Carat
It is becoming a reality; the possibility of producing entire front or rear underbodies on die-casting machines is within reach. For automotive production, this will be the next big thing. A rear underbody made from a single die simplifies production dramatically – 70 parts become one. Assembly lines with 300 robots are eliminated, saving production space. And Bühler, thanks to its experience with large structural components, will play a driving role here.
Markus Reber, December 2021
The trend toward larger body in white parts in die casting continues. About 15 years ago, a trend in die casting took off on a massive scale. Automotive manufacturers began to produce aluminum structural components such as shock towers on die-casting machines. This becoming standard was possible thanks to pioneering work by Bühler. The process has proven its worth. The trend toward even larger structural parts continues to this day, with no end in sight. “Automotive manufacturers are currently rethinking production in many ways. At Bühler we not only have the machines for them to put their future visions of even larger parts into reality, but we also support our customers in developing all the processes to do so,” says Nico Jordi, Product Manager Peripherals Die Casting at Bühler.
With our Carat 840 and Carat 920 we can offer our customers solutions for large structural parts with complex geometries and new body in white parts.
Michael Cinelli,
Product Manager Die Casting at Bühler
Lightweight yet large, the demand for body parts is the driving force of innovation for automotive manufacturers. The large machines in the Carat series have dominated this segment for more than a decade. More than 700 of them are in production worldwide every day, making up 50 percent of all structural parts manufactured worldwide. For years the Carat has been producing entire chassis sub-units, for example shock towers, longitudinal members, tailgates, or battery housings for electric vehicles. To cast such complex parts at all, diecasting machines must be powerful and precise.
Launched in October 2021, the Carat 840 and Carat 920, with incredible locking forces of up to 92,000 kilonewtons (kN) currently round off the upper end of Bühler’s die-casting platforms. “We are seeing a huge increase in the demand for everlarger machines. With our Carat 840 and Carat 920 we can offer our customers solutions for large structural parts with complex geometries and new body in white parts,” explains Michael Cinelli, Product Manager Die Casting at Bühler.
The Carat 840 and 920 are as big as a house and 8 meters high. “The Carat 920 is able to inject over 200 kilograms of liquid aluminum into a die within milliseconds, holding the die tight by applying a force of 92,000 kN to it. That’s 9,000 tons − the same weight as the Eiffel Tower. Imagine locking the die with the weight of the Parisian monument in every single shot,” explains Cinelli. With the new solutions, customers can produce structural parts of about 1.8 meters by 1.8 meters.
This brings large parts of any car within reach. “We’re talking about the rear and front underbody. This is still a glimpse into the future. But with our solutions, these large parts are coming into reach,” says Jordi. Forming that much aluminum in milliseconds is an extremely complex process. “Two years ago, our customers could only process half as much aluminum at once with our solutions. Here, together, we have made a big step, and the journey is not over yet,” he explains.
The Carat 920 is able to inject over 200 kilograms of liquid aluminum into a die within milliseconds, holding the die tight by applying a force of 92,000 kn to it. That’s 9,000 tons − the same weight as the Eiffel Tower.
Michael Cinelli,
Product Manager Die Casting at Bühler
Die casting is an energy-intensive process, especially for such large parts. But aluminum is a very elegant metal in terms of sustainability, because it can be fully recycled. “Aluminum die casting can be CO₂-neutral if foundries use secondary aluminum and run their production on green electricity,” Cinelli explains. He adds that this also applies to newly produced aluminum if renewable energy is used for the entire process, including melting. With die-casting machines, every shot should be perfect, and it should be possible to install every cast part. Therefore, Bühler’s vision for the future of the die-casting industry is zero percent scrap, 40 percent less cycle time, and 24/7 uptime. “Advancing further toward this vision is even more important: The larger the castings, the bigger the lever to minimize production costs by reducing scrap, cycle time, and increasing uptime of the die-casting system,” Jordi says.
As aluminum die castings grow, all production steps must cope with their size. This poses many challenges for the foundries. For example, they can no longer be carried by humans – and that is just one of many challenges.
That’s why Bühler is rethinking, designing, and commissioning entire solutions to offer process solutions from ingot to the body shop together with its partners. Robots and transport racks form one continuous transportation system and take over the handling from the casting to the body shop. “We at Bühler, and our partner network, can provide solutions for all these processes thanks to our wide practical knowledge in commissioning and running such large cells, collaborating with foundries and suppliers all over the world,” says Jordi.
When die-casting machines produce large body in white parts in one shot in the future, the effects will be profound. The complexity of body in white construction would drop drastically. As an example, a rear underbody would be produced in just one part, not from 70. Automotive manufacturers could massively reduce their investments.
The larger the castings, the bigger the lever to minimize production costs by reducing scrap, cycle time, and increasing uptime of the die-casting system.
Nico Jordi,
Product Manager Peripherals Die Casting at Bühler
Currently, a rear underbody is welded and glued together on the assembly line by about 300 robots. These robots would all be eliminated, which would greatly simplify the production process. A Carat 920 takes up around 100 square meters of floor space. But if it produces rear underbodies from a single die, it will save manufacturers around 30 percent production space. This level of efficiency is what Bühler is working toward.
The Carat two-platen series comes with a stiffened platen design for homogenous clamping force application that allows minimum deflection and a high degree of dimensional accuracy of the castings. In combination with the unique Bühler real-time controlled injection unit and the DataView control system, Carat provides the highest injection dynamics and quality − shot after shot. And the cell management system SmartCMS is giving customers the possibility to view, control, and program the entire cell. With a wide range of sophisticated functionalities, they can boost the productivity of their entire system.
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