Hot Stamping Becomes Press Hardening Process of Choice

The demand for resilient components that are able to comply with stricter safety regulations while upholding all Corporate Average Fuel Economy (CAFE) standards for lower emissions have pushed the boundaries of manufacturing processes. One of the most innovative processes in the industry, hot stamping, creates ultra-high quality steel components that have the needed structural performance and lightweight qualities. The process involves heating steel to temperatures of 900°C, at which point it becomes malleable, can be formed, and then rapidly cooled in specially designed dies, converting the material into high strength steel. Forming complex shapes far more efficiently than any other traditional stamping methods, it is suitable for automotive components such as body pillars, rockers, roof rails, bumpers, and door intrusion beams. This technology creates relatively complex parts in a single step and, as a result, multi-component assembly lines can be redesigned, eliminating downstream processes like welding. In order to increase safety performance, companies used to weld together heavier and thicker parts in more than one process using methods like cold stamping. In many cases, hot stamping eliminates the need for these additional parts. Hot stamping’s other significant advantage is that it resolves problems with springback and warping, a common problem when forming high strength steel through other processes.

Being one of the most advanced lightweight solutions for the car body structure, hot stamping has been swiftly adopted by metal component suppliers. Gestamp, as the largest global supplier of press hardening parts, traces its roots to cold stamping of small parts, but through an ongoing commitment to incorporate new technologies into its manufacturing processes, it has now become a company that uses multiple technologies, one of which is hot stamping. Commercial Director Luis Jaime González explains that as worldwide pioneers of this process, Gestamp has now begun developing this technology in Mexico. As more highly complex manufacturing systems are put in place in the automotive industry, one challenge that arises is the sourcing of the right raw materials. One of the limitations of hot stamping is that it cannot be applied to galvanized or pre-painted steel, only boron materials can be hot stamped. This is due to the element’s properties that give the material the capacity to change from regular to martensitic when cooled. Boron steel costs more than low-carbon materials and González admits that “with highly complex processes, we require high strength steel but it is complicated to source this kind of steel in Mexico.” Gestamp uses Gonvarry Steel Services, a company that imports steel from Europe, US, and South Korea. “The support of its service centers is beneficial because it reduces lead times for obtaining materials from overseas and increases cost savings in logistics and customs,” says González. The rising demand for high strength steel is however spurring the creation of local steel mills, and through a joint venture with Tenigal, Gestamp hopes to source locally in the future. González admits that despite the fact that Tenigal has already begun developing steel in Mexico, a lot of potential customers are still reserved about using the mill. González predicts that “in a couple of years, Tenigal will be able to manufacture high strength steel that will be approved for use by the OEMs.” Furthermore, he anticipates that local steel mills will make Mexico more productive and competitive, since this high quality in-demand steel will be produced in the country.

To ensure success in a highly competitive industry, automotive suppliers dedicated to metal components must increase their technological competencies and have a varied technological portfolio. “Gestamp basically offers the same products as competitors but we apply different technologies that are adapted to the needs of customers,” says González. “Despite its benefits, not all OEMs are convinced by hot stamping. There is a misguided belief that the heavier and more solid the component, the safer it will be.” With four manufacturing plants, Gestamp has opted for a diversification of technology rather than of products. “The business model is to continue expanding but at the same time keeping the technology and the steel product specialization intact,” says González. Having flexible manufacturing techniques means that if an OEM requires a certain type of technology it can be swiftly incorporated into the operational processes.

Despite the reservations some OEMs may have with regard to hot stamping, González predicts it will be adopted by all of them. “It has been fully adopted by European manufacturers like Volkswagen, BMW, and MercedesBenz, and US manufacturers such as GM and Ford are also starting to use it. This process will dominate other technologies but one of the challenges of transferring this to Mexico is that it requires highly qualified technicians.” To remove this barrier, Gestamp has begun sending workers for training at its US research center for them to bring the knowhow back to Mexico.