Author: Lena Barner-Rasmussen
There is a lot to factor in to make cars sustainable. Walki’s reinforced monomaterials for underbody shields and wheel arch liners in cars are suitable for recycling, free of glass fibre and lightweight. Tests show that the lack of glass fibre does not compromise physical performance.
Cars are complicated gadgets, and you want to protect them when driving under different road conditions. That is the task of an underbody shield, the material that covers the bottom side of the car, protecting the engine (and the battery in an electric vehicle) from damage that might occur from the roadside. An underbody shield also enhances the aerodynamics of a vehicle leading to lower fuel consumption and reduced vehicle emissions. While the first underbody shields were made with metal, it was eventually abandoned because of the added weight it gave to cars. Nonwoven materials have been the go-to material, but it must be reinforced with glass fibre to give the needed strength and structural integrity. However, the use of glass fibre comes with health hazards in the production and is also ill fitted for recycling as it’s not an organic material.
“There really wasn’t the perfect technical solution to reinforce the underbody shield without using glass fibre so we started thinking that there should be one”, says Steven Verheul, Automotive and Steel, Category Manager at Walki.
The underbody shield fit for the future should not only be free of glass fibre, recyclable and light, it also needs to be thermoformable and of course meet the requirements of protecting the car.
Scrims, woven materials that are usually made from polyester, came up as an option. Walki’s solution is a combination of polyester-based materials that are chemically bound during an extrusion coating process.
“Testing has showed that simply compressing the different layers is not enough to keep the scrim in the matrix and withstand a severe road test”, says Verheul and refers to the Ford bolt pull through test that Walki has used to test its solutions.
The results from the test of Walki’s material were promising: the strength of the material was significantly increased with the scrim being fully incorporated in the matrix.
Walki has two solutions for underbody shields: one lighter version of 160g and one heavier of 215 g.
“The physical performance is comparable to underbody shields reinforced by glass fibre”, says Verheul.
Walki’s polymer-based materials are thermoformable, making them more flexible both for customers’ production lines but also for getting the right shape for the end uses. These textile-based and correspondingly lightweight underbody shields skins can further be tuned to also absorb noise and therefore simultaneously reduce the interior and exterior noise, i.e. the pass-by noise, of cars. The monomaterials are also suitable for wheel arch liners. Walki’s experience from flame-retardant compositions comes in handy as fire safety is a top priority, especially with the rise of electrical cars with batteries that potentially can overheat.
“The trend is to move away from glass fibre and go towards sustainable materials that are more environmental-friendly and recyclable”, says Verheul.
Walki is well on its way.