Unravelling Polymers

The Definitive Blog on Polymers by Poly Fluoro Ltd.

Polymer Prices Go to the Moon

Anyone even remotely associated with the polymer industry would have noticed a rather worrying trend of late. Across the board, a host of different polymers have seen price increases such as the industry has scarcely experienced before.

The curve has been so steep in some cases (prices are being revised almost daily), that it has forced many raw material suppliers to declare force majeure clauses to avoid being wedded to existing rate contracts. 

For a company like ours – which has seen significant price hikes for PTFE resins in the past – this movement, while concerning, is not something unheard of. Between January 2017 and June 2018, the price of PTFE increased some 67%, jumping every month as it went from ~US$7.3 up to ~US$12.2 without stopping to pause. Today, we’re seeing something similar with other polymers, most notably Nylons (PA6, PA66), Polyacetals (POM/Delrin), Polypropylene, and ABS. 

Like with the case of PTFE prices in 2017-18, here too, the explanations are many. With ABS, for example, we were told that a fire at one of the main ABS manufacturers in Taiwan has constrained global supply and caused the spike. In the case of PA66, PP, and POM, the stories are vaguer – ranging from the impact of the cold spell and blackout in Texas to the contraction in the oil markets. Most common is the idea that after a tough 2020, resin suppliers have decided collectively to play opportunist and use the current scenario – where business sentiment and consumer spending seem to be on a bit of an uptick – to recalibrate prices that have been stagnant for most of the past 2-3 years.

As diverse as the presumed drivers for the cost hikes are, the expectations for when things will stabilise are also highly uncertain. Most opinion rests on the idea that prices will stabilise around June 2021, although it is somewhat likely that after the recent shock to shipping and trade brought about by the Suez Canal blockage, things might take until July/August to reach some kind of equilibrium. This is not to say that prices will revert to their earlier levels. As we saw with PTFE, steep shocks such as this rarely rewind back to their starting points. After PTFE prices spiked in June 2018, there was a gradual easing off, but the prices still settled at a level roughly 45-50% above their earlier lows. This became the new normal around which manufacturers and their clients based their new pricing models. The fact remains that ultimately there is a trade-off between price and volume and a manufacturer of polymer resins that experiences a volume contraction less than that of the value increase per Kg will be better off with the higher prices.

So where does this leave manufacturers? Polymers such as PA66 and POM are more geared towards engineering plastic applications, so there is usually a scope – as there was with PTFE – to re-work rates with clients and move to a higher price point. It’s never easy to do this, but when the event is so systemic, clients usually relent, even if there is a sometimes uncomfortable period where they may go looking for alternatives before realising that higher prices are here to stay.

However, in the case of PP and ABS, the situation remains tricky. These are low margin polymers, which find applications in consumer products. The price sensitivity of the end-customer means that an overnight revision is rarely possible, and this puts the manufacturer in a very difficult position. The only viable option for many is to stop supplying materials, which is hardly a solution, especially after so much of 2020 was already lost to the Covid pandemic. In India, the government has been asked to restrict raw material exports and to ease import duties, however, the former has not happened while a 5% increase in import duties since the 2021 budget has only made the local pricing worse.

Amidst this turmoil, it remains to be seen where the markets will eventually settle. However, history and economics do suggest how things might play out. First, with margins already shockingly low in the injection moulding industry, manufacturers would rather shut shop than work with higher input costs without corresponding price increases. When this happens, the resultant supply-side crunch would see an inevitable improvement in realisations for manufacturers around the new resin prices. As resin prices ease off slightly, some capacity will return to the market, but the price points will remain at higher levels, even as new/returning manufacturers eventually gravitate back to their old margin levels.

One thing is for certain. After a gruelling 2020, manufacturers must now brace for another storm that, like the pandemic, doesn’t quite come with an end-by date.


Read More

1. The mysterious relationship between Fluorspar and PTFE prices

2. PTFE Pricing Update - The Impact of Anti-dumping Duties

3. Mapping the PTFE Price Increase - An Update

Case Study - Development of a 4-axis PEEK Valve

At Poly Fluoro Ltd, we have always tried to abide by the rule: Build capability, not just capacity.

In a world where manufacturers are constantly looking to scale up operations as quickly as possible, this may sound rather counterintuitive. Scale allows for many benefits, such as lower input costs and allowing fixed expenses to be spread more thinly.

However, when it comes to niche polymers, scale is never guaranteed. In most cases, the demand for complex machined polymer components only runs into the thousands. With limited scale, the challenge becomes one of achieving higher realisations for the same time spent. In this endeavour, adding capabilities helps a company move up the value chain and scale up on value, even while volumes may remain small.

A while back, we engaged in the development of a very complex valve made from PEEK. By the analysis done by our engineering, we knew the part required a 5-axis milling machine and even though we really wanted to add the part to our portfolio, our milling machines only had 3-axis functions. We therefore needed to build this capability.

We initially stepped out to see whether a vendor could take the part up for us. However, every vendor we spoke with either gave up upon seeing the drawing (the part is very complex!) or said that they did not have capacity to take up the job. We were intrigued. Not only was the part truly a challenge – which is something we love – but the lack of capacity in the market meant that acquiring our own equipment was probably a good idea in the long run.

However, given that a 5-axis milling machine can be rather expensive, we were hesitant to jump into something requiring such a large investment, when the value of the order in question was small in comparison. We then came across a new equipment vendor offering 5-axis machines at a fraction of the cost that was being asked by the larger manufacturers. We gave them the part to develop, assuring them that if successful, we would pay the advance on a new machine immediately.

Sadly, the PEEK valve was tougher than they anticipated (I did say it was complex) and after struggling for a few weeks, they abandoned the project with nothing to show. We were back to square one.

We sat down to review the part and – in what would surely be a major loss of face – decide how we were going to inform the client that we had failed and that we could not take the development further. During our review, it was commented that in truth, we only needed a 4th axis to give us the extra dimension needed to machine the part. This caused us to stop and think. We already had 3-axis machines; what would it cost to add only one more axis? Was such an extension even possible?

After speaking with our existing machine’s vendor, we were excited to learn that they had a 4th axis attachment suited to our equipment. What’s more, it would cost a third of what we would have paid to the supplier to whom we had given our part for development. 

Within two weeks the new attachment was in place, although the part’s development still took a few weeks more (did I mention the part is very complex?).

Our obsession with making the part led us down a path of discovery that culminated in a successful outcome. However, in pushing for this outcome, we managed to add a 4-axis capability to our machining repertoire, giving us the option to take on new parts that we may have otherwise had to regret. It is this determination to constantly push what seems infeasible that leads us into newer, more interesting avenues of our operations.

And if we do come across a part more complex than what we can handle? Well, there’s always that elusive 5th axis we still need to get!


Read More

1. PEEK - The Impact of Carbon Fibre Fillers on HPV Bearing Grades

2. PEEK - Robust Enough for Nuclear Applications

3. The Effectiveness of PEEK Compressor Valve Plates

PEEK - The Impact of Carbon Fibre Fillers on HPV Bearing Grades

As a standalone material with no filler reinforcements, PEEK (PolyEtherEtherKetone) comfortably holds its own as one of the most robust polymers around. With the exception of Polyimide (aka Kapton), PEEK has no viable rivals on pure strength and high-temperature capabilities. A specific gravity of only 1.3 makes it a darling of the aerospace industry, while a chemical inertness that nearly matches that of PTFE makes it highly sought after in nuclear applications and refineries.

That said, there is always room for improvement. The same fillers that give materials such as PTFE or PPS enhanced properties also work well on PEEK. As such, with the aim being to maximise strength and durability, carbon is a key filler for PEEK.

Carbon (Coke) Powder vs Carbon Fibre

Before we proceed, a distinction must first be made between powdered carbon – which is effectively finely ground coal, and carbon fibre – which is a result of milling more complex carbon materials to yield miniscule, high-strength strands that go on to reinforce the polymer into which they are blended. While carbon fibre is far more expensive than conventional carbon powder, its impact too exceeds that of its poorer cousin by a significant margin.

Thus, when we refer to carbon filled PEEK, it should be understood here that we are speaking specifically about carbon fibre.

PEEK, PEEK+Carbon, and HPV PEEK

In this article, we will primarily be comparing three different grades.

Unfilled PEEK is the polymer in its virgin form. As stated above, even in this form – where the PEEK takes an even tan colour – the material is robust and capable of withstanding high loads and temperature.

PEEK+Carbon is usually a blend of PEEK and either 15% or 30% carbon. For the purpose of this comparison, we will be looking at PEEK+30% carbon (CF30), as we have accurate data for the same.

HPV PEEK is a special blend of PEEK popularised by the brand Ketron (Quadrant). HPV PEEK was designed to have a composition of 70% PEEK, 10% carbon, 10% graphite, and 10% PTFE. This unique blend offers a large boost to the strength of the base material – thanks to the carbon – while also bringing better wear and friction properties due to the graphite and PTFE. HPV PEEK – also referred to as bearing grade PEEK – is both difficult to blend and prohibitively expensive in comparison to regular PEEK. However, given its fantastic properties, most OEMs are happy to pay the price.

Comparing Properties

As you can see from the table below, the addition of carbon and other fillers has an appreciable impact on the properties of the material. 

Apart from an increase in tensile strength of ~35%-207% for HPV and CF30 respectively, there are increases of anywhere from over 300% to over 500% on other metrics such as Young’s Modulus, Flexural Modulus, and Flexural Strength.

In addition to pure strength, what can also be observed are lower coefficients of thermal expansion and higher deflection temperatures under load – both indicative of a more dimensionally stable material in high-temperature applications.

HPV – which has a lower coefficient of friction and can go as low as 0.05 under lubricated conditions – is ideal for wear applications and dry-running applications.

 

Unfilled PEEK

PEEK+30% Carbon

PEEK HPV

Unit

Test

Tensile Strength

97

201

133

Mpa

ASTM D638

Young's Modulus

3650

19700

11000

Mpa

ASTM D638

Flexural Modulus

3860

17500

10500

Mpa

ASTM D790

Flexural Strength

152

317

221

Mpa

ASTM D790

Coefficient of Linear Thermal Expansion

4.3 x 10-5

5.2 x 10-6

2.2 x 10-5

cm/cm/°C

ASTM E831

Deflection Temperature Under Load

162

315

291

°C

ASTM D648

Coefficient of Friction

0.35

-

0.25

 

ASTM D3702


Machining properties

As manufactures of high-precision machined components, a lot of our experience ultimately ends with understanding how well the part adheres to close dimensional tolerances.

Both HPV and CF30 are highly stable both during and post-machining. While special tools are needed to handle the material, tolerances of as low as 10 microns can be achieved on the machined parts. Further, the low coefficients of expansion allow for parts that are machined in one part of the world to travel elsewhere with no loss of dimensional integrity due to changing climates and environments.

Conclusion

While CF30 is clearly the winner on pure strength, HPV forms a decent middle ground between PEEK and CF30 and is an excellent choice for bearing applications. While it has traditionally been an expensive grade, in-house blending techniques have allowed for significant cost optimisations, allowing the price to rest only slightly above that of unfilled PEEK.

Whatever the requirement, it is evident that any application where strength is a key criteria would benefit from the addition of carbon to PEEK.


Read More

1. PEEK Components and Bearings - Durable, lightweight, and dependable

2. PEEK Seals - Numerous Applications, Many Choices

3. PTFE vs PEEK - A Comparison of Properties