Frankfurt, June 29, 2016 – Lightweight design is essential for a resource-saving, energy-efficient environment. By 2020, lightweight design around the world is expected to total EUR 140 billion for the transport sector alone, with growth rates of seven to eight percent. With this in mind, VDMA has established the Working Group Hybrid Lightweight Technologies. Mechanical engineers and representatives from user and supplier industries use this platform to exchange information and ideas on opportunities, technologies and materials for lightweight design. VDMA hears from some of the experts of lightweight design in a series of interviews.
Interview with Lothar Gräbener, Director of Sales in the Hydraulics, Sheet Metal Forming and Lightweight Construction division at Schuler Pressen GmbH and member of the Board of the Hybrid Lightweight Technologies working group
When talking about lightweight construction in cars, many people today immediately think of fiber composites. But what about metals?
Lothar Gräbener: Until ten to 15 years ago, vehicle bodies were almost exclusively made from soft deep-drawing steels, and the 200 to 300 components were welded together. But since then, the steel industry has undergone somewhat of a shift towards lightweight construction. For example, the industry has developed hot-stamped high-strength steels in an effort to reduce weight.
How does this reduce weight?
Gräbener: The sheet steel plates are heated to 930 degrees before they are fed to the forming presses. The steel is then allowed to cool to below 400 degrees in the tool. The structural transformation that takes place during this process sets the steel, which almost doubles its strength. This means that the sheet thickness can be reduced accordingly, and the overall weight of the body is lowered significantly.
Can you predict which lightweight construction process will dominate in future?
Gräbener: Various lightweight materials are currently in use. For example, plastics, composites and metallic materials such as hot and cold formed high-strength steels, aluminum and magnesium are all used in modern vehicle construction. Hot-formed high-strength steels have become increasingly popular in automotive construction over the past ten years.
Today, new vehicle models are built with up to 40 percent hot-stamped structural components. This process established itself within a very short period of time, because the material and manufacturing costs are not higher than they are for traditional cold forming, so the ratio between the body weight and static torsional rigidity could be increased significantly. in the model change from Golf III to Golf V, for example, the use of high-strength steels improved this lightweight index by more than 50 percent.
Luxury class automobiles and sports car construction increasingly involve multi-material vehicles. A diverse range of lightweight construction materials are combined here, as the special demands on the vehicle body demand the right mix of materials, plastics, composites and metals. These materials are used in different sections of the automobile depending on what the respective body design needs. Intense research and development is taking place in all fields and on all types of material, so I would have trouble picking a favorite. Ultimately, the material with the best lightweight index, including low material and process costs, will become the material of choice in large-scale vehicle production – the race between materials used in body construction has been on for years already.
What market potential do you see for lightweight construction technologies?
Gräbener: Potential is especially high in vehicle and aircraft construction. The large quantities required for both car and truck production results in considerable potential for mechanical engineering to develop effective production systems. As a leading supplier of technologies for sheet metal and solid forming, Schuler is heavily involved in the development of forming processes for the new lightweight construction materials. We invest in and develop new procedures and processes both in our own TechCenters and in collaboration with other facilities and universities.
For example, we will be opening a new Hot Stamping TechCenter at our site in Göppingen in 2016. There, we will be installing a complete production system incorporating state-of-the-art equipment, with which we hope to develop the tempering process further. The system will also be available to our customers for testing, prototyping and contingency production.
Where does Germany rank internationally when it comes to lightweight construction?
Gräbener: Germany and other European countries certainly play a pioneering role, investing considerable effort into developing lightweight construction for vehicle and aircraft construction. But the USA is also increasing its activities in this area. In Asia, China, Japan and Korea in particular are also dedicating considerable effort to further development.
To what extent does the development of new options in lightweight construction depend on efforts to achieve sustainability?
Gräbener: The driving force behind all development activities is the need to reduce vehicle emissions around the world. Today, aircraft manufacturers have their sights on more than just the fleet fuel consumption; the energy expended in manufacturing the aircraft is also subject to scrutiny. Here, mechanical engineers are called upon to optimize our systems. Schuler already uses newly-developed drive systems that have reduced the energy consumption of the presses enormously.
Schuler is heading a research project designed to reduce the production costs for CFRP components. What is your approach? What have you learned so far?
Gräbener: Schuler is coordinating the iComposite 4.0 research project. The aim of this joint project with the Aachen Center for Integrative Lightweight Production (AZL) at RWTH Aachen University is to achieve lower costs and increased productivity in the large-scale production of CFRP components. To do this, additive, near-net-shape production processes are combined with an established industrial resin injection process. The approach uses a networked production system with regulatory system intelligence, in which material cards and simulation models are recorded. The objective is to move from geometry-based to product function-based production. Schuler is currently commissioning a new multifunctional composite press at the institute, with initial results expected in 2017.
What are the biggest challenges in hybrid lightweight construction?
Gräbener: Joining technologies suitable for the use of new materials and additive production processes still pose a tremendous challenge. Production costs also have to be reduced if the technology is to succeed in large-scale industrial production. But this is exactly where the considerable potential for mechanical and plant engineering lies. Holistic process observations and concepts for complete production systems, i.e. the step from mechanical engineer to system provider, are the major challenges companies in the German mechanical engineering sector will face over the coming years.
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