Anti-corrosion compounds
Corrosion is most exposed to bearing hollow (hidden) body cavities, bottom, lower parts of doors, pillars, as well as joints of body parts, including places of spot welding. In this regard, during the operation of the car, additional protection of the hidden cavities of the body is required by applying special anti-corrosion compounds, and the joints of parts - by applying sealing mastics. The materials used for anti-corrosion treatment are shown in table. thirty.
Protective lubricant NGM-ML is used for processing hidden cavities. The hidden cavities of all new cars are treated with this material.
Autopreservative Movil is also used for the treatment of hidden cavities during the operation of the car. It is recommended to treat cavities every 2 years.
Protective film coating NG-216B is used to cover parts of the car under the body for the period of transportation.
Plastisol D-4A is used for sealing welds and joints of parts on the outer and inner surfaces of the body.
Mastic 51-G-7 is used for sealing body joints, corner joints and gaps.
Plastisol D-11A is used to protect the bottom of the body from corrosion, abrasive wear and noise insulation of new cars. Coating thickness 1-1.5 mm.
Anti-noise bituminous mastic BPM-1 is used to protect the underbody from corrosion during vehicle operation. Mastic is applied with a thickness of 1-1.5 mm.
In the hidden cavities of the body, the anti-corrosion substance is sawn by the method of air or airless spraying. Air spraying requires compressed air with a pressure of 5-8 kg/cm2, paint spray gun with reservoir, hoses and extended spray nozzles. The best quality of the coating is achieved with airless spraying at a pressure of 90-120 kg/cm2, which allows you to spray materials of significant viscosity.
Preparation and anti-corrosion treatment of hidden cavities
Due to the use of sophisticated technological equipment and the need for high-quality work, it is recommended that the processing of hidden cavities be carried out only at car service stations.
The sequence of work is as follows:
- install the car on a lift, open the holes closed with plugs, remove parts and upholstery that prevent access to hidden cavities;
- washed with warm water (40—50°C) through technological and drainage holes hidden cavities (tab. 31), bottom of the body, wheel arches until clean water flows out. In this case, the sliding windows of the doors must be raised;
- remove moisture that has entered the passenger compartment, blow out all hidden cavities and other places where the anti-corrosion compound is applied with compressed air. Keep the car in natural conditions until completely dry;
- the car is driven into the chamber for applying the anti-corrosion composition and installed on a lift. Apply by spraying the anti-corrosion composition to the places indicated in fig. 179-182. Processing is carried out at a temperature not lower than 15°C;
- remove the car from the lift, clean the front surfaces of the body from dirt with a rag soaked in white spirit.
Pic. 179. Hidden cavities of the body - front view
Pic. 180. Hidden cavities of the body - rear view
Pic. 181. Hidden cavities of the body - bottom front view
Pic. 182. Hidden cavities of the body - rear view from below
Restoration of the protective coating of the underbody and wheel arches
During the operation of the car, the coating on the bottom of the body is destroyed and worn out by the action of gravel, sand, salt, moisture. Bare metal corrodes. At the car plant, for protection and sound insulation, PVC plastisol D-11A 1-1.5 mm thick is applied to the bottom, spars and wheel arches. In case of damage to the protective coating of the bottom without disturbing the soil layer, the damaged areas are cleaned of dirt, degreased with a rag soaked in white spirit, and BPM-1 mastic 1–1.5 mm thick is applied to a dry surface with a brush. Dry the coating in natural conditions during the day or at a temperature of 100-110°C for 30 minutes.
In case of significant damage to the protective coating with damage to the soil layer, the damaged areas of the surface are cleaned of dirt and rust to the metal and GF-073 primer is applied to the dry, degreased surface. BPM-1 mastic is applied to the primed surface areas with a brush.
If the service life of the car does not exceed 1.5 years, the overlap of the new layer of mastic on the old D-11A should be minimahp a longer operation of the car, the mastic is applied over the entire surface of the bottom and wheel arches.
In the cold season, before use, the mastic is kept in a warm room to a temperature of at least 20°C. Thickened mastic is diluted with xylene (up to 3% by volume). Paintwork contaminated with mastic is cleaned with a rag soaked in white spirit.