A crash box for automotive application is an integral component for ensuring the safety and serves as energy-absorbing member. Usually, these crashboxes are made from steel sheets, which are produced by the intensive thermomechanical processing route, which is associated with high performance steel sheets. Recently, several new crashbox designs have been proposed, which required additive manufacturing (AM) techniques as the geometries are to complex for conventional manufacturing (CM). As the AM processing route is much shorter, the question arises how the environmental impact is affected by the new design and the shift to AM.
Sustainability of manufacturing processes and a precise comparison of different processing routes is of essential interest in order to be able to assess the environmental impact. The comparison between additive manufacturing and conventional subtractive manufacturing is especially important when it comes to production of complex parts.
Most of the existing studies comparing AM with CM, involve the comparison of identical components manufactured by both routes and concluded that AM has a higher impact when mass production is involved. However, the most important aspect of AM, being the geometrical freedom and resultingly new geometric designs, have not been appointed in these studies. Consequently, in the current study, two different geometric designs for a crash box are discussed, which achieve the same energy absorption. The first design is produced conventionally (from welded sheet material), while the second design is a cellular structure topologically optimized for enhancing maximum energy absorption.
A detailed Life Cycle Assessment of the process route of design optimized lattice structures and conventional crashboxes that exhibit similar energy absorption reveals a large advantage regarding the environmental impact of the additively manufactured structured and demonstrates that AM can substantially decrease the environmental impact of metallic components, if the freedom of design is applied.