Underbody Coating

UNDERBODY COATING

• In Indian road conditions a car underbody is most prone to corrosion because of the exposure to the muddy water, potholed road, stones and other obstruct on the road. So, the Underbody coating provides long term protection from corrosion to car’s underbody. It also protects parts like internal body panels frames rails and other inner cavities that are not physically accessible but are prone to corrosion.
• The under-body protection coating is used to protect the vehicle chassis from external environment. So that the under-body protection coating is used to ensure the integrity and safety of car chassis and other parts from the corrosion, because of the importance of the under-body protection coating the car manufacturing company have shown their improvements on their thickness of under-body protection coating.

MODERN AUTOMOTIVE COATING PROCESS:

The modern automotive coating consists of five steps they are

1. PRETREATMENT:

The first sequence in preparing the BIW for subsequent coating is pretreatment. Pretreatment removes & clean excess metal & forms an appropriate surface structure enabling bonding of a corrosion protection layer. It consists of cleaning the body surface to remove remaining oils from the steaming process & welding residues through three primary liquid dip processes of degreasing, conditioning, & phosphating.

2. ELETRODEPOSITION:

Second step is electrodeposition (ED) of the anti-corrosion or rust prevention layer. E-coating involves dipping automobile bodies into the coating solution & passing an electric current through the body & the liquid ED paint solution. Because of the charged nature of this coating process, the ED paint penetrates into places a spray would not reach.

3. RUST-PROOF MATERIALS (SEALER/PVC):

The third step is underbody coating & seam sealing using PVC. Fig.4 displays the lower door sections & rocker panel locations where PVC or urethanes are applied as an anti-chipping protection, & shows the cross section of this layer with respect to the other coatings on the body parts.

During this third step, it is also typical to apply a soft tip primer coat that improves the chipping resistance. This layer is applied to the front edge of the hood, which is an area prone to chipping shock, using a high elastic resin that resides between the ED & primer coats. Also, during the third step, the radiator supports, wheel housing, & under rare areas of the body are coated with a relatively dull black pigment called a blackout coating.

4. PRIMER:

The fourth coating step is the primer. It can be water-borne, solvent-borne, or a powder. The primer fills & smoothest 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 increases paint durability.

5. TOPCOAT:

The final step in the body coating process is to apply the topcoat, which consists of two layers the basecoat & clearcoat.

1. Basecoat: It contains the primary colouring pigments. As part of the topcoat, the basecoat is third layer added to the car after the primer & before the clearcoat.
2. Clearcoat: The final coating on an automobile surface is the clearcoat it provides durability, environmental etch, & scratch resistance to the overall coating.

TYPES OF UNDERBODY COATING:

The Under-body coating are categorised into various types based on the type of material used and also the cost of the material.

1. Rubberized Undercoating

Rubberized vehicle undercoating is easy to apply and offers sound-cushioning as well as protection from dust, moisture, and dings or dents.

In addition to your undercarriage, rubberized undercoating is also safe to use on wheel wells and quarter panels, and dries to a soft rubbery finish that prevents further rust, damage, or moisture seeps. The coating can be painted over and, if necessary, for bodywork, can be easily removed with an undercoating removal spray.

Overall, rubberized coating is generally the best option for protecting your vehicle's undercarriage, as it provides the simplest and best protective measures against rust and moisture.

2. Polyurethane Undercoating

The other option for undercoating your vehicle is to use a polyurethane based sealant. This type of vehicle undercoating is a little bit quicker and easier to apply.

Oftentimes, polyurethane undercoating will come in canisters ready to preload into an application gun. This type of sealant works by seeping into all cracks and seams, displacing salt and moisture and oozing around rusty areas to bond with and protect unoxidized metal. It also sands quickly in case you'll need to perform bodywork and can be painted over.

On the flipside, this type of car undercoating generally requires a little bit more surface prep work before applying sanding and applying an etching primer to bare metals before using are generally recommended.

3. Wax or Paraffin-Based Undercoating

A paraffin-based undercoating will be the cheapest and quickest option available with which to protect the undercarriage of your vehicle. However, keep in mind that it will wear off quicker than other types of undercoating and will need to be stripped and reapplied at least once every year.

Wax-based undercoating’s never truly harden. During application, they drip or flow into seams and cracks to provide protective properties. They are usually available in a spray gun canister or in an aerosol can and offer at least a base protection in moderately humid climates.

4. Asphalt-Based Undercoating

For standard vehicles, any of the aforementioned types of undercoating will provide sufficient protection. For large trucks and heavy machinery, asphalt-based undercoating provides a bit of extra durability against rocks, chips, and moisture.

Asphalt-based undercoating generally contains a little bit of rubberized material that sets up firmly and also helps soften noise. Generally sold in five-gallon containers, this type of undercoating also needs more cure time than the other three, and is NOT paintable, making it best to use only for undercarriages.

PURPOSE OF UNDERBODY COATING:

1. Protects Against Rust & Corrosion

The primary objective of getting underbody coating done is preventing metal components that are exposed on the bottom side of the car to damage from corrosion. You can shut out the Adverse effects of corrosion on your car by simply applying a rubberised anti-rust coating all over the belly of your car.

2. Reduces NVH (Noise Vibrations Harshness) Levels

Our country is filled with roads having uneven patches and potholes and while we manoeuvre our cars through such sections, the unpaved crumbs, and pebbles hit the car from underneath or get stuck in the wheel wells. The underbody coating’s consistency is so thick that the layer it creates absorbs all the unpleasant noises and vibrations and marginally improves the driving experience.

3. Prevents Paint Chipping

Running on the highway or while pacing through a city road, you will often encounter sharp gravel or any other unattended object hitting the belly of your car with high momentum. This scrapes and chips off the metal from down below. A thick layer of Underbody Coating definitely comes to aid and minimises the effects of such contacts on the body.

4. Protects Vital Components

Underneath a car is somewhere a lot of indispensable parts of a car are left exposed like the Engine, silencer, etc. One simply can’t afford to let these parts go bad due to rusting and hence in order to save yourself from a hefty repair bill, a considerably less expensive Anti-Rust Coating is a must.