Above: The BTM model 7050 double shuttle band saw features a 40-in. outboard shuttle vise and 10-degree head cant.

When it was time to shop for new band saws, JMC made sure to do its homework

October 2013 - Nothing lasts forever. Ongoing maintenance and eventual replacement are part of the plan for purchasing almost all manufacturing production equipment. Sometimes your hard working machines are on a long term path to wearing themselves out. But these days, as often as not, they simply become functionally obsolete.

As a piece of equipment approaches the end of its useful life, for whatever reason, there always are plenty of replacement options to consider. A good experience with your current machine may make you wish you could clone it and just keep going. Realistically, today’s machinery typically offers modern technology with enticing features including better energy efficiency, improved control and enhanced integration capabilities as strong reasons to interrupt the status quo.

The search for new technology was one of the driving forces when Chicago-based JMC Steel Group began looking to upgrade its fleet of saws. The largest independent manufacturer of tubular steel products in North America, JMC has 12 production facilities throughout the U.S. and Canadian Midwest. Its products range from electrical conduit and fittings to square, rectangle and round hollow structural sections. The company relies on band saws to cut its products to length, usually in bundles. Additionally it cuts samples for quality assurance testing from tube produced from the beginning, middle and end of each coil.

“We looked at several saw vendors, including some we had used in the past,” says Lindsay Fleming, JMC’s vice president of engineering and technology. “They’re all pretty predictable and I wanted to do something a little more radical this time. So I spent some time researching it, finding what the latest technology was out there.” 

JMC’s long-time supplier Peninsula Saw Co., Welland, Ontario, suggested a relatively new offering from BTM Saws might provide the answer to one pesky problem at its Plymouth, Mich., plant – too much scrap.

“When I first talked to JMC, they said, ‘If you can solve our scrap problem, we can talk. Otherwise, don’t bother us,’” says Ian Tatham, national sales manager of BTM Saws North America, Woodstock, Ontario. The scrap problem, he says, was most significant at JMC’s Atlas Tube facility in Plymouth, Mich. “At the Plymouth facility they’re cutting bundles of square and rectangular tubing in large quantities. They have two machines going pretty much nonstop.”

Making tubes

The tube production process begins with coil steel going through a straightener to a slitter. The resulting strips pass through a former where they are bent into shape. After being welded longitudinally, the completed tubes are collected into bundles. The size of the bundles varies, depending on tube size, but one bundle can have as many as 30 tubes. Bundles of finished tube go to the saw to be trimmed and cut to length.

“They can roll those pieces any length they want,” Tatham says. “The big problem was the 5-in. to 6-in. piece of scrap at the end of every tube in every bundle.” A typical band saw, he explains, has one shuttle vise that grips the bundle and shuttles it through the saw. The shuttle vise requires a certain grip length to control the material being cut and that is what dictates the remnant length.

Tatham knew BTM’s double shuttle saw, which was already in use throughout Europe, could reduce the length of JMC’s remnant pieces. But he also knew JMC would want real numbers, not just a claim to be better.

“I contacted our chief engineer in Italy and asked him what the scrap length is,” says Tatham. “His response was ‘practically nothing.’ I told him that sounded great, but that I needed to give our customer a number.” The answer was 54 mm, roughly 2 in., which at first didn’t seem possible to Tatham. But having the second shuttle is the key.

“The double shuttle saw has a 15-ft. infeed shuttle and a 15-in. outfeed shuttle,” Tatham explains. “The first shuttle goes back, grabs a bundle and brings it into the saw. The saw’s trim cut on the front cuts off probably 1⁄4 in. to 1⁄2 in.” The material is then shuttled forward a preset distance and another cut is made. The sequence of positioning and cutting is repeated until the end of the bundle is reached.

“At that point, the infeed shuttle vise stops and the bundle is grabbed by the outfeed shuttle vise,” Tatham says. “The outfeed shuttle then brings that bundle up so the saw can trim the back.” The trim length, he says, is typically even less than 2 in. That allows the scrap pieces to fall through the trap door and be conveyed out into the scrap bin, just as the scrap does on the initial trim cut.

“This new double shuttle saw will minimize the amount of scrap we generate on the last cut of each bundle of tubing,” says Fleming. “The savings are very significant on the scrap drop, so much so that they’ll almost justify the project and pay for the saw.”

Beyond the remnant issue

However, that wasn’t the only aspect of BTM saws that sold JMC. “Having looked at several manufacturers’ products, we could just tell how well-built the BTM saws are,” Fleming says. “They are very durable, high-performance equipment. They’re also designed in such a way that they reduce the vibration on the saw blade. Vibration on a saw blade is a major source of poor saw blade life.”

Fleming says BTM saws also are very user friendly. While awaiting delivery of the double shuttle saw later this year, JMC installed four smaller BMT model 7151 SA 90 saws, one each at four of its other tube making facilities. “A touch screen gives the operator access to automatic settings built into the database,” he says, “so you just tell it what size, what gauge and what grade of steel you’re cutting, and the saw automatically selects which cycle to incorporate to optimize your cuts.”

Fleming also appreciates the no-burr feature that adjusts the speed at the end of a cutting cycle. “The downward feed slows down, but the blade speeds up, and that eliminates the burr that traditionally is left behind that you later would have to touch up with a grinder,” he says.

“The heads on BTM saws have a 10-degree head cant, which means the blade is on an angle coming down on a bundle of tube,” Tatham says. “That spreads the cut over the cross-section of the workpiece. Normally, when the blade is at 90 degrees, it’s cutting basically a big, flat bar. When it gets into the tube, it’s cutting all the thinner tube walls, and then flat bar again on the way out. That’s a real problem for blade life and cut time.” The question becomes whether to select a relatively coarse blade, matched to cutting the top part of the bundle, or one that is less coarse and better suited to cutting the middle part of the bundle. Tilting the blade is a compromise.

“With our machine, having the blade come down on a 10-degree angle spreads the cut over the cross-section of the workpiece, and that lets you cut a lot faster and a lot more accurately,” Tatham says. Adding to that performance are the saw’s stress-relieved welded head and heavy-duty gearbox. Combined, the stress relieving and the high-end drive system offer 30 percent better blade life coupled with 30 percent faster cutting time. “When you’re not changing your blade,” Tatham says, “you’re getting faster cutting times, and you have more throughput.” Adding performance improvements like those to significant scrap reduction means doing your homework can have a big payoff. FFJ