Underbody Coating

 Underbody Coating:

            Underbody coating is a process to protect the car’s underbody from the corrosion.  It also protects parts like internal body panels, frame rails and other inner cavities that are not physically accessible but are prone to corrosion.

 Purpose:

• To protect against rust and corrosion
• Reduces NVH (Noise Vibrations Harshness) levels
• Prevent paint chipping
• Protects vital components

Different Types of Vehicle Undercoating:

     Having undercoating professionally applied to your vehicle can be expensive, but fortunately, if your budget is tight, you can do it yourself for a fraction of the price. Here are some of the various types of undercoating available.

• Rubberized Undercoating
• Polyurethane Undercoating
• Wax or Paraffin based Undercoating
• Asphalt based Undercoating

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.

Polyurethane Undercoating:

     The other option for undercoating your vehicle is to use a Polyurethane based sealent. 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 preparation work before applying sanding and applying an etching primer to bare metals before using are generally recommended.

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 undercoatings 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.

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.

Process of Underbody Coating:

Preheat Treatment:

            The first sequence in preparing the BIW for subsequent coating is pre-treatment Pre-heat treatment removes and clean excess metal and 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.  Pre-treatment helps the primer to bond onto the metal. A phosphate treatment applies an inert layer of metal phosphate, providing resistance to corrosion spread.  The degreasing solution is composed of alkaline salts and surfactants and can include caustic soda, sodium carbonate. The surfactants are types of detergents for emulsifying oils and lubricants on the BIW. In surface conditioner which creates nucleation sites for phosphate crystal growth. It increases the number of crystallization nuclei on the metal surface that enhance bonding mechanism for the subsequent phosphate sequence. Finally, the liquid dip phosphate ions, nitrate ions, zinc & hydrogen ions. The free acid etches the steel surface, causing hydrogen to be released while metal phosphate ions are precipitated onto the surface in a crystalline form

Electro Deposition:

            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. 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, and 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 colour & 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 enhance 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  current  E-coating process  is  that    of  water  spots  that  contaminate  coated surfaces. If  water spots are  present, they have  removed by sanding. Hence, it is necessary to use well-deionized water & routinely  monitor its conductivity.  Alternately, operators also add surfactants or ultrafiltrates to the water

rinse zone to eliminate or manage water spots also add surfactants or ultrafiltrates to the water rinse zone to eliminate or manage water spots.

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 part 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.

Primer:

            The fourth coating step is the primer.  It can be water-borne, solvent-borne, or a powder. The primer fills & smooth 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 and the E-coat & basecoat; thereby, the Primer increases 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 colour matches the basecoat to be able to impart uniform coating appearances between interior & exterior coat.

Top Coat:

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

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.  It imparts  the  automobiles  colour;  roughly  40,000  base  coat colour are  known today , &  approximately 1000 new colours are  added  to  this  list  each  year.  Three  different  types  of basecoats are used for automobiles, including solvent-borne medium  solids (MS),  solvent-borne  high  solids  (HS),  & water-borne.

Clearcoat:  The  final  coating  on  an  automobile surface is the clearcoat; it provides durability, environmental etch, & scratch resistance to the  overall coating. It  protects against  damage such  as  fading  that is  caused by  UV  rays from the sun & imparts  a gloss  & depth that otherwise are not as vivid. The clearcoat also makes repairs & maintenance easier. Environmental etch is an appearance issue associated with the formation of 

permanent  water  spots  or  non-removable  marks  from  bird droppings,  tree resin,  or  other chemicals  after  contact  with  an  automobiles  surface.  The physical damage resulting from etch=ng is associated with a localized  loss  of material  &  deformation or  pitting  of the clearcoat surface.

Need of undercoating:

• To maintain the thermal conductivity of the vehicle body.
• To hide the body works which did during manufacturing, increasing the aesthetic look ad appearance of vehicle.
• To improve vehicle acoustic performance, reducing road noise and structure-bome vibration noise, to provide a quieter ride for the both drivers and vehicle occupants.
• Making a durable anti-stone and anti-chip coating to vulnerable parts of the vehicle. 
• Helping to enhance corrosion performance of pre-applied coatings.
• It has good resistance to abrasion and is over-paintable, making it a versatile option for many different areas on a vehicle.

Significance:

• Undercoating helps to provide an additional layer of insulation and protection to the undercarriage of your vehicle.

• Manufacturers may apply car undercoating at the factory.

• The undercoating covers most of the car’s underside, including floor boards, frame, gas tank, pans, wheel wells and mufflers, suspension parts and exhaust pipes. This effect can be likened to black coating parking lot or a road.

• Undercoating materials adhere to metal, even if it is painted. Most of them come in pressurized cans for easy spray-on application, while an even spread may be tough to achieve without professional applicators.

• Ingredients used in the manufacturing of undercoating include fiberglass, ceramics, rubber, asphalt and silicone. Each has different properties in terms of heat resistance and retention, but all gives protection against the elements and damage.

• Auto Undercoating protects the undercarriage, a vehicle’s most vulnerable area. Unlike the visible portions of your vehicle, the undercarriage doesn’t get washed frequently but it absorbs most of the moisture, grime, salt and other substances when you come in contact with those, as you drive.

• In addition to protecting your vehicle from elemental damage, good undercoating can also reduce engine noise, leaving you quieter than ever before.

• Even though if you buy a new car with undercoating from the dealer, remember that undercoating wears off typically within a short period of 1 year. Worn, patchy car undercoating can get damaged when water and other elements then get trapped under the coat, further eroding metal.

Advantages of Undercoating:

1. Fights Rust

It plays an important role in keeping corrosion at bay. Underbody coating can come in handy especially if you live near the sea, where there is too much humidity, and rusting is just one of those everyday things. You should also seriously consider undercoating if you reside in a place where it snows in winter.

2. Absorbs Noise

Believe it or not, 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 – at least up to a certain extend.

3. Reinforcement

If your car comes with stock underbody coating, using another coating on top of it, is not going to hurt. 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 can surely add years to the lifespan of your vehicle. There would be fewer dents, dings and scratches on the undercarriage for you to fret about

Disadvantages of an undercoating:

1. It is less helpful if corrosion is already present.

For an undercoating to be the most effective, it should be in place before the underbelly of your car begins to rust. If you apply it over corrosion, you will still isolate the metal from further moisture and airflow, which is good, but the existing oxidizing/rusting process will still continue to occur. After rust is already present, applying an undercoating will slow the continuation of the corrosion process and will make your vehicle look better… until the rust breaks its way through the layer of undercoating you’ve applied. If you have rust present, it is better to remove the rust and then apply the undercoating.

1. It works best on new cars.

If you’ve purchased a used vehicle, then the cost of preparing the underbelly for an undercoating might be more than the value of the car. You must remove all the residue from the bottom before it can be applied. Failing to do so will seal in the debris that is present already, which can lead to more problems. The best time to have an undercoating applied is when a vehicle is purchased new because it offers a superior level of protection then.

3. Most vehicles make it five years before corrosion begins to show.

For vehicle owners who purchase something new every 3 to 5 years, then rustproofing may not be a good use of your cash. Although an undercoating does add value to a used car, that only applies when the rustproofing product used provides a transferrable lifetime warranty. Most vehicles that are on the road today are able to make it five years before any corrosion begins to show. It may be 7 to 10 years before the functionality of the vehicle is negatively impacted by the lack of an undercoating. If you wash your vehicle regularly, especially during the winter months, then you might be able to save the time and money required for this service.

4. A third-party undercoating service might void your vehicle’s warranty.

Some new cars no longer need the undercoating service provided because the structure of the vehicle has it built-in already. If you hire a third-party provider to apply an undercoating, you could void the corrosion-perforation warranty that is factory-provided. Most vehicles today that leave the factory floor are all provided with included rust-proofing.

If you are purchasing a used vehicle, an undercoating to a clean underbelly could extend the life of the vehicle and give it more value. For new vehicle purchases, you should ask the dealer what rustproofing options are included before paying for a separate undercoating option. Ask for documentation of what is provided instead of taking the word of the salesperson or the service personnel.

Many dealers have language in their terms and conditions that only written agreements are binding.

5. An undercoating is not impervious to damage.

An undercoating can provide a hardened layer of protection against dirt and debris that may cause corrosion. Depending on where you drive, however, the lifespan of this product may be minimal. If you drive your vehicle on gravel roads or dirty areas frequently, you reduce the integrity of the protective layer. You might find that your undercoating begins to chip off in as little as 25,000 miles because of this issue. Driving in a salty environment is not the only threat to the integrity of this product. 

6. It must be reapplied every 3 to 5 years for the best results.

The only way for an undercoating to provide ongoing protection for your vehicle is to have the service repeated frequently. Most owners can have a new layer applied in about 5 years without worrying about their underbelly being compromised. In salty or destructive environments, however, you may need to have a new undercoating applied every 3 years for the best results.

The pros and cons of a vehicle undercoating offer a complex opportunity to protect some new and used cars, but not all new vehicles require it. You must perform your own due diligence on a vehicle you’re wanting to purchase to decide if this service is right for you. And, if the cost is an issue, it is possible to apply your own undercoating, though such an action might void an active warranty.

Conclusion:

     Underbody coating is one of the hidden factors for prolonged life of the car. As it protects the car from dust, minor hit of small gravel, minor wear and tear and rust. It provides strength to the underbody. But the coating is not for lifetime, it removes or chipped out as time passes. In wet area, the coating damages faster as compared to dry area. So therefore, check-up is required over every 1 or 2 years.