Research for a “new age of magnesium” in the automotive industry

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Abstract

Motivation for (more) magnesium in the automotive industry — research strategies for bringing about a “new age of magnesium” by means of the vehicle modules drive train, interior, body and chassis — use of realised and potential future magnesium components, differentiated according to the time frame and conceivable likelihood of realisation — R&D activities for the implementation of the predicted use of magnesium illustrated by example components and projects.

Introduction

The automobile industry made a voluntary commitment to reduce fuel consumption by 25% in comparison with 1990 levels by the year 2005 [1]. At the same time, this will substantially reduce CO2 emissions and conserve finite oil reserves. The seriousness of that voluntary commitment is underlined by the development and launch of mass-produced vehicles capable of fuel consumption of only 3 l/100 km, such as Volkswagen’s 3l-Lupo and the Audi A2 [2]. The technologies that have been used to achieve the 3 l/100 km figure will in the future also bring about a reduction in fuel consumption for all new vehicles.

The motivation for lightweight construction, we will remember, was based in simple terms on its relation to resistance to movement. Apart from air resistance, a vehicle’s performance and fuel consumption is also affected by rolling resistance and acceleration, both of which are dependent on mass, and where uphill gradients are involved, there is also the force of gravity to overcome, which, again, is relative to vehicle mass. In terms of the MVEG driving cycle, the mass-dependent component of fuel consumption is around 60%. If engine and gearbox performance are appropriately adapted, a 10% reduction in weight can be assumed to bring about a drop in the consumption of roughly 5%.

The first “magnesium age” at Volkswagen started after the Second World War with the Beetle and reached a peak in 1971 with an annual production volume of 42,000 t. In those days, air-cooled engines and gearboxes were the main components that were produced using the Mg alloys AS41 and AZ81 and made up of roughly 20 kg of the vehicle weight.

Again Volkswagen recognised the strategic significance of Mg in motor vehicle construction some years ago. As a result, a joint venture with an Israeli company1 for the production of Mg and Mg alloys was established. The specific demands of the automotive industry with regard to the development of alloys and process technology as well as acquisition of engineering and design data were not best served by the magnesium industry. This situation encouraged the establishment of a research institute2 as part of the joint venture which now has various scientists looking into magnesium technologies.

The research strategy at Volkswagen is aimed at the technical design of the entire material production/properties process chain, design and methods of construction and application in automotive component production. There are potential uses, initially in niche-market vehicles (e.g. super-economy, 3 l/100 km vehicles) and at a later stage in other classes of vehicle, some of which are already in place and are generating demand for research on an enormous variety of semi-finished products. The “second magnesium age” will be characterised by much more than just cast housings (Fig. 1).

Section snippets

Actual and potential uses of magnesium in motor vehicles

The present and future use of Mg in motor vehicles depends on numerous technical and economic factors among which the cost is certainly of fundamental significance. How might the use of Mg in motor vehicles develop? What are the basic requirements? And what R&D efforts are required? This paper aims to tackle those questions by examining them in more detail with the aid of example components and projects, and provide answers to them.

The starting point was an analysis which details for each of

Joining techniques

Questions relating to joining techniques are under examination on prototype structures. One of the key areas of focus is the development of automatic welding processes. One of the decisive factors with regard to the potential future applications for Mg extrusions will be the transferability of established forming processes for steel and aluminium.

Mg extrusions/Mg sheets and pore-free magnesium castings can be joined using the processes commonly applied in the car manufacturing business

Outlook

Lightweight design using magnesium is in competition with lightweight design using aluminium, plastics and steel. It is our aim to establish the use of magnesium in volume production cars, wherever it makes technical sense and is economically viable. Admittedly, limited-series and niche-market vehicles will initially be used to introduce new technologies.

The projected increase in the use of Mg in the medium term and the considerable jump to a figure of 90–120 kg (by the introduction of body

References (4)

  • D. Engelhart, C. Mödl, Die Entwicklung des Audi A2, ein neues Fahrzeugkonzept in der Kompaktwagenklasse, Conference...
  • M. Dick, Die 3l-Lupo-technologien für den minimalen Verbrauch, Conference Paper on Technologien um das 3l-Auto,...
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