AUTOMOTIVE

Specialist Polyimide Polymers

Solutions for Critical and Demanding Applications

Delivering exceptional wear resistance, long part life and high durability into harsh conditions and high-pressure systems in the automotive industry

eAxle

eAxles can be characterised by high PV (pressure-velocity) conditions, often oil-free in situations where components may be axially loaded in opposing directions in quick succession. This is as a result of the axle switching from providing tractive power to regeneration in response to driver input. Such conditions tend to favour low friction, low wear thrust washers, rather than needle thrust bearings. If lubricants can be eliminated while maintaining low Noise, Vibration and Harshness (NVH), this is a decided advantage. Removal of lubricant can lead to higher temperatures on the sliding surfaces, which selected materials must be compatible with. The automotive industry always appreciates weight reduction, although in EVs, this is particularly valuable.

Ducoya exhibits low friction and high wear resistance even in demanding PV conditions of up to 14MPa.m/s unlubricated or 54MPa.m/s in mixed lubrication conditions. Additionally, Ducoya has excellent damping, minimising NVH while having high enough modulus and low friction to minimise parasitic losses.

Ducoya is relatively low density, allowing weight saving and is high temperature capable up to 400°C in a suitable chemical environment, exceeding the upper thermal limit of most lubricants. The simplicity of the humble thrust washer means rapidly changing load conditions are not troublesome.

Differential components including spherical washers can also be exposed to harsh conditions, as well as high compressive and shearing loads. Economics often precludes the best countersurfaces for wear in differential systems. Ducoya can be moulded to include anti-rotation features into tribological components avoiding wear against poor countersurfaces.

If you would like to learn more about the unique characteristics of Ducoya and its uses in the automotive industry, please see our applications guide.

Battery

Many lithium battery (LIB) and sodium battery (NIB) chemistries such as LFP (Lithium Ferro Phosphate), LMC (Lithium Manganese Cobalt) and NFO (Sodium Ferrous Oxide) require effective, long-lived and potentially high temperature sealing. Low temperature operation at -40°C is also demanded across the automotive industry.

Cell seals should survive a high impact in the event of an accident and mitigate thermal runaway within the battery pack.

In response to consumer demands, seals must also perform efficiently over the 14-year life planned in the latest battery developments, helping address concerns over EV longevity and sustainability.

Excellent electrical insulation of componentry is mandatory to prevent short circuits or parasitic current drain. This level of insulation must be maintained over the wide operating temperature range. Naturally, insulation must also be maintained over the same 14-year life mentioned above while power and energy densities also increase. The latest standard (IEC PAS 63454:2022) calls for connectors capable of 1500V to allow charging at up to 1.2MW as discussed further on this page.
Much has been written about thermal runaway of lithium ion batteries. Ideal cell and battery case materials should resist high temperatures as defined in test method UL 2596.

Ducoya G001 has high dielectric strength, exceeding 25kV/mm over the temperature range -40°C to 300°C. Ducoya also has volume resistivity of 1016 Ω and surface resistivity of 1016 Ω at room temperature.

Ducoya delivers exceptional elongation which helps sealing as well as toughness and impact resistance unmatched by alternative polyimides, including the market leader.

While a thermal runaway is undesirable, with appropriate design, Ducoya can survive thermal excursions exceeding 600°C for 10 minutes or more, providing valuable time to escape for the vehicle should this become necessary.

In the event of fire, Ducoya is non-flammable in air as can be confirmed by UL 94 V-0 and 5VA testing. Ducoya is non-halogenated and decomposes without producing excessive smoke or toxins.

Note: decomposition in a shortage of oxygen may result in formation of carbon monoxide (CO).

Electrical connectors for EVs must be capable of surviving considerable potential abuse while protecting users from the high voltages, high power density and potentially high temperatures involved in the latest charging standards due to joule heating. As an outside installation, connectors must also survive inclement weather including very low temperatures in northerly latitudes and high UV exposure in equatorial regions.

For public charging stations, especially in high use locations delivering the latest high-power charging standards, could perhaps see 100 connection and disconnection events each day. Such chargers therefore need to be wear resistant, retaining secure electrical connections while excluding water and other contaminants.

Ducoya is highly durable, having excellent impact resistance and high strength. Appropriate designs can be capable of surviving a drive-over event easily, even by a heavy vehicle. Ducoya is also relatively low density, giving a high strength to weight ratio which helps keep the weight of the connector manageable for most users.

Ducoya G001 can form exceptional sealing, excluding water and other contaminants from the electrical connection. The ability to form complex shapes with Ducoya, coupled with high elongation and low friction means simple, reliable connectivity with low insertion forces. Wear resistance comes as standard, enabling a long life, even on highly used public chargers.

Ducoya has high electrical resistance over a wide temperature range and is not substantially altered over the range of temperatures likely to be encountered from the arctic circle to middle-eastern deserts.

Joule heating can increase the temperature of the conductor proportional to the square of the current being delivered. As an excellent thermal insulator, Ducoya can insulate external surfaces from any high temperatures that may result from high power operation. In fact, Ducoya can operate at more than 300°C continuously in air.

While it is difficult to establish the long-term weatherability of new materials, similar molecules have demonstrated excellent behaviour in both high UV and adverse climactic conditions. Ducoya does not have the absorbent peaks in UV that can be exhibited by other high-performance plastics.

If you would like to learn more about the unique characteristics of Ducoya and its uses in the automotive industry, please see our applications guide.

Power Train

Automatic transmissions are increasingly found in commercial and passenger vehicles for both on-road and off-road use. The growth in hybrid and PHEV vehicles is also driving automatic transmission adoption higher. Some of the latest high performance BEVs are also beginning to use automatic transmissions.

Automatic transmissions are most frequently hydraulically actuated although electrical actuation is possible and dominant in BEVs. Hydraulic actuation relies on effective dynamic sealing to engage and disengage clutches, brakes and other features within epicyclic arrangements, while dual clutch and parallel shaft arrangements additionally require shift fork actuation.

It may be necessary to separate counter-rotating shafts with bushes as well as absorb the axial loads generated by helical cut gears in evermore silent transmissions. Complex transmissions involving multiple epicyclic stages may need to have tolerance stacks accommodated.

Where individual planet carriers and their gears have been designed with traditional yellow metal thrust washers, it is desirable that replacement components also occupy minimal axial dimensions as small as 0.5mm. This is in addition to carrying axial loads at high PV values when engaged.

Materials need to be compatible with automatic transmission fluids including corrosion inhibitors. Should lubrication be restricted or lost, continued safe operation of the vehicle without damage is greatly beneficial.

On-road and off-road commercial vehicles see particularly arduous use, running up to 8000 hours and perhaps longer between service intervals. Operators demand long lives to obtain favourable return on investment.

Ducoya can provide excellent dynamic sealing at high PV values, minimising hydraulic losses while providing very long service life and the ability to survive inhibited flow or absent lubrication without damaging adjacent metallic components.

Washers made from Ducoya can easily accommodate tolerance stacks from a single moulding tool due to the manufacturing process. This same process also allows a wide range of thicknesses from 0.5mm upwards. However, because of the high strength of Ducoya, it is not generally necessary to have thicknesses greater than 1mm. Ducoya can be over-moulded with inexpensive materials should it be necessary to fill in space provided for traditional materials, such as yellow and white metals.

Washers made from Ducoya have the additional benefit of being able to absorb limited quantities of burrs and other metallic debris that may be circulating in the transmission lubricant. Such troublesome metallics embed within the Ducoya and no longer damage adjacent wear surfaces.

Electrically actuated automatic transmissions require durable components with the excellent electrical insulation properties of Ducoya. Multiple components can be integrated into a single part, taking further advantage of Ducoya’s low wear and low friction properties.

Continuously Variable Transmissions (CVTs) are a popular choice in light vehicles such as mopeds and in passenger cars in some geographies. Theoretically, CVTs deliver seamless drive ratio changes and continuous power delivery in a single, simple lightweight transmission. Careful design of a CVT allows it to be optimised for maximum power delivery or best fuel efficiency for all load conditions.

There are two main types of CVTs; those based on a driven belt and variator pair and those based on semi-sliding contact between two rotating surfaces at variable diameters. Both of these place harsh demands on wear and friction components.

Considering the belt and variator layout; the rollers (also known as sliders) in a CVT have to slide in and out on the drive side variator as well as engaging with the belt. Both conditions can create high PV values while low friction is desired to allow a rapid response to throttle inputs.

The weight of these rollers is also important in determining how quickly the driving ratio changes in response to variations in throttle input. Light rollers giving a gentler response, as centrifugal forces are lower and vice versa for heavy rollers. While it is usually a simple matter to add weight, being able to start with light rollers allows for a wider range of responses from the transmission. Of course, finding light, strong materials that also have great wear resistance is not so easy. This search is compounded by the fact that a common application of the belt and variator layout is found in low cost small scooters and mopeds, where economical manufacture is essential for commercial success.

The driven end of the belt and variator arrangement is typically spring energised. Drive is then taken through a centrifugal clutch which is another demanding environment. Here again, low inertia is desirable to allow a rapid response to throttle input; while a high friction contact is needed to achieve good drive with minimal parasitic losses.

Rotating surface drives, such as toroidal designs create high PV conditions on components used to actuate the variable ratio contact.

While there are many variations in the above layout the need to remove lubricant from this type of transmission is common to nearly all designs. This is to reduce or remove any slippage between the driven surfaces.

This type of CVT is more common in heavier vehicles and as such the loads and resultant forces can be large. A high strength material is needed for successful operation with good longevity. Lastly, to minimise parasitic losses and avoid excess heat generation wear components also need to have low friction. This type of CVT transmission is generally heavier than belt and variator arrangements, but materials that are low density and therefore reduce weight are always appreciated in mobile applications.

In belt and variator arrangements, Ducoya’s low density results in low weight components. This is coupled with high strength to allow good transmission of torque. Longevity is provided by Ducoya’s excellent wear resistance even under high PV conditions. A low coefficient of friction allows quick responses to changing throttle inputs and reduces parasitic losses.

In the final drive centrifugal clutch, a light weight, high strength, high wear resistance yet high friction material is needed for the friction surfaces. As a dry clutch, lubricants are excluded by definition. Ducoya G001 meets these requirements effectively, having high strength weight ratio, low density, good wear resistance and appropriate friction.

Harsh conditions are also a feature of rotating surface designs which vary the contact diameters. Actuation bushes are exposed to high loads and high PV conditions. Low friction is also required to minimise parasitic losses. The chosen material must exhibit durability and wear resistance to provide sufficient longevity to meet consumer requirements. Ducoya can survive unlubricated PV conditions of 14MPa.m/s continuously and has a low coefficient of friction, even when running dry. The high strength, excellent toughness and low weight of Ducoya G021 provides the required durability.

This type of transmission can also generate significant amounts of heat through the partially sliding contacts. Ducoya can operate continuously at up to 400°C in a favourable chemical environment.

The quest to extract maximum efficiency from the internal combustion engine continues. One established technique to increase efficiency and performance is the use of variable valve timing (VVT). This system adjusts timing for inlet and exhaust valves. VVT systems are exposed to many high frequency movements as load conditions and throttle inputs vary. Mechanical, hydraulic and electrical systems all exist but all place harsh wear conditions on the VVT system. Hydraulic systems also need to effectively seal the hydraulic fluid used, most commonly engine oil. VVTs are often located at the top of the engine adjoining the cam shafts. This location can see a temperature range from -40°C up to 175°C in hard driving conditions.

Minimising the inertia of the system to enable rapid adjustment to changing conditions is desirable. Low density materials with good strength are therefore preferred.

As an outstanding wear and friction material, Ducoya performs admirably in high frequency motions, delivering long wear life. Ducoya also has a low coefficient of friction and a high strength to weight ratio. This minimises actuation losses and reduces inertia for a rapid response.

While the temperature range -40°C to 175°C may challenge some materials, Ducoya is comfortable over the much wider range of -273°C up to 400°C in a favourable chemical environment.

Ducoya is compatible with a very wide range of synthetic and mineral lubricants and hydraulic fluids. Its high unlubricated PV capability means that it can also be useful in mechanical and electrically actuated systems.

While advances in tooth belt capabilities have proven popular in some engine designs, traditional chains are still appreciated for their long services lives and reliability. To deliver this performance with minimal noise, chain guides and tensioners are required.

Chain guides and tensioners must resist wear as the chain passes over or around these components. They should be light weight and low friction to minimise parasitic losses. Being very close to the combustion chamber means these components can see temperatures from -40°C in a cold start situation to 150°C in hard driving conditions.

Cam chains may not have complete lubrication. Selected materials must be able to perform in these conditions.

As an outstanding wear and friction material, Ducoya performs in boundary or mixed lubrication conditions and even dry running. Ducoya has a consistent and low coefficient of friction, reducing parasitic losses in all conditions.

Ducoya is also compatible with a very wide range of synthetic and mineral lubricants and hydraulic fluids.

Ducoya has a high strength to weight ratio so does not add a significant burden of additional weight while performing this function.

Ducoya is comfortable over a wide temperature range of -273°C up to 400°C in a favourable chemical environment.

The implementation of advanced turbocharger designs has greatly assisted reduction in the size and weight of modern engines while also increasing maximum power and torque capabilities. This has been achieved at the same time as removing turbo-lag and occasional unreliability of earlier designs.

These advances come with the complication of high temperatures, acidic exhaust gases and high rotational speeds. Required features such as waste gates and the possible switching between two different sizes of impeller all need actuation in this harsh environment. External components cannot easily be efficiently lubricated in these locations and at high temperatures.

As well as dealing with hot exhaust gas, turbochargers compress incoming air and recirculated exhaust gas for introduction into the combustion chambers. This act of compressing generates further heat in addition to heat conducted from the hot, driven side of the turbocharger.

Bushes and seals within the turbocharger while usually lubricated can see rotational speeds up to 150,000 rpm. Effective sealing of the lubricants is of course required. While white metal bushes can perform at such high speeds, it is desirable to remove the lead that such alloys generally contain.

PMDA-ODA polyimides, such as Ducoya, have been used in applications up to 300,000 rpm with boundary lubrication. Ducoya also allows continuous operation at the high temperatures found on the cold side of the turbocharger.

As a wear resistant material, Ducoya enables reliable operation over a long service life, even in challenging environments such as turbochargers.

As actuation components are generally unlubricated and located very close to hot gas streams, the combination of high wear resistance, low friction without lubricant and high temperature capability makes Ducoya an ideal choice for such applications. Ducoya’s performance is further enhanced by its light weight and high strength, facilitating low inertia and rapid actuation of turbocharger systems.

Some sophisticated turbochargers employ variable vanes rather than different size impellers. Ducoya can usefully facilitate this function which is closely related to conditions in modern gas turbine engines; more information available in the aerospace section of our applications.

Exhaust gas recirculation (EGR) is a feature of modern engines, reducing harmful unburned hydrocarbons and oxides of nitrogen (NOx). However, such systems are exposed to high temperature, acidic exhaust gases. EGR valves must both seal and actuate to open with no lubricants, minimal force and be tolerant of small particulates (<PM20).

The high temperature capabilities of Ducoya which can be up to 400°C in continuous operation are useful in these circumstances. Ducoya also has exceptional chemical resistance including to the low pH acids (<2pH) found in exhaust gas streams.

Ducoya is soft but strong, an ideal choice for a sealing material where particulates can be accommodated in the high elongation, moderate modulus sealing envelope of Ducoya. Having low, dry friction and excellent wear resistance is an added feature delivered by Ducoya. Having a high strength to weight ratio and having low friction allows minimisation of the size and weight of the EGR actuation system.

As exhaust systems can be exposed to ground and foreign body impacts, it is reassuring to know that Ducoya also has remarkable toughness and durability.

Automotive air conditioning is a much-demanded feature of modern vehicles. However, it stands at a crossroads; traditional refrigerants such as R134A are long banned due to their high global warming potential (GWP). Modern, non-flammable replacements, HFOs, while having low GWP and low flammability, are chemically aggressive and not compatible with some sealing systems. As PFAS-containing chemicals, they may also be removed from availability in Europe in the foreseeable future for new type approved vehicles.

HFOs can also reach very high and very low temperatures during normal operation, either within air conditioning systems or the modern heat pumps, which are increasingly found on BEVs.

Operation of air conditioning systems and heat pumps requires compression and expansion of the refrigerant to induce the required phase change. The compressor stage may involve sliding and sealing componentry.

An interesting innovation in heat pump and air conditioning design from the end of the twentieth century is the use of transcritical carbon dioxide, R744. This delivers many advantages, removing PFAS, non-flammability and neutral GWP. However, in the supercritical state, carbon dioxide as a refrigerant must be compressed to very high pressures to deliver good efficiency. While in this supercritical state, carbon dioxide is also a very effective solvent, but may not be compatible with all materials.

Compressing carbon dioxide to such high pressures as 100bar for efficient operation also results in high temperatures. Sealing and sliding materials in the compressor must be compatible with these high pressure, high temperature conditions while providing efficient sealing as well as low wear and low friction.

PFAS is not added to or involved in the manufacture of Ducoya. Ducoya is also compatible with all tested modern refrigerants, such as HFOs and R744 (supercritical carbon dioxide).

Ducoya can comfortably perform as a low wear, low friction material in the high temperatures and high pressures that can be found in modern air conditioning systems. Its soft but strong character gives efficient sealing over a wide temperature range.

Lastly, Ducoya is non-flammable in air, as can be confirmed by UL 94 V-0 and 5VA testing.

If you are interested in more information on the interesting features of Ducoya and its use in this application, see our applications guide.

Electric Motors

Recent decades have seen an explosion in the use of electric motors within automotive applications; everything from seats, windows, steering columns, sunroofs, tailgates (boot/trunk), and wing mirrors makes use of electric motors.

These now ubiquitous items have a small yet vital component to absorb the axial forces resulting from normal operation of these motors. This is the humble thrust plug.

Thrust plugs must be strong in compression, resist wear, have low friction to avoid reducing efficiency and operate as close to silently as possible.

All of this while fitting into the tiny space afforded by the principal motor shaft. Electric motor manufacturers face a fiercely competitive environment; production costs must be closely controlled.

Ducoya, having high compressive strength and low wear, low friction sliding performance, is ideal for this application in its confined space. Ducoya also efficiently damps vibrations and slides without squeaking or other significant noise generation against a suitable countersurfaces.

Multi-cavity production of these components from the economically attractive base that Ducoya provides is advantageous in this competitive segment.

If you would like to learn more about the unique characteristics of Ducoya and its uses in the automotive industry, please see our applications guide.

Chassis

High-performance passenger cars and many commercial vehicles feature electrically-based brake pad wear sensors. These small yet vital components are a critical safety feature of modern braking systems.

Brake pad wear sensors are embedded into the pads used on disc brake systems. They therefore need to survive the very high temperatures that can result in stopping high speed or high weight vehicles.

A soft but strong character with good elongation and low friction greatly facilitates assembly of the sensor into the pad. As the system is electrically-based, part of the sensor needs to be an electrical insulator. This insulation is removed when the brake pad is approaching the end of its life, enabling a circuit to be formed, illuminating a dashboard warning light.

Ducoya is an excellent electrical insulator and has the required soft but strong characteristic with exceptional elongation.

Visitors to this website may already be familiar with the high temperature capabilities of Ducoya. In this application, Ducoya can survive high temperatures resulting from braking, which may be over 600°C.

Automotive OEMs demand tight cost control from their suppliers. The favourable economic foundations provided by Ducoya will be appealing for its use as brake pad wear sensor components.

Modern diesel engines do not generally use vacuum induction and EVs do not include vacuum induction as a fundamental part of their design. Modern braking systems often require vacuum assistance when engine braking or regeneration is not sufficient to retard the vehicle. Sometimes, vacuum is also used on other auxiliary systems.

As vacuum is not provided by an internal combustion engine (ICE), a vacuum pump is generally added, either electrically-driven or from the cam shaft or auxiliary drive arrangement.

Such vacuum pumps can be lubricated or dry running. Each implementation brings advantages and disadvantages; here we shall focus on the dry-running variant.

To reduce weight, vacuum pumps are typically made from aluminium, with 2 to 4 rotating vanes. These vanes must provide long wear life, effective sealing and not cause excessive wear to the aluminium countersurface. Dry sliding friction also generates heat which the assembly must be able to endure without reducing service life.

As a very high-volume component, good cost control and a favourable cost performance ratio are essential for success in today’s competitive automotive environment.

Even for Ducoya and its renowned wear resistance and low friction, an aluminium countersurface introduces additional complexity. The Ducoya will consistently show low wear and low friction. On the contrary, the aluminium may exhibit high wear if the tribological pairing is not optimised. Engineers at Duvelco have identified a particular synthetic graphite family that can deliver exceptional performance against some aluminium grades.

Ducoya can easily survive the modest temperatures generated through dry sliding. The conformal surface provided by Ducoya gives excellent sealing over a long service life.

Favourable economics are at the heart of Duvelco’s polyimide manufacturing process seen here as Ducoya G series.

If you find dry-running performance against aluminium interesting, please contact us, so that we can discuss your application in more detail.

Binary and tertiary ABS control valve systems have to seal high pressure brake fluid at low and elevated temperatures. If the system is called into operation, which is typically in an emergency, the valves need to open and close very rapidly, as demanded by the modulator.

Leakage in this application can result in loss of braking efficiency on the affected wheel which could result in a dangerous lack of stability.

Some ABS systems also contribute to dynamic stability control (DSC) systems on modern vehicles.

Ducoya is compatible with commonly used brake fluids, delivers excellent and reliable sealing even when actuated very frequently. Ducoya can also safely accommodate brake fluid reaching high temperatures. Lastly, Ducoya has high strength and great elastic recovery, making it a great choice for high pressure hydraulic braking systems.

Steering and suspension components can benefit from Ducoya in circumstances where weight saving, exceptional durability and long unmaintained service life is required. This can include off-road vehicles, racing cars (racecar), military vehicles and other specialised applications.

Particular features of Ducoya that can be interesting for such environments include excellent behaviour in lubricated and unlubricated wear and friction. High strength to weight ratio, excellent and enduring static and dynamic sealing even against imperfect surfaces while delivering these characteristics over a very wide temperature range.

If you have an exceptional or unusually demanding automotive application that you need to resolve in a long-lived but economical way, please contact us to discuss this further.

If you would like to learn more about the unique characteristics of Ducoya and its uses in the automotive industry, please see our applications guide.

Automotive Applications

Automotive customers for innovative manufacturing solutions, Duvelco® polyimide materials help to solve specialised issues like weight reduction, cost reduction, and improved reliability. Our scientists collaborate with experts from the automotive industry to identify the requirements and qualities required to constantly improve component quality to enhance vehicle reliability and performance. The Ducoya® range of powders and direct formed parts are designed to survive in arduous conditions, be this high pressure rotating hydraulic seals, self-lubricating thrust washers or high-performance polymer bushes and bearings.