How can stamping parts avoid scratches and wrinkles during stamping and achieve Class A surface quality standards?
Publish Time: 2025-04-05
In the field of automobile manufacturing, stamping parts are the core components of the body structure, and their surface quality directly determines the appearance quality and durability of the whole vehicle. The Class A surface quality standard requires that stamping parts have no scratches, wrinkles, burrs and other defects, and the surface roughness must be controlled below Ra0.8, which places extremely high demands on stamping processes, mold design and material processing. Behind this goal is a system engineering that integrates precision technology, material science and process control.Mold design and manufacturing are the cornerstones of surface quality control. Strain defects usually come from insufficient hardness or excessive roughness of the mold surface, resulting in scratches when the material rubs against the mold. To solve this problem, the industry generally uses high-hardness tool steel (such as H13 hot work die steel) and performs surface strengthening treatment, such as plating TiAlN coating through PVD (physical vapor deposition) technology to increase the mold surface hardness to above HV3000 and reduce the friction coefficient to below 0.2. In addition, the mold surface needs to be processed by five-axis CNC machining and mirror polishing to ensure that the surface roughness reaches below Ra0.4. For complex curved parts, CAE simulation technology is also needed to optimize the layout of drawbeads, balance material flow, and avoid strain caused by local stress concentration.The control of wrinkling defects depends on the precise matching of process parameters. During the stamping process, the difference in the flow speed of the sheet in the mold cavity is the main cause of wrinkling. By introducing servo presses and variable stroke technology, the stamping speed can be adjusted in real time according to material deformation, such as reducing the speed in the early stage of deep drawing to reduce material accumulation, and increasing the speed in the forming stage to suppress rebound. At the same time, the use of double-action presses and floating die handle structures can dynamically compensate for sheet thickness fluctuations and ensure uniform distribution of blanking force. For high-strength steel plates, it is also necessary to combine hot stamping processes to complete the forming at a high temperature of 850°C, and use the plasticity of the material to improve and eliminate the risk of wrinkling.Lubrication and cleaning processes are also critical. Traditional lubrication methods are prone to oil residues, affecting the adhesion of subsequent coatings. The current mainstream solution is to use micron-level dry film lubricants to form a uniform covering layer on the surface of the sheet through electrostatic spraying, which not only reduces the friction coefficient but also avoids oil pollution. After stamping, the residues need to be thoroughly removed through high-pressure water cleaning and vacuum drying systems to ensure that the surface cleanliness reaches the ISO 8501-1 Sa2.5 standard. In addition, for easily oxidized materials such as aluminum alloys, passivation treatment is required immediately after cleaning to form a dense oxide film to prevent corrosion.The application of process monitoring and digital technology provides a guarantee for quality stability. By embedding strain gauges and temperature sensors in key parts of the mold, the load and temperature fluctuations during the stamping process can be monitored in real time, and the defect risk can be predicted and the parameters can be automatically adjusted in combination with AI algorithms. For example, when the clamping force in a certain area is detected to drop, the system can immediately compensate for the pressure to avoid wrinkling. At the same time, online optical inspection equipment is used to perform 100% surface scanning of each product, and micron-level defects are identified through deep learning models to ensure zero outflow of defective products.From mold design to process optimization, from lubrication innovation to digital monitoring, the realization of Class A surface quality of automotive stamping parts is the result of multiple technical collaborations. With the higher requirements of new energy vehicles for lightweight and aesthetics, the stamping process is evolving towards intelligence and greenness, and through continuous technological iteration, it is injecting more precise manufacturing genes into the automotive manufacturing industry.
