The Forming of Metal Coils: Coil Slitting

Posted on Dec 25, 2020

Coil slitting

Coil slitting is the process that cuts the wide coils of metals such as steel, aluminum, copper, brass, etc. into narrow coils with the metal coil slitting machine or slitter, in order to provide the customers for further applications.

What Is Coil Slitting?

Coil slitting is the process that cuts the wide coils of metals such as steel, aluminum, copper, brass, etc. into narrow coils with the metal coil slitting machine or slitter. It seems that cutting wide materials into narrower parts is a normal process, while to produce the metal coils with optimal precision does require considering a lot of factors and machining techniques actually.

The metal coils can be commonly seen either in the industrial fields for being parts of the elements, such as in the wires on an EDM, or the products that are made for daily use. These metal coils may come in a wide range of sizes and widths, and both thin and thick coils require consistent and smooth edges so that they would not cause failure when they are adopted for other applications.

To achieve the precise cuts for the coil slitting process, a variety of factors like the knife clearance, sharpness of the knife, machine maintenance, burrs, edge wave, knife marks, camber, or crossbow, etc. should be carefully considered or avoided, in order to ensure the desired outcome when the products are made.


How Does a Coil Slitting Machine Form?

A coil slitting machine, also known as a coil slitter, consists of a long working station, and the station contains an uncoiler, a slitter, and a recoiler. Each part of the coil slitting machine sets the workpieces, which are the metal sheets, to be fed into or sent out in place by the conveyors.


● Uncoiler

The uncoiler is also called the decoiler, which is the first part of the machine that allows the metal coils to be sent out to the slitter as the metal sheets. The appropriate setup of the uncoiler makes a significant difference in the success or failure of the coil slitting process.

To appropriately set the uncoiler, some parameters include the weight, width, thickness, inside diameter, outside diameter of the metal coils, and the speed of the delivery of the coils are all required to be taken into account since when one of them doesn’t meet the requirement, it is possible to result in the total failure of the coil slitting process.

For instance, if the speed of the delivery of the metal coils is faster than the time the slitter, which is in charge of the next procedure after uncoiling, spends on cutting the metal sheets, the metal sheets cannot remain flat, which may cause the cambers on the metal coils. Therefore, proper setup for the uncoiler must be the first and foremost step to be conducted during the coil slitting process.


● Slitter

The slitter refers to the cutter on the coil slitting machine. It is set in the middle of the entire line and performing the second step after the uncoiling of the metal sheets. 

The slitter is a series of circular blades that are arranged in a row with equally distributed intervals. After the metal coils are uncoiled into the metal sheets, they would be sent to the top of the slitters and ready to be cut.

Therefore, the total width of the metal sheets would be equivalent to that of the series of blades, and the intervals between each circular blade of the slitter determine the width of the final products, which are the narrower metal coils.

Similar to the uncoiler, a small deviation of the slitter set-up would make a big difference in how the final products are presented. For example, the total width of the metal sheets should be the same as the total width of the series of blades. If the metal sheets are narrower, they cannot be fitted perfectly on the blades or probably twisted. In contrast, if the metal sheets are wider than the row of the blades, they are not capable of being fed into the slitter to undergo the cuts.

In addition, the intervals between each of the circular blades should be equally distributed, since they determine the width of the coils that have been cut. Both the manufacturers and the customers don’t want to obtain the products with unequal sizes so that setting up equal intervals of the blades is one of the important things before cutting.


● Recoiler

The recoiler is the last part that the metal coils that have been cut would travel to on the coil slitting machine. When the final products of this machine are made, they should be rolled into coils again, which would require the recoiler to assist.

What the recoiler does is opposite to the work that the uncoiler does, while it should also follow the parameters, including the weight, width, thickness, inside diameter, the outside diameter of the metal coils, and the speed of the delivery of the coils, just like the uncoiler.

:: Read more: What Is Steel Coil Slitting Line?


How Does Coil Slitting Work?

As far as we know, coil slitting is to cut through coiled wide metal sheets into several parts, so as to obtain the narrower metal coils and provide the customers for further applications.

The process of the slitting of metal coils can be simply divided into three steps, which are equivalent to the numbers of the components, including the uncoiling of metal sheets, metal sheets cutting, and recoiling.


● Uncoiling of metal sheets

As the name implies, this process is conducted on the uncoiler. When the wide metal coils are properly set around the uncoiler with the consistent width, inside diameter, and outside diameter, as well as the speed of the uncoiler, the uncoiler would start releasing the metal sheets to the conveyer and allow it to deliver the metal sheets to the slitter afterward.


● Metal sheets cutting

Once the metal sheets are uncoiled and sent to the slitter by the conveyer, the series of sharp circular blades that are supposed to be set under the metal sheets would start cutting them. In addition to the parameters that should be followed as the uncoiler, the motion of cutting is given by the compressive force of the slitter.

When the metal sheets are sent to the slitter on the blades, the slitter would provide a compressive force that pushes on the metal sheets in order to achieve the cuts. Once this compressive force is given, the metal sheets would be divided into narrower coils as the width of the intervals between the blades.


● Recoiling

After the workpieces are made as narrower coils, they would be sent to the final stop of the coil slitting machine, which is the recoiler, by the conveyer. When the recoiler receives the metal coils, it would help roll these coils again and lead to the completion of the end products.

In this procedure, the speed of the delivery of coils matters a lot. Since the workpieces here have been separated into thinner parts but remain long as well, whether all these coils are sent to the recoiler with the same speed or not would determine the perfection of the final coils. Therefore, during the process of coil slitting, it is necessary to have the operators supervise and adjust the machine when it is needed, so as to make sure the process goes smoothly without problems. 


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