Tesla has, Wei Xiaoli wants it all. This time, it is Tesla's integrated die casting production technology called "Giga casting". On April 7, central time, at the opening ceremony of Tesla's super factory in Texas, the company's CEO musk announced the latest progress of integrated die-casting technology.
At present, one 8000 ton die casting equipment has been arranged in the factory for the production of model y. With the support of this process, more than 70 parts on the original model 3 rear floor have been reduced to the following two parts on the new car.
The direct benefit of this is that the production time of the whole vehicle is greatly compressed. The working hours of 1-2 hours will be reduced to a minimum of 45 seconds, and the manufacturing cost can be reduced by 40%. More importantly, the floor area of the integrated die casting machine is only 100 square meters. If the existing production process is replaced by integrated die casting as much as possible, the plant area can be reduced by 30% This is obviously a rare positive factor in China where "every inch of land and every inch of gold"
So the question is, where is the power of integrated die casting? Why did domestic and foreign manufacturers, including Weilai, Xiaopeng, ideal, Volvo, Volkswagen Group, etc., layout this technology one after another after Tesla?
When it comes to integrated die casting, we must first look at the principle. You may have an impression of the round turret of type 59 tank. This real "divine vehicle" is built by integrated casting technology. In the production process, engineers first create the mold of the whole turret, then pour the molten alloy steel into it, and finally die-casting. After cooling and heat treatment, you can harvest a complete turret.
The T-72, which frequently staged the art of "bombing turrets" in the Middle East, uses cast turrets
However, with the emergence of composite armor, armor composed of homogeneous steel was eliminated. Combined with the need to hang large pieces of reactive armor on the tank turret to increase the protection capacity, the cast turret with round piers began to be eliminated. The wedge welded turret we saw in the past few military parades began to become the choice of new main battle tanks.
The leopard 2A main battle tank, which is familiar to military fans all over the world, adopts the wedge-shaped turret made by welding process
However, the process of integrated casting has begun to be revived in the automotive industry, and its "initiator" is Tesla.
Let's look back a year and a half ago. On Tesla battery day on September 22, 2020, musk announced that model y will use integrated die-casting to manufacture floor assembly. Last year, the model y produced by the integrated die-casting process in the Shanghai factory was delivered to Chinese consumers In the latest Texas factory, the 8000 ton integrated die casting machine can directly produce the front and rear two-stage body of model y
For Tesla, which cannot receive orders, the benefits of integrated die casting are very obvious. The most important one is to shorten working hours and reduce costs mentioned above. Friends who pay attention to the automobile industry must know that an automobile factory is generally divided into four process workshops, namely stamping, welding, coating and final assembly. Among them, stamping is the only part manufacturing link in the factory. The stamping machine will make all kinds of steel into various shapes according to the body engineering drawings, and then weld all kinds of parts into BIW in the welding workshop. Among them, several problems have always plagued automobile manufacturers.
First of all, the body of a car needs a lot of parts, often more than 500. Each part needs to match the corresponding mold, fixture, manipulator, assembly line and even logistics system, of which there are countless links and huge cost. In particular, the cost of producing molds is the bulk of the cost of a car. Secondly, the huge number of body parts will also bring a large number of welding points. Take Tesla Model y as an example. Since then, the body originally had 700-800 welding points, which needed to match the long assembly line and welding manipulator, resulting in an average production cycle of up to 2 hours.
Finally, a large number of parts will also cause difficulties in part matching. In traditional automobile enterprises, engineers need to spend a lot of time and resources manufacturing for trial production, and use test vehicles for virtual simulation and actual road test. All these reasons will prolong the production cycle of a car, which is fatal to a popular product.
Super die casting machine launched by Idra, a subsidiary of Lijin technology
More importantly, the long production line will also bring pressure on workers' salary. At present, the mainstream automobile enterprises need 200-300 single shift workers in the welding workshop, and double shift workers are required. Whether abroad or at home, the salary level of industrial workers is rising year by year. Moreover, in China, the difficulty of recruitment has become a key factor increasingly perplexing the development of manufacturing industry.
In addition, at the level of environmental protection, the traditional four processes are adding challenges to the carbon neutralization goal of automobile enterprises. Stamping process essentially belongs to the category of traditional machining, in which blanking, punching, trimming and other processes will produce waste and cause waste. If these wastes are to be reused, they must be sent back to the raw material factory for recycling, which also involves the emission of logistics vehicles.
At this time, Tesla integrated die casting technology is particularly easy to use. As mentioned earlier, one-piece die casting can greatly reduce the number of parts and shorten the manufacturing period. At present, the production time of the rear base plate die-casting process of model y is 45 seconds, while Musk's planned production capacity for the Texas plant is 10 million vehicles per year, that is, one vehicle will be offline every half a minute. In terms of reducing welding points, the Texas factory produces only 50 model y. The number of workers in the welding workshop can also be reduced to 20-30, a decrease of 90% compared with the previous one.
In terms of material recovery, integrated die casting can directly utilize the waste materials in processing. Under the traditional manufacturing process, the materials used for BIW are complex and the recycling rate of raw materials is low. Taking BMW 7 series as an example, its materials include not only traditional steel, but also aluminum alloy and carbon fiber with an increasing proportion. Due to the mixed use of various materials in the manufacture of BIW, there are differences in the type (steel, aluminum), brand and content of metal elements of each part. Once there are quality control problems in the process, resulting in the scrapping of some parts or the whole BIW, the waste can only be used as raw materials for steel and aluminum smelting, but can not be directly returned to the furnace as a whole to manufacture new products. Tesla's integrated die casting uses only one material, and the material recycling rate of all aluminum body can reach more than 95%. Because the integrated die-casting parts are completed by one-time filling of liquid metal, their materials are single, and the waste can be directly melted to produce other products during recycling, which ensures the high recycling rate of raw materials in the manufacturing process of BIW.
More importantly, the reduction of the number of parts by the integrated die casting process is also conducive to improving the matching of parts and the development cycle of the whole vehicle. At present, the parts of vehicles should be matched with each other, and vehicle enterprises should determine the tolerance range through simulation and trial production to ensure the final yield. Generally speaking, this time is often as long as six months. With the help of the structural optimization and quantity reduction of parts brought by the integrated die-casting process, this time is expected to be compressed to 1-2 months.
Obviously, these advantages of integrated die casting can be described as "future technology" for the new forces of car making who are struggling to reduce costs and improve the speed of production and product iteration. More importantly, after the actual verification of Tesla, the technology has become increasingly mature and moved towards the stage of large-scale application.
But the problem is that not every car company can play with this "refined steel drill".
The benefits of integrated die-casting have been discussed a lot earlier, but for automobile enterprises, the challenge of using this black technology to build cars cannot be solved by buying a few die-casting machines. The first thing to bear the brunt is that the car body and chassis engineers should update their knowledge.
As mentioned above, in the past, the main materials of car bodies, whether steel or aluminum alloy, were mainly plates. The casting is not without, but the structure is relatively simple and the volume is smaller. As for the whole vehicle and forging material team, they are relatively lack of knowledge. In contrast, engineers in the power assembly field have more decompression casting process. After all, many of the housings and cylinders of the gearbox and engine are die-casting.
However, the complexity of the body integrated die casting process is beyond the technical level of the whole industry in the past Once the structure of die casting is more complex and the wall thickness of parts changes more, it is more difficult to achieve good punching. Due to the difference between casting and stamping, it belongs to thermal processing. The high-temperature liquid aluminum metal flow pressed into the mold will cause temperature differences at different positions in the cavity. As shown in the figure below, the difference of material fluidity in different parts of the part will lead to the difference of material density everywhere. The farthest part from the inlet may have begun to solidify, while the nearest part is still in the state of high-temperature liquefaction. This may lead to the impact fusion of multiple metal pages, resulting in the failure of parts.
Analysis of turbulence and inclusion during mold filling source: Official Website of magma company
What's more, the exhaust problem of the whole die should also be put on the agenda As the amount of liquid metal to be added in the integrated processing is very large, the original gas in the mold and the gas in the metal flow should be vented, otherwise a large number of pores will appear in the material itself, which will eventually be scrapped. Therefore, engineers need to combine the simulation results to optimize the structure For example, Giga press (super die casting machine), which Tesla participated in the definition, also uses inert gas and some vacuum technology
Finally, in the cooling link, the effect of thermal expansion and cold contraction puts forward the ultimate test for the parts. After cooling, the size of the die will also change after thermal treatment. Here, the simulation system is also needed to calculate and simulate the results. Fortunately, some enterprises such as Alcoa, rheinfeld, Lizhong group and Guangdong Hongtu have developed heat-free aluminum alloy materials for new energy vehicle bodies, which can be regarded as avoiding some adverse factors. However, these links mentioned above are challenges that car enterprises have not faced in the past, and the costs brought by them must also be amortized on each car.
Therefore, we can see that most of the automobile enterprises that are exploring and laying out the integrated die-casting technology are new forces and traditional luxury brands. In addition to Tesla, Xiaopeng, Weilai, Volvo and the wealthy Volkswagen Group are all laying out the process. Among them, Weilai announced at the end of 2021 that it has developed materials that can be used for heat-free treatment of large die castings, which will be used on et5 mass produced in the second half of this year. Xiaopeng joined the integrated die casting workshop in Wuhan factory. Volvo has introduced an integrated die-casting line of aluminum components at its torslanda plant to produce the next generation of electric vehicles. Volkswagen's production line in Wolfsburg, Germany, is also planning to introduce relevant technologies.
Although the integrated die-casting process is a challenge for automobile enterprises, we still have to be tough in order to finally reduce costs and increase efficiency. But for consumers, the consequences of the new technology can only be described as mixed.
At present, Tesla's super factory in Berlin has completed the die-casting process of the front cabin on the basis of the integrated die-casting of the rear floor. At present, efforts are being made to complete the integrated die-casting of the front floor. According to the inference put forward in the relevant report of CSC, Tesla is likely to realize the integrated die casting of the whole BIW with the help of a super die casting machine with a maximum pressure of 15000 tons in 2027.
For consumers, this means that there is still room for further downward exploration of Tesla vehicle price, that is, buying a car can be cheaper. Of course, if the lithium battery material is still high at that time, the vehicle price will not become very cheap.
However, the problem of expensive maintenance brought by integrated die casting technology has increasingly become the focus of attention. As the parts of the BIW are die cast in one piece, in case of a major accident, the user needs to replace the whole body parts instead of the damaged parts. The maintenance cost is bound to be higher. Recently, a car owner accidentally hit a wall when reversing and damaged the rear shock absorber. The maintenance cost of the car with the original price of about 280000 yuan actually needs 200000 yuan, which makes the owner feel "it's better to scrap".
It is true that whether the accident injured the rear floor made of integrated die-casting on the vehicle remains to be confirmed, but the reason why Tesla first adopted the new process for the part can also be speculated. Obviously, if these parts are damaged, they are often in the rear end collision accident. Even if the loss is caused, it is also borne by the rear vehicle owner.
But in the final analysis, with more and more parts made of aluminum alloy, Tesla's maintenance costs have also become high. Taking the test of Tesla 2021 standard endurance rear wheel drive version conducted by China Insurance Research Institute on April 6 this year as an example, this car has received "general" evaluation in terms of structural crashworthiness, while "poor" evaluation in terms of maintainability and maintenance economy.
Of course, there are many reasons for Tesla's evaluation. After all, the car adopts a more expensive steel aluminum hybrid body, and the luxury brands don't give high evaluation on the economy of vehicle maintenance. In fact, the premiums of all electric vehicles were raised in 2021, especially for high-end electric vehicles. However, the challenge posed by the integrated die-casting process to the maintenance of vehicles may be a difficult problem for those new car building forces who are following Tesla's lead for a long time in the future.
After all, compared with the potential maintenance cost and increasing insurance premium, several free power changes and charging mileage gifts seem a little "drop in the bucket".