The Advantages and Disadvantages of Forging and Casting Process of Aluminum Alloy and Magnesium Alloy Wheels
Since the forging process of aluminum alloy wheels has been introduced to China, there has been a view in the industry, and it has been passed down to now that the forged aluminum alloy wheels will become the development direction of the wheel products, and will eventually completely replace the cast aluminum alloy wheels. However, judging from the production and operation practices of these three years of aluminum alloy wheels, we believe that the current two mainstream manufacturing processes should have no advantages and disadvantages, and only the difference between the market needs is not suitable. That is to say, we judge whether the choice of manufacturing process is appropriate, mainly depending on which market segment the sales of the aluminum alloy wheel products are to be positioned. Taking watches as an example, most people who like simple and low-key life will pay more attention to the precise timing, beautiful appearance and low price of the products when choosing watches. The brands of watches are often not demanding, so for this market segment. Features, watch manufacturers can only use mechanized, streamlined manufacturing processes for high-efficiency mass production, at the expense of personalization to achieve cost reduction, to meet consumer demand for "good quality and low price"; Others who like to exquisite and show off their work will pick expensive expensive mechanical watches that represent their "identity." Although they are far less accurate than quartz watches, everyone is still eager because of the timing function. Some people pay more attention to the “value” attached to the brand. Then manufacturers of such products will definitely choose traditional crafts to create personalized or even “limited edition” watches to meet the luxury goods. The needs of this part of the market consumer. So here you can't simply say that the traditional hand-made process is better than the mechanized assembly line process, or the mechanized assembly line process is higher than the manual process. Similarly, the aluminum alloy wheel product manufacturing process is also the same.
The current mainstream forming process of aluminum alloy automobile wheels is forging and casting according to the large category. Under the same conditions, the mechanical performance index of forged aluminum alloy (6061 alloy) wheels is better than that of cast aluminum alloy (A356.2 alloy) wheels. Therefore, the same structure, the same requirements of the wheel, the forging process of the 6061 material of the aluminum alloy wheel can be slightly lighter than the A356.2 material casting wheel, roughly statistics this weight difference is about 3 ~ 5%, but due to the process Limitations, the manufacturing cost of forged aluminum alloy wheels is currently much higher than cast aluminum wheels.
First of all, in terms of material costs. The processing cost of 6061 and A356 alloy materials on the market is almost the same, and the recycling price of waste scrap is the same. There is no difference between the two, but the current status of the aluminum wheel manufacturing plant using the forging process is the vast majority. There is no melting furnace and 6061 casting rod equipment, which means that the large amount of waste and waste wheels produced by the forging process line are sold at very low prices (80~90% of A00 price), while the casting process The production line itself is equipped with a melting furnace capable of recycling waste products. If the investment is increased, the aluminum chips are recycled. Therefore, for the production line of the casting process, the value of aluminum chips and scrap is equal to the raw materials. Melting avoids the huge loss of this piece.
Second, equipment investment. Before the equipment for forging of aluminum alloy wheel hubs was not domestically produced more than ten years ago, almost all the equipment for the production process needed to be imported. The huge investment was absolutely prohibitive. At that time, there were not a few production lines with an annual capacity of 200,000 to 300,000. Billion is not coming, even in the case that some domestic equipment is barely usable, the equipment investment of the forging production line is still very high. Compared with the foundry production line, the fixed assets investment per unit capacity should be two to three of the latter. More than double. Therefore, the depreciation expense in the cost of each product is naturally higher than that of the casting process.
Third, production efficiency. Due to the limitations of the process technology, the machining of the forged aluminum alloy wheel spokes and their windows is much higher than that of the cast aluminum alloy wheels for the same appearance of the product, even if the forging wheel is added during the forging process. Although the basic shape of the window and the spoke can be initially completed, the machining time of the machining process is also higher than two or three times that of the same casting wheel, and the more complex the wheel spoke shape is, the greater the difference. Therefore, in order to match the processing capability between the whole process of the forging production line, it is often necessary to equip the machining process with more CNC machining centers than the casting production line, so as not to cause the machining process to become a bottleneck when encountering a wheel shape with complicated window shape. However, when producing products with small spoke window processing, the processing capacity of these devices may be partially idle. The existence of these problems is determined by the characteristics of the forging process and will ultimately be reflected in the cost of the product.
Fourth, metal utilization. Above we mentioned that the machining capacity of forged aluminum alloy wheels is large, which means that the forged aluminum alloy wheel production line will produce a lot of metal chips in the machining process. Even if the aluminum chips can be recycled and reused, there will be 2 ~3% burnout and energy loss, the lower the metal utilization rate, the greater the energy consumption when burning and recycling aluminum scrap. This extra loss of forged aluminum alloy wheels will ultimately be reflected in the manufacturing cost of the product.
Therefore, based on the above reasons, when selecting the manufacturing process of aluminum alloy wheels, it is necessary to consider the preference of the inherent functions of the aluminum alloy wheels of different manufacturing processes in different market segments and the market's ability to withstand the cost of the products.
In recent years, the more and more aluminum alloy wheels have seized the market share of traditional steel wheels. On the one hand, it is very obvious because it has beautiful appearance, heat dissipation, light weight and uniformity compared with steel wheels. Advantages, on the other hand, with the development of the economy, the purchasing power of consumers has been greatly improved, and the effective demand for aluminum alloy wheels has increased. The definition of Demand in the textbook of Western Economics is such that, at a given price level, the number of goods that consumers are willing and able to purchase at a given price. So whether a product can generate demand, one must have the ability to make consumers want to buy, and the other is to have the cost that consumers can afford. Therefore, for the aluminum alloy wheel hub, only the combination of its inherent function and cost (price) can produce the greatest demand in its various market segments.
The market is expensive, and the market for aluminum alloy wheel products can be roughly divided into high, medium and low grades according to the different vehicles used. The following are the characteristics of the high, medium and low end markets of the wheel products. And the product manufacturing process suitable for different markets is analyzed one by one.
First, the high-end wheel market:
This market can be divided into the wheel market of competitive cars and the wheel market of top brand passenger cars.
The ultimate goal of a competitive car is to achieve good results, regardless of cost to achieve the goal, and the wheels of some high-end games are provided free of charge by sponsors, such as the World Formula One organized by the International Motor Sports Federation (FIA). The championship racing car, the wheel of our popular F1 car, is sponsored free of charge by our familiar manufacturers such as BBS, OZ Racing, RAYS and Enkei. Therefore, in this market segment, the requirements for the wheels are mainly high strength, light weight, good heat dissipation and high roundness. Since such products are often required to be replaced on time or in accordance with the schedule during the competition, these are For nearly one-off wheels, the appearance is beautiful, the wheels are not resistant to corrosion, etc. Basically, the aluminum alloy wheels commonly used in this market segment are basically made by forging process, and this market There are also magnesium alloy wheels and carbon fiber wheels, but the market is extremely small. It is negligible in the total amount of more than 300 million aluminum alloy wheels consumed every year in the world, so we don’t do too much. Exploring, just to understand it.
The wheel market for top brand passenger cars, which is the wheel market of our popular “luxury car” (a passenger car represented by brands such as Bugatti and Rolls Royce, which we know well), including OEM and A/M ( Aftermarket). The first purchase of the top "luxury car" consumers is not because of the strong practicality of the "luxury car" itself, they value the symbolic meaning of the "luxury car" brand: identity, status, quality of life and The higher the price of the car itself, the stronger the brand identity. Similarly, as an important appearance and safety part of the "luxury car", the wheel should also match the attribute of "luxury car", so the wheels of this market segment must be "expensive" and must be beautifully presented. As for whether the weight of the wheel itself is light or not, it is not a problem for consumers in this market. Therefore, in this market segment, as long as it can be recognized, the higher cost (6061 aluminum alloy) forging process and the relatively low cost (A356 aluminum alloy) casting process can be used, because the price of the wheel is sufficient to support any process. The manufacturing cost of the method, the difference is the level of profit margin. The OEMs in this market segment have little relationship with us for the time being. On the one hand, because the order volume is very small, on the other hand, this market is also monopolized by several wheel hub factories in Europe and America. We can only be in China at present. The after-sales market is entertaining and making a few “luxury car” wheels as a gimmick, making a sound for other market segments.
Second, the mid-end wheel market:
This market is actually what we usually call the "wheel market", which contains more than 90% of the entire automotive wheel market, divided into two markets: passenger wheels and commercial wheels.
(1) Passenger car wheel market: This market can also be subdivided into three high, medium and low markets according to the grades of the corresponding supporting and used passenger cars.
1. High-end passenger car wheel market:
High-end passenger cars are high-profile passenger cars that we see every day, such as Porsche, Maserati and "BBA" (Benz, BMW, Audi) and other brands of passenger cars at the same price. Buying a part of a high-end passenger car is the same as buying a top-class "luxury car" consumer. First of all, it is also a fancy to the functions attached to the high-end passenger car brand, and practical for the car itself. Sexual considerations ranked second; some consumers purchase high-end passenger cars in order to reduce corporate profits by increasing corporate expenses, to achieve the purpose of "enjoy" while avoiding tax (enterprise income tax), this part Consumers are generally non-state-owned business owners or managers with a high concentration of equity. The above two types of consumers choose high-end cars because they are worthy of the high price of high-end cars, so they can accept or not care about the high cost of the wheels, so the wheels of this market segment and the above top level Like the "luxury car" wheel, as long as it can be recognized by the OEM, forging and casting are all possible.
2. Middle and low-end passenger car wheel market:
The mid- to low-end passenger cars here refer to the sum of the mid-range configuration in the “BBA” brand and all the passenger cars below the other brands at the same price. The passenger cars in this range are passengers in mainland China. The main force in the car sales market accounts for more than 90% of the market share of passenger car sales in mainland China. The reason why we put the wheel market of mid-range and low-end cars together is mainly because the passenger cars in this grade range fully meet the basic characteristics of “rational people” in economics. “Rational people "A basic assumption that all economic theories must set in the course of research, also referred to as the "rational person" or "economic man" hypothesis, which is for all those engaged in economic activities in the economic society. A basic abstraction is that the economic behavior of every economically active person is trying to obtain his or her own maximum economic benefit at his own minimum economic cost. The consumer groups in the middle and low-end passenger car market are actually a group of normal “rational people” including ourselves (except for local readers). Their consumption logic is to pursue brand performance and price ratio, and is very sensitive to price. The main basic function of the car for this group is to travel. It is said that buying a car is used to go to work and buy food, and occasionally driving by car. This use determines that most of these cars are driving in urban areas, that is, low speed and frequent start. Stopping is the normal state of the vehicle, so for the aluminum alloy wheels on this type of vehicle, there is no chance to show any advantages such as light weight, energy saving, high thermal conductivity, good roundness and high comfort. Its function is almost indistinguishable from the steel wheel. Therefore, in this market segment, the consumer's requirements for the wheel can only be beautiful and reasonable. The so-called reasonable price is the price of the car, the wheel is slightly more expensive, but for the cheap car, the wheel must Not expensive (although the cost of aluminum alloy wheels in the same process is similar). Then, in the current mature manufacturing process, only the aluminum alloy casting process can be made to make the wheel both beautiful and reasonable, and the low-pressure casting in the casting process is easy to realize the lack of humanization or unmanned because of its high production efficiency. Operation, very suitable for the production of large quantities of small-scale OEM products; and another common gravity casting process in the casting process, due to low equipment cost and cheap casting molds, it is very suitable for the production of small-volume and multi-variety after-sales products. In particular, gravity casting and spinning processes are technically perfect, and their product quality is even better than that of low-pressure casting products of the same shape.
(II) Commercial vehicle wheel market: This market is divided into large commercial vehicle wheel market and light commercial vehicle wheel market according to the corresponding supporting and used commercial vehicles.
1. Large commercial vehicle wheel market:
This market can be further subdivided into the large passenger car wheel market and the large truck wheel market.
The main operating environment of large passenger cars is two, one is the city passenger transport, which is the bus; the other is long-distance passenger transport. The main characteristics of the city bus driving is low speed, frequent start and stop, so this determines that the requirements of the wheel in this market segment will not be too high. First, the heat dissipation of the tire is basically unnecessary; secondly, the comfort brought by the wheel Sex is not realized when driving in the city; as for the appearance of the wheel, the passengers who are in a hurry may be more concerned about whether the bus is quick and convenient; and the influence of the vehicle's energy consumption, the driving habits of the driver may be It is more influential than the aluminum wheel of the steel wheel. Therefore, in the market of bus wheels, low-pressure cast aluminum alloy wheels can fully meet the needs. If you want to further reduce costs, then steel wheels and decorative covers are the best choice. On the other hand, for large passenger cars that often travel on highways, it is very important and necessary to dissipate the heat of the tires and the dynamic balance of the wheels.
