Swedish steel prize nominee 2023
Front lower control arm
2023 | Gestamp | Spain 6 min read
In an application with challenging requirements, Gestamp is pushing material properties for strength and formability. This vital part of the chassis is crucial to everyday operation as well as to safety performance. Utilizing advanced forming technology, this front lower control arm has an optimized single shell design, made possible by introducing a new material strength level.
Supplier to the world
Gestamp was founded in 1997 as a manufacturer of body car components. Today it is a leading international automotive in the area of BiW, chassis and mechanisms/mechatronics with more than 40,000 employees at over 100 industrial locations and 13 R&D centers all over the world.
A next generation car part
In 2014, Gestamp launched a joint project with its customer Toyota. The objective was to develop a lighter, stiffer and safer front lower control arm. As a part of the car’s suspension system the front lower control arm plays a crucial role for the vehicle by transferring and absorbing loads. It connects the chassis to the front wheel and aligns the movement of the tire relative to the body. What’s more, this new generation front lower control arm needed to be designed to perform flawlessly in case of a frontal offset collision.
Start from scratch
Dr. Mehdi Asadi, Manager Materials Engineering at Gestamp Chassis Germany, and his team of experts saw the project through from start to finish. They knew from the start that they were facing a challenge. Dr Asadi explains:
“The biggest challenge was that CP1000 did not exist for any chassis application in the market. Nor did the design. So we had to start from scratch and modify both the design and the material concepts, resulting in a lot of challenging moments.”
A cold stamping solution
The greatest challenge was related to the extremely high-strength material grade and its suitability for cold stamping, while at the same time developing a geometry with the necessary complexity to provide a section that could deal with critical loads. Gestamp evaluated large number of different material concepts and designs in their extensive test facilities. By employing a new steel grade, a single-shell design, and an innovative stamping technology Dr Asadi and his team were able to come up with a design that delivered the required formability, strength, stiffness and fatigue properties.
“We were able to develop a steel grade and a product that truly delivered what we set out to achieve. And we were able to transfer the knowledge gained during the development stage so that we had the same success at the start of production”, says Dr Asadi.
Ultra high-strength breakthrough
Docol® 1000CP steel is significantly higher in strength than conventional steel grades on the market, without compromising on quality, performance or part geometry. The strength and ductility originate from the complex phase (CP) microstructure. This enables a thinner gauge, making the part up to 30% lighter than its predecessors.
Along with an excellent surface quality and high strength, the steel also performs well for fatigue, a crucial property for this car component. Gestamp and SSAB worked closely on everything from material composition to characterization and, finally, homologation of the material. It was a unique example of cross-company collaboration in the world of steel development.
On the road since 2020
Gestamp’s new generation front lower control arm that increases safety while reducing weight and CO2 emissions was successfully launched into production for the Toyota Yaris in early 2020. The grade is also being considered for future launches in other automotive brands, not least electric vehicles. “This is a case of an ultra high-strength steel grade providing great performance on weight reduction and CO2 reduction, both of which are driving factors for electric vehicles”, says Dr Asadi.
The front lower control arm is only a first step towards all the things that could potentially be implemented with the Docol® 1000CP steel grade.