Light metals save weight and the environment

Finnveden Metal Structures is leading future developments in the quest for lightweight vehicle components.
“Aluminium and especially magnesium produce lighter vehicles and lower carbon dioxide emissions,” says Sven Hedlund, Casting Engineer. 

Finnveden Metal Structures has a wealth of deep-rooted experience in light metals, and first started casting magnesium vehicle components back in the early 1990s. At the time Finnveden had already been casting products in aluminium for almost 10 years.

       “It’s experience we have built up over time, and today magnesium is a prominent part of Finnveden Metal Structures’ offering. In fact there are few companies in the world that can cast the complex products in magnesium that we produce,” Sven explains.

       The advantages of magnesium and aluminium are not only the low weight and the environmental benefits. It could ultimately be cheaper for the customer as well. Because the products are cast in a single piece, it reduces the number of pre-assembled components that have to be fitted into the final structure. Integrating these parts into a single cast component can considerably reduce costs.

EFFECTIVE CASTING METHOD

The Finnveden Metal Structures foundries are located in Hultsfred, Sweden and Bielsko-Biala, Poland, and use a technique known as High Pressure Die Casting (HPDC). In simple terms it entails pushing melted metal, under high pressure, into a steel mould. This offers several advantages over sand casting, for instance.

       “When you cast in a sand mould, you have to remake the mould after each cast. With HPDC you use a permanent steel mould that can be used for many cycles and is ideal for high-volume production. Moreover, if you’re casting magnesium pieces you double the tool life compared to aluminium due to the lower heat content,” Sven explains.

       “It’s also possible to create a more material-efficient product. HPDC is designed for casting pieces with thin walls. With sand casting, for example, the product has to be designed with relatively thick walls to ensure a good enough result; the production process sets the limits, not the construction.”

CLOSE COLLABORATION WITH CUSTOMER

Openness towards customers is a guiding principle at Finnveden Metal Structures. Through constant support and extensive process know-how, Finnveden’s engineers always strive to help customers develop a better component, often working closely alongside the customer’s own production department. The aim is to maintain a continuous open dialogue so that we can develop the best possible products together.

       When Finnveden receives a new enquiry from a customer, our engineers analyse it thoroughly and check whether the product can be manufactured, whether it needs altering to make casting possible, and whether superfluous elements can be eliminated or at least reduced.

       “After that we draw up a product critique in which we suggest modifications to the product,” says Sven.

       Thanks to this well-established approach, Finnveden Metal Structures’ engineers can reduce the product’s weight and simplify the production process, which often leads to a cheaper product.

       However, for this process to succeed, the customer has to involve Finnveden from an early stage.

       “That way our critique comments are taken into account, production is optimised and the costs are lower. It’s a lot harder if the customer brings us a product that has already been extensively tested. Even if the customer wants to make the changes we suggest, it could be much too costly at such a late stage as the product has come so far in the customer’s validation process.”

MAGNESIUM OR ALUMINIUM?

Despite all the benefits, Sven feels that not many technical designers have truly started considering magnesium.

       “Our customers’ technical designers tend to choose aluminium over magnesium simply because they haven’t considered magnesium as an option. But switching from aluminium to magnesium can quite easily save 20-30% in weight.”

       These days, aluminium is mainly used in exterior applications, primarily because it’s such a robust metal.

       “Galvanic corrosion is a parameter that has to be properly considered when working with magnesium. However, there are plenty of solutions that make it possible to use magnesium in exterior applications,” Sven adds. “We’re constantly involved in projects where we use various kinds of alloys and solutions to see whether we can use magnesium even in more unprotected environments.

       “Even though there are many benefits with magnesium, there are of course cases where aluminium is preferable,” Sven points out. “And that’s a choice we’re happy to help the customer with.”

       Of course we all remember how easily magnesium burns from science lessons at school. But how safe is it to use in cars?

       ­“With our alloys the metal has an oxidation point upwards of ~450°C, but it never gets that hot in standard applications. By then the plastic has already begun to melt. In fact some engine components in the classic Volkswagen Beetle were made from magnesium even back in the 1940s.”