Steel coil is one of the common building materials. Here, CAMELSTEEL will analyze the common quality flaws and reasons together with you.

Loose coil: The steel coil is not coiled tight and there is interval among layers which is called loose coil.

Reason: 1. Coiling tension is not set appropriately. 2. Steel strip presents serious wave shape or suffers coiling failure, thus steel strip deforms in roller bed. 3. The yield strength of steel sheet is at a high level and the coiling temperature is too low. 4. After coiling ends, coiling block rotates in reverse. 5. Binding tape is not tight or the binding tape is broken.

Edge wave or middle wave: The edge or middle part presents wave shape.

Reason: 1. The raw plate is not good. 2. The stabling roller suffers poor working condition.

Air knife stripe: Galvanized metal roofing sheet presents dendritic stripe or raised stripe along the direction of rolling.

Reason: 1. The zinc is too dense and zinc temperature is low. 2. Aluminum content is high, raising melting point. 3. Air knife position is low or pressure is small. 4. The gap of air knife is blocked partially. 5. Part of air knife suffers gap or damage. 6. The shape of plate is not good.