First, automobile lightweight is imperative, and the aluminum die-casting process has significant advantages
1.1 The goal of "carbon neutrality" drives the transformation of the automotive industry to green, and lightweight helps to achieve the goal of energy conservation and consumption reduction
Vehicle exhaust pollution continues to threaten the environment, and "carbon neutrality" is imperative to drive energy conservation and emission reduction.
By the end of 2021, the number of motor vehicles in the mainland reached 395 million, an increase of 6.18% year-on-year, and the annual increase has always remained at about 20 million, which still has a rapid growth rate in the medium and long term. The high ownership of motor vehicles makes the exhaust pollution of motor vehicles serious. According to the Communiqué of the Second National Pollution Source Census released in 2020, the emission of nitrogen oxides and volatile organic compounds from motor vehicles reached 5.95/1.96 million tons respectively, accounting for 33.3% and 19.3% of the total national emissions. Therefore, driven by the "blue sky defense war" and "double carbon" policy, the development situation of automobile emission reduction and low carbon is more urgent.
The overall consumption reduction target of fuel passenger cars has been continuously improved, and the potential of new energy vehicles to help energy conservation and emission reduction is remarkable. According to the "Energy-saving and New Energy Vehicle Technology Roadmap 2.0" officially released in October 2020, the average annual fuel consumption of passenger cars in mainland China will gradually increase from 2020 to 2035, and the pressure to reduce emissions will increase year by year.
However, according to the 2016-2019 "China Passenger Car Enterprise Average Fuel Consumption and New Energy Vehicle Credit Accounting Table" issued by the national ministries and commissions, it can be calculated that the actual average 100-kilometer fuel consumption of traditional energy passenger cars in 2016-2019 is 6.88L, 6.77L, 6.62L and 6.46L, which is always higher than the standard fuel consumption of 6.7L, 6.4L, 6L and 5.5L. However, affected by the continuous increase in sales of new energy vehicles, the average fuel consumption of passenger cars per 100 kilometers of new cars is lower than the standard value, and the pulling range is getting larger and larger. It can be seen that new energy vehicles have great potential for energy conservation and emission reduction, and with the gradual improvement of the penetration rate of new energy vehicles, the pressure of energy conservation and emission reduction in the automotive industry can be further alleviated.
The technology roadmap clearly defines the new energy development goals, and the sales volume of energy-saving and new energy vehicles will account for 50% of each in 2035. In order to further promote the process of low-carbon vehicles, the "Energy-saving and New Energy Vehicle Technology Roadmap (Version 2.0)" puts forward the vision goals of "the total carbon emissions of the automobile industry will reach the peak in advance of around 2028 before the national carbon emission commitment, and the total emissions will be reduced by more than 20% by the peak by 2035" and "new energy vehicles will gradually become mainstream products, and the automobile industry will realize electrification transformation".
The specific milestone targets are as follows: by 2035, the annual sales of energy-saving vehicles and new energy vehicles will account for 50% each, and the automotive industry will achieve electrification transformation; the number of hydrogen fuel cell vehicles will reach about 1 million, and commercial vehicles will achieve hydrogen power transformation.
The global electrification trend continues to accelerate, and the penetration rate of new energy vehicles continues to exceed expectations. According to data from the International Energy Agency (IEA), from 2010 to 2020, as governments accelerate the transformation of electrification, the automotive industry fully marches towards the "new four modernizations", the global new energy vehicle sales achieve annual sales of "ten consecutive increases", CAGR is about 81%, and the penetration rate of new energy vehicles (pure electricity + plug-in hybrid) has risen from 0.01% to nearly 4%.
Since entering 2021, China and Europe, as the world's top two new energy vehicle markets, have continued to exceed expectations in terms of sales performance. In 2021, the cumulative sales of new energy vehicles in China were 3.521 million units, +158% year-on-year, and the penetration rate reached 14.2%, an increase of 8 PCTs, breaking through double digits for the first time. In the same period, the sales volume of new energy vehicles in Europe reached 2.142 million units, +70% year-on-year, and the penetration rate reached 14.6%, an increase of 6 PCTs, continuing the ultra-high boom performance since 2020; the sales of new energy vehicles in the United States reached 652,000 units, +101% year-on-year, and the penetration rate reached 4.3%, an increase of 2 PCTs, and it is expected to reach 8% in 2022.
Vehicle weight restricts consumption reduction, endurance is improved, and lightweight demand is born. Electric vehicle power system includes battery, motor and electronic control of the three major systems, usually accounting for 30 to 40% of the total mass of the vehicle, in the power battery energy density of the existing level, electric vehicles and generalized new energy vehicles power system quality and space ratio is significantly higher than the traditional fuel vehicle, the weight of the vehicle is higher than the traditional fuel vehicle 5 to 25%, the future equipped with intelligent network related configuration, the weight of the vehicle will further rise. Taking the C-HR of the GAC Toyota brand and its pure electric model C-HR EV as an example, the curb weight of the pure electric model is 18.27% higher than that of the fuel version.
At present, due to the problem of excessive weight of the electric drive system and the low maturity of supporting facilities, the actual endurance of electric vehicles is seriously restricted, which has become an important factor affecting consumers' car purchase decisions. Therefore, by reducing the weight of the vehicle to improve the endurance of the car has become a hot technical route to solve this problem, and the lightweight demand for electric vehicles has been born.
Lightweight can comprehensively improve the consumption reduction and endurance efficiency, and is one of the effective means of energy saving and emission reduction. Under the demand for energy conservation and emission reduction and continuous improvement of the long mileage of new energy vehicles, automobile lightweighting is the most direct and effective means at present. According to the 2020 Chinalco Group's "Demand and Supply Status and Development Recommendations for Aluminum for Lightweight Passenger Cars" report, for every 10% reduction in the curb quality of electric vehicles and fuel vehicles, the cruising range will increase by 6-8%, and the exhaust emissions and energy consumption will be reduced by 6-8%. In addition, under the premise of ensuring safety strength, the lighter the weight of the car, the shorter the acceleration time, the more flexible the dynamic response of the body, and the braking distance, body vibration and noise will be reduced.
With the continuous improvement of consumers' requirements for car driving experience, the improvement of economy, safety and comfort brought about by lightweight will be more in line with the needs of consumers, and the competitive advantage of car companies that adopt lightweight technology will be more prominent. Therefore, through lightweight solutions to improve energy saving and electric vehicle consumption reduction and endurance has become the current priority.
1.2 Multi-point breakthrough of lightweight technology, comprehensive advantage of aluminum die-casting process
Materials, processes, design multi-point breakthroughs, the three major initiatives complement each other.
At present, the path to lightweighting mainly includes three directions: material, process and design.
1) Lightweight materials: the use of high-strength steel, aluminum alloys, magnesium alloys, carbon fiber materials and other lightweight materials instead of ordinary steel materials, by reducing the amount of use or reducing the density to achieve weight reduction;
2) Lightweight process: develop integrated die casting, laser welding, hydraulic forming, lightweight connection and other manufacturing processes, and achieve weight reduction by reducing the amount of parts or connectors;
3) Lightweight design: through computer automation design software and mechanical theory, the existing parts and components are optimized for dimensional optimization, shape optimization, topology optimization to achieve product weight reduction.
Among them, material lightweight is the basis of process and structural lightweight, according to the selection of lightweight materials, the process and structure on its basis for further weight reduction design; at the same time, for the process and structural weight reduction technology development, can also further expand the scope of application of different lightweight materials. The three major initiatives of lightweighting complement each other and develop together.
The comprehensive advantages of the aluminum die casting process are outstanding, and the trend of integrated die casting is gradually highlighted. Among the different lightweight materials, the comprehensive advantages of aluminum alloys such as performance, density, cost and machinability are outstanding, and they are lightweight materials with great cost performance and technological maturity compared with a variety of metal alloys and carbon fibers.
In the manufacturing process, high-pressure die-casting products are molded under high pressure, which has the advantages of high compactness, high product strength and surface hardness, and good surface finish, and is suitable for the production of complex, thin-walled structural parts. At present, the demand for automotive technology iteration and capacity improvement is accelerating, and the comprehensive advantages of aluminum die-casting solutions are obvious.
With the continuous breakthrough in the research and development of new aluminum alloy materials and large-scale die-casting equipment, car companies and die-casting manufacturers have begun to successively lay out large-tonnage die-casting machines, and the maturity of integrated die-casting technology has climbed rapidly. With the landing and production of large-tonnage die casting machines, the trend of using integrated die casting technology to produce large-scale automotive structural parts will be clearer. Integrated die casting technology enables the production of more complex structural parts, providing a more reliable production process for lightweight designs.
Second, the automotive aluminum alloy market space is vast, and the application of automotive aluminum castings accounts for the first place
2.1 Aluminum alloy has comprehensive advantages, and the amount of aluminum used in bicycles has increased significantly
Steel and aluminum body is the mainstream solution at present, and the medium- and long-term incremental advantages of aluminum alloy are obvious. According to existing processes and cost factors, high-strength steels and aluminum alloys account for a large share of the lightweight market. The material cost of high-strength steel has obvious advantages over aluminum and magnesium alloys due to different ranges of strength, mature process technology, and is more used for structural parts and safety parts on body-in-white. High-strength steel achieves lightweighting by improving its own strength performance and reducing the amount of body steel used.
The advantage of aluminum alloy is that its density is lower than that of steel, and its excellent metal properties make it possible to better combine material weight reduction with process and structural lightweight, and comprehensive weight reduction. With the trend of lightweighting, technology and materials continue to advance, aluminum alloys will become the most important materials in the lightweight market. The "Energy-saving and New Energy Vehicle Technology Roadmap" plans the mainland's lightweight phased goals, and the single-vehicle aluminum alloy will reach 250kg and 350kg in 2025 and 2030, respectively, and the amount of high-strength steel will be greatly exceeded.
Magnesium alloy weight reduction effect is better than aluminum, generally used in interior and transmission parts; at present, it is mainly limited by the active chemical properties of magnesium itself, high processing and production costs, and the price is 2-3 times higher than aluminum, which cannot be widely used in Volkswagen models. Carbon fiber composites have the best weight reduction rate, corrosion resistance and good machinability and designability; but carbon fiber is currently limited by factors such as high manufacturing cost and difficulty, low recycling and reuse, and the price is as high as 120 yuan / kg or more, which is mostly used in luxury cars such as racing and supercar.
The weight reduction rate of aluminum alloy is balanced with the cost performance, and the amount of aluminum used in bicycles has increased significantly. Compared to other lightweight materials – high-strength steels, magnesium alloys and carbon fibers,
(1) From the cost point of view: the price of aluminum alloy materials is slightly higher than that of high-strength steels, and far lower than that of magnesium alloys and carbon fiber materials;
(2) From the perspective of weight loss rate: the density of aluminum alloy is 2.8g/cm3, and the weight reduction rate is between 40% and 50%, which is only weaker than carbon fiber and magnesium alloy, and significantly stronger than high-strength steel;
(3) From the perspective of process difficulty: aluminum alloy related processes have been very mature, production efficiency is high, aluminum die casting, aluminum rolling, aluminum extrusion, aluminum forging process has achieved large-scale application;
(4) From the perspective of recovery rate: the recovery rate of aluminum alloy is the highest, and its wide application can promote the development of the recycled aluminum industry, which is in line with the current urgent needs for energy conservation and emission reduction, and can also further reduce the cost of upstream raw materials.
Combining the above advantages in high specific strength, high weight loss rate, excellent corrosion resistance, etc., the amount of aluminum alloy materials in automobiles has increased year by year. According to the "China Automotive Industry Aluminum Consumption Assessment Report (2016-2030)" commissioned by cm group commissioned by the International Aluminum Association, from 2016 to 2019, in terms of the amount of aluminum used in Passenger Cars in China, the aluminum used in fuel vehicles, pure electric vehicles and hybrid vehicles increased by 15.7%, 33.6% and 28.1% respectively, and the growth rate of aluminum used in pure electric vehicles was significantly higher than that of traditional fuel vehicles.
2.3 Application: Automotive aluminum alloy is widely used, and automotive aluminum castings account for more than 70%
2.3.1 The coverage of aluminum alloys for vehicles is wide, and the amount of aluminum used in bicycles continues to increase
Automotive aluminum alloys are currently mainly used in body-in-white, powertrain, chassis and interiors, and continue to penetrate into the rest of the components. Aluminum alloy is widely used in the whole vehicle, mainly including the body-in-white, power system, chassis and other parts of the car. From the perspective of the quality distribution of various parts of the car, the body, power and transmission system, chassis, interior, etc. accounted for a relatively large proportion, 27.2%, 22.5%, 20.4%, 20.4%, respectively, a total of more than 90% of the vehicle quality, the main breakthrough direction of lightweight. According to the Ducker Frontier report, the amount of aluminum used in north American light vehicles will total 208.2Kg in 2020; of which the amount of aluminum used in bicycle engines, transmissions and transmission systems, wheels and coverings will be 47.2Kg, 38.6kg, 32.7Kg and 26.8Kg respectively, accounting for about 70% of the total. It is estimated that by 2026, the penetration rate of aluminum alloys for body structural parts and covering parts will grow rapidly; the share of suspension components will also increase to 7%; the three electric components (such as battery boxes, motor shells, converter shells, BMS shells, etc.) will become the largest parts with aluminum increments; and the amount of aluminum used in vehicles will increase to 233.2Kg.
2.3.2 Aluminum alloy processing is divided into casting and deformation, and the die casting process is the most mature and efficient
The processing process of automotive aluminum alloy is divided into casting and deformation, and aluminum castings account for the highest proportion of automotive aluminum.
(1) Cast aluminum alloy: the aluminum alloy is heated to a molten state, which flows into the mold and is cooled into auto parts after being processed. Cast aluminum alloy has good thermal conductivity and corrosion resistance, taking into account the improvement of the performance of the car in longitudinal and transverse vibration. Cast aluminum alloy is widely used by car companies in engine cylinders, car rocker arms, wheel hubs, transmission housings and other positions with high durability requirements and more complex structures.
(2) Deformed aluminum alloy: Deformed aluminum alloy refers to an aluminum alloy that changes its organization and shape through stamping, bending, rolling, extrusion and other processes. In terms of applications, cast aluminum alloys are generally used for parts with more complex structures, and deformed aluminum alloys are suitable for automobile parts with simple structures and higher mechanical properties. According to the data of China Shipbuilding Industry Group, the actual proportion of various types of aluminum alloys in automobiles is 77% of cast aluminum, rolled products and extruded materials account for 10% each, and forging materials are the lowest, accounting for only 3%.
The deformation aluminum alloy has good mechanical properties but a limited range of applications, and it is impossible to complete the precision structural parts of the automobile. Automotive deformation aluminum alloy mainly includes forging, extrusion and rolling aluminum alloy, the three kinds of deformation aluminum alloy force method is different, the forming and performance are also different.
(1) Forged aluminum alloy has good quality and strong impact bearing capacity, which is used in rolls of large rolling mills, rotors of steam turbine generator sets, crankshafts and connecting rods of automobiles and tractors.
(2) Extruded aluminum alloy process is highly flexible, extruded aluminum profiles as body frame in addition to reducing weight, but also through the special structure of local parts to increase the strength of parts, but there are large waste losses, tool losses lead to high costs and other issues.
(3) Rolling is the main forming process of aluminum profiles and aluminum plates, mainly used in metal material profiles, plates and pipes. The deformation aluminum alloy has the advantages of high plasticity and good mechanical properties, but it cannot complete the precision structural parts of the automobile, and the application range of products is limited.
The casting aluminum alloy process is divided into two categories: sand casting and special casting, and special casting is more suitable for automotive aluminum alloy processing. Sand casting is the most traditional casting method for producing castings in sand molds, but the product accuracy is not high and the productivity is low; although the gravity casting that is further developed on its basis can further improve the problem, there are also problems that limit the volume of the casting and strictly control the mold temperature or it will affect the quality of the casting.
Therefore, the application of sand casting in automotive parts is not extensive. Casting processes other than sand casting are collectively referred to as special casting, including pressure casting, extrusion casting, centrifugal casting, continuous casting, etc. Among them, the pressure casting process is the most mature and efficient; the mechanical properties of extruded casting products are better than those of the general die casting process, which has the advantages of high utilization rate of liquid metal, simplified process and stable quality, but it is difficult to produce components with complex structures, affecting the scope of product application; while centrifugal and continuous casting product production is relatively fixed, centrifugal casting is generally used for the production of tubular instruments, and continuous casting is used to produce long castings with unchanged cross-sectional shape.
Die casting is one of the most mature and efficient manufacturing technologies in the casting process, accounting for more than 70% of automotive castings today. Die casting is a manufacturing process that uses high pressure to melt metal into a mold and cool the molding under pressure. According to the data analysis of the China Nonferrous Metal Processing Industry Association, die castings in automotive aluminum account for more than 70% of castings. Process advantages:
(1) When die casting, the metal liquid bears high pressure and has a fast flow rate;
(2) Good product quality, stable size and good interchangeability;
(3) High production efficiency, die casting mold use times;
(4) Suitable for mass production, good economic benefits.
Process disadvantages:
(1) The casting is easy to produce fine pores and shrinkage, resulting in low plasticity of the die casting, and it is not suitable for working under the condition of impact load and vibration;
(2) When high melting point alloy die casting, the life is low, which affects the expansion of die casting production. In order to solve the above shortcomings such as bubbles, die casting processes such as differential die casting and vacuum die casting are also constantly evolving and iterating.
Previously, the die-casting process was mainly used for engine cylinder heads and cylinder blocks, cantilever frames, transmissions, generator brackets, clutch shells, automotive air conditioning compressors, etc. At present, with the advancement of integrated and large-scale die-casting technology, it is gradually extended to the direction of large-scale three electrics and body structural parts
Third, integrated die casting leads the technological change, and process upgrading enhances industry barriers
3.1 Integrated Die Casting: A Disruptive Technological Revolution in Automotive Manufacturing
Traditional body manufacturing covers four major processes, and OEMs and parts manufacturers divide labor and cooperate. (1) Stamping: with the help of presses and molds to continuously stamp the plate into small sheet metal parts; (2) welding: the stamped body parts with a fixture positioning, the use of post-assembly welding method to form a body assembly (that is, the body in white) ;(3) spraying: spray paint on the body in white, play a role in corrosion prevention and decoration; (4) assembly: the body, power system, electronic control system, interior and exterior and other parts assembly and production as the whole vehicle.
The traditional body manufacturing process by the oem and parts manufacturers to complete the cooperation, stamping link is divided into the OEM stamping outer cover and external parts factory stamping structure components, because the size of the structural components in 300mm or less, generally using small and medium-sized presses, and the size of the covering parts is usually above 800mm requires large press continuous stamping. After the stamping process is completed, the parts manufacturer uses multiple robots to form a solder joint workshop for component welding, and then sends it to the automaker to weld the outer covering parts it produces into a body-in-white body, and then paints and finalizes. Compared with parts factories, the presses, molds and robots used in the production lines of OEMs are much higher than those used by parts factories, and the investment in production lines is also higher.
The demand for lightweighting has driven the application of aluminum alloys, and the traditional die-casting process has been improved in multiple paths. The demand for lightweight automobiles has driven some parts of the body and chassis to gradually replace steel parts with aluminum alloy parts, of which aluminum castings account for the highest proportion. The high-pressure die-casting process is a common process for the production of aluminum castings. It usually refers to the die-casting process with a pressure of 4~500MPa and a metal filling speed of 0.5-120m/s. High-pressure die-casting products have the advantages of precision molding and high production efficiency, but because the gas in the mold cavity cannot be effectively eliminated during high-speed injection, porosity defects will be formed, resulting in relatively weak mechanical properties of castings. In order to meet the performance and quality requirements of automotive components, the industry needs to solve the problems of traditional high-pressure die-casting processes, including three main technology upgrade paths: reducing pressure, reducing speed or reducing air content.
Path 1: Low pressure / differential die casting by reducing the filling pressure to improve the internal quality of the casting, the difficulty of equipment operation increases, and the process efficiency needs to be improved. In order to overcome the pore defect caused by the rapid filling of castings under high pressure, the industry began to try to reduce the pressure during the filling cavity and solidification of liquid metals, that is, low-pressure die casting. Low pressure using bottom injection type filling, metal liquid filling smooth, no splash phenomenon, can avoid the involvement of gas and the erosion of the mold wall and core, improve the pass rate of the casting, the casting formability is good, for the forming of large thin-walled castings is more favorable, is currently used in wheels, cylinder racks and other traditional products. However, some castings have high internal quality requirements, hoping to crystallize at a higher pressure, and the crystallization pressure of general low-pressure casting cannot be too large, so on the basis of low-pressure casting, differential die-casting has been developed. Compared with the general casting method, differential die casting increases the strength of the casting by about 25% and the elongation by about 50%; but the equipment is larger, the operation is troublesome, and it is only applied when there are special requirements, and is currently used in products such as steering knuckles.
Path two: Ultra-low speed die casting can reduce the process injection speed, but the production efficiency is greatly reduced, and it will bring difficulties to the subsequent cleaning work. In addition to reducing the pressure, it is also possible to use the ultra-low speed die casting method, on the basis of ordinary die casting, reduce the injection speed of the low-speed stage of the die casting process, and keep the liquid metal in a high pressure state, so as to fill the die casting mold cavity in a laminar flow manner, and quickly solidify under pressure to obtain a casting with a very low gas content. However, the production efficiency of the ultra-low speed die casting method is greatly reduced, and in order to reduce the speed, the gate in the casting is larger, which brings difficulties to the subsequent cleaning work, so the practical application is less.
Path three: vacuum/oxygenated die casting reduces the air content in the cavity, the equipment cost is high, and the process technology requirements are high. Another way to improve the mechanical properties and surface quality of castings is to continuously reduce the air content during the die casting process. At present, there are two processes in this method. (1) Vacuum die casting: Eliminate or significantly reduce the pores and dissolved gases in the die casting by removing the gas in the cavity of the die casting mold during the die casting process. Vacuum die casting can use alloys with lower specific pressure and poor casting performance, it is possible to die cast larger castings with small machines, and by improving filling conditions, die casting thinner castings. However, the mold sealing structure of the vacuum die casting process is complex, the manufacturing and installation are more difficult, so the cost is higher, and if the control is not right, the process effect is not very significant.
At present, vacuum die casting is used in frames, shock tower parts, etc. (2) Oxygen-filled die casting: before the injection, oxygen active gases are injected into the pressure chamber and the cavity to replace the air in the cavity, and when the metal is filled, part of the oxygen is eliminated, and the other part is chemically reacted with the spray metal liquid to produce metal oxides, and dispersed inside the casting, thereby reducing the gas content inside the casting. The oxygenation process has high requirements for gate speed, and the operation process is complex, the process parameters are not easy to control, and it is less used in actual production
The aluminum alloy welding process is difficult, and the integrated die casting technology has another way. With the continuous development and maturity of the die-casting process, the proportion of automotive aluminum die-casting is increasing. However, in the process of assembling and welding, because of the high melting point of the oxide layer on the surface of the aluminum alloy, the traditional melting welding has problems such as deformation, porosity, and low coefficient of welding joints caused by excessive heat input, and because the thickness and section of the profile are different, many combinations are produced during welding, especially when the thickness is very different, the heat input is very difficult to control.
Therefore, the traditional welding process can no longer meet the requirements of the connection of aluminum alloy materials. One of the solutions currently used is the development of advanced welding technology, including mainstream friction stir welding and more advanced laser welding. Or the development of new joining technologies including punching riveting technology, bolt self-tightening technology and gluing technology.
Solutions with new welding and joining technologies increase the difficulty of the process while increasing equipment and time costs. Therefore, the integrated die-casting technology that changes the traditional body production process to produce structural parts first and then weld and assemble came into being, and the number of production parts required for integrated die-casting has decreased sharply, while greatly reducing the welding and gluing links, which greatly simplifies the overall production process of the body. The Giga Press, an all-in-one die-casting device given in Tesla's patent, has a production cycle time range of 60-120 seconds, which can significantly improve the production efficiency of the body.
Tesla broke the game of body integration die casting, setting off a revolution in automobile manufacturing. On September 22, 2020, Tesla announced that its Model Y will use an integrated die-cast rear plate assembly that will reduce the weight of the assembly by 30% and reduce manufacturing costs by 40%. Due to the one-time die-casting molding of all parts, the number of parts of Model Y is reduced by 79 compared with Model 3, and the number of solder joints is reduced from about 700-800 to 50; the new alloy material makes tesla's one-piece die-casting back plate assembly no longer need to be heat treated, and the manufacturing time is reduced from 1-2 hours in the traditional process to 3-5 minutes, which can achieve direct supply in the factory, if the traditional stamping welding process must be multi-line in parallel to meet the production rhythm. In the next step, Tesla plans to replace the entire assembly of 370 parts with 2-3 large die castings, which will further reduce the weight by 10% and increase the corresponding mileage by 14%. The success of Model Y demonstrates the increase in production efficiency and the effective reduction of production costs brought about by integrated die casting. Under the leadership of Tesla, the new car-making forces represented by Wei Xiaoli have actively laid out integrated die-casting technology, which is expected to lead a new technological revolution in the automobile manufacturing industry
The lightweight potential of the new energy three-electric system is huge, and the lightweight of the battery box is an incremental field. With Tesla's successful breakthroughs and applications in body parts, the lightweighting of other systems and components is also accelerating. New energy vehicles using motor drive, the power transmission system is greatly optimized, the power source is provided by the on-board battery pack, the three-electric system leads to a new energy vehicle compared with the traditional fuel vehicle weight increased by 200-300kg, greatly affecting the mileage, so the new energy vehicle three electric system has great potential for lightweighting. After the battery energy density improvement gradually enters the bottleneck period, battery box lightweight has become an important technical path. In addition to the battery box to play a bearing role in the battery, it is also required to protect the battery cell from being damaged when it is hit or squeezed by the outside world, improve the safety of the power battery system, and on the other hand, it also has higher requirements for its thermal, conductive, waterproof and insulation performance. Therefore, with the continuous improvement of the penetration rate of new energy vehicles, lightweight battery boxes that meet various safety performance requirements are a new incremental market.
The current battery box production process efficiency is low, integrated die casting is expected to release the bottleneck of battery box production capacity, the current extrusion aluminum alloy process is the mainstream production scheme of the battery tray, the performance of the extruded aluminum alloy battery tray has high rigidity, vibration resistance, extrusion and impact and other properties, but also through the splicing and processing of profiles to meet different needs, with flexible design, convenient processing, easy to modify and other advantages.
However, the battery box has many and long weld beads, and at the same time requires the weld beads to be small, which puts forward very high requirements for production technology. Increasing production costs will also reduce the production efficiency of battery boxes, and cannot adapt to the rapidly increasing penetration rate of new energy vehicles. With the continuous breakthrough of large tonnage die casting machine process and new aluminum alloy materials, integrated die casting technology is expected to produce battery boxes that meet safety performance requirements. Referring to the production efficiency of Tesla Giga Press, the integrated die casting process has the potential to replace some of the traditional extrusion welding process capacity, helping the battery box break through the production capacity bottleneck while reducing production costs.
The continuous simplification of the internal structure of the battery pack is a trend, and the integrated die-cast battery box has broad prospects. At present, the structural trend of battery packs is evolving from the structural end to the moduleless solution. The most classic is the "small module" technology, that is, the "cell-module-PACK" three-layer hierarchical structure, the module can protect, support and integrate the battery cell, while helping to control the temperature, preventing thermal runaway propagation and easy maintenance. However, the existence of modules has reduced the space utilization rate of the entire battery pack, the more modules, the more parts, and the more complex the structure of the battery box.
Therefore, making the module bigger and smaller or even without modules is the main focus of the battery system process design level in recent years, and the large module of Tesla Model 3 also reflects this trend. According to the CATL era, CTP (cell to Pack) technology and BYD's blade battery technology are module-free solutions, according to the CATL era, CTP can eliminate or reduce the end plates, side plates and screws used to fix the module and other fasteners, the number of parts is reduced by about 40%, and the battery tray structure is further simplified.
Tesla's CTC (Cell to Chassis) battery integration solution is to integrate the battery cells directly inside the floor frame, and use the floor upper and lower plates as the battery housing. It is a further integration of the CTP program, completely using the upper and lower plates of the floor instead of the battery housing and cover, and the body floor and chassis integration design, fundamentally changed the installation form of the battery, but also for the integrated die-cast battery box to provide a broad application prospects.
3.2 Integrated die casting will comprehensively improve the financial and technical barriers in the production process
3.2.1 Industry characteristics: The automotive aluminum die casting industry has both capital and technology-intensive characteristics
Automotive aluminum die casting is a capital-intensive industry, and integrated die casting further raises the threshold. In order to ensure that the technical indicators such as precision, strength and machinability of the product reach a high level, automotive aluminum die-casting enterprises need to invest in smelting, die-casting, mold production, machining, precision testing and other processing equipment, and the upfront purchase cost is high.
In order to improve product quality and production efficiency, some leading enterprises in the industry continue to promote the strategy of automation and intelligence, and introduce industrial robots widely used in die casting, precision machining, deburring, polishing and other production processes to improve production efficiency, reduce production costs, improve working environment, streamline production labor, reduce defective rates and improve product quality stability, and put forward higher demand for enterprise funds.
Since 2021, large-scale and integrated die casting has further raised the purchase threshold of large die casting machines. The unit price of die casting machine is proportional to the tonnage: small and medium-sized die casting machines (clamping force of less than 50 tons) are below 150,000, the price of more than 100 tons rises synchronously with the clamping force, the price growth rate of more than 1000 tons is significantly accelerated, and the purchase amount of 5000T die casting island single machine is about 15 million-20 million yuan; the peripheral supporting equipment of the die casting machine usually increases by 20%-30% Of the cost; the price of foreign imported die casting machines is 2-3 times higher than that of China. The procurement and production of large-scale integrated die casting machines has greatly raised the capital threshold of the aluminum die casting industry.
The increase in the penetration rate of new energy drives the acceleration of demand, and the iterative upgrading of three-electric technology raises the technical threshold. With the rapid increase in the penetration rate of new energy vehicles, the mileage problem is an important driver for new energy vehicles to actively lay out lightweight technology. Tesla's first attempt to use integrated die-cast structural parts to select the rear baseplate for die-casting in the Model Y model is largely due to the small probability of collision damage in this part, and the front body and rear body parts have higher requirements for the impact resistance of the die-casting parts, and the consistency of the performance of the far and near cast ends is also more demanding, which puts forward higher challenges to the integrated die-casting technology of large body parts and even the whole body. According to the data of China Energy News, the three-electric system of new energy vehicles usually accounts for 30-40% of the total weight of new energy vehicles, and the lightweight of the three-electric system is the key path for new energy vehicles to achieve lightweight and improve endurance.
With the integrated design of the three-in-one system by the automaker, such as the high-voltage three-in-one (DC-DC DC conversion device, OBC vehicle charger, PDU high-voltage distribution box), the drive three-in-one (motor, motor controller, reducer), etc., the structure of the all-in-one device is becoming more and more complex, and the requirements for the structure, accuracy and performance of the aluminum die-casting housing suitable for the all-in-one device are becoming more and more stringent. Therefore, the use of integrated die-casting technology to produce structurally complex aluminum body structures, three-electric system cylinder blocks and housings requires more advanced processes and longer-term parameter accumulation to ensure the yield of castings. The increasing diversification and high standardization of new energy customer needs have promoted the technological differentiation and track competition of aluminum die-casting enterprises. The technical barriers in the automotive precision die casting industry are constantly increasing.
3.2.2 Raw material barriers: New aluminum alloy materials are the basis for integrated die casting
Large overlay complex structures increase flow requirements and reduce flow length amplification margin to offset remote performance degradation.
The body parts of the integrated die-casting usually have the characteristics of large size and complex structure, so the flow length of the aluminum liquid in the mold cavity during the die casting process is long, and the raw material needs to have good fluidity. At the same time, integrated die castings need to meet the different requirements of different parts of the body for force, strength and toughness. Strength-related structural parts, tensile strength is usually ≥ 210mpa, elongation ≥ 7%. The tensile strength of the structural parts related to toughness is usually ≥ 180mpa, and the elongation ≥ 10%; however, with the increase of flow length, the mechanical properties of the far end of the raw material filling will decrease, and even the near end of the filling will have a huge difference, and it is difficult to ensure the consistency of the mechanical properties of the product.
At present, on the one hand, on the basis of not changing the structural shape of the product, the mechanical properties of the filling end can be greatly improved by reducing the flow length. From the perspective of material improvement, the decline in mechanical properties of the far end of the filling can be offset by continuously improving the basic mechanical properties of the raw material, and the increasing size of the integrated die-casting product can be met by enlarging the performance margin of the raw material.
The properties of different series of aluminum alloys vary greatly, and the balance of fluidity and mechanical properties is the key barrier. Traditional automotive die-cast aluminum alloys include three main series: Al-Si, Al-Cu and Al-Mg.
(1) Al-Si alloy: The addition of Si elements can improve fluidity. Increasing the content of Si can improve the wear resistance, hardness and strength of the aluminum alloy, reduce the shrinkage, but also reduce the conductivity. Alloys containing 16 to 18 percent silicon can be used as engine blocks.
(2) Al-Cu alloy: Cu can improve the strength of the alloy through solid solution strengthening and aging strengthening, have a higher heat treatment strengthening effect and better thermal stability, suitable for casting parts used at high temperature, with higher mechanical properties, better machinability; but the disadvantage is that the casting performance is poor, easy to produce cracks, corrosion resistance is not good.
(3) Al-Mg alloy: magnesium in aluminum-magnesium alloy accounts for more than 5%, has good tensile strength and hardness, and has good corrosion resistance. Although different series of aluminum alloy materials are mature in application, the performance varies greatly. In order to ensure fluidity, the aluminum alloy applied to integrated die casting needs to retain a certain amount of silicon element, but the coarse crystalline silicon formed after die casting will seriously affect the mechanical properties of the material, which requires the addition of different other alloying elements to refine the grain. This in turn will increase the cost of materials, resulting in a significant increase in product costs, which cannot be used in batches. Existing mass-produced materials have patent barriers.
Heat treatment may reduce the yield of integrated products, and heat-free materials further enhance the technical content. Traditional aluminum die-cast body parts usually need to be heat treated to meet the high elongation performance, but as the size of the integrated casting becomes larger and larger, it is easy to deform when heat treatment, resulting in a decrease in yield rate, so it is necessary to develop heat-free aluminum alloy materials. Improving material properties by adding new trace elements to existing alloys or adjusting the proportion of trace elements is the mainstream path in the development of heat-free materials.
Tesla, Alcoa, Rhinefeld, Lizhong Group, Shuai Yichi Group, Huaren Express and Shanghai Jiaotong University have layouts. Taking the heat-free alloy developed by Lizhong Group as an example, the heat-free alloy contains a higher amount of silicon and can have higher strength without thermal processing. Tesla's self-developed new aluminum alloy material strength can be adjusted to 90MPa to 150Mpa, and the conductivity can reach 40% IACS to 60% IACS. Each company has strictly kept the ratio of new materials confidential, and once the new heat-free treatment material formula is successfully trial-produced and patented, it can form a first-mover advantage over competitors and further build competitive barriers.
3.2.3 Equipment barriers: Integrated die casting requires large-scale equipment and customized molds
Die casting machine is the core equipment of casting production, and the tonnage increases the difficulty of production.
Die casting machines are standardized machines that produce diverse parts and components depending on the molds installed. According to the process mode, the die casting machine is divided into hot chamber and cold chamber die casting machine, of which the hot chamber die casting machine has a high degree of automation, less material loss, and the production efficiency is higher than that of the cold chamber die casting machine, but it is limited by the heat resistance of the machine parts, and can only be used for the production of castings with low melting point materials such as zinc alloys and magnesium alloys, mainly used for the production of small aluminum and magnesium alloy die castings.
Due to the high melting point of the cold chamber die casting machine, the aluminum alloy die casting parts widely used today can only be produced on the cold chamber die casting machine, and the large die casting machine of more than 1000 tons is a cold chamber machine. After the die casting machine closes the mold, the high-temperature molten metal liquid is quickly filled into the mold by the pressure injection system, and the molten metal liquid is cooled under pressure, and the solid metal casting can be obtained after the mold is opened.
Die-casting machines, die-casting molds and supporting melting furnaces, side furnaces, collection and cleaning spray robots, cutting equipment, machining machine tools, testing equipment, cooling systems, exhaust systems and other peripheral equipment are combined to form a die-casting island. According to the clamping force, die casting machines are divided into small (160-400 tons), medium (400-1000 tons), large (more than 1000 tons) and very large (more than 5000 tons) die casting machines.
Integrated die casting requires a higher level of process, and the tonnage of die casting machines continues to break through and improve. At present, the mass-produced aluminum alloy monomer die-cast structural parts, such as rear longitudinal beams, shock absorption towers, tailgate inner plates and door frame reinforcement plates, etc., have regular shapes, compact structures, small profile changes, and relatively uniform material thickness, so they are easy to die-cast. However, the integrated die-casting parts include the rear wheel cover inner plate, the rear longitudinal beam, the floor connection plate, the reinforcing plate in the beam and other parts on the left and right sides of the vehicle, and the changes in the profile, section and material thickness are more intense. Therefore, the one-piece body has more stringent control over the flow state, injection ratio pressure and speed parameters in the process, and the precision and threshold of the equipment and the resistance to impact deformation ability of the mold are more demanding.
When producing castings such as transmission housings and engine blocks for passenger cars and commercial vehicles, the clamping force of die casting machines is roughly within 5,000 tons. With the continuous breakthrough of integrated die casting technology and the industry's demand for lightweight, the size of the body structure parts of integrated die casting has gradually increased, and the tonnage of the required die casting machine has increased accordingly.
Therefore, the large tonnage die casting machine required for the integrated die casting process is still an important factor restricting the mass production of the enterprise, but with the continuous breakthrough of the die casting machine, the problem is about to be solved. Taking Tesla as an example, the integrated die-casting technology has been laid out as a standard process, and 14 integrated die-casting equipment has been placed in four factories, of which the Texas factory plans to introduce 1 IDRA 8000-ton die-casting equipment, and IDRA jointly develops a 12,000-ton super die-casting machine.
Domestic large tonnage die casting machine has international competitiveness, die casting manufacturers actively layout large die casting machine. L&G Group took the lead in breaking through the 6,000 tons of clamping force of large die casting machines to become Tesla's global supplier, and its subsidiary Yidra delivered and undelivered 6000-9000T of different tonnage of super large die casting unit orders (sets); in April 2021, Meriture Technology & Haitian Metal 8800 tons of die casting machines debuted in the world, so that domestic large tonnage die casting equipment has a stronger international competitiveness.
At present, Wencan co., Ltd. and Lijin Group signed a "strategic cooperation agreement", intends to purchase 7 large die casting machines including 6000T, for the development and production of body structural parts, integrated battery box tray, motor housing, gearbox housing, etc., of which 6000T, 4500T models a total of 2 die casting machines have passed the company's pre-acceptance. Chervon Automobile Nanjing headquarters 2700T and 5000T die casting machine has entered the state of mass production, Ma'anshan production base will add 2000T, 2200T (two), 2700T (two), 3000T, 4000T, 4200T, 4400T, 6000T, 8000T each a large die casting equipment. Ecodi plans to purchase 45 die casting machines, including 35 die casting machines of more than 1000T, including 4 sets of 4400T, 2 sets of 6100T, and 2 sets of 8400T to meet the production needs of medium and large die casting products.
Integrated die casting raises mold barriers, resistance to pressure and surges in shape design requirements. Mold design and manufacturing is an important front-end process for the production of integrated die castings, with the improvement of die casting machine clamping force, the increase in the accuracy of integrated die castings and the "all-in-one" trend of die castings bring about an increase in design complexity, mold angle, hot runner and manufacturing molding difficulty increase, resulting in a surge in mold pressure resistance, and shape design requirements.
(1) Anti-pressure. The clamping force of integrated die casting is enhanced, the clamping force of the previous die casting machine is mostly below 5000t, with the continuous popularization of 6000t, 8000t and even 12000t die casting machine, the mold will withstand more pressure when working, resulting in damage. At the same time, when metal smelting and casting demoulding, the mold needs to withstand the influence of tensile force and thrust of various dimensions, which is easy to cause cracks and affect the service life of the mold.
(2) Shape design. Integrated die casting parts are often integrated die casting of multiple parts, such as the "all-in-one" shell of the Great Wall and BYD, so the mold volume is larger and the metal circulation channel is more complex. In the die casting process, the molten metal will flow in the mold, and as the mold structure is complicated, the molten metal is prone to not being sufficiently filled at the corners of the flow channel, causing defects, and it is more likely to produce bubbles that affect yield.
Domestic integrated die-casting molds are gradually developing to customization, and aluminum die-casting enterprises basically have the ability to develop molds themselves. There are differences in the size, space and structure of different models, resulting in integrated die castings cannot become the standard parts common to most car companies, and it is necessary to design separately according to different models and carry out customized development.
Due to the improvement of mold barriers, aluminum die casting enterprises have expanded the technical team to set up a separate subsidiary or department, strengthen the mold self-research and customized development capabilities, with the integration of die casting technology advancement, aluminum die casting enterprises continue to strengthen independent research and development, some leading enterprises have large and complex mold development capabilities, with first-mover advantages.
3.2.4 Process barriers: Integrated die casting manufacturers need to have both R & D capabilities and production experience accumulation
Provide product solutions for customer needs, and research and development capabilities have become an important competitive link. With the application of integrated die casting technology, because the structure of large-scale products of integrated die casting is more complex than that of small castings, the mechanical properties and required process parameters of different parts that need to be met may also vary greatly, so before the production of new products, die casting enterprises need to be deeply involved in the development and design process of integrated products for customer needs, that is, to participate in the design of the early stage of the product, according to customer needs and product requirements, the die casting process is targeted parameter optimization, mold design and technical transformation. It is necessary to go through a lot of testing and demonstration and optimization before passing the production approval process and finally entering the product manufacturing process. Whether there is the ability to develop independently or even develop simultaneously is an important evaluation criterion for automotive first-tier parts suppliers and OEMs to select suppliers. Product development is a process of joint research and development between customers and the company, and the company's technical research and development capabilities have become one of the core competitiveness, and it is also one of the important means to obtain orders.
The integrated die-casting process is complex, and the whole process operation elements ensure product quality. The trend of large-scale and structural complexity of integrated die-casting products has put forward higher requirements for the control of die-casting process parameters and production process management of enterprises.
(1) Alloy melting and treatment: in the process of melting, it is necessary to avoid metal impurity pollution, rapid melting should not be overheated at the same time, to prevent oxidation and segregation of metal liquid, oxides and hard inclusions have adverse effects on the casting performance and mechanical properties, but also need to control the melt loss, to ensure the high plasticity of the alloy.
(2) Feeding liquid (pouring) method: the molten metal liquid enters the mold from the injection port, because the structure is complex, the path through which the metal liquid needs to flow is different, and how to ensure the consistency of the performance of different parts of the die casting is the key to the integrated die casting process.
(3) Mold release agent spraying process: mold release agent or lubricant can produce gas into the casting, in the selection of mold release agent or lubricant, to be verified, the use of low gas and good volatility of the product.
(4) Die casting process: Die casting process is very important for the production of qualified automotive structural parts, the correct selection of injection mode, injection parameters, etc. is conducive to reducing defects in die castings. The performance of the die casting machine is stable, and it is necessary to have a flexible programming mode and a real-time control system to ensure that the entire die casting process is reasonable and the process parameter deviation is minimized.
The mold temperature should be precisely controlled, and the flow and temperature of each cooling circuit should be monitored through the cooling water distributor to form the required temperature distribution. At present, only a few of the manufacturers with traditional high-pressure die-casting production lines have mastered the die-casting process of integrated structural parts. It can be seen that the integrated die-casting process has a high technical threshold, and the industry pattern will be further concentrated to the head enterprises.
The requirements for product accuracy are constantly improving, and the importance of precision machining capabilities is highlighted. In addition to the high requirements of the melting of raw materials, transfer insulation and die casting molding, integrated die casting also puts forward new requirements for casting cleaning and casting post-processing. Die casting after molding needs to be cleaned of the casting, the product and the auxiliary molding of the runner exhaust plate slag pack separation, the use of impact, punching, sawing and other ways to achieve; casting post-processing refers to the use of casting burr grinding and other processes to ensure that the product meets customer requirements, through solid solution, aging treatment or separate aging treatment and other processes to improve the internal microstructure performance of the casting, through grinding, sandblasting, blasting and other processes to achieve the surface quality requirements of the casting. Due to the requirements of the pitch of the die casting process, the die casting process is limited by the precision of mold manufacturing and the specific processes of high-pressure die casting such as thermal deformation and demolding deformation, resulting in the dimensional accuracy and position accuracy of the casting may not meet the design requirements of the drawing.
In addition to meeting the mechanical strength and other properties, it is also necessary to strictly ensure the consistency of the product and the standardization of the assembly, so as to ensure the sealing performance of the three-electric system housing to avoid the failure of the three-electric system in some extreme temperature and high-pressure environments. Therefore, the casting blank needs to be precisely processed by precision machining equipment. With the structural upgrading of integrated die-casting products, the accuracy requirements of auto parts require enterprises to have higher machining capabilities.
3.3 Integrated die casting will comprehensively reduce the cost of production lines, welding, labor and batteries, and improve material utilization
Die-casting island is composed of die-casting machines and peripheral equipment, and the cost of Tesla's body-in-white integrated equipment is estimated to be about 300 million yuan. Die casting machine and melting furnace, cutting equipment, machining machine tools and other equipment combined to form a die casting island. From the perspective of Tesla's realization of the body integration die casting process, the industry currently generally follows the technical development idea of the first part and then the assembly, that is, to realize the integrated die casting of the lower body with relatively low difficulty, and then to realize the integrated die casting of the body assembly, and finally to realize the integrated die casting of the whole body, and it is expected that the maturity time of the integrated die casting technology from the part of the body to the body assembly will take 2-3 years.
According to tesla battery daily public information, Tesla has used 6000T die casting machine to achieve Model Y rear plate mass production, the price of a single set of die casting island is about 50 million yuan, according to the current technical stage, the existing die casting machine clamping force conditions need to use 2-3 die casting parts to achieve the integration of the car body die casting, until the technical level is relatively mature, the future industry may directly use a larger tonnage die casting machine to achieve a body assembly of one die casting molding. Taking the plan announced by Tesla Battery Day as an example, we believe that Tesla will use 3 6000-8000T die-casting machines for the car body, and 1 8000T die-casting machine may be used on the car body, and it is estimated that the current cost of die-casting island equipment required for the body-in-white car needs about 300 million yuan.
The all-aluminum die-cast body has a cost advantage over the traditional all-aluminum body, and it is expected to achieve further exploration with the maturity of technology in the future. Traditional fuel vehicles generally use steel welded body, with the continuous improvement of lightweight demand, steel and aluminum hybrid body and even all-aluminum body has become the choice of new energy vehicles.
Initially, Volkswagen, BMW and other car companies in the luxury model chose to try all-aluminum welded body, although the weight of the car significantly reduced but the production and maintenance costs are high, and then the car companies gradually from the all-aluminum welded body to the general use of steel and aluminum hybrid body. From the perspective of improving production efficiency, Tesla has developed integrated die-casting technology to save a lot of production and welding links, and to achieve a significant reduction in the manufacturing cost of some body parts. From the current stage of technological development, due to the large-scale die-casting technology has not yet matured, the current all-aluminum non-die-casting body cost > all-aluminum part of the integrated die-casting body cost > steel-aluminum mixed non-die-casting body cost > steel-aluminum mixed part of the integrated die-casting body cost > steel body cost, integrated die-casting full maturity still needs time, the future with the gradual upgrading of technical maturity gradually reduce the number of parts and welding links required, The cost of the all-aluminum integrated die-cast body will be further reduced as the number of die-casting parts increases and the solder joint decreases.
Integrated die casting will comprehensively reduce production line investment, welding costs, labor costs and battery costs, and improve material utilization.
(1) Reduce investment in production lines. Integrated die casting due to the increase in integration significantly reduced the number of parts required to produce, in the past the production of a single parts need to be invested in different production lines, integrated die casting can significantly reduce the number of production lines, equipment and molds.
(2) Reduce welding costs. The integrated die casting no longer requires a large number of welding/gluing processes due to the overall one-time molding, saving the process flow. At the same time, there are many welding and riveting processes after stamping, resulting in a large area of equipment, a long overall molding beat of a finished product, and integrated die casting can save site area.
(3) Save labor costs. Integrated die casting improves production efficiency, greatly increases the degree of automation of production lines and reduces the number of workers, resulting in lower overall labor costs.
(4) Reduce battery costs. Taking the common 100kwh battery as an example, assuming that the weight of the vehicle is reduced by 10% after using all-aluminum, the battery capacity can be reduced by about 10kwh. Calculated by the cost of lithium iron phosphate battery pack of 800 yuan / kwh, the integrated die-casting process can save battery cost of 8000 yuan or the same battery cost under the same endurance conditions to improve the mileage.
(5) Improve material utilization. Traditional stamping parts are welded from a variety of alloys, and raw material recovery is difficult and can only be sold as scrap. The aluminum alloy content of the aluminum alloy used in die castings is very high, and the material reuse degree can generally reach more than 95%, which is significantly higher than that of stamped parts.
Fourth, the leading car companies have entered the game, and the integrated die casting is in the ascendant
4.1 Volkswagen: The world's first to try all-aluminum bodywork, the next generation of SSP platform to introduce integrated die casting
Based on the research of space architecture technology, Volkswagen took the lead in mass production of all-aluminum body. Volkswagen is the first car company in the world to try to reduce weight, through the Audi Space Architecture Technology (ASF) to optimize the frame structure, and the application of ultra-high-strength materials in key parts, non-load-bearing parts of the use of lightweight materials to achieve the purpose of vehicle lightweight.
The Volkswagen Group has different market positioning and uses different lightweight materials: the luxury sports car Porsche uses carbon fiber and aluminum alloy materials in large quantities; luxury cars such as Audi use lightweight metals such as aluminum and magnesium alloys; and economy cars such as Santana use high-strength steel plates instead of traditional steel plates. Volkswagen's Audi is the world's first car company to achieve mass production of all-aluminum body, as early as 1982 Audi began to study the "highly aluminum car" project, in 1987 the first application of all-aluminum body technology Audi V8 mass production, 1993 Frankfurt Motor Show Audi A8 turned out, since then more than two decades gradually promoted all-aluminum body technology to other models.
Volkswagen's all-aluminum body is not only aluminum alloy, and the splicing between different materials makes the process more difficult. The body of the Audi A8 uses aluminum alloy, high-strength steel, carbon fiber and magnesium alloy, of which the body frame and key parts use aluminum alloy and high-strength steel, the rear of the car uses carbon fiber, and the magnesium alloy is used less. Aluminum alloys, high-strength steels, carbon fibers and magnesium alloys accounted for 58%, 40.5%, 1% and 0.5% respectively.
The application of a variety of materials means a change in the way of connection, the new generation of Audi A8 body connection methods reached 14, laser welding, resistance spot welding, friction stir welding, MAG welding and other 8 kinds of welding technology and hot melt self-tapping connection, crimp connection, riveting and other 6 kinds of connection technology. Early all-aluminium bodies failed to be rapidly promoted due to high manufacturing costs and 14 joining processes that made the process more difficult.
4.2 Tesla: Take the lead in launching integrated die casting, setting off a new revolution in automobile manufacturing
Tesla took the lead in mastering the integrated die casting technology and successfully reduced the weight of the model Y rear backplane. In September 2020, Tesla announced at Battery Day that the Model Y will use an integrated die-cast rear plate assembly, which replaces the traditional body "stamping + welding" process, through a single die-casting molding can reduce the weight of the body assembly by 30%, manufacturing costs can be reduced by 40%. Limited by the insufficient tonnage of the die-casting machine, Tesla was unable to die-cast the entire car body assembly at one time, and could only divide it into two front/rear bottom plates or three front/middle/rear bottom plates. At present, Tesla has been able to reduce 79 parts of the rear bottom plate through the die casting machine with a clamping force of 6000t, and the follow-up plan will be to replace all 370 parts of the lower body through 2-3 die castings, and the quality of the lower floor assembly will be further reduced by 10%. According to Tesla data, the model Y integrated die-cast body weight of 66kg, than the smaller size of the Model 3 in the same part of the same part of the light 10-20kg, the technological revolution brought about by the weight reduction effect is remarkable.
Integrated die casting can reduce solder joints and heat treatment time, reduce manufacturing costs and improve production efficiency. Integrated die casting technology can make Tesla Model Y body-in-white solder joints from 700-800 to 50, compared with the traditional "stamping + welding" process, it is expected that the Model Y integrated die-casting backplate reduces the complicated welding process and a large number of personnel, shortens the manufacturing time, reduces the complexity of the factory production line and the cost of post-maintenance. At the same time, the integrated die casting process no longer requires heat treatment compared with the traditional die casting process, tesla disclosed that the manufacturing time after using integrated die casting has been shortened from 1-2 hours to 3-5 minutes in traditional die casting, and the manufacturing cost and production efficiency have been further optimized.
After the successful trial production of the rear baseplate, Tesla purchased another 13 die casting machines to achieve integrated die casting of the front body and Cybertruck. In August 2020, Tesla's Fremant plant in California took the lead in using a 6000t die casting machine to successfully achieve mass production of the Model Y rear baseplate assembly. Since the maximum die casting volume of the 6000t die casting machine can only achieve the integrated die casting of the rear baseplate, Tesla decided to purchase another 13 6000t die casting machines from Lijin Group, of which 8 were put into the German factory and 3 were put into the Shanghai factory. In addition to the rear baseplate assembly, Tesla will also implement model Y front body integrated die casting at the Texas and Berlin plants. In March 2020, Tesla announced at its earnings conference that it had ordered an 8,000t die-casting machine to produce the Cybertruck backplane. According to Alex Avoigt, Tesla and Edera (a subsidiary of Lide) are jointly developing a 12,000t die casting machine for integrated die casting of the entire body in-white.
CTC technology uses the battery pack as a body structure to connect the front and rear backplates of the body, opening up a new direction of integrated die-casting. Battery pack technology has gone through three generations of traditional technology - CTP technology - CTC technology, and there are differences in space utilization and integration schemes. In 2020, Tesla Battery Day Musk proposed the battery package technology CTC (Cell to Chassis), canceling the pack design to directly install the battery cell or module on the body.
The second-generation battery pack packaging technology CTP integrates the battery itself before installing it on the body, while CTC technology directly uses the body baseplate as the battery cover. Specifically, Tesla mounts the seats directly on the battery cap and connects them to the integrated die-cast front and rear body floors. The technology will be used at the Berlin plant to produce the Model Y. CTC technology is another measure for Tesla to achieve car lightweight, and it is also a new direction for the development of integrated die casting. CATL also announced that it will propose highly integrated CTC battery technology in 2025
4.3 New car-making forces are quickly following suit, and traditional OEMs are on the eve of change
Nio ES8 creates an all-aluminum body and takes the lead in launching body integration. Integrated die casting has significant advantages in production efficiency and manufacturing cost, due to tesla's driving effect, the new domestic car manufacturing forces actively follow up the integrated die casting technology. Based on lightweight considerations, NIO has independently developed a lightweight all-aluminum body platform from the beginning of the car, and also uses high-performance aluminum on the most critical force transmission path and bearing parts of the body.
According to THERA official data, taking the NIO ES8 as an example, the white body weighs 335kg, which is nearly 40% lighter than the traditional steel body, and the aluminum rate used in the body is as high as 96.4%, which is the highest in the world. However, because the ES8 still uses the traditional aluminum die-casting process, 7 connection technologies are still required, including aluminum spot welding, riveting, gluing, laser welding, etc.
In addition to the body structure, NIO's chassis, powertrain and interior and exterior lightweight propulsion speed is faster, and the control arm, subframe, "three electric" housing and other basic aluminum materials are used. In October 2021, the company announced that it had successfully developed a heat-free material for manufacturing large die castings with Shuai Yi chi, and cooperated with Wencan to take the lead in adopting integrated die casting for the rear bottom plate structural parts.
Xiaopeng's independent research and development ideal is actively promoted, and the transition to integration is gradual. Xiaopeng and Ideal's integrated die casting process lags behind Tesla and Weilai, and is faster than domestic independent OEMs. The Xiaopeng P7 uses a high-strength steel and aluminum hybrid body, with a steel and aluminum alloy accounting for 60%, taking into account the needs of stiffness and lightweight, but actively transformed into integrated die casting in the second half of 2021. The company adopts the strategy of "two legs" walking, one is to use the integrated die casting scheme of Guangdong Hongtu in the Zhaoqing factory, and the other is to build the die casting island self-developed integrated die casting technology in the Wuhan factory.
In July 2021, Xiaopeng Wuhan factory project was officially launched, covering an area of about 1,500 mu, with a planned production capacity of 100,000 vehicles, and an annual output value of 30 billion yuan after reaching production. At the same time, the company announced that it will build an integrated die-casting process workshop, plan to introduce two 7300t die-casting machines, and gradually build more than one super-large die-casting island and automated production line. Ideal has adopted an aluminum die-casting process on the powertrain and chassis of the ideal ONE model, and the progress of the smaller Peng and Weilai in terms of body is slightly slower. At present, the company is actively cooperating with suppliers such as Wencan and plans to launch the integration of body structural parts in 2022.
Fifth, the wave of integrated die casting has arrived, and leading enterprises have set sail
5.1 Chervon Automobile: Based on the ingenuity of die casting, deep ploughing new energy bravely climbed the peak
The "2+N" expansion plan is in full swing, and new production capacity and new orders need to be released urgently. The company is a high-quality supplier of aluminum die-casting, heat exchange, engine and other traditional businesses are rising steadily, the transmission business benefits from the independent DCT transmission penetration rate increases rapidly, and the new energy business lays out new products and new projects around the "three electric systems". In 2021, new orders in the fields of pure electricity and hybrid will blossom at multiple points, and continue to break through by BYD, Great Wall, New Forces and other OEMs and international Tier 1 new energy parts orders such as ZF and Valeo to achieve revenue doubling. Limited by the pressure of capacity suppression and delivery, the company has repeatedly accelerated the construction of production capacity, the Ma'anshan plant was officially put into operation after the Spring Festival in 2022, and the European factory will be completed and put into operation in the second half of the year, while adding new production capacity of the Nanjing plant. It is expected that after all the factories reach production, the company's total output value will exceed 5.5 billion yuan, and the "2+N" expansion plan will greatly alleviate production capacity anxiety.
Attach importance to R & D to build technical barriers, 5000t integrated die casting order to achieve stable supply. The company attaches great importance to research and development for a long time and is firmly based on technology. In 2013, the company has a forward-looking layout of new energy auto parts and components, and has accumulated deep accumulation in the field of three electrics, and in 2020, the company keenly captured the trend of transformation of the aluminum die casting industry to large-scale and integration, and actively laid out integrated die casting. At present, 5,000 tons of integrated die casting orders have been stabilized, and 6,000 tons and 8,000 tons of die casting machines will be gradually put in place in the second half of the year. 2021Q1-Q3 The company's revenue and attributable net profit were 1.189 billion yuan and 101 million yuan respectively, an increase of 30.66% and 76.60% respectively year-on-year. The lightweight aluminum die-casting track ushered in the golden age of rising volume and price, and the company is expected to consolidate the moat with its core technical advantages and fully seize the opportunities for the development of the industry.
5.2 Wencan shares: leading the layout of body structural parts, integrated die casting to seize the opportunity
It is the first company in China to realize the integrated die casting of the body, and the die casting technology layout is comprehensive. Founded more than 20 years ago, Wencan Co., Ltd. is the leader of domestic high-pressure cast aluminum structural parts, headquartered in Huizhou, Guangdong Province, and has factories in Foshan, Guangdong, Nantong, Jiangsu and Tianjin. After the acquisition of the French Bailian Group in 2020, the full layout of the aluminum alloy high-pressure, low-pressure and gravity die-casting process was completed. In November 2021, the company took the lead in realizing the mass production of integrated die casting parts for the body of the body, and the terminal was equipped with Weilai Automobile, becoming the first company in China to have the integrated die casting technology of the body after Tesla, with a first-mover advantage. 2021Q1-Q3, the company's revenue of 2.965 billion yuan, an increase of 103.60% year-on-year, overseas epidemic and company integration dragged down the net profit attributable to the mother.
Customers, equipment and materials are leading in China, and integrated die casting technology has the advantage of being a first mover. The company's largest customer is the Volkswagen Group, and the remaining important customers cover Mercedes-Benz, Weilai, Tesla, etc., with CR5 accounting for 50.3% in 2020. With the continuous expansion of new customers and new projects, the proportion of CR5 continues to decrease. In 2020, the company carried out the equipment and research and development layout of the integrated die-casting track in advance, and purchased 6,000 tons of large-scale die-casting equipment, which has a strong first-mover advantage. In May 2021, it ordered seven large die-casting machines of 2800-6000T from Yidra, a subsidiary of Lijin Group, for the integrated die-casting production of body structural parts and battery boxes. In the same month, the 9000T die casting machine was purchased again and delivered in February 2022, aiming to achieve a more difficult all-in-one die casting technology. In terms of material and mold research and development, the company cooperates with Lizhong Group to develop heat-free alloys, self-made die casting machine molds below 6000T, and plans to complete 9000T mold self-production from January 2022. At present, the company's customers include Tesla, Weilai Automobile, Ideal Automobile and other new energy OEMs at home and abroad, seizing the opportunity in the integrated die-casting track.
5.3 Xusheng shares: Tesla's core suppliers, customer structure optimization and growth can be expected
Tesla three-electric system supplier, fundraising to break through the bottleneck of production capacity. As a leading aluminum die-casting supplier in China, the company mainly focuses on aluminum alloy parts for new energy vehicles. In 2014, the company signed a contract with Tesla to become a supplier of Tesla's three-electric system, and Tesla's sales revenue accounted for 40% of the company's total revenue in 2021H1. With the high prosperity of new energy and customers continuing to increase, in July 2021, the company issued no more than 1.35 billion convertible bonds to help the company break through the bottleneck of production capacity. Among them, 970 million yuan is used for high-performance aluminum alloy auto parts projects, and after production, 2.34 million new energy vehicle transmission system housing production capacity, 570,000 new energy vehicle battery system components production capacity and 500,000 new energy vehicle body parts production capacity will be added; 380 million yuan will be used for the precision processing project of automobile lightweight aluminum profiles, and the new energy vehicle transmission system housing production capacity will be 620,000 pieces and the new energy vehicle battery system component production capacity of 950,000 pieces after production. Benefiting from its global expansion and rapid volume increase, the company's performance continued to grow at a high level, with Q1-3 revenue (2.012 billion yuan, +82.10% year-on-year) and attributable (331 million yuan, +43.67% year-on-year) significantly better than the industry in 2021.
The continuous accumulation of technology has gradually upgraded to integration, and the optimization effect of customer structure is remarkable. The company continues to carry out technology research and development, becoming one of the few enterprises in China that has three kinds of aluminum alloy forming technology of die casting, forging and extrusion. With the trend of Tesla-led integrated die casting, the company, as a supplier of Tesla's three-power supply, is expected to upgrade product parts such as battery boxes to an integrated structure. In June 2021, Xusheng signed a strategic cooperation agreement with Haitian Metal to order a total of about 200 million yuan of die-casting island equipment from Haitian Metal in the next three years, covering 1300T-4500T, 6600T and 8800T, and jointly develop super-large die-casting machines for integrated die-casting. In addition, the company invested in the construction of automotive molds and core components research and development, manufacturing, production and processing projects in Huzhou, Zhejiang Province, further strengthening the company's die casting and mold and other supporting technologies. With the consolidation of the company's leading position and the construction of a comprehensive experience system in the core areas of lightweight aluminum alloy parts, the company's customer structure is also continuously optimized, expanding important customers including Great Wall Motors, Ningde Times, Yiwei Lithium Energy, etc., which will bring obvious performance flexibility to the company in the future.
5.4 Guangdong Hongtu: the first die-casting faucet in the domestic market share, to achieve integrated die-casting curve overtaking
The aluminum die-casting leader with the largest market share in China has opened up new opportunities for cooperation among new domestic forces. As a veteran aluminum die-casting leading enterprise, Guangdong Hongtu has a good technical foundation and customer reserves, and has long been in the first position of domestic market share. In 2021, H1's aluminum die-casting business accounted for 63.6% of revenue, and its main products include powertrain systems, transmission systems and new energy vehicle structural parts. In 2018, the company's revenue and net profit reached a peak, and then entered a period of transformation exploration, and the net profit margin was under pressure relative to the industry. In 2020, the company's new energy and high-tech business accounted for 21.78%, the newly developed new energy product projects accounted for 43% of life cycle sales, and the net profit of the year increased by 465% year-on-year. In Q1-3 2021, the company's revenue (43.49, +13.48% year-on-year), attributable to the mother (1.92, +147.75% year-on-year), continued to maintain performance growth. In 2021, Guangdong Hongtu will develop customers of domestic new forces such as Xiaopeng and Weilai, and carry out synchronous development and cooperation with Xiaopeng around integrated parts, bringing new growth opportunities to the company.
Layout of large die-casting equipment + self-developed heat-free alloy, the first to complete the super-large integrated aluminum die-casting structural parts. In the integrated layout, the company has independently developed high-strength, tough and heat-free aluminum alloy materials to provide a material basis for large-scale integrated die casting. In the first half of 2021, the company carried out the overall planning of a large-scale die-casting island of the "Structural Parts Integration Molding" project and purchased a 6800-ton die-casting equipment. In January 2022, the company's 6800 tons of ultra-large integrated aluminum alloy die-casting structural parts were successfully trial-produced, and the casting pouring value was about 100Kg, realizing the independent controllability of the ultra-large integrated die-casting technology. Taking this as an opportunity, the company started the research and development of key core lightweight components such as 12,000 tons of super intelligent die-casting units and integrated front cabin assembly, integrated rear floor assembly and integrated battery tray of new energy vehicles
5.5 Tuopu Group: platform-based parts leader, establish a one-stop solution
All-round product layout, experienced in the field of lightweight. Based on the original advantages in the NVH field, Tuopu Group continues to invest in research and development, and is committed to building a product matrix in five major areas: automotive shock absorption system, trim system, intelligent driving system, chassis lightweight system and thermal management system. With its high sensitivity and rapid response to market changes, the company has obtained a large number of orders from traditional and new domestic and foreign OEMs, including Tesla, BYD, Great Wall, Xiaopeng, SAIC, Changan and so on. Among them, in the field of lightweight, Tuopu has gradually established a one-stop lightweight solution, has a light alloy field of high pressure, vacuum die casting, low pressure, differential pressure, extrusion casting, forging of the six major processes, has been mass-produced product types covering chassis system, powertrain structural parts, battery pack structural parts, body structural parts and thermal management valve plate, etc., and can provide customers with customized lightweight services. With the ultra-high prosperity of new energy and the rapid release of car companies, in 2021, Q1-3 company achieved revenue of 7.823 billion yuan, +81.1% year-on-year, and net profit attributable to the mother reached 753 million, an increase of 94.4% year-on-year.
Integrated die casting R & D multi-pronged, the development process of industry-leading. In terms of materials, Tuopu Group cooperated with Huaren Express and Shanghai Jiao Tong University to successfully apply its jointly released TechCast high-strength and toughness heat-free aluminum alloy materials. The fluidity of the material is more than 15% higher than that of the same level of material, and the strong plastic product is more than 30%, which ensures that the performance of the vehicle collision and other properties reaches a higher dimension. In terms of equipment, the company signed a strategic agreement to purchase 21 sets of die-casting units, including 6 sets of 7200 tons, 10 sets of 4500 tons and 5 sets of 2000 tons of die-casting equipment, for the production and manufacture of super-large structural parts of new energy vehicles, such as front cabin, rear body and battery housing. In February 2022, Tuopu Group officially rolled off the production line of the 7200-ton integrated super large die-cast rear cabin for Huaren Express.
Investment advice
Driven by the "carbon neutrality" policy, the penetration rate of new energy vehicles in China has increased rapidly, and the penetration rate of new energy vehicles will reach 14.2% in 2021. With the sales of new energy vehicles exceeding expectations and the mileage anxiety highlighted, the automobile lightweight track showed a super high boom. As the current comprehensive and optimal lightweight solution, under the background of major breakthroughs in materials, equipment and processes, the technical barriers have gradually increased, and they have gradually upgraded to large-scale and integration. Integrated die casting is on the eve of the outbreak, the current penetration rate is low, and the future market space is vast.
With the continuous iterative landing of technology in Tesla, new car-making forces and traditional car companies, the industry is expected to rapidly increase its volume. Aluminum die casting plate after the early correction, the stock price has a margin of safety, 2022 is a big year for the integration of die casting to make substantial progress, we believe that we should pay attention to the integrated die casting business first aluminum die casting leading enterprises, recommended Chervon Automobile, Wencan shares, Guangdong Hongtu, Tuopu Group, it is recommended to pay attention to the active transformation of Xusheng shares, Ikodi, Rongtai shares.
This is a condensed excerpt from the report, the original text of the report:
"One of the Waves of Automotive Technology: Integrated Die Casting Gathering, The Emergence of a Lightweight Big Market"
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