Repairing and painting wheel rims is a common work process in bodywork and paint shops, due in large part to its location and continuous exposure in the body of a vehicle.
Kerbstones scrapes and scratches (especially on low wheel profiles), impacts from small stones or gravel, and different pollutants cause a deterioration of the paint coat used to protect and embellish the wheel rim.
The following tutorial will let us delve into the different methods there are to repair and paint wheel rims, describing the steps to follow to obtain a durable and quality repair.
Wheel rims are undoubtedly one of the parts of vehicles that have gained most importance and aesthetic presence in their bodywork over the years.
The eye-catching designs and large dimensions wheel rims are no longer merely associated with top-of-the-range models but are a common equipment option on standard vehicles.
Beyond their aesthetic function, let us not forget that the purpose of painting a wheel rim is to provide extra protection against rust or other pollutants.
The new designs and materials used in the manufacture of wheel rims also have an impact on the increased demand and complexity of the repair
Being an increasingly important item in the aesthetics of the vehicle, the number of requests for repair, customisation and painting of wheel rims has increased significantly.
How does the process of repairing and painting wheel rims differ from other work processes in the workshop?
The difference between this and other repairs in the bodywork and paint shop lies mainly in two areas the cleaning and preparation of the wheel rim, and its sanding.
Due to their exposure to all kinds of pollutants and dirt, such as grease, oil or dust, the use of specific cleaning products is required to ensure proper deep cleaning of the wheel rim.
On the other hand, due to the geometries, angles and nooks and crannies of most wheel rims, with little flat and regular surface, it seems essential that almost the entire sanding process takes place manually.
This involves increased work time and physical effort, in addition to the need to use of a correct sanding technique to avoid leaving marks.
Methods for painting wheel rims Spray or Spray Gun
In the bodywork and paint sector, there are two types of techniques for painting wheel rims: by spray or by spray gun.
Both methods provide a good final quality, so it will be the repair requirements what makes you choose one technique or the other.
Thus, in partial repairs it may be advisable to use the spray paint for wheel rims. This process offers advantages such as suppression of mixing preparation times and tool cleaning and the fact that they are not subject to catalyst times (in 1-component sprays).
An example of this specific type of product is URKI-LACan enamel that has been specially designed for painting wheel rims and that provides fast drying, high covering power, resistance to friction and to the washing tunnel.
The other method is the spray gun painting of wheel rims .
In this case, the repair process will be similar to that of painting any other part of the bodywork, and it will not be necessary to use additional products or tools.
In addition, by using a spray gun you will not have limitations on the colour formulation (although generally the predominant colour in this type of parts is silver).
Despite the increased working time in product preparation and equipment cleaning processes, spray painting of wheel rims can provide an extra measure of strength compared with the spray finish.
Which are the most common damages in this type of repair?
The work process to be used in repairing and painting wheel rims depends primarily on two aspects: the extent of the damage and the type of material.
The most common defects you can find are:
- Small material losses, mainly in the wheel rim profile.
- Scrapes, marks and scratches of varying depth.
- Discolouration and loss of gloss of the surface, due to atmospheric and environmental conditions.
The wheel rim repair and painting process will depend on two aspects: the extent of the damage and the type of material
As for the manufacturing material, in the automotive sector there are mainly two types of wheel rims: forged steel wheel rims, a standard type of wheel rim that provides strength and resistance, and aluminium alloy rim wheels, which add lightness and aesthetics to the vehicle’s bodywork.
Repairing and repainting steel wheel rims
Steel rims are still largely present on the roads today. Their steel composition provides strength and resistance to the part, and sometimes they can be covered by plastic hubcaps.
Painting steel wheel rims involves a repair process that is quite similar to that of other sheet metal parts of the vehicle. Therefore, this tutorial we will focus on a type of more complex and usual repair in the bodywork and paint shop : painting aluminium wheel rims.
Repairing and repainting aluminium wheel rims
As we have pointed out, aluminium wheel rims are increasingly used by users and manufacturers. However, their cost is also higher than that of steel wheel rims, so repairing is usually chosen over replacing the part.
Therefore, most bodywork and paint shops often have specific products and tools for repairing and repainting wheel rims.
Aluminium rims, not being as strong as those made of steel, can suffer further wear and tear over time, resulting in loss of gloss or colour, scratches, etc.
The aluminium wheel rim painting process aims to provide the part with the necessary resistance to withstand wear and tear from various mechanical or chemical agents, recovering the original our-of-factory appearance.
Let us now look at the steps to follow to carry out a complete process of repairing and painting aluminium wheel rims:
1. Disassembly of the wheel
Even though there are some repairs where it is not essential to remove the wheel from the vehicle, this will help you work more comfortably.
Place the wheel rim on a worktable at medium height and unscrew the wheel, separating the wheel rim from the tyre for a more efficient painting.
2. Prior cleaning
Use specific products to ensure a thorough cleaning of the entire wheel rim.
This step is essential for removing dirt and pollutants that have adhered to the surface and that may compromise the correct adherence of the paint coat.
3. Identification of damages
Carry out a detailed inspection of all the wheel rim’s damage and defects, in order to be certain of the kind of repair to undertake. If the defects are superficial, such as small material leaks or scratches, all you need to do is repair and paint the wheel rim.
On the other hand, if the damage is structural, such as deformations or cracks in the wheel rim, it is advisable to assess whether you have the right tools to repair this in the workshop.
Mask the tyre and the parts of the wheel rim that are not going to be painted, but that need to be protected from the sanding process or possible spraying.
Sand the flat and smooth areas to be repaired with an abrasive paper P150-P180 and eccentric-rotary sander. For hard-to-reach surfaces, sand manually with a block.
This sanding will remove surface defects and areas that have suffered material loss.
6. Cleaning and degreasing
Clean and degrease the dirt and dust generated by sanding.
7. Repairing with aluminium filler
Apply a polyester filler with aluminium content in the areas that have deep scratch damage or lack of material.
An excellent option for this type of filler is BESA-SILVER, which is a filler for filling dents, cracks, holes or splinters in steel, aluminium, galvanised steel and zinc coated substrates.
Then sand the filler with abrasive papers with grit range P150 – P320 depending on the type of repair to be carried out. Then blow and degrease the surface again.
8. Application of the primer
Mask the internal areas of the wheel rim, and of the rubber, to protect them from the spray paint.
Then sand the surface with a rotary orbital machine reaching the easily accessible areas (P400-P500 / orbit 3) and use manual sanding on the corners and nooks of the part. After this process, blow, clean and degrease the surface again.
9. Application of the finish
9.1 Spray painting of wheel rim
As noted above, if the type of repair requires so, spray paint the wheel rim.
Given the limited colour range of this application format, make sure the colour of the wheel is compatible with the chosen spray.
A very common colour shade is silver grey, which covers a wide range of repairs. Apply the spray on the surface, complying with the indications on the product’s technical data sheet.
Finally, apply a spray varnish to the wheel rim to give it the shine, durability and protection it needs.
9.2 Wheel rim painting with a spray gun
Choose the colour of the wheel rim to repair. For these types of formulations, the colour management software will be of great help to find the right colour shade.
There is also the possibility of using the spectrophotometer to ensure correct colour reproduction.Prepare the colour and apply to the wheel rim following the guidelines laid out in the technical data sheet.
Finally, prepare and gun spray a varnish that provides excellent performance in terms of gloss, extendibility and resistance.