Vauxhall Workshop Service and Repair Manuals

Corrosion Protection Measures in Series Production  

General  

In recent years, the subject of corrosion protection has been forcefully pushed into the foreground as a result of increasingly corrosive environmental pollution.  

The customer expects that his vehicle is provided in the series production with high-grade corrosion protection with a long-term protective action.  

For these reasons, improvements are continually being introduced into production:  

•  Increased use of sheet metal galvanised on both sides.  

•  Additional PVC sill protection for vehicles without panelling in the area of the sill.  

•  Cavity protection wax in the entire underbody area.  

•  Cavity protection wax for all frame side members and crossmembers.  
 

In this section, the typical corrosion protection steps in series production will be explained using a flowchart and subsequent description of the individual steps.  

The details of the individual steps may differ depending on production plant.  

Notice: 

All of the measures for corrosion protection discussed in the operations can be understood with reference to the descriptions in this section.  

 

Standard Corrosion Protection Measures (Continued)   Flowchart for Corrosion Protection Steps   Step   Designation   1   Body shell   2   Spray dip phosphatisation   3   Cataphoretic dip priming   4   Seam seal   5   PVC underseal   6   PVC sill protection

 

Standard Corrosion Protection Measures (Continued)   Flowchart for Corrosion Protection Steps   Step   Designation   7   Primer   8   Top coat   9   Cavity protection wax   10   Underbody protection wax   11   Transit protective wax

Standard Corrosion Protection Measures (Continued)  

Body shell  

Effective measures to prevent corrosion start as early as the structural design of the body shell such as, e.g.:     •  Development of water-deflecting and dirt-deflecting body shapes   •  Deliberate selection of material at areas at risk of corrosion due to galvanised metal sheets   •  Optimum shaping and joining methods for body sheet-metal parts   •  Production of well-ventilated cavities   •  Introduction of water drain holes       Example   The good drainage of dirt and water is assisted by water drain holes in door shells.

Standard Corrosion Protection Measures (Continued)  

Spray / Dip Phosphatisation  

Spray / dip phosphatisation with cleaning and rinsing operations before and afterwards is the base of the paint structure.   The following sequence applies:     •  Clean and degrease   •  Spray / Dip Phosphatisation   •  Rinse   •  Blow with warm air       Spray / dip phosphatisation takes place by treating with a phosphatising solution.   This causes a crystal layer to form which neutralises points of different potential.

Standard Corrosion Protection Measures (Continued)  

Cataphoretic Dip Priming (CDP)  

CDP is the next corrosion protection step in series production.   The following sequence applies:     •  Cataphoretic dip priming   •  Rinse   •  Dry at approx. 180 ° C / 25 minutes       The body (cathode) passes through a dip tank with water-soluble paint (anode).   The positively charged paint particles displace to the body under the effect of the electrical voltage and form a layer of paint.   The thickness of the layer is determined by the amount of electricity, the length of coating and the temperature of the paint bath.

Standard Corrosion Protection Measures (Continued)  

Seam seal   Heat-curing and solvent-free seam seals are applied to flanged seams and folds and smoothed.   Included in this are flanges, welding flanges and open seams in the following areas of the body shell:     •  Front frame   •  Wheel well   •  Outer bulkhead   •  Inner bulkhead

Standard Corrosion Protection Measures (Continued)  

Seam seal     •  Inner floor   •  Inner rear end panel   •  Outer floor

Standard Corrosion Protection Measures (Continued)  

Seam seal     •  Outer rear end panel   •  Rear quarter panel   •  Rear roof frame

Standard Corrosion Protection Measures (Continued)  

Seam seal     •  Front wheel well   •  Front door hinge   •  Rear door hinge

Standard Corrosion Protection Measures (Continued)  

Seam seal     •  Bonnet.   •  Front door   •  Rear door   •  Tailgate   •  Luggage compartment lid

Standard Corrosion Protection Measures (Continued)  

PVC underseal  

PVC underseal is applied after CDP.   The areas of the vehicle underbody at risk of stone impacts are coated in a targeted manner with PVC underseal.   This produces long-term protection against mechanical stress (e.g. stone impact) and corrosion.   To a greater extent, PVC underseal is applied fully automatically using robots.   The remaining surfaces and flanges are sealed manually with PVC or a combination material.   The final curing is carried out by drying the primer..

 

Standard Corrosion Protection Measures (Continued)   PVC underseal     •  Underbody   •  Front underbody/wheel well   •  Rear underbody/wheel well

Standard Corrosion Protection Measures (Continued)  

PVC sill protection  

PVC sill protection cures on heating, is solvent-free and is sprayed in a complex automatic spraying operation to give "visible edges".  

With regard to corrosion protection, PVC sill protection has the following advantages:  

•  Adhesive  

•  Wear resistant  

•  Temperature resistant  

•  Water resistant  

•  Highly elastic  
 

A straight and clean visible edge without any transition is achieved in the spraying operation using a special application procedure  

Standard Corrosion Protection Measures (Continued)  

PVC underseal/sill protection     •  Front wheel well   •  Front wheel housing dome   •  Sill         i  Installation locations free of underseal   ii  Fade-out area   iii  Sill protection applied to overlap with underseal

Standard Corrosion Protection Measures (Continued)  

Primer  

The water-soluble primer is applied with an electrostatic rotary atomiser unit.   The following sequence applies:     •  Clean   •  Coat with primer   •  Dry at approx. 160 ° C / approx. 35 minutes       Advantages of primer:     •  Application with rotary atomiser, therefore application almost without loss.   •  High surface quality.   •  Optimum Adhesion to CDP and PVC   •  Optimum metal primer for top coat.   •  Damping layer between CDP and top coat.

Standard Corrosion Protection Measures (Continued)  

Top coat  

The top coat forms the final layer of the paint structure due to its blocking action towards the diffusion of water and oxygen.   The following sequence applies:     •  Clean   •  Apply top coat   •  Dry at approx. 130 ° C / approx. 30 minutes       Two different top coat systems may be used:     •  1-layer coat based on synthetic resin   •  2-layer coat with metallic or mica effect base coat and clear coat       The top coats in the body outer area are sprayed on in electrostatic rotary atomiser units.   The interior of the body is painted manually.   Plastic parts are provided with a special paint structure in separate processes prior to assembly.

Standard Corrosion Protection Measures (Continued)  

Cavity protection wax   Advantages of cavity wax:     •  High creep capability   •  High non-volatile matter content   •  Low solvent content   •  Environmental compatibility   •  Long-term protective action   •  Once dried, forms a strong, sealed wax layer       •  Sill   •  A-pillar   •  Front / rear door

Standard Corrosion Protection Measures (Continued)  

Cavity protection wax     •  Bonnet.   •  Underbody / frame

 

Standard Corrosion Protection Measures (Continued)   Underbody protection wax   In the further production sequence, all vehicles are given an underbody protection wax to the vehicle underbody.   The entire vehicle underbody and its body attaching parts are coated, such as, e.g.:     •  Fuel tank   •  Wheel wells with coil springs and shock absorbers   •  Axle body       Catalytic converters and parts in the exhaust area are not coated.   Advantages of underbody protection wax:     •  High non-volatile matter content   •  Low solvent content   •  Environmental compatibility   •  Optimum adhesion   •  Once dried, forms a smooth clean wax layer   •  Insulation and moisture barrier due to water-deflecting property.       Underbody protection wax is applied in an automatic spraying operation.

 

Standard Corrosion Protection Measures (Continued)   Bearing and Transit Protective Wax   The final application of bearing and transit protective wax prevents corrosion damage caused by.     •  Dust, dirt during transport   •  Environmental pollution such as, e.g. soot   •  Corrosive substances such as, e.g. bird droppings, insects or tree resin       All vehicles are given bearing and transit protective wax in the following areas:     •  Roof   •  Bonnet.   •  Tailgate   •  Wing.   •  Doors   •  Rear quarter panels       Paint-damaging particles only settle on the surfaces accessible from above.   Therefore, enclosed, vertical surfaces (front, side, rear, bumpers) are not included in the wax coating.