The production of sheet metal for car doors automotive door metal panels is a highly automated and technology-intensive process, mainly divided into three core processes: stamping, welding, and painting.
This is the first step in shaping flat metal materials into the inner and outer panels of a car door. High-quality cold-rolled steel sheets and galvanized steel sheets are typically used, and some models also use aluminum alloy sheets. First, the coiled material is unrolled and cut into rectangular sheets of specific dimensions using a blanking line. A complete car door usually requires 4-6 consecutive stamping processes to complete:
- Drawing: This is the most crucial step. The blank is pressed into the basic three-dimensional shape of the car door in a die.
- Trimming: Excess material is removed from the edges of the drawn part.
- Punching: Holes are punched out for installing door locks, hinges, window regulators, etc.
- Flanging: The edges are folded up to prepare for subsequent welding and installation.
- Shaping: The details of the part are refined to ensure accurate dimensions and shape.
After passing through the stamping line, the produced parts mainly include: the outer door panel (the outermost layer we can see, requiring a smooth and flawless surface) and the inner door panel (internal structure, responsible for strength, mounting accessories, and crash safety).
Then, smaller parts are welded together. For example, the inner door panel is first welded to the anti-collision beam, reinforcing ribs, hinge mounting plates, etc. This step is usually completed by welding robots or manually on tooling fixtures. The outer door panel is then assembled with the already welded inner panel as a sub-assembly. Welding is typically completed by hundreds of welding robots on a highly automated production line.
After welding, the dimensional accuracy of the door assembly is rigorously inspected using equipment such as a coordinate measuring machine to ensure a perfect match with other parts of the car body.
Painting is the process that gives the door corrosion resistance and a beautiful color, crucial to the final quality and aesthetics.
1. Pre-treatment:
Degreasing: Removing residual oil and dirt from the stamping and welding processes.
Phosphating: Forming a phosphate crystal film on the metal surface through chemical treatment, which greatly enhances the adhesion and corrosion resistance of the coating.
Electrophoresis: This is the most important rust prevention step. The entire car door is immersed in an electrophoresis tank and electrified, allowing the paint film to adhere evenly to every corner and interior cavity. This primer layer is the core of the car body's corrosion protection.
2. Send Underbaling aody Protection:
* Applying Sealant: Sealant is sprayed onto the welds and seams of the car door to prevent the intrusion of water, air, and noise.
* Applying Undercoating: A thick layer of PVC coating is sprayed onto areas susceptible to stone impact, such as the bottom of the doors, to provide stone impact resistance and sound insulation.
3. Intermediate Coat and Topcoat:
* Intermediate Coat: A layer of paint is sprayed, primarily to improve the fullness of the topcoat and its UV resistance.
* Topcoat: The color paint that determines the final color of the vehicle is sprayed.
* Clear Coat: A clear coat is sprayed on the outermost layer, providing gloss, feel, and resistance to environmental corrosion (such as UV rays, acid rain, and scratches).
4. Baking: After each layer of paint is applied, it is placed in a drying oven for curing to ensure the paint film achieves the designed hardness and durability. 5. Finishing and Inspection: The paint surface is polished to remove minor imperfections. Finally, it undergoes rigorous inspection by both manual labor and machinery to ensure a flawless finish.
Factory shot
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