Why are castings beneficial in automotive applications?

Squeeze casting technology is an advanced forming technology that combines casting and forging. Liquid metal is formed and solidified under high pressure or accompanied by slight plastic deformation, which can eliminate defects such as shrinkage cavities and looseness inside the casting. The casting has a fine structure and the mechanical properties can be greatly improved through heat treatment, approaching or equivalent to the level of die forgings. It is a light metal near-net casting forming process with good application prospects.

With the development of new energy vehicles and the need for lightweight vehicles, the application of advanced squeeze-casting technology in automotive structural parts will become more and more extensive. For example, chassis parts such as control rods, swing rods, connecting rods, engine brackets, wheel brackets, etc. have been partially made of aluminum alloy materials. Replacing some forging to produce high-performance complex structural parts, replacing low-pressure and differential pressure casting, and metal mold gravity casting to produce those structural parts with high-reliability requirements has become the preferred trend for automobiles in the future.

1, Squeeze casting technology

Aluminum alloys are usually divided into cast aluminum alloys and forged aluminum alloys, and cast aluminum alloys are divided into aluminum silicon, aluminum copper, aluminum magnesium and aluminum zinc, etc. Forged aluminum alloys are divided into many series, such as 2 series, 6 series, 7 series, etc. Although some of these alloys have similar compositions, their performance and process performance vary greatly. Some can be further strengthened by heat treatment, and some are difficult to cast. How to correctly select aluminum alloy materials suitable for extrusion casting production can not only meet the use requirements, but also meet the extrusion casting process requirements. This is also the premise and guarantee for obtaining high-quality castings.

The parts produced by the extrusion casting process should first be structurally suitable for the process requirements of extrusion casting. Due to the low filling speed of the extrusion casting alloy liquid, the average wall thickness is usually greater than 6 mm, and the local minimum wall thickness is not less than 3 mm, otherwise it will be difficult to form.

2, Design of extrusion casting mold

The parting surface has a great influence on the formability, precision and quality of the casting. Once the parting surface is determined, the mold structure is basically finalized. Therefore, the selection of the parting surface is very important. All parts are formed in the fixed mold, and the large end face is located on the parting surface. The advantages are that it is easy to exhaust, set up the overflow system, and set up the push rod. The disadvantage is that the forming process is a long distance for the liquid flow. By relative comparison, using fixed mold molding is the most optimized and ideal solution in product design and production.

During the casting process, when the maximum wall thickness of the workpiece is 6-20 mm, the effective thickness of the material handle is 25-30 mm; when the maximum wall thickness of the workpiece is greater than 20 mm and less than 50 mm, the effective thickness of the material handle is selected between 40-60 mm. Through heat exchange cooling with the mold, the mold absorbs the heat brought by the high-temperature molten metal, and at the same time dissipates heat through space and the die-casting machine. The temperature of the mold cavity will change greatly. During aluminum alloy extrusion casting, the mold cavity temperature fluctuates up and down by about 300 ℃. Maintain the mold temperature basically constant. The main function of the cooling system: to make the mold reach a better thermal balance state and improve the sequential solidification conditions of the extrusion casting, improve the internal quality and surface quality of the casting, stabilize the dimensional accuracy of the casting, and increase the service life of the mold.

3, Advantages in Automotive Applications

Complex Shapes

Casting is ideal for producing parts with complex geometries, such as control rods and swing rods. These components are essential for the steering and suspension systems of vehicles, requiring precise shapes to function effectively. The casting process allows for intricate designs to be created with tight tolerances, ensuring that control rods and swing rods fit perfectly within their respective systems. This precision is crucial for maintaining vehicle stability, handling, and safety.

High-Stress Components

Components like connecting rods and engine mounts are subjected to high levels of stress and vibration. Connecting rods, which link the piston to the crankshaft, must withstand the intense forces generated during engine operation. Engine mounts, on the other hand, are responsible for holding the engine in place while absorbing vibrations and shocks.

Casting allows for the use of strong, durable materials, such as alloyed steels and aluminum alloys, which provide the necessary strength for these components. The uniform grain structure achieved during the casting process enhances the durability of connecting rods and engine mounts, ensuring they can handle the rigors of automotive performance without failing prematurely.

Effective Production

Casting is a cost-effective manufacturing method, especially for producing parts like wheel brackets, which are needed in large quantities. The ability to create multiple parts in a single mold significantly reduces production costs. Additionally, casting minimizes material waste, further enhancing cost efficiency.

For wheel brackets, which support the wheels and bear the vehicle’s weight, casting ensures that these components are produced economically without sacrificing quality. This cost-effectiveness is particularly beneficial in the automotive industry, where controlling production costs is critical to maintaining competitive pricing.

Lifespans

This versatility in material selection ensures that each part is optimized for its specific application, contributing to the overall performance and reliability of the vehicle. For example, control rods and swing rods may be cast from lightweight aluminum alloys to reduce vehicle weight and improve fuel efficiency, while connecting rods and engine mounts may require stronger materials like cast iron or steel to handle higher stresses. Casting enables the production of components with excellent wear resistance, which is essential for extending the lifespan of these parts. By using materials that offer superior hardness and durability, cast components can withstand prolonged exposure to friction and stress, reducing the need for frequent replacements.