Underbody Coating
AIM:
To explain the underbody coating and its purpose.
UNDER-BODY COATING
Underbody coating is usually a dense cladding (often based on rubber) applied uniformly to the undercarriage of the automobile. It is normally sprayed or painted on when the car is just out of the dealership and is clean. But even if you are getting the undercoating applied after a couple of years, it's fine too. This is because it can prevent further damage to the undercarriage.
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. Getting a fresh coat can cost you up to ₹ 6,000.
Automotive Underbody Coatings
Underside of vehicles serves as an intermediate between metal components of a vehicle and outer environment. Underbody of vehicles is prone to damages due to harsh environmental conditions. Cootings are applied to the underside of vehicles to protect them against factors such as corrosion chemicals, moisture, water damage, and chipping of the underbody. Automotive underbody coatings offer a protective layer to vehicles underside.
Most of these coatings provide chemical and corrosion resistance, along with several other properties based on different product formulations Protection of underbody and wheel arches against chip damoge is achieved by applying automotive underbody coatings, which protect the metal from debris of gravel stones, salts, etc, tossed by the road.
Coating process of a vehicle body (automotive coating process) comprises minimum five layers of paint, while the underbody coating process comprises the first two layers in the overall coating process. These two layers provido durable protection against corrosion; however, domage over time requires renewal of these coatings. Automotive aftermarket service providers often provide these services during scheduled vehicle maintenance.
Automotive underbody coatings also offer protection against humidity, moisture, and wet conditions that can seep through the undercarriage of a vehicle through joints or cracks in the paintwork; and cause corrosion
Elasticity of polymers used in automotive underbody coatings allows for low noise when struck by road debris compared to that with uncoated underbody. As a result vibrations of vehicles are dompened and kept to a minimum.
Automotive coating process
• Pre-treatment:
The first step in preparing BIW for subsequent coating is the pre-treatment process. Pre-treatment consists of cleaning the body surface to remove remaining oils from the stamping process and welding residues through three primary liquid dip processes of degreasing conditioning and phosphating. The degreasing solution is composed of alkaline salts and surfactants and can include caustic soda, tri-sodiurn phosphate, and sodium carbonate. The surfactants are types of detergents for emulsifying oils and lubricants on the BIW.
• Electrodeposition (ED):
The metal underbody and frames of automobiles are coated to prevent corrosion, whereas other areas like the roof are not rust-proofed. When not coated to prevent corrosion, the structural metals (or other materials) are primed before applying additional coatings. The ED processes are modified as per the BIW material property. This ED coating provides rust and corrosion protection.
Rust-proof materials: Sealer/PVC
The third step is underbody coating (UBC) and seam sealing using PVC and urethane, The sealant is applied
around and inside the doors, hood, trunk, and front dosh and onto the exterior and interior of metal joints and outer area of the back wheel well.
• Primer:
The fourth coating step is the application of a primer surface or simply primer, it can be water-borne, solvent
borne or a powder. These primers are used to improve odhesion between the E-coat and topcoat, provide chipping)
protection, enhance paint appearance and also be environmentally compatible with emission regulations.
.Top-coat
The final step in the body coating process is to apply the topcoat, which consists of two layers-the basecoat and clear coat. The basecoat contains the primary colouring pigment and the clear coat provides a protective coating against environmental effects, corrosion, and UV light degradation promotes unmatched colour retention and provides a smooth unblemished even finish.
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:
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 polyarethane-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 cozing around rusty areas to bond with and protect unaxidized 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.
Wax or Paraffin-Based Undercoatings
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
Asphalt-Based Undercoating
at least a base protection in moderately humid climates For standard vehicles, any of the aforementioned types of undercoating will provide sufficient protection. For large
moisture.
other three, and is NOT paintable, moking it best to use only for undercarriages.
trucks and heavy machinery, asphalt-based undercoating provides a bit of extra durability against rocks, chips, and 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
Advantages of Underboody coating
• Undercoating gives an extra layer of protection against rust and corrosion, protecting your car.
• Undercoating will eventually wear out, but you can get years of protection from it. Even vehicles in warmer
climates gain protection as debris is repelled and kept away from eating at the vehicle.
• It can be self-opplied.
• It minimizes the sound from underneath the car.
• It insulates the interior of the car from the extreme temperature from beneath the vehicle.
• The coating does not chip away when hit by stones
Disadvantages of Underboady coating.
• Undercoating will not help you if corrosion atroady exists and the corrosion needs to be removed first before it can be applied, which can be expensive for you.
• It must be reapplied every 3 to 5 years for the best results
• Its added weight to the vechile.
• It adds weight to the vehicle.