Thermoplastic composites have long been used in automotive interiors, but the past ten years have seen the material make inroads into other areas of the vehicle, such as the engine bay, exterior and body-in-white. Increased strength and temperature resistance has given OEMs a wealth of new lightweighting possibilities. Furthermore, the ability to cut, stamp and mould the new materials without the lengthy curing process required by thermoset composites allows for far shorter cycle times more suited to mass production.
Speaking to Automotive World, Patrick Cazuc, Global Marketing Automotive Director at DuPont Performance Materials, certainly isn’t lacking in confidence when it comes to plastic’s prospects: “There are some exceptions, the biggest of which is the engine block, but I think that virtually everything else in a car could be done with plastic.”
Make no mistake, he says – vehicle manufacturers face a serious challenge. By 2021, new cars in Europe will be expected to emit no more than 95g/km of CO2, representing a reduction of 40% compared with the 2007 fleet average of 158.7g/km. Meanwhile, CAFE regulations in the US will require light vehicles to achieve 54.5mpg by 2025.
There are some exceptions, the biggest of which is the engine block, but I think that virtually everything else in a car could be done with plastic
Though the two approaches are slightly different, Cazuc says that both converge on the same concern, and that global standards for both gasoline and diesel have been established that other nations will imitate. India, for example, will enforce regulations compliant with Euro 6 from 2020 onwards, bringing down NOx emissions in the country by 82%. The jump from the current Bharat Stage IV regulations, which lag behind European norms by around ten years, will see the country effectively leapfrog Euro 5 legislation.
“A global standard is emerging,” says Cazuc. “As such, our approach is to make products that meet that global standard available in all regions of the world, with local production. Some regions might have a slightly different emphasis, but fundamentally they all have the same objective, which is to reduce fuel consumption and CO2 emissions.”
OEMs need to take several factors into account when optimising fuel consumption, such as engine efficiency and tyre rolling resistance. But for Cazuc, lightweighting remains the biggest leverage available to vehicle manufacturers. Typically, he says, a 110kg (242lbs) weight reduction can reduce CO2 output by 10g/km. By comparison, a 10% improvement on rolling resistance is likely to yield only a 2g reduction.
In addition, lightweighting can create a virtuous circle – the lighter a vehicle, he says, the less fuel it consumes. This in turn means OEMs can downsize the engine, resulting in a further weight reduction on the vehicle. Unsurprisingly, the challenge lies in keeping costs low and attractive for OEMs.
Plastic’s fantastic
Like many material suppliers, DuPont looks to become involved in the vehicle design process at as early a stage as possible. Maximum cost efficiency, says Cazuc, requires a three-way discussion between DuPont, the OEM and the relevant Tier 1 or part supplier. This is the essence of what Cazuc dubs ‘smart design’, in which engineers design parts with plastics in mind from the outset.
Lightweighting can create a virtuous circle – the lighter a vehicle, the less fuel it consumes. This in turn means OEMs can downsize the engine, resulting in a further weight reduction on the vehicle
“Key for us are the material specialists at the OEMs, because they’re familiar with polymers and what they can do,” he explains. “If you look at the performance data for our materials, there are differences that mean you need to design for plastic. You can’t just change out metal for plastic and hope that does the trick. At best, the result is sub-optimal. At worst, it’s a failure.”
What’s important, he continues, is that DuPont works on ‘socialising’ plastics in an industry where metal is not only incumbent, but is improving in terms of weight and durability all the time. “Steel isn’t getting idle,” he says. “Steel suppliers are improving the performance of their material by lowering thickness, and use of high-strength steel is pretty common on specific vehicle parts where needed.” Steel giants like ArcelorMittal are developing steel sheets that can achieve strengths of 2500 MPa; at the other end of the scale, smaller specialist companies are developing unique solutions, such as NanoSteel’s nano-structured steel, which can achieve high strengths without compromising on ductility.
DuPont runs training initiatives that help designers at OEMs and Tier 1s to understand plastic’s potential. Compared with the century of experience OEMs have with metals, says Cazuc, plastic is still a ‘toddler’, and suppliers like DuPont have to provide manufacturers with as much service and support as they can offer. “Data availability on metals is pretty commoditised, but plastic remains relatively niche,” he says. “All OEMs will have specialists, but a part of our role involves teaching engineers how to design for plastic in order to ensure the optimal solution can be achieved.”
The last 20 years have brought success, adds Cazuc, who remembers a time when the idea of building a plastic air intake manifold would prompt ridicule. “Everybody would say, ‘no, you can’t do that,’ but now we see it as standard. Now nobody in their right mind would design a metal air intake manifold.”
Socialising plastics is also important to help OEMs adopt and install the technologies needed in plants for thermoplastic applications. When developing solutions, says Cazuc, suppliers like DuPont have to take account of the availability of machines, and how standardised they appear to the industry. In particular, the replacement of body-in-white parts with plastic is a long term hurdle for OEMs, as this will require expensive investment.
There will always be metal parts in a car, but so far as plastic is concerned, there are clear areas for further penetration
But thermoplastic solutions do have an advantage: “We’re talking about a process which, when described to an OEM, involves taking a sheet, stamping it and over-moulding,” explains Cazuc. “These are steps that the industry can appreciate and relate to because they’re similar in essence to stamping a sheet of metal.”
Virtual workshops
A further tool that Cazuc identifies as key in minimising costs is predictive engineering. Using computer aided design (CAD) and simulation technology, designers can anticipate both the static and, crucially, the dynamic performance of parts prior to their manufacture. This is a process that will only improve over time – all data gathered on qualities such as fibre orientation is fed back into systems, providing a backbone on which calculations can be made.
“This has been one of our key developments over the last few months,” says Cazuc. “Take the example of developing an engine mount on a car. These days, traditional finite element analysis can only offer so much, as it can only look at static loads. We need to go above and beyond to look at dynamic performance, which takes into account factors such as the noise, vibration and harshness of the engine environment, which can affect how the mount is coupled.” In addition, says Cazuc, predictive engineering has allowed for conversion of further engine parts to plastic, such as brackets and fans.
Future combinations
The course for the automotive materials market looks irreversible – tomorrow’s cars will be sophisticated combinations of high-tech alloys and advanced composites. “We can’t talk about the death of metal,” concedes Cazuc. “There are economic barriers that make it difficult for us to work with certain parts, such as the engine block.” This would present major technical challenges, requiring economically unattractive solutions. “It makes more sense to do it with metal, even if it is heavier.” At the heart of any vehicle lightweighting exercise lies the business case, and the question of how much cost can be afforded to reduce the weight of a part. Multi-material solutions will prompt further research from DuPont into the tooling required to bond these materials together, particularly for body-in-white applications – riveting, webbing inserts and gluing will all be explored.
Part of our role involves teaching engineers how to design for plastic in order to ensure the optimal solution can be achieved
“Fundamentally, there will always be metal parts in a car,” he concluded, “but so far as plastic is concerned, there are clear areas for further penetration. We’re already seeing and experiencing this. There are things we do now I would never have dreamed possible when I started my career 30 years ago.”
Looking forward, DuPont fully recognises the electrification of the vehicle as a continuing trend, not least because alternative powertrains will play a role in achieving efficiency targets. Certain principles, such as chassis design, will remain the same regardless of a vehicle’s propulsion type, but both hybrid and pure electric vehicles will bring with them a new field of applications.
“Equipment like cabling, battery supports, battery trays, stacks and separators are typically geared towards our type of materials,” said Cazuc, “so there will be plenty for us to investigate.”
What these investigations uncover will contribute to the overall growth predicted for the global automotive plastics market. An August 2015 report from Grand View Research, a San Francisco-based research and consulting firm, suggested that the automotive plastics market amounted to 8.69 million tonnes in 2014. This will grow at an estimated CAGR of 9.5% between 2015 and 2022, reaching the value of US$53.49bn. Manufacturers may be daunted by Euro 7 and CAFE, but many lightweight solution providers, like DuPont, ultimately stand to benefit from increased demand.
This article is part of an exclusive Automotive World report on lightweighting. Follow this link to download a copy of ‘Special report: Vehicle lightweighting‘
