Common defects in disc brake pads are: cracks (between friction material and backing plate), Missing corners, cracks, water ripples, uneven filling holes, loose filling Excess adhesive on the hole and back plate, flash of backing material, and color of the abrasive coating. All, skin cracks, uneven distribution of primers, unclear marks, unground materials Surface, friction material surface paint, surface foaming, surface pits, friction material Surface has wear scars, high porosity area, poorly cured friction material, and surface difference. The spots of the material, the material itself, and the friction surface structure are unreasonable.