Several purposes of slitting

1. Cutting by specified length (unit weight)

When the slitting steel strip is sent to the customer's factory for stamping, the unit weight is required to improve production efficiency (the length of the steel strip is as long as possible).

New factories can prepare corresponding equipment to accept steel coils with large unit weights, but old factories or small and medium-sized enterprises cannot accept steel coils with small outer diameters and small unit weights. The segmented delivery in the length direction (i.e., small unit weight) also leads to low production efficiency of steel coil slitting processing centers.

2. Rewinding and reprocessing

The end user's specified width for slitting processing varies greatly, so there will always be times when it is uncertain. When cutting wide steel coils, there are many different cutting methods to maximize material utilization, and most of them are determined by human feelings. Differences between individuals (a kind of stunt) cannot be avoided. Recently, there are many methods for optimal cutting with the help of computers, and some half-rolled steel coils are often produced.

These half-rolls can be cut in the width direction by the slitting machine, or connected at the head and tail on the slitting line to make a large unit weight steel coil. Sometimes, there is also an operation to rewind the coils that have been coiled poorly.

The head and tail joints of the steel coils are sometimes taped and sometimes fixed by welding. Welding methods also include spot welding, TIG welding, and MIG welding (for thick plates).

3. Cutting by order

In order to improve production efficiency, steel mills have a trend of wide finished steel coils and large single weights. This is mainly due to the detailed service requirements of end users such as multiple varieties, small quantities, and timely supply. This requires suppliers to open steel coil processing and distribution centers near users.

Sometimes, customers require that they be supplied to customers according to specified widths, specified weights, and even specified outer diameters. The processing accuracy of the specified width will vary depending on the purpose and the next process. For example, the requirements for continuous die stamping materials are stricter than those for single die stamping materials. Particularly representative are electrical steel plates, integrated circuit lead frames, and waste-free processing (that is, when the longitudinal shearing edges are directly used as finished products), which also limit the width accuracy and strip snaking (sickle bend).

4. Processing and inspection to remove defects

When steel mills produce in large quantities, there will always be some defects that are not seen. However, it is not acceptable to hand it over to users as it is, so the bad parts must be removed in the final process (i.e. longitudinal shearing process).

Therefore, the steel mill is required to provide defect information such as the parent material development diagram, and conduct inspections during processing based on this.

Of course, in principle, the cross-cutting line processing should not cause scratches, crushing, edge damage and other problems. Especially when the surface gloss is strictly required, a strict visual surface inspection must be carried out before winding.