Understanding the Cut to Length Line

Posted on Apr 28, 2021

Cut to Length Line

The cut to length line, which is also widely known as coil slitting line, blanking line, or CTL, is designed for unrolling and flattening the steel coils and then slit them into a desired width or length and recoiling to achieve the final profiles.

What Is the Cut to Length Line?

The cut to length line, which is also widely known as coil slitting line, blanking line, or CTL, is designed for unrolling and flattening the steel coils and then slit them into a desired width or length and recoiling to achieve the final profiles. The production line handling with the wide steel coils typically equipped with a quick tooling change system to fit in different cutting applications, decoiler, and recoiler systems, and collecting systems, which stack the sheet products into bundles. High-performance slitters are used in cut to length lines, which are generally circular cutters, handling various metal rolled coils and effectively cut to precision lengths.

The slit mults manufactured from the cut-to-length line refers to the coiled steel that has been cut to specific lengths via the master coil, which is also called the slit-to-width coil. In general, the cut to length line consists of three primary parts, which are the de-coiler, the slitter, and the recoiler. As the production cycle begins, the rolled coil is fed and flattened through the de-coiler system, removing the defects from the coil surface. 

At the next stage, the flattened material will be loaded to the nip between the circular cutting wheel which is installed both on the top and the bottom side of the slitting system. The slit-to-width coil will then be rewound by the recoiling equipment. To achieve ideal coil slitting and shaping, it is vital for the mechanists to identify whether the arbor size, tooling package, tool change system, horsepower, tensioning devices are suitable for the materials and the specifications of the applications.

Coil Cut-to-length Process

● Uncoiling: 

The uncoiling process in the de-coiler system starts with feeding the steel coil or master coil automatically onto the dual cone form or expanding mandrel single end de-coiler. The dual cone style of the de-coiler is more suitable for heavy-duty applications while the versatile mandrel type is a great solution for both light and heavy loads.

Rolled coils are fed to the cones via the pusher ramp and quick loading coil car. The raw material is loaded into the cones of the de-coiler through a pusher ramp and quick loading coil car. The loading car threads the mandrel into the inside diameter of the master coil materials, which will then be rotated off the cone or mandrel. 

The material will be peeled to make the coil head smoothly entering into the edge guides prior to the straightening tools. The flattening operations of the steel coils are particularly important when flatness, as well as free of defects on the surfaces of the materials, is critical in further coil handling processes.

● Cutting to Length: 

In this stage, the uncoiled materials will be loaded in the slitting system, which is composed of two arbors that are parallel to each other with knives that cut under rotation. The cutting knives will partially enter into the coils, causing a crack or fracture on both sides of the steels. The cut-to-length sheets will then be separated from one to another. Rubber stripper rings are required in many applications to provide more ideal edges and eliminate any burr and defects that may disturb the downstream operations.

After the precision cut, the outside edges of the products have edge trims requiring treatment by the scrap winder. In some cases that the products being cut are critically thin, the mechanists can utilize the looping pit. This can take up the varying thickness of the slit-to-width coils, especially when the edge is significantly thinner than the center part. The looping pit mentioned here can also manage the extra volume prior to the tensioning stage. 

Typically, tensioning stands are used in the slitting line before the re-coiler system. The tensioning device is responsible for creating the master coil, which has a larger diameter in the center parts than the edges. Without this tensioning stand in the cut to length line, the material will be taken up faster from the central parts of the stock while both sides will be loosely hanged.

● Recoiling: 

Before stacking the sheet products, the slit-to-width coils require to be recoiled through the expanding mandrel re-coiler system is cut to length lines. The re-coiler system can typically expand ranging from a diameter of 60 cm or more working with the expansion pads or leaves. The recoiler system fits with an overarm shaft with separating discs, which are mounted directly in line with the circular slitters. This keeps any interleaving condition of the narrow coil applications. Next, the processed sheets will be forced off from the mandrel to the coil car, stacking into bundles by the sheet stackers.

:: Read more: Cut to Length Line Manufacturers at A Glance

Why Do You Need the Cut to Length Line?

First of all, the high-performance circular cutters in the cut to length line, which are critically manufactured and machined can slit the steel coil with minimum burrs, making the cut to length line a reliable system to produce high-quality sheet products with precision lengths. 

Secondly, the cut to length line that features precision cutting can effectively decrease the material costs and the production time. To complete the production of the slit-to-width coil, the manufacturers no longer need secondary coil handling equipment, the entire production cycle including the flattening and recoiling process can be completed in the cut to length line. On the other hand, the customers of the sheets can find the steel coils in standard and accurate widths or lengths. 

Last but not least, the cut to length line for steel coils offers a high level of automation and simple manipulation. This makes the system easier to operate, monitor, and maintain, enhancing reliability and accuracy as well as production efficiency. The automatic feed of the de-coiler system and high precision stacking tools can further upgrade the cut to length line to achieve efficient operations.

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