1. Defect analysis
1. The most common is that during the delivery, the coil is slightly damaged due to lifting, moving, etc.
2. In the process of distribution and shipment, there are cushions and small pits caused by foreign objects on the vehicle, such as small stones, steel nails, etc.; or collisions caused by the movement of the coil due to the transportation personnel not fixing the coil.
3. In the lifting operation, due to the brutal operation of the lifting personnel, serious pits are caused; the key operation is wrong, the spreader hits the roll surface; the collision between the roll and the roll; the roll processing, the drop speed is not controlled, and the collision with the loading table after falling .
4. When the coiled material is stored in the warehouse, the nails and bolts on the coiled rack are loose, and the nut is raised, resulting in cushion injury.
5. "Pound difference" here refers to the difference between the weight of the cargo target and the weight of the spot goods, and the weight caused by the actual weighing of the cargo. Judgment method or tools used for weight loss: hanging scale display, hanging scale floor display.
2. Defect analysis of raw materials (packaging has been removed)
Visual inspection/feel
A. ①Unpacking: You can see some defects of the roll: such as uneven winding, tower type, bad paper (pad), loose roll or loose roll.
②Unfolded roll: The width changes from time to time, and it is called "S" shape bend. For example, if one section of the S shape bend is intercepted, it is called L shape bend.
③ Side waves, there are single side waves and bilateral waves, and intermediate waves.
④Crimping layering, cracking, default, wrinkling or folding (caused by spreader).
B. The surface has no water feeling or poor pickling, etc.
C. Scratches or bright marks on scratches, paper creasing, etc. can be found to have a slight feel
D. Scratches, abrasions, scars, inclusions, pressure points, pits, pits, etc. have obvious feel.
With the aid of tools-measuring tools / instruments
A. Defects in specification deviation: mainly due to relatively large thickness, followed by width.
B. Chemical composition deviation: divided into finished product analysis and melting analysis.
C. Mechanical properties, cracking during stamping, stretching, etc., difficult to form.
![Common defects and causes of stainless steel coils]()