Is it all ‘giga’ or ‘mega’? There’s no ‘right’ or ‘wrong’
Like all leading car manufacturers worldwide, the Bavarian premium carmaker BMW in Landshut has been examining the pros and cons of so-called ‘giga’ or ‘mega’ castings for some time now. Tesla had attracted a great deal of attention with the introduction of large die-cast components for its vehicle structure, such as the rear underbody structure of the Model Y.
The approach of using large castings to replace as many individual parts and processes as possible – and thereby even further reducing costs; weight and CO₂ emissions whilst simultaneously simplifying the manufacturing process, sounds tempting. On the other hand, there are high upfront investments in new plant and infrastructure, the reconfiguration of production lines, as well as technical challenges relating to the manufacture and subsequent use of the large components.
During an in-depth discussion with Klaus Sammer and Dr Thomas Kopp at BMW’s light-metal foundry in Landshut, we were able to discuss the key arguments for and against and gain an insight into BMW’s specific perspective.
“When it comes to giga/megacasting, there is no ‘right’ or ‘wrong’
Kopp and Sammer are sought-after speakers at conferences and symposia, as they have dealt extensively with issues relating to the production of large castings and are well aware of the advantages and disadvantages.
What will the situation be like at BMW’s light-metal foundry in Landshut by 2024?
The BMW Group’s light-metal foundry in Landshut is a highly innovative facility characterised by a broad and unique range of casting technologies. These include both conventional gravity casting and low-pressure die casting. A specialised gravity casting process is the injector casting process, which was developed and patented in 2007 by casting specialists in Landshut. It combines the advantages of gravity and low-pressure die casting. In this process, the cavity is filled by means of an injector, with the outlet located in the lower part of the mould at the start of the casting process. During the casting process, the injector is slowly guided upwards.
The outlet remains below the surface of the molten metal at all times during the filling process. This results in layered mould filling, which has a positive effect on the solidification process. This process enables the production of highly complex and functional components, such as the central housings of electric motors. The sand cores required to create undercuts are produced exclusively using inorganic binder systems. This results in virtually emission-free casting – and has done for more than 15 years, as Kopp and Sammer emphasise. In addition to conventional core shooting, sand cores can also be produced at the Landshut site using additive core printing with inorganic binder systems. This ensures the site’s long-term viability.
However, in addition to the potential for lightweight construction, there are a number of other factors that must be taken into account in the decision-making process. These include the functional requirements that may be associated with heat treatment. The importance of a repair solution should not be overlooked either. This is limited in the case of large castings and usually involves additional effort.
Another key aspect is the logistical effort involved, which increases significantly as component size grows. To counter this, the foundry would need to be integrated with the vehicle plant, which would require investment in new die-casting facilities. The number of facilities required depends largely on the vehicle plant’s output and the number of variants per production line. To ensure a reliable supply to the vehicle production line, several die-casting machines are often necessary.
Die-casting moulds present a similarly significant challenge. Due to the large size of the components, increased mould wear is to be expected, resulting in shorter maintenance intervals and, consequently, a higher number of moulds required.
It should be noted that, at present, there are no valid advantages at BMW for the use of die-casting cells with a clamping force > 6,000 t. The BMW components plant in Landshut operates with a strong supplier network, thereby ensuring the supply to the vehicle plants.
At BMW, the focus is less on feasibility and more on the approach of achieving optimal results through innovation and extensive expertise, whilst casting the right material using the right process in the right place.
About BMW Landshut:
At the BMW Group plant in Landshut, around 3,700 employees produce engine, chassis and body structure components made from light-alloy castings, plastic components for the vehicle exterior, body components made from carbon fibre, cockpit and interior trim, engines and drive shafts. The Landshut plant is the BMW Group’s largest components plant worldwide and supplies parts to all BMW Group vehicle and engine plants globally – and thus to almost every BMW, MINI, Rolls-Royce and BMW Motorrad. The BMW Group Landshut plant stands for component manufacturing characterised by digitalisation and focused on sustainability, as well as for the responsible use of resources.
With forward-looking technologies, the BMW Group Landshut plant acts as a driver of innovation in the technological transformation of the automotive sector and its supply industry. At the Lightweight Construction and Technology Centre (LuTZ), which is directly adjacent to the plant, specialists from a wide range of disciplines are actively driving forward the sustainable development of future vehicle models. They are involved in the development processes for new vehicles at an early stage. In the Landshut and Lower Bavaria region, the BMW Group Landshut plant is a socially responsible, innovative and attractive employer.
About Dr Thomas Kopp and Klaus Sammer
Klaus Sammer has been part of the BMW Group since 1985 and was most recently Head of Planning for the Painted Body Shop at the Dingolfing plant, as well as Head of the Painted Body Shop for the plant under construction in Debrecen (Hungary). He subsequently took over as Head of Product and Process Planning for the light-alloy foundry at the BMW Group’s Landshut plant. In addition to his roles within the BMW Group, Sammer serves as a member of advisory boards for various associations.
2001 to 2005: Project Manager – BMW Munich Plant
2005 to 2011: Team Lead Research and Development – BMW Munich Plant
2011 to 2015: Head of the Department for Assembly and Total Vehicle Validation – BMW Munich Plant
2015 to 2018: Head of Planning, Body Shop – BMW Dingolfing Plant
2018 to 2021: General Manager Press Shop and Body Shop – BMW Debrecen Plant
2021 to 2023: Head of Technology Centre for Foundry, Toolmaking, Maintenance and Prototyping, as well as Product & Process Planning – Landshut Plant
Dr Thomas Kopp has been with the BMW Group since completing his PhD in 2016. As Team Coordinator for Advanced Development at the Light Metal Casting Technology Centre, he is currently responsible for the further development of innovative cast components for future vehicles. His previous roles include, amongst others, Sub-project Manager for Production and Team Leader for Quality in gravity and low-pressure casting. In addition to his work at the BMW Group, Dr Thomas Kopp is also a member of advisory boards for various associations.