Tesla’s stunt friends all want to dream – manufacturing, Tesla, new car-making forces – Fast Technology (Driven Home’s media) – Technology changes the future

Tesla has it, and Wei Xiaoli wants it. This time, it is Tesla’s one-piece die-casting production technology called “Giga Casting”.

On April 7th, Central Time, at the opening ceremony of Tesla’s Gigafactory in Texas, the company’s CEO Elon Musk announced the latest progress in one-piece die-casting technology.

At present, an 8,000-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 back panel of the original Model 3 body were reduced to the following two parts on the new car.

The direct benefit of this is that the vehicle production time is greatly reduced. The 1-2 hour man-hour will be compressed to a minimum of 45 seconds, and the manufacturing cost can also be reduced by 40%.

What’s more, the all-in-one die casting machine occupies only 100 square meters. If the existing production process is replaced as much as possible with one-piece die casting, the factory area can be reduced by 30%. This is obviously a rare positive factor in China where “an inch of land is an inch of gold”.

Then the question arises, where is the power of integrated die casting? Why after Tesla, domestic and foreign manufacturers including Weilai, Xiaopeng, Ideal, Volvo, Volkswagen Group, etc. have all laid out in this technology?

When it comes to one-piece die casting, you have to look at the principle first. You may have an impression of the round turret of the Type 59 tank. This “miracle car” in the true sense was built with one-piece casting technology.

During the production process, engineers first created a mold for the entire turret, then poured the melted alloy steel into it, and finally die-cast it. After cooling and heat treatment, a complete turret can be harvested.

However, with the advent of composite armor, armor composed of homogeneous steel was eliminated. Combined with the need to add large pieces of reactive armor to the tank turret to increase the protection capability, the cast turret of the round pier began to be eliminated. Wedge-shaped welded turrets, which we have seen at the past few parades, are starting to become the choice for new main battle tanks.

The Leopard 2A main battle tank, which is familiar to military fans around the world, uses a wedge-shaped turret made of welding technology.

However, the process of one-piece casting is now beginning to be revived in the automotive industry, and its “initiator” is Tesla.

Let’s go back a year and a half. At Tesla Battery Day on September 22, 2020, Musk announced that the Model Y will use a one-piece die-cast floor assembly. Last year, the Model Y produced by the Shanghai factory using an integrated die-casting process was delivered to Chinese consumers. In the latest Texas factory, the 8,000-ton integrated die-casting machine can directly manufacture the Model Y’s front and rear two-section body.

For Tesla, which cannot receive orders, the benefits of one-piece die-casting are very obvious. The shortening of man-hours and cost mentioned above is the most important one. Friends who are concerned about the automobile industry must know that an automobile factory is generally divided into four process workshops, namely stamping, welding, painting, and final assembly.

Among them, stamping is the only part that is manufactured in the factory. The stamping machine makes various types of steel into various shapes according to the body engineering drawings, and then welds various parts into the body-in-white in the welding workshop. Among them, there are several problems that have always plagued car manufacturers.

First of all, the body of a car requires quite a lot of parts, often more than 500. Each part needs to be matched with corresponding molds, fixtures, robotic arms, assembly lines and even logistics systems. There are countless links and huge costs. 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. Taking the Tesla Model Y as an example, the rear body originally had 700-800 welding points, which needed to be matched with a long assembly line and welding robotic arms, resulting in an average production cycle of up to 2 hours for one piece.

Finally, the large number of components can also make part matching difficult. In traditional car companies, engineers need to spend a lot of time and resources to manufacture for trial production, and use test vehicles for virtual simulation and actual road testing. All of these reasons can lengthen the production cycle of a car, which can be fatal for a product that is gaining popularity.

Super die-casting machine launched by IDRA, a subsidiary of LK Technology

What’s more, long production lines also bring pressure on workers’ compensation. At present, the welding workshop of mainstream car companies needs 200-300 workers in a single shift, and double-shift work requires double the number of workers.

The salary level of industrial workers is rising year by year, both at home and abroad. What’s more, in my country, the difficulty of recruiting has become a key factor that increasingly plagues the development of the manufacturing industry.

In addition, in terms of environmental protection, the traditional four major processes are adding challenges to the carbon neutrality goal of car companies. The stamping process essentially belongs to the category of traditional machining, in which the blanking, punching, trimming and other processes will generate waste and cause waste.

In order to reuse these wastes, they must be sent back to the raw material factory for refurbishment, which also involves the emission of logistics vehicles. At this time, Tesla’s one-piece die-casting technology is particularly useful.

As mentioned earlier, one-piece die casting can greatly reduce the number of parts and shorten the manufacturing time.

The current production time of the Model Y’s rear floor die-casting process is 45 seconds, and Musk’s planned production capacity for the Texas factory is 10 million vehicles per year, which means that one vehicle will be off the assembly line every half a minute. In terms of reducing welding points, the Model Y produced by the Texas factory is only 50. The number of workers in the welding workshop can also be reduced to 20-30, which is 90% less than before.

In terms of material recycling, one-piece die casting allows direct use of waste in processing. Under the traditional manufacturing process, the body-in-white materials are complex and the recycling rate of raw materials is low. Take the BMW 7 Series as an example. The materials used are both traditional steel and an increasing proportion of aluminum alloy and carbon fiber.

Due to the mix of materials used in the manufacture of body-in-white, there are differences in the type (steel, aluminum), grade, and content of metal elements of each part. Once there is a quality control problem in the process, some parts or the whole body in white are scrapped, and the scrap can only be used as a raw material for steelmaking and aluminum production, and cannot be directly returned to the furnace to make new products.

Tesla’s one-piece die-casting uses only one material, and the material recycling rate of the all-aluminum body can reach more than 95%. Since the one-piece die-casting parts are filled with molten metal at one time, the material is single, and the waste can be directly melted to manufacture other products during recycling, which ensures a very high raw material recycling rate in the body-in-white manufacturing process.

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, vehicle parts need to be matched with each other, and car companies need to determine the tolerance range through simulation and trial production to ensure the final yield.

Generally speaking, this time can be as long as 6 months. With the optimization of the component structure and the reduction in the number of components brought by the integrated die-casting process, this time is expected to be compressed to within 1 to 2 months.

Obviously, these advantages of integrated die-casting can be described as “future technology” for the new car-making forces who are struggling to reduce costs and improve the speed of production and product iteration. More importantly, after Tesla’s actual verification, the technology has become increasingly mature and has entered the stage of large-scale application.

But the problem is that this “fine steel drill” is not something that every car company can play.

The benefits of one-piece die casting have been discussed a lot earlier, but for automotive companies,The challenge of using this black technology to build a car is definitely not something that can be solved by purchasing a few die-casting machines. The first and foremost is the replacement and update of their knowledge by the car body and chassis engineers.

As mentioned above, in the past, whether it was steel or aluminum alloy body, the main material was mainly plate. Castings are not absent, but the structure is simpler and the volume is smaller. Therefore, for the vehicle engineering team, the knowledge of die casting, forging and materials is relatively lacking.

In contrast, powertrain engineers have a better understanding of the die-casting process. After all, many of the casings and cylinder blocks of the gearbox and engine are die-casted.

However, the complexity of the body-integrated die-casting process is beyond the technical level of the entire industry in the past. Once the structure of die casting is more complex, the wall thickness of the part changes more, and it is more difficult to achieve a good punching shape. Since casting is different from stamping, it belongs to thermal processing, and 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, differences in material flow in different parts of a part can lead to differences in material density everywhere. The part farthest from the feed inlet may have begun to solidify, while the closest part is still in a state of high temperature liquefaction. This may cause multiple metal pages to impact fusion, resulting in part failure.

Analysis of turbulence and inclusions in the filling process Image source: MAGMA official website

What’s worse, the exhaust problem of the entire mold should also be mentioned on the agenda. Due to the large amount of liquid metal that needs to be added in the integrated processing, the original gas in the mold and the gas in the metal flow must be exhausted, otherwise, a large number of pores will appear in the material itself, which will eventually be scrapped.

To do this, engineers need to combine simulation results to optimize the structure. Like Tesla’s participation in the definition of the Giga Press (super die casting machine), it also uses inert gas and part of the vacuum technology.

Finally, in the cooling process, the effect of thermal expansion and contraction poses the ultimate test for the parts. The dimensions of the mold in the hot state will deform after cooling, and the material will also change after heat treatment. A simulation system is also required here to calculate and simulate the results.

Fortunately, companies 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 unfavorable factors.

However, these links mentioned above are challenges that car companies have not faced in the past, and the costs brought about by them must also be amortized on each car.

Therefore, we see that most of the car companies currently exploring and deploying 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, NIO announced at the end of 2021 that it has developed materials that can be used for large-scale die castings without heat treatment, which will be used in the ET5 mass-produced in the second half of this year. Xiaopeng added an integrated die-casting workshop in its Wuhan plant.fertile

Galvo has introduced a one-piece die-casting line of aluminium components at its Torslanda plant for the production of next-generation electric vehicles. Volkswagen’s production line in Wolfsburg, Germany is also planning to introduce related technologies.

Although the integrated die-casting process is a challenge for car companies, for the ultimate purpose of reducing costs and increasing efficiency, everyone still has to bite the bullet. But for consumers, the consequences of the new process can only be described as mixed.

At present, Tesla’s super factory in Berlin has completed the die-casting process of the front cabin based on the one-piece die-casting of the rear floor, and is currently working to make the front floor complete with one-piece die-casting. According to the inference put forward in the relevant report of CITIC Construction Investment, Tesla is likely to use a super die-casting machine with a maximum pressure of 15,000 tons to realize the integrated die-casting of the entire body-in-white in 2027.

For consumers, this means that the price of Tesla’s complete vehicle has further room to drop, that is, it can be cheaper to buy a car. Of course, if lithium battery materials are still at a high level at that time, the price of the whole vehicle will not become very cheap.

However, the problem of expensive maintenance brought about by the integrated die-casting technology has increasingly become the focus of attention. Since the body-in-white components are die-cast in one piece, in the event of a major accident, the user needs to replace the entire body part, not the damaged part. The maintenance cost is bound to be higher.

A few days ago, a car owner accidentally hit a wall while reversing and damaged the rear shock absorber. The maintenance cost of a car with an original price of about 280,000 yuan actually required 200,000 yuan, which made the car owner feel that “it’s better to scrap it”.

Granted, it remains to be seen whether the accident damaged the car’s one-piece die-cast rear floor, but Tesla’s reason for the new process for the part in the first place can be speculated. Obviously, if these parts are damaged, it is often in a rear-end collision. Even if the loss is caused, the owner of the rear car will be responsible.

But at the end of the day, as more and more parts are made of aluminum alloys, Tesla’s maintenance costs have also become high. Taking the test conducted by the China Insurance Research Institute on April 6 this year on Tesla’s 2021 standard battery life rear-wheel drive version as an example, this car received a “general” evaluation in terms of structural crashworthiness, while repairability and maintenance economy. Sexuality received a “poor” rating.

Of course, there are many reasons for Tesla to get this evaluation. After all, the car uses a more expensive steel-aluminum hybrid body, and luxury brands do not have a high evaluation of vehicle maintenance economy. In fact, premiums for all EVs are being hiked in 2021, especially high-end EVs.

However, the challenge posed by the integrated die-casting process to vehicle maintenance may be a problem for the new car-making forces that are catching up with Tesla for a long time in the future.

After all, compared to the potential repair costs and growing insurance premiums, a few free battery swaps and giveaways of charging mileage seem like a drop in the bucket.

Hashtags: Tesla, a new force in car-making, manufacturing