The impact of the development of new energy vehicles on the die-casting industry

A boost to the die-casting industry

2.1 Speed ​​up and upgrade the application of aluminum alloy structural parts

The replacement of traditional fuel vehicles by new energy vehicles requires major technological breakthroughs, one of which is to increase the cruising range. At present, the key to breaking through this dilemma is to develop high-energy batteries or other new energy sources, and then to reduce the weight of vehicles. In the process of reducing the weight of traditional fuel vehicles, die casting has played an important role with a series of advantages such as clean forming, rib structure, high integration, easy handling and high efficiency, replacing many ferrous metal castings and expanding the use of die castings. Scope of application. Entering the stage of new energy vehicles, the requirements for lightweighting are more prominent and urgent. New energy vehicles have promoted the process of lightweighting and the application of die-casting structural parts.

Aluminum alloy die castings are mainly used in automobiles, machinery, electronics, communications, instrumentation, household appliances and other fields, of which auto parts account for the largest proportion, accounting for about 70%. The automobile industry is the pillar industry of the die-casting industry, and the output of die-casting parts has a significant positive correlation with the output of automobiles. The trend of the output of die-casting parts and automobile output in recent years is shown in Figure 4. Due to the continuous increase in automobile production, the output of die castings has increased, and the increase has exceeded 10% for more than ten consecutive years. As can be seen from Figure 4, the increment of die castings consists of two parts, one part is the increase in automobile production, which drives the increase in the output of die castings, and the other part is driven by the increase in the amount of automobile die castings. One of the important reasons for the increase in the amount of die-casting parts for bicycles is the development of new energy vehicles in recent years, which has accelerated the application of structural parts. Especially in 2020, under the circumstance of declining automobile sales, the output of die castings will rise against the trend. The main reason should be that the amount of structural parts has made a great contribution. The upward trend will be more obvious in 2021, indicating that new energy vehicles have a significant impetus for the application of structural parts.

Figure 4 The trend of die casting production and automobile production

At present, the die-casting production technology of automobile structural parts has made great progress. After the initial batch production of structural parts such as A-pillars and shock towers, it has expanded to structural parts such as rear side beams and subframes that are difficult to process. The typical structure The parts are shown in Figure 5. Among them, the shock-absorbing tower was originally composed of 10 parts, but was integrated into one piece after being produced by the die-casting process. The rear longitudinal member was originally composed of 18 parts, which were integrated into one piece after die casting. The subframe die-casting process is very difficult. Most of them used low-pressure process or gravity process before. After changing to die-casting, the shape and size are accurate, the wall thickness is reduced, the weight is reduced, and the production efficiency is greatly improved. Castings such as suspension arms and rear longitudinal beams have relatively high performance requirements, and generally require heat treatment. At present, the die casting of structural parts basically adopts vacuum die casting to ensure the heat treatment and weldability of the castings.

Figure 5 Typical structural parts

2.2 Die casting application conversion

The amount of die castings used in some parts of traditional fuel vehicles and new energy vehicles has changed, and the amount of die castings has increased or decreased. The changes mainly come from the power system and transmission system. In a fuel vehicle, the power and transmission system, including the engine block, gearbox and clutch housing, are used in a relatively large amount of die castings. There are about 16 die castings in the engine and 8 die castings in the transmission system. But in an electric vehicle, there are about 4 die castings for the drive system and 2 die castings for the transmission system. Compared with traditional fuel vehicles, the application of electric vehicles in the power system and transmission system is significantly reduced. However, the power and transmission systems of hybrid vehicles in new energy vehicles include two systems of fuel and electric, and the amount of die-casting parts has increased. If ICEE (die-casting machine clamping force (cycle time) is used to represent the application index of die-casting parts, size and quantity factors, etc.), the application index of die-casting parts for fuel vehicles, electric vehicles and hybrid vehicles is shown in Figure 6.

Figure 6 Die casting application index of powertrain and transmission system of three models

Although the amount of die-casting parts in the power and transmission system of electric vehicles is reduced, the amount of die-casting parts in the three-electric system has increased, which can partially make up for the reduction in the amount of die-casting parts in the power and transmission system. The typical application is battery bracket, As shown in Figure 7. With the continuous increase of electric vehicles, the average amount of aluminum used in battery boxes and motor casings will increase rapidly, and the amount of aluminum used in battery boxes will account for nearly two-thirds of the average increase in future aluminum consumption. In order to increase the battery capacity, the size of the current vehicle battery is larger, and the size of the battery bracket is larger. Some models can be up to 2 m in length. Require. In addition, the motor shell, end cover, rotor, junction box shell, etc. are also produced by die-casting process, which makes up for the amount of die-casting parts, as shown in Figure 8.

Figure 7 Various battery bays

Figure 8 Electric vehicle drive system die casting

If a dual motor drive is used, the compensation for the amount of die castings is stronger.

2.3 Promote integrated die casting technology

Under the multiple pressures of weight reduction, efficiency improvement and cost reduction, in 2019, Tesla proposed the body integral casting method. The entire rear body of Model Y is produced by means of integral die-casting, which integrates more than 70 parts originally required by multiple processes into one, which reduces the procedures such as assembly and welding, reduces the weight by about 30%, and reduces the manufacturing cost by about 40%. Model Y's one-piece die-cast body weighs only 66 kg, which is 10-20 kg lighter than the same part of the smaller Model 3, see Figure 9. The CTC version of Tesla Model Y4680 will use 2-3 large die-casting parts to replace the entire lower body assembly consisting of 370 parts, the weight will be further reduced by 10%, and the subsequent mileage can be increased by 14%. At present, there are also die-casting manufacturers planning or implementing integrated die-casting car chassis or skateboard chassis, as shown in Figure 10 and Figure 11. If the integrated all-aluminum die-cast body is used, the weight will be 200~250 kg, while the weight of the steel body of the same level is 350~450 kg, which is about 150~200 kg lower.

Figure 9 Model Y body rear parts integrated die-casting

Figure 10 Integrated die-casting frame

Figure 11 Skateboard car chassis

The integrated die-casting solution greatly simplifies the manufacturing process, eliminates the cumulative error caused by the connection of a large number of parts, improves the manufacturing accuracy, saves a lot of time cost, equipment cost, labor cost, and greatly reduces the manufacturing cost of the whole vehicle.

Integrated die-casting brings technical advantages such as weight reduction, efficient manufacturing and cost reduction, and has attracted great attention from various OEMs. Some people think that the integrated die-casting technology is a revolutionary technology in the automobile manufacturing industry, and will surely become a trend of automobile manufacturing in the future. At present, many OEMs have indicated that they will follow up the integrated die-casting technology, or have entered the implementation stage.

Integrated die-casting not only provides a new way to manufacture automobiles for OEMs, but also provides opportunities for auto parts die-casting enterprises. Many auto parts die-casting companies actively cooperate with OEMs to jointly develop integrated technology, increase investment and financing intensity, expand production capacity, accelerate the layout of integrated die-casting, and strive to gain market share in integrated die-casting. Industry insiders estimate that the sales volume of models equipped with integrated die-casting parts is expected to rise to 3.03 million in 2025, and the market space of integrated die-casting will increase from 900 million yuan in 2021 to about 27 billion yuan in 2025. The market space is huge. At present, integrated die castings are mainly used in new energy vehicles to achieve the purpose of reducing body weight, reducing energy consumption and increasing cruising range. The industry believes that by 2030, the market share of new energy vehicles will increase to 50%. If large-scale integrated die-casting penetrates into fuel vehicles, the application prospect of ultra-large integrated die-casting is very promising.

It should be noted that the integrated die casting increases the overall weight of the die casting, which has a significant effect on the weight gain of the die casting. However, it may reduce the number of die-casting parts, because the integrated die-casting parts have a higher degree of integration, and may combine several adjacent die-casting parts, such as rear side beams, shock towers or chassis longitudinal parts, into one piece, such as Figure 12. Therefore, companies producing such die castings should respond in advance.

Figure 12 High integration of integrated die casting

2.4 Driving the Super Large Die Casting Machine Market

There is no strict professional definition of how large a die-casting machine belongs to a super-large die-casting machine. It is generally considered that a die-casting machine capable of die-casting large-scale integrated rear parts of the body is considered to be a super-large die-casting machine, with a clamping force of more than 6,000 t. The weight of the integrated body die-casting parts can generally reach more than 60 kilograms, the pouring weight can reach more than 100 kilograms, and the size is about 1 700 mm × 1 500 mm × 800 mm. The weight and size are beyond the limit of die-casting products. In this context, it is inevitable to manufacture super-large die-casting machines. Large-scale integrated die-casting has opened up the era of super-large die-casting machines. In the short three years since the concept of integrated die-casting was proposed, die-casting machine manufacturers have developed rapidly, and 6,000 t super-large die-casting machines have been used to produce integrated die-casting of auto parts. The 8 000 t class and 9 000 t class super-large die-casting machines have entered the market and can form production capacity in a short period of time, and the 15 000 t class has also entered the R&D and design stage. The recognition of integrated die-casting by automobile OEMs will further popularize integrated die-casting, and the market demand for large-scale die-casting machines will enter a normalized demand and will continue to exist.