Challenge

Underbody Coating

Underbody coating:

It is usually a dense cladding applied uniformily to the undercarriage of the automobile.

Types of underbody coating:

Rubberized undercoating:

it is easy to apply.
it is also safe to use on wheel wells and quarter panels & dries to a soft rubbery finish that prevents further rust, damage.

Polyurethane coating:

little bit quicker & easy to apply.
it will come in canisters ready to preload into an application gun.
this type of sealant works by seeping into all cracks & seems displacing salt & moisture and oozing around rusty areas to bond with & protect unoxidized metal.
these type of car undercoating generally require a little bit more surface preparation before applying, sanding and applying an etching primer to bare metals before using are generally recommended.

Paraffin based undercoating:

It is cheapest & quickest option.
It will wear off quicker than other types of undercoating & will need to be stripped & reapplied atleast once every year.
Never truly harden, during application they drip & flow into seams & cracks to provide protective properties.
they are usually avaialablle in a spray gun canister (or) in a aerosol can & offer atleast a base protection in moderately Humid climate.

Asphalt based undercoating:

It is mainly used for large trucks & heavy M/C.
It provides a bit of extra durability against rocks, chips, moisture.
It contains a little bit of rubberized material that sets up firmly and also soften noise.
these type of undercoating also needs more cure time than the other three, it is not paintable making it best to use only for undercarriage.

Process:

Pretreatment:

1st step in preparing BIW for subsequent coating.
the process mainly consists of cleaning the body surface to remove remaining oils from the stamping process and welding residues through 3 primary liquid dip processes of Degreasing, Conditioning, Phosphating.
The Degreasing solution is composed of alkaline salts & surfactants and can include caustic soda, tri sodium phosphate and sodium carbonate.
The surfactants are types of detergents for emulsifying oils & lubricants on the BIW.

Electrodeposition:

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 are primed before applying additional coatings.
The ED Processes are modified as per the BIW material property, this ED Coating provides rust & corrosion protection.

Rust Proofing: (Material: sealer/PVC)

3rd step is UBC and seam sealing using PVC & urethane.
The sealant is applied around & inside the doors, hood, trunk and front dash and onto the exterior and interior of metal joints and outer area of the back wheel well.

Primer:

The 4th coating step is the application of primer surface.
It can be waterborne, solvent borne (or) a powder.
These primers are used to increase adhesion between the E-coat and top coat, 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 2 layers the base coat, clear coat.
The base coat contains primary colouring pigment and clear coat provides a protective coating against environmental effects, corrosion, UV light degradation promotes unmatched colour retention & provides a smooth unblemished even finish.

Benefits:

disadvantages:

Ship work like this
in your own course.