As industries advance, the demand for slit coil to meet strict and precise requirements also increases. Steel coils must improve efficiency and productivity while exceeding rigorous industry standards. One way to meet this demand is through slitting and edge conditioning.
Slitting and edge conditioning (also known as skiving) are essential parts of steel processing that increase the quality and safety of the final product. While some applications do not require extensive or precise slitting and edging, most industries profit from the practical benefits offered only by slit and conditioned metal.
The Slitting and Edge Conditioning Process for Stainless Steel Slit Coil
Steel slitting is a process that cuts a wide master coil of metal into narrower strands that have more consistent measurements. Manufacturers feed the large stainless steel through a machine called a slitter, then recoil the resulting strands into a finished coil. After this process however, the machine’s knives leave behind a burr on the slit edge.
A slitting burr can sometimes be beneficial when it comes to welding, but typically the sharp edges are a hindrance. That’s where edge conditioning, or edging, comes in. Edging is the process that smooths or rounds the sharp edges of slit metal to remove the burr and make it safer to handle and use in exposed applications. Conditioned edges are available in several shapes: deburred, square, round, rolled, beveled, or they can be custom shapes.
Types of Steel Used in Slitting and Edging
Any type of steel can undergo slitting and edging, but not every metal is compatible with every type of edging. You may be limited in your choice of edging by steel grade, size, and width tolerance. Some edges work better on harder grades of stainless steel, but the same edging process could weaken or even shred softer steel. Moreover, certain edge shapes also have restrictions when it comes to width and material thickness. Even if the preferred edge isn’t suitable for the application, you don’t need to worry about quality. Any type of edging improves the quality of your strip and removes rough edges.
The cutting machine also makes a difference to the material that you use. Most cutting machines function similarly, but parameters like the cutting tool, the rake angle, and even how the metal is coiled can affect the finished product.
Benefits of Slitting and Edge Conditioning
Proper slitting and edge conditioning is important for three reasons: functionality, safety, and aesthetic.
There are many functional benefits of a slit coil. These include improved efficiency as it’s easier and faster to feed through machinery, coil customizability, higher-quality products since edging provides a more uniform result, and extended life expectancy since conditioning prevents edge cracking and increases formability.
In addition, stainless steel objects like food trays or soup ladles simply wouldn’t be functional without proper edge conditioning. In other words, conditioning is much more than removing a slitting burr; it’s often a required processing step for product functionality.
Practical Applications for Slitting and Edging Stainless Steel Strip
A slit coil has countless practical applications. First, slitting allows you to buy metal strip closer to the finished size of your product, which reduces waste and saves processing time. In addition, because slitting and edging produce more consistent and higher-quality metal products, you can use the conditioned steel in markets and applications that demand precision and tight tolerances, such as electronics, medical, automotive, aerospace, commercial, and more.
Some of the most common uses for conditioned stainless steel include surgical instruments, flexible metal hose, hypodermic needles, and superconductors. Rounded and polished coils can also serve decorative purposes, and they often feature as design elements in the automotive industries.
In short, stainless steel slit coil is attractive to many industries; it’s versatile, easy to sterilize, and not prone to corrosion or rusting. With the addition of processing like slitting and edging, it becomes an even more practical and efficient choice for many precision products. Precision cutting methods can create ideal characteristics for many critical applications.
The USSM Manufacturing Process
At Ulbrich Specialty Strip Mill (USSM), we convert strip metal from widely available standard specifications to meet unique customer needs including thickness, width, specific mechanical properties, industry specifications and many other critical characteristics. The conversion process can be broken down into three basic steps:
1. Rolling: To reduce thickness
2. Annealing: To restore ductility
3. Slitting: To separate a wide strip into narrower cuts.
Rolling
Rolling is a continuous metal forming process in which metal stock is fed between two hard work rolls which apply enough pressure to plastically deform the metal, inducing a permanent reduction in thickness uniformly across the width of the strip. Rolling at USSM is considered “cold rolling” because we do not increase the temperature of the material before we roll it. Modern rolling practices employ a combination of screw down pressure, perpendicular to the strip surface, and longitudinal tension to ensure that the reduction in thickness translates exclusively into an increase in strip length instead of
Annealing
The difference between the starting material thickness and the final ordered thickness of a given product is often greater than the maximum reduction an alloy can withstand without breaking. In this case, the equiaxed grain structure of material must be recovered before it can be rolled further, which is done through annealing.
The material is heated to an intrinsic critical temperature and held at there long enough for the microstructure to essentially reset. The thermal energy introduced by the furnace allows the grains to recover from the effects of the work hardening introduced during rolling, at which point the metal will re-crystallize, or precipitate all new equiaxed grains.
The grains start very small and grow in size over time. Once the equiaxed grain structure has been restored, the strip is ready to be rolled again. This rolling and annealing cycle can be repeated as many times as necessary to reach the final ordered thickness. Products ordered in the annealed condition do not require subsequent rolling.
Slitting
The strip is fed through an “arbor” containing two sets of hard, rotating tool steel “knives”. These knives penetrate deep enough into the strip to weaken the adjacent material to the point of fracturing. The slit mults continue from the arbor to a re-coiler where they are accumulated back into coil form.
The depth of penetration, or, clearance, of these knives is closely monitored, as the burr on the edges of the mults will vary with the clearance. USSM standard #3 slit edge maximum burr is 10% of product thickness. Our operators will make adjustments to the clearance as they are preparing to slit in order to minimize the burr as much as possible.
Slitting can serve as both the initial and final operation in the conversion process at USSM. All of the slitters at USSM are similar in concept and operation but vary greatly in size. Our larger machines are dedicated to slitting the heavy gauge incoming coils up to 54″ wide to mults used for re-rolling.
At the other end of the process, slitting is used to separate a material at finish gauge and temper into the width ordered by the customer. Many considerations regarding coil configuration must be made during a final slitting operation as the output is often a coil in delivery condition.
Apart from width: edge condition, coil support, coil inner diameter, coil size, interleaf and accumulation method are all characteristics of the final product that are realized during final slitting. Once a coil is slit to final width it can be packaged and delivered to the customer.
Learn More about Slitting and Edging
For the safest and most efficient processing, your slit coil must be cut above the rest. Properly slitting and edging your stainless steel strip ensures the best-quality final product and an improved handling experience. Slitting and edging are crucial for clean and safe metal edges in all industries and applications.
For more information about the slitting and edge conditioning services available at Ulbrich, contact us today. A specialist can answer questions about your specific needs, or you can request a quote right away.
