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It's All About Sheetmetal Velocity

By: Brad Kuvin

Tuesday, November 1, 2016
 

Leer’s new Salvagnini FMS stars, left to right: a 12-shelf automated material-storage tower, combination shear/punch machine and CNC panel bender. Compared to the more conventional sheetmetal-fabrication process it replaced, the FMS has enabled an evolution from batch production to kitted, and greatly improved output while slashing labor content.
The evolution from batch production to kits has dramatically improved manufacturing efficiency at Leer, Inc., an OEM manufacturer of ice merchandisers, as well as walk-in coolers. That lean conversion to kit production, occurring in 2015, hinged on the successful implementation of a sheetmetal production line that integrates a shear/punch combination machine with a CNC panel bender, all from Salvagnini. Installed at Leer’s 200,000-sq.-ft. plant in New Lisbon, WI, early in 2015, the line replaced a more conventional, and relatively inefficient, production process.

“Previously, we ran coil stock through a cut-to-length line,” says manufacturing systems manager Dan Muth, “and then processed blanks through a shear, CNC turret press, press brakes, notchers and rollforming machines. That labor-intensive batch process required a lot of unproductive material handling. With the new Salvagnini flexible manufacturing system (FMS), the majority of our sheetmetal production is centralized and automated, delivering kits to downstream assembly operations much more efficiently.

“We no longer have people dedicated to just pushing carts and tables of parts around,” Muth continues. “Productivity is up while labor has decreased substantially, all leading to a 2.5-yr. payback on the new FMS.”

Muth calls the FMS a “monument running through the middle of the plant.” It measures 115 ft. long, and includes a Salvagnini S4 combination shear/punch and P4 panel bender, along with a 12-shelf material-storage tower that feeds raw material as blanks to the S4 on demand, one sheet at a time. After punching and shearing, a series of conveyors and a pair of cartesian robots help position the blanks as they travel to the panel bender.

Productivity Gains Beget New Customers

‘Production thus far in 2016 is running more than 55 percent ahead of 2015, says Muth, “with a significantly lower head count. And, we now are able to ship larger orders oftentimes ahead of schedule, which we could never have done before without greatly increasing our labor costs. All of that is due to our new production process, and has led to the addition of several new customers.”

Material moves directly from the end of the FMS line in kits and into the Leer assembly area. Here, cut, punched and formed panels (above) will be assembled into cabinets (right) for the company’s line of ice merchandisers.
Leer’s new and improved sheetmetal-fabrication process begins with sheetmetal blanks of primarily 26- and 24-gauge material—galvanealled, galvanized, prepainted galvanized or embossed galvanized steel. Blank size ranges from 39 by 60 to 60 by 120 in. The plant processes some 4.25 million lb. of sheetmetal per year, most of which gets routed through the Salvagnini, and with most programs generating 90-percent or better sheet utilization. Noting how flimsy 26-gauge material can be, Muth credits Salvagnini engineers with helping to adapt the line to fit Leer’s application and ensure successful material handling through the FMS.

“Before, our turret press limited blank size to 50-in. width,” says Muth. “The ability to now run 60-in. blanks gives us more flexibility with nesting, and helps optimize material utilization.”

That move from 50- to 60-in. material didn’t come easily, however. Muth notes that much time and effort was spent by both himself and Leer's product designers in redesigning the firm’s ice-merchandiser cabinets to match its new manufacturing capabilities—a true design-for-manufacturability accomplishment.

“Our cabinet aesthetics now are greatly improved, and we obtain enhanced dimensional accuracy and repeatability from the panel bender when compared to the press brakes,” says Muth. “That makes fitup in the assembly department simpler and quicker.”

Unique Punch and Bending Setups

The punch on the S4 works differently than on a conventional turret, explains Muth. All of the punch tools are live, and the machine can fire any tool at any time, even firing more than one punch at a time.

“Also, we can tool-up the punch head with redundant punches but with different die clearances, one for heavy-gauge sheet and one for lighter-gauge work (0.008-in. clearance, for example, for thin sheet and 0.014-in. clearance for thicker work). We have enough capacity in that machine to run material 12- to 26-gauge thick without tool changes. Before, we were constantly changing turret-press tools as die clearance changed.”

Likewise, the P4 panel bender works completely differently than does a conventional press brake. It uses lateral bending force to form sheetmetal, generated by a pair of oscillating blades. The machine’s manipulator quickly and accurately moves the sheet, in order to position the side to be bent in front of the blades. A blankholder grips the material as the blades work their magic, making any number of bends up or down in rapid succession. Processing time is minimized since the blank only needs to be centered once, at the beginning of the process. This, according to Salvagnini, keeps cycle time, and more importantly, dimensional errors, to a minimum.

“We obtain tighter seams between panels with the P4,” Muth says, “which in assembly are hinged, snapped and locked together—no welding or fasteners needed. And, the operators no longer need to use a hammer to close the seams, as before. While the new design was challenging to engineer and could not be repeatably manufactured before, it now saves a lot of time in assembly. Assembly time has been reduced significantly, primarily due to the capabilities of the panel bender. It definitely gives us a competitive advantage.”

Finally, Muth notes that the single-sheet delivery system employed by the storage tower adds further to the flexibility provided to the FMS operators. “Most towers,” he says, “require the machine to feed off of one pallet of material at time. The tower that Salvagnini has designed and its single-sheet delivery systems give us instant access to run 12 different pallets of material, one sheet right after the next. Also, if there’s an emergency of a nonscheduled production run and the pallet of material is not in the tower, the operator can just slide a pallet of material underneath the tower and the manipulator will pick up one sheet at a time—there’s no need to shut the line down in order to load raw material. The tower is never a bottleneck.”

Empowered Workers

Leer has enjoyed multiple days with more than 22 hr. of green-light time on the panel bender during a 24-hr. shift schedule, and an even higher run-time percentage on the shear/punch.

“We typically see well over 1000 panels produced per day off of the panel bender,” Muth says. That productivity, he notes, largely is due to empowered operators who schedule the line to level-load the panel bander and shear/punch as best they can. To help, the FMS includes three buffer stations.

“Our operators have done a great job managing the work flow through the FMS,” says Muth. “They can, for example, look at which jobs have longer bend-cycle times and which will stay in the S4 longer, and juggle the schedule to better help balance the line so that one machine isn’t waiting for the other.” MF

 

See also: Salvagnini America, Inc.

Related Enterprise Zones: Fabrication, Materials/Coatings


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