Classification and Characteristics of Aluminum Alloy Wheels Rims

With the increase in vehicle ownership, the demand for vehicle spare parts is also increasing. As decorative parts and safety parts, people is becoming more and more picky about the choice of wheels. A variety of differentiated and personalized wheels are becoming more and more popular, resulting in aluminum alloy wheels becoming popular products. Aluminum alloy wheels are widely applied to cars, trucks, buses and semi-trailers, etc.

According to the manufacturing process, aluminum alloy wheels can be divided into: low pressure casting aluminum alloy wheels and forged aluminum alloy wheels.

1. Low-pressure casting aluminum alloy wheel rims

Low-pressure casting is a casting process between pressure casting and gravity casting. Low pressure casting aluminum alloy wheels have many advantages, which can be summarized as follows:

1) The pouring process parameters of low-pressure casting are artificially controlled and can be determined according to different structures of castings and different materials of molds. During pouring, the alloy liquid is filled under the action of controllable pressure, which can effectively control the filling speed and make the alloy filling stable. Therefore, the tumbling, impact and splash of the alloy liquid during filling can be reduced or avoided, so as to reduce the formation of oxide slag, reduce or avoid the defects of castings and improve the quality of castings;

2) The mold filling of alloy liquid under pressure can improve the fluidity of alloy liquid and help to obtain castings with clear contour. It can be applied to castings with different wall thickness, different size, different height and different structure;

3)The casting crystallizes and solidifies under pressure, and can get sufficient feeding, so as to obtain a densely structured casting , and to improve the mechanical properties of the casting;

4) The utilization rate of metal is high and the production efficiency is high. The gating system of low－pressure casting mold is simple, and the riser can be greatly reduced or even completely eliminated;

5) It has the advantages of simple equipment, easy manufacture, less investment and less floor area, and is easy to realize mechanized and automatic production. One person can operate 2 ~ 4 low-pressure pouring machines at the same time. Due to the high degree of automation, it is conducive to the quality control of the production process;

6) The working conditions during pouring are improved. In the pouring process of low-pressure casting, the operator only needs to control the air valve or press the button, and the metal liquid is placed in the holding furnace, which reduces the heat radiation of high-temperature alloy liquid to human body and is conducive to the health of workers. Pressure pipes are water pipes that transport water from the pool, pressure forepool or surge chamber to the turbine, and are generally under pressure. 

It is characterized by concentrating most or all of the water heads of the hydropower station. In addition, the slope is steep, the internal water pressure is large, and it also bears the impact of hydrodynamic pressure (water hammer pressure). It is close to the power house. Once damaged, it will seriously threaten the safety of the power house. Therefore, pressure pipes are of special importance, and there are special requirements for its materials, design methods and processing technology.

2. Forged aluminum alloy wheel rims

In recent years, the growth rate of forged aluminum alloy wheels is much faster than that of casting wheel. Although the forged wheels have more production processes and higher production cost than casting, but it has higher cost performance. At present, the forging wheel forming method can be divided into the following three categories:

1) Casting forging method

It is a method in which castings are used as blanks in the forging process and subjected to plastic processing. Because forging is the final forming process of parts. Therefore, casting defects can be eliminated. The mechanical properties of the product are much higher than those of the casting by improving the structure of the product. At the same time, it gives full play to the advantages of casting technology in forming complex parts, so as to reduce the forging process of products with complex shape, reduce the material utilization rate, greatly improve the production cost and reduce the production cost.

The properties of aluminum wheels produced by casting forging technology can fully meet the mechanical properties of forgings, but the production cost can be reduced by 30% compared with ordinary forgings. At present, since the process was successfully applied to mass production in September 1996, it has been adopted by many Japanese companies with good economic results. There are some researches and applications in casting forging process in China.

2) Semi-solid die forging

The so-called semi-solid die forging is the process of heating the semi-solid blank to the semi-solid state with about 50% volume liquid phase, and then forming by die forging at one time to obtain the required finished parts close to the size. This is a new process between solid forming and liquid forming. Semi-solid die forging has many unique advantages. The shrinkage of parts in the die is small, easy to form, and the amount of machining is reduced. The surface of semi-solid die forgings is flat and smooth, the internal structure is dense, the grain is fine, the mechanical properties are higher than those of die casting and squeeze casting, the macro pores and micro porosity are much less than those in conventional castings, the forming temperature is low, and the die life is long.

3) Conventional forging method

Forging is one of the earlier forming processes for aluminum wheels. Forged aluminum wheels have the advantages of high strength, good corrosion resistance, accurate size and small processing capacity. Generally, its weight is only half or lower than that of steel wheel of the same size. The grain flow direction of forged aluminum wheel is consistent with the direction of stress. Its strength, toughness and fatigue strength are significantly better than those of casting aluminum wheels.

At the same time, the performance of forged aluminum wheels has good reproducibility, almost every wheel has the same mechanical properties. The typical elongation of forged aluminum wheel is 12% ~ 17%, so it can well absorb the vibration and stress of the road. Generally, casting wheels have a strong ability to withstand compressive force, but the ability to withstand impact shear and tensile load is far less than that of forged aluminum wheels.

From: China spvTime

Translated by; WONDEE Autoparts

2021/12/3