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How are wheel rims produced? There is a reason why high-quality wheel rims are sold at a higher price.

Wheel rims can definitely be considered one of the hottest topics in the car
modification community. Brands like BBS, APSPEED, OZ, and RAYS are all popular top-tier choices. However, not everyone who changes their wheel rims is solely pursuing performance; many also seek a balance between performance and cost-effectiveness. So, how should one choose the wheel rims for their car? Let’s start by understanding how wheel rims are produced.

Firstly, in terms of production processes, wheel rims can be divided into two main categories: casting and forging. Casting can further be categorized into gravity casting, low-pressure casting, and spinning casting. Currently, approximately 80% of aluminum alloy wheel rims on the market are produced using casting methods.

Production of Cast Wheel Rims

Representative models: Volkswagen Passat (low-pressure casting), Toyota Corolla (gravity casting)

Low-pressure casting refers to the process of injecting liquid alloy into the casting mold under low pressure. It is highly automated, has excellent stability and precision in the finished product, and has a short production cycle. It takes around 3 to 5 minutes to complete one wheel rim. However, due to the higher cost of molds and slower mold changes, it lacks flexibility. This production method is typically used for large-scale orders from automobile manufacturers.

After coming out of the casting mold, the wheel rim is placed in a nearby cooling tank for cooling. After cooling, it essentially possesses all the characteristics of a wheel rim, including the spokes, wheel frame, and some design details. Subsequently, it only requires additional heat treatment, refinement, and coating to complete the production process.

In contrast, gravity casting is considered more traditional compared to low-pressure casting. The ancient casting technique has been passed down to the present, which is a testament to its merits. Gravity casting generally refers to the process of pouring molten metal into the mold under the influence of Earth’s gravity, also known as gravity pouring. In the case of wheel rims, gravity casting involves pouring the prepared alloy liquid into the mold. The quality of the final formed wheel rim is highly dependent on the pouring process, as even small air pockets can potentially lead to wheel rim fractures.

Although it may seem similar to low-pressure casting, with both methods involving a “one-piece formation” approach, low-pressure casting has advantages in terms of stability and precision, while gravity casting excels in flexibility and cost-effectiveness. However, this traditional and ancient gravity casting technique is currently facing the trend of being replaced by low-pressure casting and forging processes.

Spinning casting, on the other hand, adds a spinning process on top of the two aforementioned methods. It is typically performed on the cast wheel rim blank and mainly involves rotating stamping of the wheel frame section. During this process, the wheel frame is heated, and a rotating cutter gradually stretches and thins the frame, reducing it from 15mm to 7mm. The metal molecules within the wheel frame become more tightly arranged, resulting in increased metal strength and reduced weight. For example, the casting wheel rim products from renowned brands like RAYS often utilize the spinning casting process, which is considered the main process for high-end casting wheel rims.

The wheel rims manufactured using spinning casting technology have achieved qualities, strength, and ductility comparable to forged wheel rims, and they are relatively easier to produce compared to forged ones. Although there may be some differences in weight, they have a greater advantage in terms of price. Some international major brands of cast wheel rims have also started adopting this manufacturing process.

The next process is called heat treatment, which, similar to steel, determines the various strengths of the wheel rims. Heat treatment involves heating, holding at a specific temperature, and then cooling to achieve the desired structure and performance. Different strength and toughness requirements require different heat treatment temperatures for control. After heat treatment, the wheel rims go through machining, cutting, coating, and other processes to become finished products.

The aristocrat of wheel rims is the forged wheel rim.

Representative models: Audi R8, Porsche Cayenne

Now that we have discussed cast wheel rims, let’s talk about forged wheel rims. When many people modify their wheel rims, they prefer to choose the forged process, even though forged wheel rims tend to be more expensive. So, how do forged wheel rims achieve higher strength and lighter weight?

Unlike the alloy liquid used in casting, the raw material for forging is an “aluminum billet.” The cut aluminum billet goes through a production line and enters the preheating process, where it is heated to 400°C to 500°C before entering the forging stage. It is worth mentioning that the larger the tonnage of the subsequent forging machine, the lower the preheating temperature required. Conversely, for smaller tonnages, the preheating temperature needs to be correspondingly higher.

Currently, there are two main methods of forging wheel rim internationally:

The first method is to directly forge the shape of the spokes by forging and pressing. This is the most commonly used method by top brands like BBS and RAYS for their forged wheel rims. The advantage of this method is that it achieves extremely high strength. However, it also leads to greater wear and tear on the forging dies and requires higher demands on forging equipment and processes. The forging machine directly forges the rough shape of the wheel rim through several forging and pressing operations, followed by spinning, heat treatment, and subsequent machining and coating to complete the production.

The second method involves using a forging machine to first forge a disc-shaped wheel rim blank, and then using machining to carve out the required spokes and design. However, for the rigid and enclosed structure of the forged blank, subsequent machining may cause damage to the molecular layers and release internal stress, resulting in lower rigidity compared to the first method. However, this production method allows for a wide variety of styles and more affordable prices. Currently, the majority of aftermarket forged wheel rims sold in the domestic modification market in China use this production process.

Since forging does not undergo the solid-liquid-solid phase transition, the forging process establishes a refined grain structure and improves the physical properties of the metal. Therefore, forged wheel rims have much higher rigidity compared to those produced by casting.

How to differentiate between forged and cast wheel rims when choosing a car?

Wheel Rim Identification:
Forged wheel rims usually have the word “FORGED” imprinted on them. However, it’s not excluded that some cast wheel rims may also have the same inscription to deceive buyers. It is important to pay attention and be vigilant.

Examining Wheel Rim Details:
Forged wheel rims generally have a smooth and shiny surface on both the front and back, exhibiting a good metallic luster. On the other hand, cast wheel rims may have a bright front surface, but the backside might appear darker with noticeable signs of mold release or burrs.

Tapping and Listening to the Sound:
Using a small metal rod, tap the wheel rim and listen to the sound it produces. Forged wheel rims will produce a clear and pleasant ringing sound, while cast wheel rims will produce a dull and low thud.

It’s worth noting that some cast wheel rims may undergo surface treatments to enhance their appearance and details, making them more challenging to differentiate. Therefore, the most reliable method is to confirm the wheel rim manufacturing process through wheel rim identification and purchase from reputable sources. If you specifically desire forged wheel rims, it’s recommended to choose authorized channels and well-known brands to ensure the authenticity of the forged wheel rims.

When it comes to replacing wheel rims, many people believe that forged rims are synonymous with high-end quality. However, in reality, cast wheel rims provide sufficient strength for most people’s needs. They are also relatively affordable and often undergo additional spinning processes, making them suitable for the majority of users looking for an upgrade. On the other hand, forged rims are more like “ironwork,” created by directly forging aluminum billets using forging machines. They offer significantly better strength compared to cast rims and are suitable for advanced players or car owners with strict aesthetic requirements.

The most important aspect of wheel rim selection is to understand your own needs and make an informed choice. There’s no need to blindly pursue original factory rims or forged rims just for the brand. Cast wheel rims already meet the requirements of the majority of people. It’s essential to have a clear understanding of your needs and choose accordingly without being swayed solely by brand names or marketing tactics.

 

 

Our factory , Ningbo Jianglu Auto parts Industry & trade Co.,LTD  have been professional in forged wheels for many years.  You can visit our website at this link https://jlwheels-manufacturer.com/products/gutchon-forged-wheels/  to get  more

style of forged wheels.

 

17 de diciembre de 2023