“The automotive industry continues to move toward Mega- and Giga-castings, but at different speeds”

Sergio Orden. Lightweight Materials and HPDC technologies researcher. 

The GLOBAL GIGA-CASTING CONGRESS (Kassel, Germany) brought together the main advances in the field of this revolutionary technology that directly impacts the automotive sector. The AZTERLAN Metallurgy Research Centre Lightweight Materials and HPDC foundry expert has analyzed the main trends and technical aspects linked to the development of Mega- and Giga-castings, which, “nowadays, still lack the necessary foundations to consolidate as a main manufacturing technology in the short term.”.

What are currently the main drivers pushing the development of Mega- and Giga-castings?

Being such a disruptive technology and due to its level of impact on the way automobile design and manufacturing are approached, Mega- and Giga-castings have several open development facets: market, metallurgy, sustainability, manufacturing … All of them of great importance.

It is clear that the automotive industry continues to move toward Mega- and Giga-castings, but at different speeds, as different strategies are proposed depending on the OEM or the geographic region. In this sense, the differences between the European, American, and Asian industries are evident. The industry continues to analyze and debate the place of this technology, and all involved players continue trying to gauge its impact and penetration, as well as the level of impact it will have on the existing automotive industry in each zone.

Without a doubt, Asia is making a significant effort to consolidate Giga-castings with very strong investments in infrastructure and with cars ideated with this technology from the design phase. Meanwhile, the Americas, particularly the US, remain halfway. Logically, we have Tesla, in some ways the “father” of the unboxed process idea (a manufacturing methodology consisting of modular assemblies that are joined at the end of the production line, rather than through conventional conveyor belt assembly lines), which has promoted the boost of Giga technology. This well-known brand has also led to the emergence of American and Japanese OEMs that include Giga-casting in their future strategies.

Finally, Europe remains the most reticent or cautious. Behind this reluctance lies not only the high investment cost of implementing this technology, but also the difficulty of integrating these types of parts into existing assembly lines. In addition, other fundamental barriers should be mentioned, such as uncertainty about the future of the automotive industry in Europe and uncertainty about the viability of Giga-casting and Mega-casting technologies. Unlike Europe and America, the emergence of this technology in China is driven by the significant growth of electric vehicles associated with new brands and gree-field assembly plants that have adopted the unboxed process strategy. China has required a very high level of investment from both OEMs and TIER 1 suppliers, with the government’s commitment to promoting electric vehicles.

However, it is important to emphasize that, at the moment of truth, there are not many machines capable of creating these types of parts worldwide, and their production capacity is also limited. Therefore, much remains to be defined, and neither the technology nor the infrastructure are yet ready to make the leap to mass production.

 

From a technical perspective, what are the most critical areas for promoting Giga- and Mega-casting technologies in the automotive industry?

As mentioned, the concept behind Giga-casting technology is the unboxed process, which basically seeks to make an important part of the car, its structure, from a single part, thereby reducing the number of vehicle components, the number of joining points, the assembly process, and its weight. Of course, this technology also has a direct impact on the timelines for the design for new concepts and for the development of industrialization projects, which are significantly shortened.

In reality, when discussing Giga-castings, we are maing talking about three parts: the Rear underbody, the Battery frame, and the Ffront underbody. These are structural parts playing a key safety function. For this reason, they require a certain degree of deformability to absorb impacts to ensure passenger safety. However, depending on the assembly method selected, they require even a greater deformability. This family of structural products is currently primarily covered with the AlSi10MnMg alloy. With this transformation to Giga-components, other variants of this alloy with lower silicon content come into play to improve the component’s deformability.

In the production of these large components, there is also an aim to eliminate heat treatment. In addition to being a costly process, it is perceived as a source of problems due to the deformations and distortions that can occur during heat treatment and, consequently, increases the risk of non-compliance regagrding tolerances. This is one of the main challenges faced by Giga-castings, and although heat treatment is not the only source of deformations, eliminating it offers significant advantages. Avoiding heat treatment also requires new metallurgical approaches, based on incorporating alloys that are outside the usual families used in HPDC technologies but that provide good mechanical characteristics. However, this is a field in which much research remains to be done, and to date, no final decision or consensus has been made regarding the “ideal” alloy.

In any case, this technology has broken down certain barriers that existed until now and, moreover, has been developed in record time. It should be noted that any technical solution, even if disruptive, could be a good one. An example of this is the double injection molding proposed by L.K. Technology, which may end up being the technical answer to Giga-casting, although it is still in its early stages.

 

What do you think are the key areas of work to position companies for this technology?

Above all, we must continue developing knowledge and tools that allow us to demonstrate the viability of the proposed solutions and ensure the in-service performance of these parts.

Optimizing the resources needed to manufacture Giga-components is essential given the level of investment required. This is the main focus of some European OEMs, who are proposing maximum utilization of each ton of machine clamping force, for example, with three-platen molds or capillary injection. However, any improvement in resource efficiency is necessary, in terms of ogistics, mold life, part rejection, and even in the kilometers of tubing required for cooling lines.

From a materials perspective, as I said, metallurgy remains a key aspect due to the structural function required of these parts. On the one hand, it is essential to minimize the porosity of the parts (which requires highly efficient vacuum systems). On the other, the mechanical properties of the components must be guaranteed, preferably without requiring subsequent heat treatment. Added to this challenge is the need for increased incorporation of secondary alloys by the industry (for sustainability and supply reasons), which will require significant metallurgical quality control.

Another fundamental factor to positioning this technology is the complete modeling of the manufacturing process so that all key aspects of the process can be predicted, such as part defects, deformation after cooling, and even mold life. The development of these digital tools will make it possible to optimize the manufacturing of Giga-casting components from the design stages without incurring additional costs.

From a process perspective, I believe that the industry around us can make small advances approaching this technology, pursuing a middle path, that is, creating medium-sized components that integrate several components, while also seeking to reduce weight. However, to make these kind of decissions involving such significant changes for them, it is important, first and foremost, to ensure that these adaptations bring real benefits to the industry, in terms of time, costs, weight reduction, and emissions, among others.

Finally, as a product, in addition to reaching mass production and ensuring performance in service, a fundamental aspect to work on is the repairability of parts and vehicles after an impact. It may seem like the last link in the chain, but it is a highly relevant aspect, as resolving this issue can ensure the attractiveness and economic viability of vehicles that incorporate these large components and, ultimately, represent a differentiating element for the consumer.