Inspecting the Quality and Weight of Strips From a Hot Rolled Mild Steel Coil

This is the checking of the quality of the raw material; before the process of slitting a hot rolled mild steel coil, during the process of slitting it into strips and after, so as to produce good quality strips and to prevent further damage - if any had occurred - to the strips. To make sure everything was done properly, measures are taken after the process is complete by calculating the weight of each strip produced.

After the coil has been inspected and placed into the slitting line machine and the process of slitting the coil into strips commences, the strips are inspected for un-slitted parts, burrs, dent edges, waviness, rubber marks, blisters, splits, laminations, notches and cracks.

Definition of Terms

Un-slitted part: This is a deformity caused by poor balancing of the extra material (scrap) at both ends of the coil. This is commonly found on the first strip and the last. It can also be caused by the reduction of the coil width at mid process thus resulting in reduction of the strip's width size. To prevent this, when the deformity is noticed, the slitting machine's cutters should be carefully lowered so that they create a uniform overlap.

Burr: This is a sharp edge protuberance on the strip facing upward or downward and is caused by poor slitting machine's setting or blunt cutters. Burrs may cause openings when the material is being processed in the making of tubes.

Dent edges: The mishandling of the strips, especially at the edges, during the process of slitting, causes this deformity. The mishandling mostly occurs when the strips are constantly moved during the slitting process.

It can also occur when the dents of the hot rolled coil are too deep for the extra material, known as scrap, to pass through at its sides. When this happens, the extra material is rolled to the scrap winder thus causing notches, cracks and dents.

Waviness: This is the deformity in which there is lack of flatness on a strip. It is caused when the coil itself is wavy or by poor slitting machine's setting at the beginning of the slitting process. To make sure the slitting machine settings are correct, so as to avoid a majority of the aforementioned deformities, before the process of slitting begins; pass a half a meter strip through the slitting machine's cutters. The strip's width is then measured to check if it is correct once it comes out of the cutters.

Once the process is completed, one can save time in knowing the weight of each strip without having to weigh them individually. To do this, one should start by measuring the weight of the waste material that includes the material at the sides, which is attached to the scrap winder. After getting the total weight of the material, subtract it from the coil's weight. The result is then divided by the total width of all the strips and multiplied by each strip to find individual weights.

Another method:
Use the length and width of the slitted strips to find the area then
multiply the results by the actual thickness to get the volume, after getting the volume multiply by the density of mild steel to get the weight.
Use the length, width and thickness of the strips to get the volume,
The weight can then be calculated by multiplying it by the density of mild steel.
The density of mild steel can be directly measured and used to calculate the weight of the slitted strips.

A defective strip should be marked or the defective parts cut off. Once a part of the strip is cut off, its weight should be taken and subtracted from the original strip's weight.