molecular structure, which involves a carbon atom, shielded by 2 atoms of fluorine. When we chemically etch PTFE, we effectively remove 1 flourine atom and expose the carbon atom, making it bondable. A similar transformation may be happening in parts of the material due to reprocessing – which cause a degradation in the chemical resistance of the material.

PTFE machining considerations – tapping

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Machining PTFE, as we have touched upon before, is never a straightforward process. Most machining handbooks will suggest that PTFE should be treated much like wood when it comes to machining, as this is the material it most closely behaves like when machined. And while this is a good starting point for tool selection and CNC programme settings, as we delve deeper into the aspects of machining PTFE, we see that it behaves much like it’s own material. So learning by doing becomes the only option – since PTFE is a niche product (when compared with other known polymers).

Recently, we faced an interesting issue when creating a rather complex part. The part is approximately 200 Grams in weight and machining it involved multiple operations including CNC turning, CNC milling, drilling and finally tapping. All in all, the drawing highlighted over 28 dimensions that needed to be within a strict tolerance and it took us the better part of a week to just get 10 prototypes ready.

We were pretty happy with the result: everything measured, as it should. We almost didn’t check the tapping – which called for an M3 tap in two places. The M3 taps used were brand new and the first tap was done on the VMC as part of the programme – so there was no way it could be an issue, we thought. But we were wrong.

The no-go gauge entered in the hole all too easily and we were pretty shocked to realise that even an M3 bolt was sitting loose in the hole. At first we though we had the wrong tap – which we didn’t. We then argued that the gauge would always enter – as it was designed mainly for harder materials and PTFE would yield all too easily, since it was much softer. To check this we used the same taps on a mild steel plate and confirmed that the no-go did not enter. But this still did not answer why the bolt itself was loose.

We searched extensively for an answer online, but there was very little information on tapping and even less on the issue we in particular were facing. We then decided to start experimenting with different combinations of taps and drill holes.

On the part, we had used a 2.2mm drill with all 3 taps. The first tap was done on our VMC, while the next 2 were done by hand. We tried the following combinations:

Drill Hole	Tap 1	Tap 2	Tap 3	Result	Remark
1.5	Y	Y	Y	Reject	Bolt loose
1.5	Y			Reject	Bolt loose
1.5			Y	Reject	Bolt tight
2	Y	Y	Y	Reject	Bolt tight
2			Y	Reject	Bolt loose
2.2	Y	Y	Y	Reject	Bolt loose
2.2			Y	Reject	Bolt loose

In a couple of cases – where we used only the 3^rd (finest) tap, the bolt was tight. However, none of the holes were answering to the no-go gauge, which passed equally easily in all the holes. We once again argued that this was a PTFE related issue and that as long as the bolt was tight, it should not be a problem. But many of the consultants and experts I spoke with said that they had come across parts in PTFE that answered to the no-go gauge, and hence there must be a way to machine such a part.

The problem was finally solved when an engineer in our client’s side suggested we use a “Form Tap”. I had never heard of a form tap and when I searched it, it seemed to apply mainly to tapping soft metals (such a aluminium). There was no mention of applications to PTFE. Nonetheless, it was our last shot, so we tried it and were pleasantly surprised.

We eventually went with a 2.0mm drill and an M3 form tap to get a result that was both functionally good and which answered to the gauge.

The reason the form tap works, is because unlike a regular tap, it does not bore into the PTFE, taking out material as it does. Instead, it merely forms the tap profile within the drilled hole and as PTFE is soft, it yields quite easily. The result is that the tapped hole is much fuller than when a normal M3 tap is used – making it tighter and ensuring the pitch profile does not yield to the no-go gauge.

Surprisingly, this does again strengthen the PTFE-Wood similarity in machining. Tapping is unheard of in wood; a screw can be passed through a drilled hole and sit tight forever! In many ways, a form tap is nothing more than passing a screw/bolt into the PTFE to imprint its profile within the hole. Only that the form tap is possibly more exact and can ensure that the resulting tap is accepted when inspected with the correct gauges!

UHMWPE - the unknown polymer

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One of the few good things to happen due to the unprecedented escalation of PTFE prices globally was that it allowed us to look at alternate materials and seriously gauge the feasibility of manufacturing them.

In an earlier post, we looked at the various properties of PTFE and compared them to the other polymers. And although the key takeaway from that exercise was that PTFE was an immensely versatile material which was difficult to replace, we did make mention of possible alternatives, provided the user was willing to compromise on some parameters.

A key polymer which struck us then and continues to feature prominently in our product offering today is UHMWPE. We would like to take a more detailed look at UHMWPE for 2 reasons:

1. It does measure up against PTFE as a low-cost substitute (with certain limitations)
2. It’s properties do not seem to be as widely known to end-users, resulting in limited use in many applications where it would otherwise be ideal

What is UHMWPE?

Sometimes referred to as just “UHMW”, UHMWPE or Ultra High Molecular Weight Poly Ethylene is an off-white polymer that exhibits superior strength while being both light-weight and possessing a low coefficient of friction.

While it is not entirely accurate to refer to it as an “unknown” polymer – our own analysis of search terms within Google tells us that a total of ~62,000 searches per month are done globally for UHMWPE and/or UHMW. This is tiny in comparison to searches for PTFE/Teflon (1,300,000 per month) or for Nylon (5,500,000 per month).

Comparison with PTFE

So how does UHMWPE compare with PTFE? In our own opinion – it compares rather well. In fact, if you take all the applications involving PTFE and remove the ones that call for heat resistance, UHMWPE is a very workable substitute.

Although a full comparison chart is given at the end of this article, we would like to look at some specific properties more subjectively.

1. Temperature resistance
   Let’s get this one out of the way, since we know that it is UHMWPE’s weakness. Having an operating temperature of only about 80°C compared with 260°C for PTFE, UHMWPE is automatically disqualified in a range of industrial applications where the temperatures surrounding the material are expected to be well in excess of it’s upper limit.
   
2. Wear resistance
   Before we were familiar with UHMWPE, we were asked to advice a cement plant on whether they could use Lubring sheets (PTFE+Bronze) in a wear application. We were confident that it would work and when they mentioned that they had tried UHMWPE and it had failed, we did not think it was worth looking into. But when we did compare the materials, we realized that if UHMWPE had failed, there was little chance PTFE would work – since the gap between the two materials on this parameter is quite wide.
   Keep in mind that PTFE+Bronze is the most wear resistance grade of PTFE available. So if we compare UHMWPE with plain PTFE, the rift is even wider.
   
3. Coefficient of friction
   It is difficult to beat PTFE on this parameter, although UHMWPE comes fairly close. While it remains true that the coefficient of friction between PTFE and polished stainless steel is the lowest between two known solids (0.03-0.05), UHMWPE is able to reach a somewhat respectable 0.1-0.15 on this metric. While this does put it out of range for many applications where the recommended coefficient cannot exceed 0.1 (eg: sliding bearings) – it is a useful substitute in components where smooth movement between parts is the only requirement.
   
4. Dielectric strength
   Both materials are pretty much neck and neck on dielectric strength. Where UHMWPE loses out is on its ability to be skived into thin tapes. While we regularly skive PTFE down to 0.04-0.05mm thicknesses, the same is more challenging with UHMWPE, since it lends a much higher wear on to the skiving blade, making it difficult to achieve long lengths of tape before the blade dulls out and breaks the tape. Nonetheless, thicknesses of 0.1mm and above are more than feasible, meaning that as an insulating pad or even a component used in high voltage applications, UHMWPE is more that suitable.
   
5. Chemical inertness
   PTFE is well known for it’s inertness and this allows it to lend itself to applications ranging from biotechnology to medical devices and chemical linings. While UHMWPE does not have quite the same extreme inertness as PTFE, it does find use in medical applications (it is used in parts for joint replacements) and can easily be used in both biotech and chemical applications, provided the exact nature of chemicals is known and compared against it’s capabilities.
   
6. Weight
   While weight has never been a consideration for PTFE in any of it’s applications, we would still like to highlight that UHMWPE is less than half the weight of PTFE (specific gravity of 0.95 vs. 2.15 for PTFE). The key difference this adds is in their respective cost cacluations. Not only is UHMWPE cheaper in resin form (roughly 1/4^th the cost per Kg), the fact that you consume only half the weight to get the same volume part implies that the effective cost is 1/8^th the cost of PTFE. This represents a significant saving.

So where can we use UHMWPE?

There are a range of applications where UHMWPE could and should be used. In many cases, we have tried to suggest to the end-user that we can offer them UHMWPE in stead of PTFE, but due to restrictions on standards and because changing specifications can be time consuming, very few have opted for the change.

Strangely, in many cases, clients have opted for suppliers offering reprocessed PTFE, but not UHMWPE. Given the highly diminished properties of reprocessed PTFE, this is functionally not a great trade-off in the medium to long term.

Automotives

Most automotive applications use PTFE in high temperature environments, so UHMWPE does not fit the requirement. However, there are a number of applications where the parts operate at room temperature eg: car doors, seats, hand levers etc. and here UHMWPE can find a lot of use. We are aware that the wear strip used inside car doors employs UHMWPE.

In general, UHMWPE wear strips offer a low cost and effective alternative to PTFE wear strips.

Valves and seals

Typically, valves and seals require a low coefficient of friction with a good wear resistance.  UHMWPE is an excellent replacement for PTFE in these areas.

Medical

UHMWPE is widely used in joint replacements due to its chemical inertness and light-weight.

Infrastructure

Although regulatory restrictions prevent materials other than PTFE to be used POT bearings, there are many sliding bearing applications which do not fall under the government codes and are therefore potential areas where UHMWPE can be used. UHMWPE could be employed successfully in sliding bearings and as plain sliding pads.

Electronics

Many components used in electronics have traditionally employed PTFE components for insulation. In a number of cases, we have successfully tested UHMWPE for these applications and convinced the client to shift.


Overall, there continues to be a resistance to employ a material like UHMWPE. Part of this is regulatory – drawings and specifications that call for PTFE cannot be changed over night. But mostly there is a genuine dearth of awareness about the material – which is equally difficult to change. While it is true that UHMWPE is a substitute for PTFE – we see it as more of a partner in application – allowing many end-users to find a competitive, low-cost solution where they would otherwise be unable to proceed with their development or manufacturing.

Comparison chart between PTFE and UHMWPE

	UHMWPE	PTFE	Units
Colour	Off-white	White
Specific Gravity, 73°F	0.944	2.25
Tensile Strength @ Yield, 73°F	3250	4000	psi
Tensile Modulus of Elasticity, 73°F	155,900	150,000	psi
Tensile Elongation (at break), 73°F	330	350	%
Flexural Modulus of Elasticity	107,900	145,000	psi
Compressive Strength at 2% deformation	400	1650	psi
Compressive Strength 10% Deformation	1200	2200	psi
Deformation Under Load	6-8%	2.5-5%	%
Compressive Modulus of Elasticity, 73°F	69,650	79,750	psi
Hardness, Durometer (Shore "D" scale)	69	55-65
Izod Impact, Notched @ 73°F	30	161	ft.lbs./in. of notch
Coefficient of Friction (Dry vs Steel) Static	0.17	.06-0.12
Coefficient of Friction (Dry vs Steel) Dynamic	0.14	0.12
Sand Wheel Wear/Abrasion Test	95	90	UHMW=100
Coefficient of Linear Thermal Expansion	11	6-7.2	in/in/°F x 10-5
Melting Point (Crystalline Peak)	135-145	380	°C
Maximum Service Temperature	80	260	°C
Volume Resistivity	>1015	NA	ohm-cm
Surface Resistivity	>1015	NA	ohm-cm
Water Absorption, Immersion 24 Hours	Nil	Nil	%
Water Absorption, Immersion Saturation	Nil	Nil	%
Machine-ability Rating	5	3	1 = easy, 10 = difficult