What is CTC and how does it relate to the aluminum unibody trend?

What is CTC?

In October 2021, at the Berlin factory open day, Tesla showed the Model Y integrated die-cast front body + CTC + rear body, combined into a monolithic body. As the leader of new technology, Tesla's release of CTC technology has attracted many followers, and recently Zero Running Motors became the first domestic company to eat the crab.

CTC technology eliminates the two steps from the cell to the module and then to the battery pack, and directly installs the cell on the vehicle platform, which is a further integrated solution of CTP (Cell to Pack). According to the picture information released by Tesla and zero run and according to industry habits, the accurate expression of CTC should be the battery shell integrated in the body floor. The reason why it is called CTC is probably an extension of the concept of skateboard chassis; however, CTC is not the only option for skateboard chassis.

02

Technical features of CTC

The CTC technology concept, pioneered by Tesla, is similar to the design of an airplane where the fuel tank is integrated into the wing rather than a separate tank, and is designed to be highly integrated to reduce the number of components and the assembly process to reduce weight, efficiency and cost.

CTC solution inspired by wing fuel tanks

In Tesla's CTC technology, the Pack design is eliminated, two large body castings are connected front to back, the original passenger compartment floor panels are eliminated and replaced with a battery top cover, and the seats are mounted directly on the battery top cover. The battery is both the energy device and the structure itself.

CTC battery integration solution: eliminating the need for modules

In order to solve the problem of battery pack insulation, Tesla filled the interior of the battery pack with glue to block the conduction of heat to the interior of the car. In addition, Tesla filled the battery pack on both sides of the door sill near the body with relatively thick glue, this part of the glue can play a side impact process to prevent the battery cells from being squeezed and fire cushioning role.

Tesla Model Y's CTC solution is to directly involve the battery pack in the collision energy absorption, the radical Tesla took away the front floor and floor seat beams that originally belonged to the body, and welded four beams on the battery pack shell (the location corresponds to the B-pillar and pillar touch contact points), these four beams are used to install the front seats, but also involved in the side impact and pillar touch force transfer, to prevent the battery pack in the side impact hit is transition squeezed. In addition, the adhesive inside the battery pack shell can also play a certain role in crash cushioning. Tesla has adopted such a program to solve the potential safety problems of side impact.

CTC battery technology helps to further unitize the vehicle's structural platform, thus further reducing manufacturing costs. Musk has said that the use of CTC battery technology, together with integrated die-casting technology, can save 370 parts, reduce the weight of the body by 10%, and reduce the cost of the battery per kWh by 7%.

To summarize the advantages of Tesla CTC are as follows.

1. Space saving. With the elimination of modules, more batteries can be stuffed in a limited space, which is conducive to long range and high performance in smaller models.
2. Weight saving. Eliminate the original design of the floor and combine the battery case cover and floor into one, reducing the parts configuration.
3. Time saving. Simplify parts, highly integrated design, and reduce intermediate manufacturing links.

4、The body is more rigid in torsion, and the whole structure of CTC is involved in the force.

CTC technology is integrated into the car body, and the main control is in the hands of the OEM.

There are two sides to everything, the back side of an advantage is a disadvantage, and CTC is no exception.

To summarize the limitations of the Tesla CTC as follows.

As a structural part of the body, CTC loses the possibility of independent replacement of battery packs and various cost-effective repair solutions. For example, the same angle of the collision led to damage to the bottom structure, CTC program may not be able to replace a part alone, the need to replace the whole frame + battery, just like the domestic Tesla Model Y after a one-piece die-cast body collision is likely to report a total loss.

CTC is a highly integrated solution with the body as a whole, the battery and the body are an inseparable whole, which means that Tesla's CTC is completely cut off from the replacement of electricity as a technical route.

The material basis of all technologies of CTC and one-piece die-casting technology is aluminum alloy, and the precision machining of aluminum alloy is facing rapidly increasing demands and challenges. With 25 years of history in manufacturing efficient tools for precision machining of aluminum alloys, Zhengzuan has accumulated a lot of experience in on-site tool application, which can help customers easily meet all the challenges of aluminum alloy material machining, optimize the machining process and increase productivity.