Although both folding and bending have their niches, folding can increase productivity along with part quality while offering other advantages.
Fab Shop Magazine Direct has interviewed Rick Wester, V.P. of RAS, a supplier of both automated and manual folding machines to offer some guidelines for folding versus bending.
FSMD: Where does folding fit in compared to bending?
Wester: To begin with, we are comparing a manual press brake to a manual folding machine, both need operators. A folding machine is best used for very difficult parts, surface sensitive materials or for big panels that need bending.
On a press brake, difficult parts need multiple setups, and large parts are hard to manage and often require two to three operators. With a folding machine, manipulating large panels isn’t a difficult task, because it has an integrated sheet-support backgauging system that holds the part’s weight and supports the material. Only the flange is created and changes plane. One operator with little training is all that’s needed to produce quality parts.
Folding should also be used for bending surface-sensitive material such as stainless steel, painted or coated metals. During the folding process, a folder clamps the material and doesn’t allow it to slip or move.
Perforated material is also a perfect candidate for folding.
FSMD: Is folding a better choice than bending?
Wester: A press brake and a folder are niche machines, and they really shouldn’t compete against each other. One should make the other one exist. When we sell a folder to a potential job shop, one of things that I tell the owner is that I will make his press brakes more productive, because he’s trying to run parts on a press brake that he should be running on a folder.
If a company has two or more press brakes, then management should be looking at a folding machine, because we can increase productivity.
What a folder does compared to a press brake is that a press brake gauges the flange, and then the operator needs to ride or hold the overall part as it’s being bent by the brake. For instance if we have a 90-degree V-die, we are just going to make a 90-degree flange. If the flange is 0.5 in. on a 47.5-in. wide sheet, the operator would have to support the overall width and ride it up into the air while holding it on a press brake.
Now if the same part was done on a folding machine, we would be doing it backwards compared to a press brake. We would gauge the 47.5 in. on our backgauge table and expose the 0.5 in. flange in front of the machine. We wouldn’t need the operator to ride the part up, since it’s flat on the folder. This would eliminate any possible part warping or kinking that could damage the part.
With the part flat, a 0.5-in. wide flange by maybe 8-ft.-long can be turned up, and one operator can do this. But if a 0.5 in. flange on a 48-in.-wide sheet by 8-ft. long part is being bent on a press brake, it requires two operators just to keep from kinking the part. If this was a critical stainless-steel part for a stove for instance, and it kinked during bending using a press brake, it would be an expensive piece of scrap.
FSMD: Are there other advantages to folding?
Wester: If I see a shop that is making two to three bends on a press brake, setting the part down, resetting the press brake with new tooling to make another two to three bends, and if the part is finished at this point, then this shop is in absolute candidate for a folding machine. The reason is that a folder can do all these processes without multiple tool changes.
If I see two operators in front of a press brake, then this shop is also a candidate for a folding machine. Because I can eliminate the labor of one person quickly with our manual folder. There is a $50,000 to $60,000 labor justification right there.
Today’s press brake operators are some of the highest paid people in a shop. An operator should be able to read a drawing, pull the tooling, set up the machine, run parts and do QC while maintaining the brake. These are six very important things. At 90 percent of the shops we visit, one person doesn’t do it all. It’s probably two or three people. It’s an engineer who reads the drawing. Then there is a set-up person along with an operator and a QC person along with a separate maintenance staff.
Folders however, have eliminated all this. All the operator needs to do is download a program to the folder’s CNC controller, plug-in the material thickness and the machine automatically sets itself up. The computer on this machine has eliminated the press-brake operator’s bending expertise.
FSMD: Can folding offer better part quality?
Wester: On a press brake you have to work with both sides of the material. The punch goes into the die and the material is in the middle, and if there are any variances in the material thickness you could have a problem.
On a folding machine, the folding beam swings up with a 0.1-degree accuracy, adding to part quality and repeatability. Plus we only work with one side of the material. So we cut any intolerance in half. This gives us a much better degree of bending angle and a more accurate part. Not only do we expedite the folding process, but we have a part that fits much better. If it gets welded, all the joints will be much tighter. It can eliminate part fixtures for welding, it saves tremendous time and the cost of the fixtures.
FSMD: Which machine is faster?
Wester: A press brake for long run parts is probably faster than a manually operated folder. However, today, short run parts are the norm. If 200 parts are made, a press brake would probably beat a folding machine. But now shops are running between five and 50 parts. Folding will produce half of these parts before a press brake gets set up, because there is hardly any set-up time on a folding machine that can’t be done in less than five minutes. Whereas, a press brake will probably take 10 to 30 minutes to set up the tooling.
The smallest manual machine we offer is 10 ft. wide. Shop owners ask me if we have a 4-ft. wide machine. They are thinking in a press-brake mentality mode. On a 4-ft.-wide press brake, an operator will do one setup and make one or two bends. Then they put the part down and reset the press brake again, if there is another degree of angle or another flange length being bent. On a manual folding machine, we might set up four different stations across the machine. The operator would pick up a blank and go from each station to get a finished part, rather than having to re-set the machine and tooling for other bends.
FSMD: Why are the longer runs better accomplished on a press brake?
Wester: It’s faster, it will cycle a 90-degree bend faster than a manual folder. A manual bender with an operator is moving at about 90 degrees per second. While the manual folder would take about 30 seconds to make a four-bend part.
FSMD: What types of parts would fit best on a folding machine?
Wester: What’s best is a very complicated part that would require hems and internal flanges such as a door or metal cabinets. For instance, a hollow-metal-steel door requires a 92-degree bend on one side and an 88-degree bend on the other side. These require two setups on a press brake. A lock-seam door requires a hem on top of this, and this would be a third setup to make a lock-seam door on a press brake. Because of these bends, most door manufacturers use a folding machine.
FSMD: For parts that are produced on a folding machine, what is a common thickness?
Wester: We can handle up to 0.25-in.-thick material for folding for mild steel. But other manufacturers can process 0.625-in.-thick material. A majority of our customer base will be dealing with nine-gauge material and lighter. From the thin side, we can manage 28 gauge.
FSMD: Does tonnage matter for a folding machine?
Wester: That’s one of the disadvantages of a folding machine. We don’t rate our machines in tonnage. All the forces of a press brake are pushing down while the forces on a folding machine are pushing up.
For instance, our FLEXIbend machine can manage up to 11-gauge material thickness with only 20 tons of clamping pressure, but it’s not meant to be a hammer. If a shop is going to do a lot of hemming in thick material, it will need a press brake. But if they hem 16-gauge-thick material and lighter, it’s not a problem for a folding machine. Although our 0.25-in. capacity machine does have 130 tons of clamping pressure. This machine has a very unique design.
FSMD: What about tooling for a folding machine?
Wester: When you run different material thicknesses on a press brake you need a different die-opening on the bottom tool. Whereas a folding machine just needs a material adjustment through the software program. This moves the lower folding beam either down and/or out to compensate for the thicker material. The same tooling is used. That’s why we like to say that the tooling is universal, because we can adjust for material thickness and the degree of angle that we are making as the angle is produced through the folding beam.
Usually we’ll put together a turnkey machine with tooling that meets the customers needs. Then hopefully the customer would never need to buy tooling again.
FSMD: Are your tools precision ground?
Wester: Yes, they are precision ground and laser hardened it’s almost the same quality as precision-ground-press-brake tooling.
FSMD: How does automated folding compare to automated bending equipment?
Wester: If you compare automating a press-brake bending process using a robot for part manipulation to an automated folding machine, the folding machine is far superior and much faster.
For automated folding, there are two or three manufacturers besides RAS Systems that could be considered. These companies design and build systems for large production, but also offer the flexibility in these systems to do small batch and kit production. When considering folding automation, after talking about a folder that is manually operated, we’ve gone from a machine that could range in price from $90,000 to $250,000, to easily a $1 million folding system.
But this automated system is capable of out-performing five to seven press brakes and the labor needed to operate them. An automated folding system could easily eliminate 18 to 20 operators over a three-shift operation using multiple press brakes.
These automated folding systems can include processes such as blank loading, unloading folded parts and part stacking. If the production facility has the folding needs to keep these systems busy, the justification is certainly there.
RAS
