Automotive Painting Process Flow

I. General Standard Process of Automotive Painting

The standard automotive paint repair process covers full-process refined construction, including inspection of sheet metal repaired parts, base surface polishing and bevel trimming, comprehensive dust removal and cleaning, vehicle masking and protection, primer coating, putty filling and multi-stage polishing, fine polishing of old paint layers, silicon and stain removal, intermediate coating spraying and polishing, minor base surface repairing, secondary dust and stain removal, gap dust cleaning and micro-dust adhesion, solid-color topcoat spraying, base coat spraying, clear coat spraying, paint baking and curing, waxing and quality inspection. Each procedure strictly controls construction quality to ensure the flatness, adhesion and appearance of the finished paint surface.

II. Detailed Construction Procedures

1. Sheet Metal Flatness Inspection

Conduct a comprehensive inspection of the area to be painted, verify the lines, flat surfaces, arc surfaces and gap flatness of repaired sheet metal, clean the original paint areas without repair requirements, and check for surface depressions and deformities to ensure the base surface meets painting construction standards.

2. Base Surface Polishing Treatment

Trim sheet metal edges with a grinding machine and polish uniform feather edges with sandpaper. Polish the surrounding old paint layers and appropriately expand the polishing range to eliminate paint steps and burrs, creating a flat base for subsequent putty application and painting.

3. Cleaning and Degreasing

After polishing, thoroughly clean and wipe the construction area and surrounding paint surfaces to completely remove dust, oil stains and impurities. Residual oil stains will cause putty peeling, paint blistering and insufficient paint adhesion, which must be strictly avoided.

4. Intermediate Primer Spraying

Control the spraying range of intermediate primer accurately to avoid color difference caused by over-spraying. Ensure gradual and smooth transition of primer edges without obvious steps to achieve seamless connection with the original vehicle paint.

5. Intermediate Primer Polishing

After the intermediate primer is fully dried and cured, finely polish the primer surface with professional sandpaper to remove particles and orange peel defects, smooth the base surface and complete pretreatment for subsequent putty filling.

6. Putty Filling and Leveling

Apply special automotive putty evenly to fill depressions and paint defects on the vehicle surface to achieve a full and flat finish. Leave the putty to dry naturally and polish after complete curing.

7. Precision Grinding and Transition Treatment

Adopt targeted polishing methods according to the flat and curved structure of the vehicle body. Finely grind the putty surface and edges to ensure a smooth transition between the repaired area and the original paint, fully conforming to the original vehicle surface radian and flatness standards. Fine leveling with ultra-fine putty is adopted in the final stage to eliminate tiny surface defects.

8. Primer Spraying and Pinhole Putty Repair

Spray special primer on putty-repaired areas and apply pinhole putty to fill tiny pinholes, fine scratches and partial damage on the putty surface. This further optimizes base surface flatness and eliminates subtle paint defects.

9. Precision Polishing for Adhesion Reinforcement

Level the primer and pinhole putty surface by fine polishing, and expand the polishing range appropriately to remove aged old paint layers and strengthen the adhesion between new and original paint layers. Thoroughly clean dust and impurities to complete pre-painting base preparation. Use P280# sandpaper to completely polish the old paint layers for intermediate coating construction to guarantee paint bonding quality.

10. Dust Removal and Masking Protection

Blow dry residual water and dust in edge gaps of the construction area with compressed air, and remove dust and stains thoroughly with pressure guns and silicon removers. Paste masking paper accurately to fully protect non-construction areas and prevent paint fog contamination. Conduct secondary dust cleaning, remove gap dust and adhere micro dust on the surface to create a dust-free and clean spraying environment.

11. Multi-layer Topcoat Spraying

Spray solid-color paint and base coat layer by layer in accordance with standard procedures to ensure uniform color, sufficient coverage, no sagging and no mottling. After flash drying of the base coat, spray transparent clear coat to form a protective layer, improving the paint surface gloss, weather resistance and scratch resistance.

12. Baking Curing, Polishing and Quality Inspection

Send the vehicle to the paint baking room for constant-temperature curing after spraying to ensure full cross-linking and drying of the paint film. Perform fine waxing and polishing after curing to eliminate tiny orange peel and particles. Conduct comprehensive final inspection to ensure the paint surface is smooth, glossy, color-consistent and defect-free.

III. Technical Requirements for Automotive Painting Construction

At present, automotive paint repair in domestic auto maintenance industries mainly relies on refined manual operation. To guarantee stable and consistent paint quality, all paint repair work must be completed in a professional paint spray and baking room.

Paint spray and baking rooms are divided into large, medium and small models, applicable to coaches, minibuses and sedans respectively. Large and medium-sized equipment can be used as substitutes if small equipment is unavailable. There are two main heating modes: electric heating and diesel heating. Electric heating features convenient operation and precise temperature control but with higher equipment cost and required circuit capacity expansion. Diesel heating mostly adopts imported burners with high thermal efficiency and low energy consumption, requiring strict safety operation specifications. Preheating is mandatory before equipment operation, and continuous batch operation can effectively reduce costs and improve efficiency.

Paint rooms must comply with strict air purification standards and be equipped with high-efficiency non-woven filter materials. The filter cloth shall be replaced regularly once severely polluted after long-term use.

Strict requirements are imposed on indoor lighting and baking equipment. Bright, soft and long-service lighting is required for clear surface observation and stable painting quality. Baking equipment must provide constant and uniform heating temperature. Most paint rooms adopt electronic control systems for procedural operation, ensuring convenient, stable and reliable equipment operation and achieving high-quality automotive paint repair results.