Unravelling Polymers

The Definitive Blog on Polymers by Poly Fluoro Ltd.

The Challenge of Injection Moulded High-Performance Plastics

The high performance plastics space is a wide spectrum of different products, each with properties, characteristics, and processing nuances that could take a lifetime to fully learn. On the one hand, melt-processible plastics – such as Polypropylene, Polyethylene, ABS, and Nylons – form the mainstay in terms of volumes, since these are commonly used in consumer goods and are both cheap and relatively easy to handle. In contrast, non-melt processable polymers – such as PTFE (Teflon) and UHMWPE – are relatively niche in their application and can only be machined into a final component using a ‘stock shape’, such as a rod, sheet, or tube.

Somewhere in between these two extremes are a collection of polymer grades that, while being melt-processable, are still mainly machined, due to certain challenges that not everyone can surmount in the moulding process.

Our journey through the polymer space has seen us delve deep into two such plastics: PEEK and PPS. While both PEEK and PPS are certainly injection mouldable (that is to say, they have a decent enough ‘melt flow’ that would allow them to be injected into a mould to give a final shape), there remain some complications with regards to the processing.

  1. Temperature – both injection moulding PEEK and PPS requires melting at temperatures well above 300°C. This implies that any heating equipment designed for low-temperature plastics, such as Polypropylene (which melts at ~160°C) may struggle to maintain such high temperatures

  2. Equipment – while higher temperatures can be attained using additional or higher kilowatt heaters, the equipment itself often needs to be modified to handle PEEK. Our own experience with compression moulding told us that PEEK reacts to metals in a way that makes handling it in its liquid state very difficult. The screw and barrel of a normal injection moulding press would be unlikely to survive more than a few months with PEEK flowing inside it

Similarly, the mould itself would need to be specially constructed to maintain consistency over the long term

  1. Cost one of the nice things about low-cost polymers is that trials are not expensive. The mould is usually the bulk of the development cost, after which throwing raw materials into the mix until all the kinks are ironed out does not burn any holes in one’s pocket. Polypropylene, for example, is presently selling for ~US$2 per Kg (after a recent spike of over 75%!). In contrast, injection moulding grades of PEEK sell for ~US$100 per Kg, while PPS is a slightly more sedate ~US$25-30 per Kg. In other words, we’re looking at a cost multiplier of 12-50X, meaning each trial becomes expensive to conduct and the financial risk of not getting a part right can be significant.

  2. Properties  compounding the cost issue is the fact that PEEK and PPS are temperamental materials. PPS, for one, tends to crack easily unless we use exactly the right combinations of temperature, pressure, and other fillers, such as glass. PEEK, which is a little better behaved, can still exhibit excessive shrinkage in some areas (leading to tool modifications and more trials), and also prone to internal stresses unless annealed properly.

With so many hurdles to getting it right, there is little doubt that even medium to high volume project requirements prefer to machine these high performance polymers from stock shapes rather than mould them. The risks involved in moulding mean that the upfront development charges do not only include the cost of making the mould but also need to factor in high trial costs, which push the economics back in favour of machining.

However, there will always be parts that cannot be machined; where the dimensional complexities entail that injection moulding is the only way forward. One of the reasons that both PEEK and PPS are so sought after in fields such aerospace, automotive, and chemicals is that there exist few other materials that have both the physical strength, are lightweight, and have the chemical resistance needed to hold their own in any environment. Therefore, when PEEK and PPS are needed, there are no alternatives for an OEM other than to invest in the development of these components. In such a situation, processors that understand the material, invest in the right equipment and are willing to take a chance to develop and learn the behaviour of these polymers stand the best chance to thrive in an industry where injection moulding has devolved into a very commoditised space.

At Poly Fluoro, we have always stayed one step ahead in terms of our understanding and our willingness to explore new high performance polymers. We did this when we put up India’s first paste-extrusion plant for PTFE tubes. We did it again with expanded PTFE, where we remain India’s only manufacturers and where we are even presently developing new variants of ePTFE tapes, tubes, and membranes for specialised applications. The same boldness allows us to expand into PEEK and PPS injection moulding, while our success with our other ventures fills us with the confidence that here too, we will succeed.

Read More

1. Case Study - Development of a 4-axis PEEK Valve

2. Polyphenylene Sulfide (PPS) - A robust polymer with multiple applications

3. The Effectiveness of PEEK Compressor Valve Plates

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 PTFE resin prices 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 polymer prices, 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 polymer 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

Development of a 4-axis PEEK Valve - Case Study

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 PEEK valve 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 development  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