Rubber as a material has been known to humankind for thousands of years, initially used by the native South Americans and observed by Cortez in the 1520’s and then brought to Europe as a “curiosity” by explorers in the 1750’s. So it might surprise engineers in the Formula 1 industry and beyond that this very traditional substance still has properties that cannot be matched by more “modern” and exotic materials, although of course, starting with the work of Charles Goodyear and Charles Mackintosh in the 1850’s, the chemistry of “rubber” and its oil based synthetic derivatives has dramatically progressed over the years.
It is the case that thermoplastics, which were seen as the future of manufacturing for a long time, are not the universal solution originally envisaged, and thermoset materials such as rubber play an increasingly key role in high technology applications, where extreme chemical resistance, temperature range and physical strength are delivered in a range of compliant, resilient materials. Without these unique combinations of properties, many of the technological advances that we take for granted today would not be possible, typically in the fields of Energy, Aerospace and Transportation, and an extreme example of this is the F1 industry.
The motorsport industry in general, and F1 in particular, is now a significant global industry with millions of dollars spent annually in the pursuit of performance advantage, with development, design and build programmes that really challenge the limits of manufacturing and material science. Yet it is often the case that humble “rubber” proves to be the key element that makes new designs functional and reliable. Everyone knows of course that rubber is the key ingredient of tyres, and motorsport really pushes the boundaries of tyre technology, but in F1 in particular, the advent of very high performance power units that offer spectacular improvements in fuel consumption by integrating various hybrid technologies has also challenged sealing materials and designs.
F1 constantly seeks improvements, and rubbers which can withstand ever higher temperatures, more aggressive chemicals, have controlled levels of stiffness or deliver reduced friction are constantly sought, as all this contributes to passing the ultimate test – is the car faster! Whether this means rubber seals and parts that reduce friction, increase reliability, eliminate vibration or move as required when in the airflow, it is often the rubber element of the design that actually delivers the functionality of the component.
It may surprise you to learn just how many elements of a current F1 car contain a rubber component, and we discuss some of the more unusual applications for rubber in current F1. Of course, despite more than 250 years of development, there is still not one “magic” rubber that does everything, so specifying or developing the right material and construction for the application is key, but clearly the future for rubber as an engineering material is bright.
Wheel Rim Aero Seals
The control of air around and inside wheels, rims and upright assemblies is critical for reliable performance of the brakes and tyres. Controlling the tyre and brake temperatures, either to warm them up or cool them down can make huge differences to lap times and endurance. Shaping and ducting the air flow generated through the hub assembly uses the unique properties of rubber to form compliant seals between mating surfaces, in both static and dynamic applications. The environment can often be quite aggressive, and special grades of rubber are required to provide the necessary performance and service life.
Spark Plug Boots
The energy required to reliably create a controlled spark in the combustion chamber of a new generation F1 power unit is immense, and avoiding insulation breakdown is a priority.
Specially developed high dielectric rubber grades provide the necessary electrical and thermal performance to ensure a high quality spark is consistently generated at just the right time and place by the coil pack.
Moog Valve Hydraulic Pipe Separators
The ever more complex control systems designed to actuate the clutches, gears, differential and steering of a current F1 car require a series of small but strong high pressure hydraulic lines to feed them. Every time these complex pipes pass through a housing or bulkhead, a rubber “grommet” is required in order to protect from chafing and damage to the pipe. The geometry of these parts is often very complex due to the extreme packaging requirements demanded of all the mechanical installations in order not to compromise the aerodynamic performance of the car.
Flexible Air-Wetted Components
Where parts of the car move in relation to the chassis, such as in suspension mounts and steering arm gaiters, rubber has a key role to play. Whilst a conventional road car rubber boot certainly performs its primary role of keeping dirt and grime out of sliding or rotating assemblies, these traditional boots are quite bulky items, and deform in inconvenient ways when stretched. On a current F1 car, rubber gaiters and boots which are in the airflow stream have to remain stable in shape at all times, in order not to compromise or introduce unpredictability into the flow of air around the component they work with. This does require some clever design and material selections, but is a key area where rubber is still the best material to help in the ceaseless search for performance gains.
Anti-Vibration Mounts
Whether traditional rubber and metal bonded components (albeit highly specialised, individual bespoke grommets and bushes or integrally moulded inserts), rubber helps control the enemy of reliability on a modern F1 car: vibration. The damping properties of rubber have a vital role to play in protecting assemblies and sensors from damage by excess vibration, thus allowing long term optimum reliability and performance. The design for any given mount and the material it is made of will depend on the environment it has to operate in, with extremes of temperature requiring high specification synthetic rubbers, or repeated impact perhaps finding other rubber materials to be more suitable. Damaging vibration harmonics can be changed unexpectedly by things apparently unrelated such as a change of camshaft profile, or ECU mapping. Under these circumstances, anti-vibration mounts that used to be entirely satisfactory can suddenly start to fail due to the changed harmonics, requiring another round of R&D to be done in order to address the new environment.
Steering Wheel Inserts
We all know that the contact the driver has with the ground is through the rubber tyres, but often the first contact the driver has with the car is with rubber grips on the steering “wheel”. This is where design and engineering get put to one side as individual driver ergonomic preferences take over; highly personalised solutions are often required. Each driver will have a different preference for the shape and hardness of the coating they are using, in order to give them that critical feel. The rubber may also be covered with other natural or synthetic materials to provide that final, perfect feel that allows the driver to fully express his talent behind the wheel without distraction.
Powertrain System Seals
The highly complex KERS / ERS energy storage systems that collect and discharge electrical energy from the MGU-K and MGU-H many times per lap on a current F1 car need to be very efficiently cooled, and rubber plays a key role in this. Keeping the respective fluids contained in the primary power storage casing requires seals of very specialised materials and designs, and often, very tight tolerances. There is also a secondary containment for safety to prevent release of potentially dangerous materials and components in the event of a crash, and this also requires seals to complete the enclosure. Of course, the power cell unit also contains more than its fair share of rubber grommets, anti-vibration mounts and cable seals. Other parts of the powertrain such as the turbo of the MGU-H and the motor generator of the MGU-K also present their own sealing problems, with some fairly extreme environments.
Radiator Duct Seals
Controlling airflow around and inside a modern F1 car is critical; too much cooling costs extra drag and loss of speed, too little costs reliability and engine performance, yet it is often a quite mundane piece of sponge or solid rubber that solves the problem of how to seal up the various small gaps between the highly sculpted bodywork and radiator systems on the car. Given the extreme aerodynamic shapes and the tight packaging of components on a modern F1 car the shapes of these “boring gaskets” can be quite interesting, and they do perform a vital service in delivering the full performance of the car.
Driveshaft Boots
We all know what a road car one looks like, and until a few years ago, F1 components looked quite similar, as did Boots in other racing applications requiring all wheel drive or control. However, once again the ever present drive for aerodynamic efficiency has dictated that they have become almost unrecognisable compared to their road car cousins, with the lowest possible interference with the airflow past the gearbox and driveline being continuously sought. The closer the gearbox “Boot” and the associated driveshaft bearings can sit to the centreline of the car, the better the airflow can be around the rear of the car, reducing drag and optimising the amount and predictability of the downforce generated by the car. The performance gains in this area when considering the design of a “boring” piece of rubber can be quite significant in the overall solution.
Low Friction Seals
Although rubber has quite a high coefficient of friction in its own right, there are ways to modify its characteristics to have the best of both worlds. Rubber can be specially compounded with low friction additives to reduce drag, or it can be bonded to other materials such as PTFE so that the sealing contact surface is low friction, but is surrounded and energised by rubber. It is also possible to fluorinate the surface layer of a rubber part and modify the surface molecular structure to give a much lower level of friction while retaining the original properties of the part. All these methods come into play when making that “boring” rubber part deliver a key element in enhanced performance by reducing friction, wear, or increasing the service life of components. Although the vulcanisation process for natural rubber was discovered in the 1850’s, and synthetic rubbers were first developed in the 1930’s, there are constant developments in rubber technology, and novel combinations of properties are being driven by the development of new solutions such as nano technology and graphene applications.
This article was contributed by Martin’s Rubber Company – www.martins-rubber.co.uk
