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Today’s automotive industry wheels are usually made of aluminum rims. All kinds of good-looking wheels are precisely machined to improve their appearance. Forging, casting, lighting, painting, and other processes have improved the appearance and luxury of the car. The car’s wheels are constantly turning, sometimes cracking or hitting the curb, so they are easy to damage. The more luxurious and refined the model, the bigger the problem if the rim is damaged. This means car owners are willing to spend much money to repair the wheel hub. Does restoring it to use work? Is the operation complicated? It is said that in some cases, wheel repair also brings new potential risks. In this article, we will give detailed answers to the technical operation of the wheel hub.

Wheel rim damage and CNC repair 

Damage to aluminum wheels can be roughly divided into three categories depending on the cause and severity of the damage:

  • The first is friction against the road surface and curb when parking on the side of the road.
  • The second type, large deformation and distortion, is common when suddenly encountering large potholes or high ridges at high speed.
  • The third type, fracture, is common in cases of shock and impact at high speed.

Rim repair using CNC – notes 

The repair methods for these three situations are also different, and the effect varies from person to person. Even some repair cases introduce new risks: 

  • The first is the repair of surface wear, which is the most common situation. Since this does not affect the supporting structure of the hub, only the surface needs to be beautified. In practice, therefore, the first step is sandblasting and polishing. First, the hub must be matted and polished before refinishing. The primary method is to clean the wheel hub by sandblasting to create a good foundation for later cosmetics. 
  • The second step is polishing with sandpaper. After cleaning most of the hub by dust-free sandblasting, the next step is to re-polish the details with finer water sandpaper. 
  • The third step is to fill in the putty. After the wheel hub is sanded and leveled, the scratches are filled with aluminum putty. This step is easy to understand. It is the same as applying putty when painting a car sheet metal. The wheel hub is made of alloy putty, which is more complex and softer than the putty used for car sheet metal.
  • The fourth step is aluminum welding repair. This situation often occurs when the wear gap is slightly larger and the filling effect could be better. Aluminum welding will be used to fill and level aluminum alloys.
  • The fifth step is polishing. Since the filler often exceeds the original flat surface, the restoration must be polished so that the final metal remains approximately flat.
  • The sixth step is professional painting. After finishing, it’s time to paint. This step is similar to painting sheet metal in most workshops, but the difference is small. It is more about checking the color difference and the uniformity of the painting. 

Implementation of CNC for rim restoration 

The next steps are directly related to the use of a CNC machine for rim restoration: 

  • Step seven programming the lathe. However, due to the bright surface of the hub of some models, the brushing process must be polished. They must be machined on CNC machines. At this point, wonderful details such as correct curvature and spacing are required to ensure a satisfactory final tooth brushing result.
  • The eighth step is the CNC wire drawing. Once programmed, the hubs are precisely cut on the lathe to ensure the same finish. In addition, since this step reduces the thickness of the hub, it is not suitable for repeated repairs, as the rubbing of the hub’s support surface will greatly affect the effectiveness of its strength.
  • Step nine, nano metal protective paint. After the previous steps, the hub should also be sprayed with nano-metallic paint, which will be shinier after firing.
  • The tenth step is thorough polishing. Finally, the wheels are thoroughly polished for a more shiny effect. In addition to the second and third types of damage, due to changes in the structure of the hub, or even cracks, after repairing this situation, the strength and internal structure of the hub itself is less complete than before. This significantly impacts the safety, so it is not recommended to repair its carcass.


Renovating rims is a process that saves a lot of money and can restore the beauty and chic of our vehicles. Nevertheless, we should remember to outsource such a task to CNC machining centers aware of this type of processing, as it can only sometimes be done. If the main structure is permanently damaged, refinishing is not advisable. If, on the other hand, the damage is too insignificant parts of the rim, CNC machining can help save a lot of resources and restore the rims to perfect condition!