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2023.2.23
At present, the reduction of automobile weight is mainly focused on the research of traditional processes and materials. Although non-metallic materials such as plastic and carbon fiber also account for a certain proportion, metal materials are still mainstream materials, such as iron, aluminum and magnesium. Especially at present, aluminum alloys and magnesium alloys and the casting process using them as raw materials have great weight reduction potential. As a technical expert in casting technology, GF Automotive Products Division develops and produces high-performance ductile iron, aluminum alloy and magnesium alloy castings.
At present, the castings developed and manufactured by GF mainly include steering knuckle, steering gear bracket, shock absorber bracket, spring bracket, wheel bracket, cylinder block, transmission housing, differential housing, seat frame and other lightweight parts, which are not only for the supply of passenger cars of BMW, Audi, Volvo, Chery Jaguar Land Rover, Volkswagen, DPCA, JAC and Dongfeng, but also for China National Heavy Truck, Shaanxi Automobile, Beiben Heavy Truck Dongfeng, FAW and other commercial vehicle brands also serve customers of components such as ThyssenKrupp and ZF. In addition, GF has developed a unique hollow crankshaft, aluminum/magnesium alloy door inner panel, etc., which has been verified by the market for many years and has confirmed its feasibility and reliability. At present, it is conducting preliminary cooperation with domestic customers. GF provides customers with whole-process services in terms of product design, materials, technology, testing and verification, and constantly develops a variety of innovative applications, serving many main engine manufacturers and parts suppliers in China and even the world
GF’s R&D technical team is good at using bionic design, combined with the best raw materials and efficient manufacturing process, and can be involved in the early stage of customer’s product development. Based on the comprehensive optimization of function, strength, fatigue life, NVH, tribology and feasibility, it provides the maximum possibility for 10% to 30% effective weight reduction.
For example, GJS 400-15 material was originally used for the steering knuckle of a passenger car main engine factory, with a mass of 4.39 kg. In the first stage, GF’s technical experts optimized the structure through bionic design, and achieved 22% weight reduction. In the second stage, GF applied appropriate materials (GF ductile iron patented material SiboDur ® 700-10) in combination with design optimization, another 10% weight reduction. GF’s technical experts combined high-performance materials to carry out bionic lightweight design, designed the optimal geometric structure in a limited space, and achieved highly integrated functions. This project also won the KoGlobe Green Sustainable Product Award. Similarly, GF’s technical experts have developed lightweight wheel mounts with Volkswagen. They also adopted SiboDur through a series of bionic design ® Spheroidal graphite cast iron material, the final weight reduction is 31%.
GF also has many successful applications in commercial vehicles. In Volvo’s 3P heavy trucks, GF uses EN GJS 500 6 material to design a variety of lightweight front end brackets; GF has also cooperated with CNHTC to develop a series of combined support products with a mass of 36~52 kg for many models. The materials used are EN GJS 500 and SiboDur ® 700, better performance and lighter weight; In the front end combined support of a heavy truck in another main engine factory, GF’s technical experts used their rich lightweight design experience to optimize the structure on the premise of ensuring performance, helping customers change this part from 41.1 kg to 33.9 kg, effectively reducing weight by 18%.
In response to customer needs and future development needs, based on the traditional ductile iron materials, GF has continuously innovated, successively developed austenitic ductile iron, high-temperature application ductile iron and solid solution solidified ferrite ductile iron materials, and also newly developed the patented SiboDur ® 、 SiMo1000 ® SiboDur, a ductile iron material with high tensile strength ® The ultimate elongation can reach about 17%. Several typical application cases mentioned above have also well illustrated SiboDur ® Function and performance in lightweight cast iron products.
In addition, GF also developed AluSiDur, a cast aluminum material with excellent ductility ® And AlSi10MnMg and other aluminum alloy materials with optimized process, so as to design and manufacture aluminum alloy castings with better performance and lighter weight for customers, especially creating more possibilities for lightweight of structural parts.
AluSiDur ® It is an aluminum alloy material with very high mechanical properties, which can provide high impact performance and low corrosion for parts, and is an excellent choice to further reduce the weight of the body in white. AluSiDur ® The typical applications of AlSi10MnMg and AlSi10MnMg are mainly body-in-white structural parts, such as shock absorber bracket, door inner frame, etc.
Chery Jaguar Land Rover is a model of aluminum alloy application. The proportion of its body aluminum alloy application is up to 75%, ranking first in domestic peers. Chery Jaguar Land Rover attaches great importance to the introduction of high-end materials. Its body innovatively uses a variety of advanced aluminum alloy materials of different series and different characteristics, which greatly reduces the weight of the whole body, but increases its stiffness by 20%. In the high rigidity shock absorber bracket developed in cooperation with GF, Chery Jaguar Land Rover has selected AlSi10MnMg aluminum alloy material. The whole shock absorber bracket is designed as a whole by modularization. Through the optimization of stiffeners and the integration of high-pressure die-casting process, its rigidity is much higher than that of traditional steel plate stamping and welding sheet metal parts. Its strength, corrosion resistance, connectivity and other aspects have excellent performance.
materials and structures on a variety of vehicles. Advanced high-strength steel and hot-formed steel are widely used in the body structure of the XC90, aluminum profiles are used in the front end of the front/rear bumper crossbeam and longitudinal beam, aluminum plates are used in the engine hood and fender, and high pressure cast aluminum technology is used in the front and rear shock absorber supports. This is a successful cooperation between Volvo and GF. AlSi10MnMg material not only brings lightweight, It also brings good connectivity – the connection between the shock absorber bracket and other components mainly adopts the composite connection method of structural adhesive and riveting, which brings the lowest assembly tolerance.
GF’s high pressure die casting technology is the world leader. Speaking of die casting, it can be said that it is the highest level of basic molding. At present, no other process can produce such precision parts in a single production step. Based on this, the application range of this process is quite wide. In the automobile manufacturing industry, the die-casting process is mainly used to manufacture various powertrain parts, chassis parts, instrument panel parts and body structural parts.
In one of Audi’s aluminum alloy shock absorber support components, the original one was a sheet metal assembly, with a total mass of 8.8 kg. After GF’s R&D and optimization, the shock absorber support was made of AlSi10MnMg material and high-pressure die-casting process, and the whole product was formed as a whole, which is a perfect example of “one casting product replacing 10 sheet metal assemblies”. Compared with the previous sheet metal parts, its mass is only 4.3 kg, and the weight reduction is up to 51%. It not only perfectly realizes the lightweight, but also saves the assembly process, and the product quality is greatly improved. In addition, through heat treatment, the product also fully achieved the required impact performance. At present, the shock absorber supports of Audi A6/A7/A8 series are made by die-casting process.
In the power battery shell provided by GF for Sanyo, the high-pressure die-casting process is also adopted. The mass of the battery shell made of AlMg5Si2Mn aluminum alloy material is only 16.7 kg, which is not only lightweight, but also superior in structural strength. Sanyo’s battery has been used in Volkswagen Golf GTE plug-in hybrid vehicles and Audi e-tron models.
Of course, the realization of a successful lightweight product is definitely not just a contribution from one aspect. GF usually provides customers with the best overall solution by combining lightweight design, the application of new materials and related technologies.
A typical case is that GF has brought considerable weight loss to a steering knuckle of Volkswagen. In this case, GF’s technical experts carried out detailed analysis and verification of the product from the selection of materials, to the function, strength and fatigue life of lightweight design structure, to the realization of casting technology, etc. Finally, GJS 450-10 solid solution solidified ferritic ductile iron material was used for this steering knuckle, which was optimized by bionic design, and not only achieved the lightweight effect, And all aspects of performance have been perfectly optimized.
For another example, GF provides die-cast aluminum alloy housing for ZF’s 6HP GWM transmission. In the early design, GF’s technical experts adopted the bionic design to optimize its structure. In terms of material selection, the product adopted AlSi9Cu3 aluminum alloy material. In the production process, GF modified the parting surface, improved the exhaust, and added the pre-casting process, greatly improving the solidification sequence of the entire die-casting process, ensuring that it can provide high-quality die-casting parts for ZF.
GF has also recently developed a unique hollow crankshaft, which has been successfully applied to a 4-cylinder 1.6L diesel engine in Europe. The original design of the engine crankshaft uses 38MnSV5 material with a mass of 12 kg, while GF’s innovative and improved solution is to use GJS CS800 material and unique hollow design, which reduces its mass by 22%. The final mass of this new hollow crankshaft is only 9.37 kg, and the weight reduction effect is very obvious. Moreover, its average stress and stress amplitude are much higher than that of traditional crankshaft, and the average stress value can reach 1.9~2.0.
The aluminum/magnesium alloy door assembly is another innovative application of GF. In this product, GF uses AlMg5Si2Mn aluminum alloy material as the door frame, MgAl5Mn magnesium alloy material as the window frame, and the riveting connection process, which makes the whole door inner panel lose 17% weight compared with the traditional sheet metal inner panel. GF has verified the feasibility and reliability of hollow crankshaft and aluminum/magnesium alloy door components through a large number of simulations and tests. At present, it is conducting preliminary cooperation with automobile manufacturers, and believes that it will bring new lightweight applications to more and more vehicles in the future.