February, 2024- Manufacturers often demand that the raw materials they receive be perfect: the edges are clean, there is no variation on gauge or width, and they can enter miles of strip through their own processes without having to reject anything that’s out of tolerance. Manufacturers want reliability, repeatability. That is why service centers and metal processors look for equipment that will help them meet those goals. One equipment builder that makes high-precision slitters is Athader S.L. in northern Spain.

A division of Moundridge, Kansas-based Bradbury Group, Athader has designed and built custom metal processing equipment for 30 years, and each permutation of its slitting line design has to tackle something “more” than before, such as the tensile strengths that must be cut with the same degree of accuracy as less challenging materials.

Athader first introduced its double eccentric slitting heads in 2005, and now can manage coils from 0.006 inch to 0.75 inch thick with precision components that guarantee width tolerances and minimum strip burr.

      A hydraulic system applies the right amount of pressure to keep slitter knives and spacers tightly in place 

       Athader’s double eccentric slitting heads are designed to cut a wide range of material of various gauges and tensile strengths. 

The slitter arbors are mounted in precision double eccentrics for precise penetration of the coil. Strong, rigid housings prevent movement that might negatively affect the cut. The eccentrics are supported by pre-loaded precision bearings providing “zero” axial clearances. The eccentrics are adjusted via motorized AC drive that can automatically set the required gap and display it on the operator’s HMI.

The slitter tooling is locked in place on the arbor by an automated, hydraulic, high-pressure, 360- degree locking system to guarantee the correct pressure on the tooling setup.

The double eccentric heads provide a consistent pass line; the heads work in tandem to allow the slitting of high-strength material with near zero penetration. This gives the slit material enhanced edge quality, no strip burr, reduced knife traction marks and much tighter width tolerances.

These conditions improve edge quality while prolonging the life span of the slitter knives and stripper rings. Customers operating these lines have experienced increases of over 200 percent in time between knife grindings, which lowers operational and maintenance costs.

Inaki Vazquez, technology director for research and development at Athader, notes that for lines without these features, assembly on the arbor of the correct knives and spacers was done manually by slitter operators, which meant the slitter wasn’t running.

“Taking each blade and each spacer, and putting it manually on the arbor—this assembly of tooling for a new setup took at least 40 minutes to finalize. Imagine this is 40 minutes of downtime on the machine,” Vazquez says. With Athader’s system, which has preprogrammed setups and an automated tooling assembly robot, the removal of old tooling and placing of new tooling takes only 10 minutes. (More on the robot later.)

Several years ago, “we decided to insert a four-arm turret and assemble the tooling on one side while the machine kept running. It is very common in service centers that they build wonderful coils,” Vazquez says. “But the real situation is that you do one tooling assembly and produce two coils. After those two coils, you remove those coils and reassemble for another setup for different widths. All this was done manually. We designed this turret to assemble new tooling setup offline” while the next slitting order was already set up on another arbor and the slitter continues to run that other job.

      Slit coils must have clean edges with minimal burr so that customers can move material into their own processes without refinishing. 

HYDRAULIC PRESSURE

In the past, to fix tooling on the arbor shaft so it did not move sideways while cutting, “an operator had to get inside the machine, insert the tooling and with one nut here, and another there, perform all the locking of the tooling,” says Vazquez. “These nuts were installed and tightened with a key and hammer.” Then, when the job is done, the operator had to, by hand, unlock and remove the tooling.

“We designed a hydraulic system that moves out and in automatically. Cylinders lock the tooling into place by applying the right amount of pressure on the tooling, without human intervention.”

The complete process of loading and locking in the tooling is no more than 15 minutes, Vazquez says.

All the selection of the new tooling is done by computer. The control is robotic. Each knife and separator is identified on the computer, which instructs the robot—gliding back and forth along the length of a tooling storage wall—to select and carry each knife and separator that is needed for the job.

“The tolerance for each piece of tooling spacing is down to 0.002 millimeters,” says Vazquez. “You might install 40 knives and spacers. Imagine that each has a little particle and that might be adding extra width. You need very high pressure to eliminate any dust or particle, or even a thin film of oil that is on the coil. All the extraneous material has to be cleared,” he explains. “One operator can determine the pressure for each tooling setup. It has to be very controlled. The upper and lower shaft pressures can be modified separately.”

QUALITY

As for speed, Vazquez says, “we can work up to 2,000 feet per minute.” Yet, the cuts have to be exact or else the processor or service center will have the material rejected by the customer. “The quality of the edges also must be very accurate. It must be perfect. That is because the coil will be further processed and they don’t want to refinish the profiles.”

Edges have to be especially clean when the material has to be welded, he notes.

“Today, we have more than 200 slitting lines installed with this system. We work with high-grade steel and aluminum, and now we are working with materials in the U.S. and Europe up to 1900 MPA of tensile strength. In aluminum, we are talking about 180 MPA. So the system works with soft and hard materials. We even cut galvanized.

“One machine often has to handle multiple materials. Even if two customers have the same thickness and widths, there are parameters that will be different, however. Formerly, you had one machine for stainless, one for carbon, one for aluminum. With this single system, each material has a custom solution,” Vazquez says.

“Customers will need more productivity with these machines.” Looking forward to further iterations of the design, Vazquez says that “on the point of production, we have to gain time in the process. We have to reduce man hours per ton. And we have to produce fully automatic machines. That is the challenge.”

Athader S.L., 620/345-6394, athader.com

 

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