I recently found this YouTube video from a company in China showing their process for stamping brake pad backing plates. Besides the safety violations, they are doing several things that will eventually cause the final brake pads to eventually rust and cause delamination of the friction material due to rust jacking.
The biggest mistake they are making is using a steel plate covered in rust.
Iron oxides are the precursors to rust are being pushed deeper into the backing plate material during the stamping process. Some of these microscopic inclusions can’t be shot blasted or sandblasted off the surface. Also, most inclusions can’t be removed with some chemical processes.
The only option is to use high-quality steel with fewer oxides and clean it before it is stamped.
The other mistake is the lack of quality control. First, the operator should have rejected the steel plate before it was stamped due to the layer of rust. Second, the blank steel is moved into the press by the operator and the spacing is inconsistent. If the backing plates are stamped too close together, it can change the dimensions and flatness. If they are stamped too far apart, it is a waste of materials. Most modern backing plate manufacturers have automated this process to eliminate human error.
If the backing plate is the foundation of the brake pad, would you trust the final product from this factory on your vehicle after watching this video?