Williams Advanced Engineering has developed a pair of innovative technologies that promise a step-change in the affordability of composite materials. Known as 223 and Racetrak, these technologies offer comparable performance to existing composites solutions, but with a range of additional benefits, and at a cost that brings them within reach of mainstream applications.
These are not simply manufacturing innovations: they are end-to-end, whole-life solutions that address every aspect of the manufacture, use and recycling of carbon fiber reinforced polymer (CFRP) and the way in which its properties can enable new approaches to vehicle design and manufacture.
CFRP is a material of huge promise. Its exceptionally high strength-to-weight ratio, impressive stiffness and excellent fatigue and environmental resistance make it an attractive choice for a wide variety of industries and applications.
This is particularly pertinent to the automotive industry, where lightweighting is seen as one of the primary tools needed to meet increasingly stringent fuel economy and emissions targets, as well as support the range required from electric vehicles. However, the advantages of CFRP extend across many sectors, from railway carriages to wind turbines.
Despite these compelling benefits, and recent process advances from the automotive and aerospace industries, a number of factors have held back the mass adoption of CFRP. Chief among these is cost, with traditional composite production methods involving expensive materials and lengthy process times.
They also incur a relatively high scrap rate (typically around 30%), compounded by the challenges of recovering the carbon from pre-impregnated off-cuts, and of finding value from the material at the end of the product life.
These challenges have seen the application of CRFP largely confined to niche applications. In the automotive sector, for instance, a body-in-white structure produced with traditional composite techniques is typically around 60% lighter than one manufactured in steel, yet around 20 times the cost. This has limited its application to vehicles that are low volume / high cost, or where the vehicle manufacturer subsidizes the process as part of their learning around new technologies.
The innovations from Williams Advanced Engineering aim to address these challenges to unlock the benefits of CFRP.
The heart of the 223 innovation is a radically different (and therefore confidential) process for the integration of woven, dry fiber reinforcement sheet with a separately-prepared resin matrix.
The 223 process was conceived as a cost-effective means of creating three dimensional composite structures from a two-dimensional form. It is suited for box-like geometries, such as battery containers for electric vehicles, or potentially even complete vehicle monocoques.
The name is derived from one of the process’s defining features: while composite components generally have to be laid up in their final geometry, 223 allows the part to be created initially as a two-dimensional component before being folded into a three-dimensional structure.
This lends itself to a wide array of applications. In particular, 223 suits structures that are currently assembled from many separate components, and where access for fitting-out adds time and cost. A good example is an automotive body-in-white, which typically consists of around 300 metal pressings, made with perhaps 600 different tools; a vehicle hood may require four different press operations. Using 223, the number of pressings could be reduced to around 50, all created on a single machine with a significant reduction in the capital expenditure for tooling.
A weight saving of around 25 to 30% could be achievable on a car’s body- in-white, compared to an equivalent aluminium alloy structure. With 223, this could be delivered in higher volumes and at a lower cost than a traditional composite solution. Where less strength is required, further cost savings could be made by specifying lower cost materials, for example glass fibres, while alternative resins can be specified to increase toughness and heat resistance.
Racetrak is a novel process for creating very high strength structural members that link two or more points, such as automotive wishbones or the link arms of aircraft landing gear. The technique draws on a proven design concept, where a continuous loop of unidirectional material—in this case carbon fiber—provides extremely high hoop strength.
This localization of very high embedded strength allows substantial cost reduction which, when combined with high levels of automation, allows an affordable component that is significantly lighter than traditional alternatives.
In the case of a wishbone for an automotive application, the finished part could be around 40% lighter than the equivalent forged aluminum item and up to 60% lighter than steel, making it cost-competitive with a premium aluminum forging.
The Racetrak parts consist of three main components: a core of low cost, non-woven bulk material, a loop of unidirectional carbon fiber and on both sides of this, a protective shell made from die-cut woven fibre sheet. Manufacturing is fully automated, with the unidirectional loop robotically wound to create precise, repeatable tailored fibre placement. This reinforced material preform is then placed dry into a tool, which applies a light shaping pressure to create a removable cartridge.
This is placed into an industrial press, where a vacuum is applied and the resin is injected into the heated mould. Under these conditions, the resin takes approximately 90 seconds to cure. It is then ejected from the machine and a fresh cartridge loaded.
With a cycle time currently at just 120 seconds, a single press using this process can produce more than 500,000 units a year.
Williams Advanced Engineering FW-EVX electric vehicle platform concept. The FW-EVX is a vision of a future electric vehicle platform that integrates a range of new approaches, including Racetrak and 223 , into a single, highly integrated solution that addresses the challenges of effective, affordable electric vehicles.