Cut the scrap

Fabrication logo COMPANIES can save $300,000 over a 15-year period by reducing their scrap by just 1%, according to Shane Simpson, TruBend Product Manager for TRUMPF Inc.

In his presentation at Fabtech, “Reducing Costs in Press Brake Processing,” Simpson based his calculations on an average of five million pounds of mild steel per year. One percent would be 50,000 pounds per year, at an average cost per pound of 50 cents and a scrap return per pound of 10 cents. That works out to $20,000 per year and $300,000 over 15 years — the average lifespan of a press brake.

“This does not include lost money of laser or punch time,” Simpson said. “Reducing stainless or aluminum scrap would be an even greater savings. There are massive amounts of cost savings if you can reduce even 1% of scrap. When you talk about scrap, you're talking about parts that were bent wrong, bent backwards, or the overall part size was not correct due to tolerances.

“The initial cost of the machine has less relevance when scrap is considered. I know this is difficult to tell a customer when he's paying a lot of money for a machine. But in the long run, initial cost should be less of a consideration if you're buying a piece of equipment that can help you with savings and improve production through the lifespan of that machine.”

He said that when he recites those figures in a seminar, he tries to observe the faces of those in the audience. He typically sees people turn to their neighbor and start talking, which tells him that they know they're struggling with the issue of scrap.

“Most fabricators I talk to don't even know their true scrap rate,” he said. “That's because they mix in all their skeletons and everything else from their punches and lasers, and the remainder of their sheets, with parts they're just dumping in. They can tell you what they're getting back from poundage: ‘I turned in 500,000 lbs of material last year and this is how much we made back.’ But they don't know how much scrap they're actually creating, only the amount of total return from their scrap vendor because it is too cost and time consuming for most to differentiate scrap parts for leftover materials.

“The other factor is, a lot of fabricators create scrap on purpose. If they need 10 parts, they cut 12. They made a Test Part #1 and #2 to get to the final 10 parts. You've just created 10% scrap on purpose. We tell them, ‘That's an inefficient way to run your production. If you want to do that on the first run, maybe. But you should certainly not be doing that the next time you run that part.’

“A lot of people have these problems. They just don't know how to overcome them. It has a lot to do with having an operator making parts incorrectly and blank sizes developed incorrectly. Every day I have a 55-gallon barrel full of parts. People don't really know how to eliminate it. They have problems routinely with a press brake — scrapping, longer parts setup times, and an increase in the number of fabricators now doing one- or two-part lot sizes instead of 100 parts.

“Setup time is critical because if you're setting up half an hour to bend two parts for five minutes. That's not very efficient. We're trying to show fabricators how to get down to a three- to five-minute setup. Or maybe they're taking three parts they bend and weld together — we're trying to show them how they can redesign a part into one piece so now they eliminate secondary operations like welding.”

Clamping system

He said a tool-clamping system can help with setup times, rotated tooling, and hardened surfaces. Upper and lower automatic tool clamping is a fast setup featuring punches that can be rotated 180 degrees and inserted vertically with a safety click.

“Everything is self-seating and self-aligning so literally we snap the tools in and we're off and running in three to five minutes,” he said.

Operators can get to that point through a documented setup plan, which typically comes from offline programming, “which is a huge factor in reducing costs because you can see the bend sequencing before you ever get out to the press brake. We're specifying exact tools and where to position them on the rail, so the next time you call up that job, it should be even easier to jump in and repeat run that part. Speed increases on a repeat job more than it would on a first-time run.

“Many fabricators don't save programs, so they're starting from scratch. Other fabricators don't document setup plans, so it leads to operators using different styles of tools, which can affect parts sizes. With a tool-fitting plan, everybody bends it the same way and uses the same tools, so parts come out the same. It's easier to track problems if everybody's using the same information, which doesn't always happen at a lot of shops.”

He said TRUMPF's TruBend 5130 has optical LEDs that light up to show the length and position of tool setup — a visual aid to help an operator locate his tools.

“Once you start the program and start bending, lights start shifting to the station you're actually bending under, and they shift to the location of the bend and length of the bend. It helps the operator not scrap parts by making an error in the bend sequence and helps him locate where a part is to be located. If you're doing one, two, or five parts, this helps the operator because he doesn't know where it's always going initially.”

Automatic Angle Correction is TRUMPF technology that takes into account variations of material.

“Grain direction has an effect on bending,” he said. “The operator is then left to try to determine what corrections should be made for each bend. They can start fluctuating from part to part because of the grain direction. They could also fluctuate simply because the materials are not very good or the material thickness has changed, so they've cut five sheets of this material: one sheet is .060, another is .063, and another .059. All of these variables have a direct effect on the angles that come out. These systems are made to overcome those obstacles. They automatically check and correct the bends for you on the fly. So rather than typically making a bend and checking with a protractor, then putting a correction into the control, this is doing all of that on the fly.”

He said that any time a customer has multiple setups due to having operations of flattening and folding, offsets, or tools of different heights working together, they use die shifting. The whole die base shifts front to back, and that reduces the amount of setup, so if a customer has two to three setups to make a part, it can typically be done in one. This reduces costs because a part is not handled multiple times.

Simpson said a customer can experience headaches if he has tapered bends or needs geometry. A very good operator is needed to figure out angles and how to orient the part. Back gauges allow an operator to pinch corners easily and eliminate any fixturing.

“A lot of times fabricators have side stopping or front stops with compound angles on them,” he said. “It's going to take a lot of time to set that part up. With a six-axis back gauge with unique cutouts in the fingers, combined with offline software, we simply trap the corner and we're done. We're talking seconds of time, compared to half an hour or hours of setup. We just want to eliminate fixturing wherever we possibly can.”

More efficiency

He said many fabricators who use older technology are reluctant to move into offline programming, but it could save them dramatically in efficiency, along with preventing them from bending parts wrong, since they can visualize everything offline before they even walk to the press brake and actually start bending a part.

“You know if a bend sequence is going to work or if there are going to be collisions with the tools or bed or floor,” he said. “You have created documented setups because of that. Offline programming generates that setup for you, and the length of tools required to bend parts automatically, so you don't have to use a tape measure to determine part length and tooling you need. All that is set up automatically in minutes. That eliminates a lot of human error. You don't have the scrap rates because you don't get halfway through a part and realize, ‘I need different tooling or should have used a different bend sequence.’

“The problem in the field is that fabricators can't find skilled operators. We're trying to make technology more simplified to use and basically have a guy on the shop floor who doesn't have to know a lot other than following a graphical representation of a bend sequence and where the tools go. We're trying to help fabricators alleviate trying to go out and find high-end skilled operators or what I call ‘sheet-metal mechanics.’”

He said ergonomic improvements are critical, because people who are more comfortable with a machine are going to be more productive and will suffer less fatigue. To a great degree, the productivity of the bending process is dependent on the operator's performance. He said machines such as the TruBend Series 7000 offer a seated operation, adjustable rests (foot, hand), adjustable control system, iLED technology for customized lighting in the working area, and a bend line laser.

Customer benefits:

  • Ergonomics: A sit/stand rest recommended by ergonomics experts provides relief for the operator's spinal column.

  • Productivity: Reduced operator fatigue and hence continuous productivity.

  • Processing characteristics: open machine table, and sit/stand/rest positions are individually adjustable in height and tilt.

The comfort support table has an arm rest in the optimal bending position, there are shorter distances when putting down blanks and finished parts, and the swing-down table increases the space available for bending large parts.

Machine control technology features numerical and graphic programming.

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