One of the most common questions is whether it is possible to insert a rim covered with an old, well-adhering paint coat into an automatic rim shot blasting machine, and after a few minutes, remove the element completely free of paint and ready for painting.
When it comes to the regeneration of aluminum rims, it is worth separating two different processes: removal of the old coating and subsequent surface preparation.
Why are old coatings on rims difficult to remove?
Factory-made and properly applied paint coatings can have very good adhesion and high mechanical resistance.
You can, of course, increase the time and intensity of abrasive blasting. The problem, however, is that the abrasive affects not only the paint but, once it penetrates, also the underlying aluminum.
For thick steel components, aggressive shot blasting can be a huge advantage. Industrial shot blasters are used to rapidly remove rust, scale, and coatings from steel plates, profiles, and castings.
However, an aluminum rim is an element with completely different properties than a thick steel profile.
More power doesn't always mean better results
During long and intensive machining, the component receives a large amount of energy. The surface begins to heat up, and the abrasive continues to affect the exposed aluminum.
Therefore, when attempting to mechanically remove a very resistant coating, a point may be reached where further increasing the intensity of the process begins to deteriorate the surface faster than it brings benefits in removing paint residues.
In the case of aluminum, industrial shot blasting systems are specifically selected for a specific type of processing – including cleaning, surface finishing, deburring, and preparation for subsequent processes.
So why repaint?
Removing the old coating chemically allows you to perform a completely different task than shot blasting.
The chemistry is primarily intended to separate the coating from the aluminum.
Only later can abrasive blasting:
- remove small remnants of the coating,
- clean the surface,
- remove light deposits,
- level the structure,
- dull the aluminum,
- prepare the surface for the next technological process.
In this arrangement, each technology performs the task for which it is best suited.
What about small amounts of paint leftovers?
After stripping, individual pieces of coating may remain, especially in recesses, corners or hard-to-reach places.
Small residues can be removed during further surface preparation.
However, if a particularly resistant coating remains in one place, it is not always worth extending the entire automatic cycle just for that fragment.
Such a place can be corrected manually later.
Are there shot blasting machines capable of removing coatings?
Yes.
It should not be concluded that shot blasting technology itself cannot remove paint. Industrial shot blasting systems are also used for coating removal and can operate at very high energy levels.
The key question, however, is not:
„Can paint be removed by shot blasting?”
but:
„Is this the correct and cost-effective process for your specific aluminum wheel?”
Summary
In wheel rim regeneration technology, it is best to treat depainting and shot-blasting as two consecutive stages.
Refinishing removes the old coating.
Shot blasting prepares the surface for further work.
Trying to force one technology to perform both tasks can be less efficient, lengthen the process, and lead to unnecessarily aggressive aluminum processing.
Therefore, a customer considering the purchase of an automatic shot blasting machine should first consider what process they want to automate: the removal of the old coating itself or the preparation of the surface after its removal.