The frame is mainly used for commercial vehicles such as trucks, passenger cars, and passenger and cargo vehicles, and is mostly formed by riveting, welding or bolting of hot-rolled steel plate stamping structural parts. In China, depending on the scale of production and the conditions of equipment, the coating process is quite different. It is classified into mass production and small batch production.
Mass production process is the cutting and blanking of the steel plate, removal of scale, rust prevention, stamping, welding, riveting, degreasing, phosphating, electrophoresis or dipping, drying, and adding a top coat as required. Most of the truck manufacturers in China use this technology. Small-volume production process is the cutting and blanking of the steel plate, stamping (or purchase stamping vertical and horizontal beams), drilling, welding/riveting, assembly derusting cleaning, dipping or painting, drying or natural drying. Due to the difference in materials and process control levels, the coating quality varies greatly.
The difference in the coating level of China's vehicle frames is very different. Mass production is generally better than small-volume production. The common problem is the incomplete painting of sharp edges, welds, and gaps. Even with cathodic electrophoresis, these defects cannot be avoided due to structural limitations and poor pre-treatment due to rust between processes. Compared with foreign countries, our best level is comparable to Japan and South Korea, but not as much as Europe and the United States.
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