Flexible manufacturing systems at work, with towers of material connected to one or more lasers or other cutting machines, are a symphony of material handling automation.Material flows from the tower box to the laser cutting bed.Cutting starts when the cut sheet from the previous job appears.
The double fork lifts and removes the sheets of cut parts and transports them for automatic sorting.In state-of-the-art setups, mobile automation — automated guided vehicles (AGVs) or autonomous mobile robots (AMRs) — retrieve parts and move them into bends.
Go to another part of the factory and you don’t see the synchronized symphony of automation.Instead, you’ll see a crew of workers dealing with a necessary evil that metal fabricators are all too familiar with: sheet metal remnants.
Bradley McBain is no stranger to this conundrum.As Managing Director of MBA Engineering Systems, McBain is the UK representative for Remmert (and other machine brands), a German company that manufactures machine-brand-agnostic sheet metal cutting automation equipment.(Remmert sells directly in the U.S.) A multi-tower system may serve multiple laser cutters, punch presses, or even plasma cutters.Flat-plate towers can even be combined with Remmert’s tube-handling cellular towers to provide tube-to-tube lasers.
Meanwhile, McBain worked with manufacturers in the UK to dispose of the residue.Occasionally he may see an operation that carefully organizes the remnants, storing them vertically for easy access.These highly mixed operations aim to get what they can from the material they have.That’s not a bad strategy in a world of high material prices and uncertain supply chains.With the rest tracking in the nesting software, and the laser operator’s ability to “plug in” certain parts on the laser cutter control, programming the cut on the rest is not a daunting process.
That said, the operator still needs to physically handle the remaining sheets.This is not a lights-out, unattended thing.For this reason and others, McBain sees many manufacturers taking a different approach.Since residues are too costly to manage, cutter programmers use filler parts to fill nests and achieve high material yields.Of course, this would create a work-in-progress (WIP), which is not ideal.In some operations, it is not unlikely that additional WIP will be required.For this reason, many cutting operations simply send the remnants to the scrap pile and only deal with less than ideal material yields.
“Remnants or odds and ends often go to waste,” he said.”In some cases, if you have a large residue after cutting, it’s hand-picked and put on a rack for later use.”
“In today’s world, this makes neither ecological nor economic sense,” Stephan Remmert, owner and managing director of Remmert, said in a September release.
However, it doesn’t have to be that way.McBain described the latest version of Remmert’s LaserFLEX automation platform, which uses automated residue handling technology.After the part is unloaded, the remainder is not thrown away, but returned to the storage system cartridge.
As McBain explains, in order to maintain reliable operation, the residual system can handle squares and rectangles as small as 20 x 20 inches.Smaller than that, and can’t put the remnants back in the storage case.It also cannot handle remnants with doglegs or other irregular shapes, nor can it manipulate loose mesh segments of an empty skeleton.
The central control system of the Remmert system guides the management and logistics of the remaining sheet metal.An integrated warehouse management system manages total inventory, including surplus materials.
“Many lasers now have destructive cutting and material cutting sequences,” McBain said.”This is a fairly common feature of most [laser cutter] manufacturers.”
The nest is laser cut, then a skeleton destruction sequence is performed on the portion protruding from the remnant so that the remaining portion is a square or rectangle.The sheets are then transported to parts sorting.Parts are taken out, stacked, and the remainder returned to the designated storage box.
System cassettes can be assigned different roles according to the needs of the operation.Some tapes can be dedicated to carrying uncut stock, others can be stacked on top of uncut stock with remnants, and still others can act as buffers dedicated to holding remnants until the next job that requires it comes along.
If the current demand requires paper with a large amount of remnant, this operation can allocate more trays as a buffer.This action can reduce the number of buffer boxes if the job mix is changed to fewer nests with residue.Alternatively, the residue can be stored on top of the raw material.The system is designed to store a surplus page per tray, whether that tray is designated as a buffer or holds a surplus page on top of the entire sheet.
“The operator needs to choose whether to store [the residue] on top of the raw material or in another cassette,” explains McBain.”However, if the remnant is not needed for the next material call, the system will move it away to access the full sheet stock… Every time the remnant is returned [to storage], the system updates the sheet size and location, so the programmer You can check the inventory for the next job.”
With the right programming and material storage strategy, the system can add automation flexibility to residual material management.Consider a high-product mix operation that has a department for high-volume production and a separate department for low-volume and prototyping.
That low-volume area still relies on manual but organized scrap management, racks that store paper vertically, with unique identifiers and even barcodes for each scrap.Remaining nests can be programmed in advance, or (if controls allow) parts can be plugged directly into machine controls, with the operator using a drag-and-drop touch interface.
In the field of production, flexible automation shows its full potential.Programmers allocate buffer boxes and adjust box utilization based on work mix.Cut paper to preserve rectangular or square leftovers, which are then automatically stored for subsequent jobs.Since residual material is handled automatically, programmers can freely nest with maximum material utilization in mind, without the need to produce infill parts.Almost all parts are sent directly to the next process, whether in a press brake, press brake, folding machine, welding station or anywhere else.
The automated part of the operation won’t employ many material handlers, but the few workers it does have are more than just button pushers.They’ll learn new micro-tagging strategies, perhaps linking groups of small parts together so that part pickers can pick them all out at once.Programmers need to manage kerf width and execute strategic skeleton destruction sequences in tight corners so that part extraction automation runs smoothly.They also know the importance of slat cleaning and general maintenance.The last thing they wanted was for the automation to stop because a sheet of sheet was inadvertently welded to the slag pile on the toothed slats below.
With everyone playing their part, the symphony of material movement begins, in tune.The manufacturer’s automated cutting department becomes a reliable source of parts flow, always producing the desired product at the right time, for maximum material yield even in high product mix environments.
Most operations have not yet reached this level of automation.Nonetheless, innovations in residual stock management can bring sheet metal cutting closer to this ideal.
Tim Heston, Senior Editor at The FABRICATOR, has covered the metal fabrication industry since 1998, beginning his career with the American Welding Society’s Welding Magazine.Since then, he has covered all metal fabrication processes from stamping, bending and cutting to grinding and polishing.He joined The FABRICATOR staff in October 2007.
FABRICATOR is North America’s leading metal forming and fabrication industry magazine.The magazine provides news, technical articles and case histories that enable manufacturers to do their jobs more efficiently.FABRICATOR has been serving the industry since 1970.
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Post time: Feb-17-2022