Q: What causes the "orange peel" finish on the surface of cold-rolled coils after deep processing (such as stamping)?
A: Orange peel is caused by uneven surface deformation. Causes include: low r/n value of the material, uneven die clearance, excessive blank holder force, and inconsistent surface roughness of the sheet metal.
Q: Can cold-rolled coils undergo surface treatments such as spraying and electroplating?
A: Yes, cold-rolled coils have a smooth surface, making them an excellent substrate for spraying, electroplating, and coating. Rust-preventive oil and surface impurities must be removed before treatment.
Q: Can different grades of cold-rolled coils be mixed for processing?
A: It is not recommended. Different grades have significant differences in mechanical and stamping properties. Mixing them can lead to dimensional deviations, cracking, and even die damage in the processed parts.
Q: What impact does the "flatness ratio" of cold-rolled coils have on processing?
A: The flatness ratio (the deformation rate after slight rolling after cold rolling) is typically 1-3%. This eliminates yield plateaus, improves sheet shape, and enhances surface finish. Excessive flatness ratio reduces plasticity.
Q: What precautions should be taken when processing ultra-thin cold-rolled coils (<0.3mm)?
A: Specialized molds (small gaps, high precision) must be used to control the stamping speed and prevent wrinkling and tearing. They should be stored vertically to prevent deformation.