Straightening is a function to remove “Coil Set”. When metal is wrapped in a coil, over time, the material can often still have some “memory” of being wrapped in a coil and have a curve to it. Machines with straightening have a set of rollers that remove this coil set, allowing for blanks that lay flat without this curve.  When applications always go from slitting to forming, sometimes the removal of coil set is not needed.  This is because when the first bend is put into the material the coil set is then removed.  We see this mainly on application with 26ga, 28ga & 29ga.  Primarily in the metal building industry or some call it pole barn industry.

When customers are forming 24ga or thicker, sell flat stock, process soft or sensitive material, the straightening becomes needed.  With 24ga material being a little thicker the material will retain the memory or coil set in a more dramatic way.  Paired with the more diverse applications that 24ga is used for, the coil set provides a problem in the process.  For example, since the material is curved it can span over backgauge fingers, backgauge grippers, or be cumbersome for the operator to get the material into a shear due to the safety gap of the shear’s hold down.  For these reasons, we recommend straightening.

When straightening soft materials, opting for a slitter with CNC straightening rollers or “Sensitive Material Mode” is recommended. CNC-controlled rollers are automatically raised anytime the machine stops. This prevents dwell marks in the material. A great analogy is a steam roller on a newly paved asphalt road. A steam roller should never stop on the new, hot asphalt. Doing so would leave marks on the pavement!

This will, of course, vary based on a customer’s business. Most machines can have one to as many as nine knives. Typically, you want to find a balance.

• Too few knives many not make as many slits as you need.
• Too many knives reduce the slitting capacity of the machines and make the machine ‘crowded’. Whether the machine has manual or CNC knives, knives need to be moved when changing slits and could waste time.
• Most of our customers purchase a machine with 5 to 6 knives.

Note that on all machines slitting knives are considered consumables.  The knives will wear over time.  The wearing time is a product of what material, how much is processed and is the blade gap set up properly  (~10% of the material thickness).  If the slitting production need is high, we would suggest purchasing a few pairs of extra slitting knives to be able to change out the slitting knives when they dull and need to be replaced or sharpened.

Coil width
Most slitters are offered in 50” (1250mm) and 60” (1500mm). 50” versions are the most popular as 40” to 48” coil widths are the most common. Keep in mind, that a wider slitter will often have slightly less slitting capacity.

Step cutting
While this option is only available on a nuSLIT it can be a useful solution. Step cutting allows for maximum material use. During a cut to length process the Step cut option can cut blanks independently at different lengths. If you have mostly standard lengths, the option is not as beneficial.

nuEVOLUTION software, the system can automatically nest out jobs of common materials.  If you have various lengths, the options saves on material waste.

Film Applicators
Due to sheet metals cosmetic aesthetics it is common for the surface to be painted, polished or treated with a finish. Fabricators want to protect the surface, which means many of our customers like to apply film to their material. Specifically, when selling flat stock.  These options can be added at any time.  If you happen to be a start-up, we are happy to recommend film suppliers for you to talk to.

Label printer
Label printing is ideal when blanking pieces for multiple jobs with multiple parts. Using the label printer paired with NuEvolution allows you to avoid making mistakes. Each cut piece automatically has a QR code label applied, and then, the folding machine can scan it to pull up the profile automatically and bend the correct part every time.

Stripper Rings
Stripper rings are used on manual adjusted slitting knife machines. Due to psychics, when metal is silt in narrow dimensions, the material wants to twist or pigtail.  However, many of our customer’s want narrow slits so a set of stripper rings, or rubber coated collars go on the slitting shaft to hold the material when it is processed.  If it is a common practice for you to slit less than 3”, these will be recommended.

Decoiler Options
There are many ways to feed a slit to width, Cut-to-Length machine. From a manual decoiler to a coil farm.  Most common is a single motorized decoil system, but with more customer wanting automation, CIDAN has answered our customers need with the Coil Farm.

Coil Farm
The coil farm takes coil storage and coil changes to the next level. At the push of a button, coils are automatically changed over without an operator or forklift. For large shops with many coils, the Coil Farm streamlines your operation.

This is one of the most common questions we receive.  A slitter with CNC knives is a more significant investment than manual knives. In terms of the finished product, both machines will offer the same high-quality finished product. In terms of speed, a CNC machine will likely be faster than a novice operator. However, an experienced operator can change knives faster than a CNC machine. The bottle neck of the slitting operation, often comes down to the coil handling system.  Operators are spending far more time loading and unloading coils than changing knives.

When making this decision, consider where the production bottle necks will be today and in the future.  For example, a smaller operation with plans for growth that has one up acting long folder for the forming operation.  When a decently experienced operator is on the slitter, they will be producing on average 3-5 slit blanks per cycle of the shear.  When we watch the video below, that is about 1min 20 seconds including a knife changeover, and about 15 seconds if there is no knife change over.  With that speed, there is no question that the constraint for production will be on the forming side at the up acting longfolder.  Therefore, we would recommend saving the money to invest in the future for an additional forming machine.

On the other hand, if a operation does have multiple forming machines, or blank fed rollformers, automation can be justified to look at.  That said, consider the constraint of the slitting process.  Many times it comes down to coil handling.

When looking at an automated slitting ease of programming should always be considered.  If using now or planning to use shop software like NuEvolution, cuts are sent directly to the machine, giving the most efficient use of time and material.

Since stainless steel is a harder material than mild steel, a machine’s capacity will decrease. If processing more than about 25% stainless steel, HVC Hardchrome on straightening rollers is recommended to extend the life of the rollers. If your  material has a sensitive finish you will need to consider the “Sensitive Material Mode” option that is mentioned in the “What if I use soft materials?” section.