Popular Science on Automotive Wheel Hub Knowledge

2024-09-25

Automobile wheel hub is a cylindrical metal part in the automobile tire that centers on the axle and is used to support the tire. Generally speaking, it is the part at the center of the wheel where the axle is installed. It is an important component connecting the brake drum (brake disc), wheel disc and half shaft. Here are some knowledge about automobile wheel hubs:

Types:
- Iron wheel hub: The manufacturing process is simple and the cost is relatively low. The metal has strong fatigue resistance, but the appearance is ugly, the weight is large, the inertial resistance is large, the heat dissipation performance is poor, and it is easy to rust and corrode.
- Casting wheel hub: Manufactured by casting process, it is divided into three types: gravity casting, low pressure casting and spinning casting. Gravity casting has a simple manufacturing process and low cost, but it is easy to produce bubbles and uneven density; low pressure casting has good formability, clear outline, uniform density, smooth surface, more evenly distributed internal molecules, fewer sand holes, high strength, moderate weight and controllable cost. The yield is more than 90%, which can meet complex and delicate shapes; spinning casting has higher mechanical performance than ordinary casting, manifested as higher strength and higher toughness. In addition, the spun rim has a thinner section, so the overall weight of the wheel rim is reduced.
- Forged wheel hub: A processing method that uses a thousand-ton forging press to apply pressure to a metal blank to make it undergo plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes. The advantages of forged wheel hubs are that they can eliminate casting porosity and other defects generated in the smelting process of metals, optimize the microstructure, have uniform density, smooth and detailed surface, thin wheel rim wall and light weight, the highest material strength and the best mechanical properties; the disadvantages are high production cost, low yield and high manufacturing cost.
Parameters:
- Diameter: Refers to the size of the wheel hub, in feet.
- Width: Refers to the distance between the flanges on both sides of the wheel hub, commonly known as "J value", in inches. The width of the wheel hub determines the width of the tire that can be installed.
- Offset: Refers to the distance from the center line of the wheel hub to the installation surface, in millimeters, also known as "ET". The smaller the offset, the more the installed wheel hub will protrude out of the vehicle. The offset determines whether the wheel hub will rub against the vehicle parts. If the offset of the new wheel hub is larger than that of the original wheel hub or the width is too large, there may be friction with the vehicle suspension system.
- Wheel hub pitch and hole position: The wheel hub pitch is also called "PCD", which is the diameter between the fixed bolts in the center of the wheel hub. Most wheel hubs have 5 bolts and 4 bolts in the hole position, but the distances between the bolts are also different.
- Center hole: Refers to the position where the wheel hub is fixedly connected to the vehicle.
Manufacturing materials:
- Steel: Commonly seen in some low-equipped models, it is cheap to manufacture, has a simple manufacturing process, is strong and durable, but it is heavy, has large sports inertia, is not conducive to the heat dissipation of the braking system, and the appearance is not beautiful.
- Aluminum alloy: Compared with steel wheel hubs, aluminum alloy wheel hubs are lighter, reducing the vehicle's overall weight, have diversified appearances and are more beautiful, are more conducive to the heat dissipation of the braking system, have smaller sports inertia, and have higher manufacturing precision. However, aluminum alloy wheel hubs are relatively expensive and not as strong as steel wheel hubs. The appearance is easily damaged by slight scratches.
- Magnesium alloy: Magnesium alloy wheel hubs are lighter and stronger than aluminum alloy wheel hubs, but the cost is also higher. Currently, they are less applied.
- Carbon fiber composite material: Carbon fiber composite material wheel hubs have the advantages of ultra-high temperature resistance, good fatigue resistance, small thermal expansion coefficient, good corrosion resistance, and good electromagnetic shielding performance. However, due to the high cost, it can only be seen on high-end racing cars at present.

When choosing an automobile wheel hub, you need to comprehensively consider according to your own needs and the characteristics of the vehicle. If you pay attention to appearance and performance, you can choose aluminum alloy or forged wheel hubs; if you pay attention to cost performance, you can choose casting wheel hubs. At the same time, you also need to pay attention to parameters such as the size, width, and offset of the wheel hub to ensure that it matches the vehicle.