Gauge to automatically measure the widths of multiple strips of coil provides multiple benefits

April, 2023- Gauge to automatically measure the widths of multiple strips of coil provides multiple benefits

Measuring mult widths manually is time consuming, a potential safety hazard and prone to errors. (A mult is short for multiple, and multiple strips of coil are created when slitting wide coils.)

Customers of Advanced Gauging Technologies LLC (AGT) requested that the company develop a method to measure each strip width automatically and accurately while improving worker safety, says Nick Hunkar, sales and marketing coordinator for the Plain City, Ohio-based company. “Interest is split probably 50/50 between the time savings element of it and the safety element of it.”

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       The laser finds the strip’s edges with the AGT Mult-Width gauge

Measuring by hand requires using a caliper to determine the width of each mult, which might not be performed correctly, and the width information must be documented correctly, which might consume five to 10 minutes to write down all the information.

“If you have 20 [mults] and you have to measure each one and either remember all the numbers or write them all down, there are all kinds of bits and pieces of error that can creep into it.”

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      A recent installation of the AGT Mult-Width gauge at a coil processing facility

In addition, older, compact coil processing lines usually do not have an area where an operator can place a caliper and take measurements while newer, larger lines do, Hunkar says. Besides having to handle sharp metal, operators working on the older lines must climb on machinery and work above a looping pit. “You have a safety hazard there.” Realizing end users wanted a better way to measure mults, Hunkar says AGT began the development process. “We thought, yeah, sure, not a problem, we can figure that out.”


The company, which specializes in manufacturing and servicing non-contact thickness gauges, introduced the AGT Mult-Width gauge last year after three years of research and development. Hunkar says AGT initially tried a camera-based technology but eventually realized that a camera doesn’t know how far a metal strip is from the camera, and the width will change as the material moves up or down. Also, cameras rely on a backlight underneath the material and an inconsistent backlight brightness changes the measurement.

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      The software for the AGT Mult-Width gauge displays production measurements

Next, the company tried a profile laser and determined that a high-quality unit measures mults accurately, Hunkar says. However, the profile laser technology can be costly. “It’ll work great, but to get enough coverage across the standard 60-inch or 72-inch-wide coil processing line, you need a number of lasers, and it gets real expensive real fast. That gets real hard to sell and real hard to get your ROI back.”

Some simpler types of lasers proved to be too slow or had reflection issues, he adds. AGT finally determined that a displacement laser did the trick and went with one from LMI Technologies Inc. in Vancouver, British Columbia, because of its long range.

The laser sensor, mounted on a robot, continuously traverses the slit material to consistently measure and record the width of each mult. Hunkar explains that one advantage of the displacement laser compared to other lasers is an encoder reader can be installed inside of it. “It’s got a microprocessor inside of it that can basically very quickly say, ‘here’s the edge, here’s the encoder reading.’”

The first version of the gauge performed a measurement scan in about 90 to 120 seconds, but customers told AGT that that was too long, Hunkar says, so the company got it down to 30 seconds. “That’s a good number and it’s just as accurate—maybe even a little bit more accurate since we did some more work last year to fine tune things.”

The time savings from measuring mults automatically instead of manually adds up, according to Hunkar. “By the end of the day, you’re getting a whole other coil through. That’s where the ROI comes in.”


The AGT Mult-Width measuring system enables metal processing operations to consistently ship finished coils with mult strips that meet their customers’ specifications. Hunkar says a company that ships coils with incorrect mult widths faces higher reject rates, the expense of replacement, the hassle of trying to resell the rejected coils to customers that can use them and reputational damage.

AGT’s system also provides data storage and analysis. According to the company, mult-width verification is saved with a date and time stamp and is included in the coil report documentation. All mult width data is stored automatically on the system or on a networked drive or both.

“It’s documentation that’s either being asked for by a customer or backup in case a customer complains about something,” Hunkar says. “If they send a coil to a customer and the customer comes back and says, ‘Hey, this isn’t right,’ they can pull the data and say, ‘Nope, here it is. Here are the recorded measurements.’”

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     The AGT Mult-Width measures and records every mult across the entire width of the line in about 30 seconds

The gauge is suitable for measuring material as thin as that used to make beverage cans to ½ inch or more, he notes. The thicker the material and the wider the strips, the less difference there is between the static scan and the dynamic scan.

“In production, the accuracy goes from ±0.005 inch to about ±0.010 inch because of side-to-side movement. Thin, narrow strips move around the most,” Hunker says.

Technically, the gauge is material agnostic, he notes. “As long as I get an edge, I can find the opposite edge and [measure] the distance.”

Because a gap, or separation, is needed between each mult to locate the edges, Hunkar says the strips cannot be measured too close to the slitting head where the strips are right against each other after being created. Instead, AGT strongly recommends positioning the gauge on the opposite side of a pit where the separators are located.

AGT will examine a coil processing line and develop complete drawings of the brackets to hold the gauge. “We do all the engineering and everything on the brackets for every installation because it’s that important to make sure that it’s right. They can get a fabricator or one of their guys to make them.”

Even with the advantages the AGT Mult-Width gauge provides, Hunkar says most prospective customers still rely on their eyeballs to convince them. “Even though lots of people said they wanted this gauge, it’s proving to be a unicorn. People don’t believe it can work. Everybody wants to see it. MM

Advanced Gauging Technologies LLC, 614/873-6691,