Underbody Coating

UNDERBODY COATING PROCESS

During operation, a mixture of resin, binder, & a paste containing the pigments is fed into the ED tank. The automobile body is lowered into the tank, & an electric current applied; the solution in the tank consists of 80-90% deionised water & 10-20% paint solids.

The resin is the backbone of the final paint film & provides corrosion protection, durability, & toughness. Pigments are used to provide color & gloss. After E-coat, the automobile body enters a bake oven, in which heating & keeping at a temperature of 160_C for 10 min causes film curing to promote maximum performance properties. The oven temperature & heating time primarily enchance chip resistance & film adhesion to the body; corrosion protected is affected less by these conditions.

Because surface roughness influences the smoothness & brilliance of the topcoat, some sanding of the surface is usually performed to remove or eliminate defects before the body enters the next application step.

A common challenge in the cureent E-coating process is that of water spots that contaminate coated surfaces. If water spots are present, they have removed ny sanding. Hence, it is necessary to use well-deionoised water & routinely monitor its conductivity.

1. Primer Coating

It can be water-borne, solvent-borne, or a powder. The primer fills & smoothes minor imperfections & scratches that may be created during prior steps & by the intermediate sanding or grinding used to remove small imperfections.

It also provides additional protection against corrosion & maximizes adhesion between it & the E-coat & basecoat; thereby, the primer incrases paint durability. Primer coating operations in an automobile assembly plant are usually implemented in three stages: Interior coating, Exterior coating, & then cutting in an oven.

Manual spray painting is used for the interior coating of the doors, engine compartment, & luggage or trunk space. Some of the areas are not sprayed with basecoat. It is important that are primer color matches the basecoat to be able to impart uniform coating appearances between interior & exterior coats.

Coating Perfomance:-

The performance of an automotive coating can be accessed from different views, e.g., the durability of the exterior & interior paint finishes or the aesthetic features. However, limitations exist on the paint properties, process capabilities, & most importantly, the amount of money that can be spent to improve the finish. Consequently, each automotive company define its color & appearance standards, which are to meet or exceed the levels reached by competitors & customers expectations. For checking of coating performance we consider some features like: a)

Coating Quality:

It can be judged on three main criteria: protection against harsh environment; durability; & appearance quality. b)

Color:

Uniform & consistent color is essential to achieve the impression of a high-quality finish & avoid customer complaints. This issue is important not only at the time of purchase but also at the time of purchase but also throughout the lifetime of a vehicle. Factors that influence color tone are pigment orientation & concentration. c)

Corrosion Protection:

Automobile coatings are subjected to a number of different environments & situations during their service life. Degradation of the coating depends on three main factors: coating formula, the intensities of the environments or situation, & their duration. Exposure to UV from the sun, heat, & humidity has a long term deleterious effect with different degrees of intensity depending on the climate & weather conditions.