The new crossbeam uses polyamide from BASF instead of diecast aluminium
A polyamide from BASF has been used to produce the world’s first plastic transmission crossbeam for use in a rear axle subframe in Mercedes-Benz’ S-Class vehicles.
The crossbeam, developed by BASF in conjunction with ContiTech Vibration Control, is made from the engineering plastic ‘Ultramid A3WG10 CR’, a specialty polyamide that is particularly reinforced and optimised to withstand high mechanical loads.
The switch to polyamide from the previous beam, made from die-cast aluminium, has reportedly enabled a weight saving of 25 percent, better acoustics, excellent mechanical properties and conformity to the latest crash requirements.
“The new rear axle transmission crossbeam is a milestone in the use of polyamides in the chassis. It has the potential to set a new trend in the automotive industry,” said Kai Fruehauf, Head of the ContiTech Vibration Control business unit.
“In order to replace metal with high-performance plastics, it is necessary to make optimum use of the material and adapt it to the particular load situations, as BASF has demonstrated in the development of Ultramid for the transmission crossbeam.”
The plastic load-bearing structural component meets all the requirements for the static and dynamic loads that act on a transmission beam, says BASF. As a central component of the rear axle, it supports part of the torque that is transferred from the engine to the transmission, and bears a constant share of the load of the differential.
The plastic used in the part had to meet certain criteria in order to replace the existing aluminium. BASF says Ultramid A3WG10 CR (CR = crash-resistant), which is 50 percent glass fibre reinforced, shows “optimum strength and rigidity and displays a low tendency to creep under constant loading”. In addition, the material has to withstand high bending torques. The component shows “good NVH performance (NVH= noise, vibration, harshness),” added BASF.
In addition, BASF used its ‘Ultrasim’ simulation tool in the early phase of development of the new crossbeam, which it says ultimately helped define the component geometry at an early stage and reduce the number of prototypes required.