Underbody Coating

AIM:

To study the underbody coating used in automobile industries.

Objectives:

• To study about underbody coating
• To study about types of underbody coating and its advantages and disadvantages.

Underbody Coating:

Underbody coating, commonly referred to as undercoating, is usually a dense cladding (often based on rubber) applied uniformly to the undercarriage of the automobile. Underbody coating provides long term protection from corrosion to car's underbody. It also protects parts like internal body panels, frame rails and other inner cavities that are not physically accessible but are prone to corrosion. The main purpose of undercoating is to check rust especially in the body components like frame rails along with other exposed metal parts. Underbody coating can also reduce wear and tear.

Modern automotive coating process:

The modern automotive coating consists of five steps:

• Pre-treatment: removes and cleans excess metal and forms an appropriate surface structure enabling bonding of a corrosion protection layer.
• The next step is electrodeposition (ED) of the anti-corrosion or rust prevention layer.
• A sealer like Poly Vinyl Chloride (PVC) is applied for anti-corrosion, elimination of water leaks, and minimization of chipping and vibrational noise.
• A primer is then applied to promote adhesion between the surface and the basecoat; it also imparts a smoother surface for subsequent layers and has anti-chipping properties.
• Finally, the topcoats that include a basecoat and clear coat are applied; they provide surface properties that are sought after, including colour, appearance, gloss, smoothness, and weather resistance.

Types of undercoating:

There are four different undercoating methods that are commonly used on vehicles that require this service. The electronic method is used when rust is present to stop its corrosive effect, which is a method that receives mixed reviews. A standard undercoating method applies a tar-like substance to the exposed components of the vehicle underbelly. A dripless oil spray applies a waxy substance that fills in the entire body of the vehicle, which hardens when it dries.

Then there is the drip-oil method, which may cause dripping for up to 48 hours when applied. From a cost perspective, it is this final option that is most often applied at the dealership.

Types of Underbody Coating based on methods:

1.Rubberized Underbody Coating:

The most common method of undercoating a vehicle is via the use of a “rubberized” spray-on product. Utilizing a tar-like substance that has been infused with solvents and protectants, spray-on undercoating stick to whatever they touch, acting as a barrier against salt, moisture, oxygen, and other foreign substances that may lead to rust and corrosion. 

2.Electronic Rust Inhibitors:

Electronic rust inhibitors are marketed as a permanent, discreet, easy to install solution to corrosion. But the jury is still out as to whether or not they actually make a damn bit of difference when it comes to repelling and removing rust on automobiles. While the notion of electrical current coursing along the underbelly of a vehicle is undeniably odd, it has been proven to work, but not in the way that one might expect.

3.Lanolin Wax/Wool Grease:

When choosing an undercoating, the lanolin approach remains a proven, if not slightly strange solution. Commercially, lanolin coatings are used as both a rustproof coating and as a lubricant, with everything from ship hulls and rigging equipment, to heavy-duty excavation machines and production facilities relying upon this water-repelling corrosion inhibitor.

When it’s sprayed, lanolin fills in all of the nooks and crannies of the chassis with a sticky, wax-like substance. Curing times will vary depending upon air temperature and how heavy of a coating has been applied, so there will likely be some downtime between car rides after this stuff has been sprayed.

4.Dripless Oil Spray:

The final common undercoating option is dripless oil spray. Once allowed to harden on a surface, this wax-like, colorless substance has the ability to repel moisture and corrosion for years on end. Just note that dripless undercoating oil sprays typically require holes to be drilled into the body of the vehicle at specific points for the product to penetrate unseen areas that are prone to rusting out.

Types of Underbody Coating based on material properties:

• Rubberized Underbody coating

This is generally thought of as the best underbody coating for your car. It preserves the underbody well, protecting it from scratches. Applying this to the undercarriage is not much of a hassle either.

• Wax Based Underbody Coating

This more or less ephemeral undercoating will wear away in a few months’ time. On the upside, wax-based undercoating puts up a big fight against moisture. It is also the most affordable option out there.

• Asphalt Based Automotive Undercoating

Best suited for lorries, trucks and large vehicles this provides a greater degree of protection compared to rubber-based coatings. However, asphalt-based coatings contain little amounts of rubber for sound-insulation purposes. The process of applying this coating is a bit time-consuming though.

• Polyurethane Underbody coating

This coating closes up splits and fractures on the underbody of the vehicle. It offers up good protection against corrosion and also bonds with the metal. Unlike in the case of asphalt-based coating, you can paint over the polyurethane coating.

Advantages of Undercoating

1. Protects Against Rust & Corrosion- It plays an important role in keeping corrosion at bay. Underbody coating can come in handy especially if one lives near the sea, where there is too much humidity and rusting. One should also seriously consider undercoating if they reside in a place where it snows in winter. 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. One could shut out the adverse effects of corrosion on your car by simply applying a rubberized anti-rust coating.
2. Reduces NVH (Noise Vibrations Harshness) Levels-   A very thick undercoating can soften the noises that reach the cabin. Since the undercoating is often made up of rubber it absorbs some of the rackets. The occupants of the car could spare themselves of the road noises up to a certain extend. It minimizes the sound from underneath the car resulting a noiseless, smooth driving experience.
3. Reinforcement- If the car comes with stock underbody coating, using another coating on top of it, is not problematic. It will offer additional reinforcement, protecting the underbody from water, road debris, gravel and small pebbles. There would also be a lesser chance for the factory coat to flake away.
4. Prolong Car’s Life- Good undercoating not only defends the underbody from corrosion but also protects the engine and transmission as well. Less rusting coupled with slower wear and tear surely adds years to the lifespan of the vehicle. There would be fewer dents, dings and scratches on the undercarriage.
5. Heat Insulation- It insulates the interior of the car from extreme temperatures from beneath the vehicle providing a comfortable cabin experience.
6. Anti-chipping property-If any stone hits the coating it does not get chipped away hence protects the underbody from exposure to water. A thick layer of Underbody Coating definitely comes to aid and minimizes the effects of such contacts on the body.
7. Protects Vital Components-Underneath a car, a lot of indispensable parts of a car are left exposed like the Engine, silencer, etc. Rusting could damage these vital components and hence in order to avoid hefty repair bill, a considerably less expensive Anti-Rust Coating is a must.

 Disadvantages of Undercoating

1. Add Weight- Although the layering of underbody coating is in micrometers but underbody coating may add some minimal amount of weight to the vehicle's body.
2. Fail to Protect Existed Rust- Undercoating will work best on new vehicles that have not been exposed to road conditions. A used vehicle may already have residue on the bottom of the car or even have spots of rust and corrosion. Undercoating will not help you if corrosion already exists and the corrosion needs to be removed first before it can be applied, which can be expensive.
3. High Cost-Applying Underbody coating on a vehicle can be expensive.
4. Damage Risk-There can be chances of risk of damage during application, that the coating should be applied carefully otherwise the coating can get into moving parts such as CV- joint in propeller shafts and can cause failure of the parts.
5. Re-application is required after Time- The life span of the coating generally about 3-5 years, to get the benefit need to reapply the coating after a time period.

Conclusion:

• Studied about underbody coating
• Studied about types of underbody coating and its advantages and disadvantages.