Quality objection case of edge waves
A customer purchased a batch of stainless steel plates, but they could not be used because the edges of the plates were undulating. The customer was very upset and complained to the purchaser.
Case Analysis:
After receiving the complaint, the supplier immediately organized an on-site inspection and found that the wave-like undulations of this batch of products were sided waves with a wave height of 3mm and a length of about 300mm.
Because the customer wants to weld the edges, the existence of waves makes welding difficult.
The cause of the edge wave is that the edge of the steel plate is stretched too far, which causes the edge length to be greater than the internal length. The main reasons are the thermal crown of the roll, the improper roll curve, the uneven roll pressure, the improper reduction and tension, and the raw material Poor thermal convexity, etc.
For the defect of edge wave, it is difficult to eliminate in the opening process. Because the straightening in the flattening process is generally only repeated bending in the leveling roll to eliminate the bending stress of the original steel plate, it is difficult to eliminate the edge waves without tensile stress.
However, it is possible to improve the existence of side waves by using some leveling rollers with smaller roller diameters to straighten and adjust the reduction of the middle roller appropriately.
Because the edge waves are difficult to eliminate, and the national standard has very loose requirements for edge waves, customers who have higher requirements for plate types will be noted in the special requirements when purchasing. The customer did not know much about stainless steel, so he did not make an explanation, which led to this objection.
Case Handling:
After determining the cause of the quality problem, the supplier exchanged a new batch of steel plates for the customer.
Because the defects of this batch of steel plates with edges and waves are not serious, they can be sold to customers with low requirements within the internal control standards.