Fabricators looking to tighten turnaround time focus on press brake performance
April 17, 2013
The speed of fabricating is increasing at a rapid pace, but the press brake remains a bottleneck for many companies. Laser cutting and punching machines can run unattended if necessary without the need to program a robot, but the same can't be said for a press brake. Human operators still are pretty much a necessity. Advancements in bending software, however, can help to streamline the bending process. Fabricators only need to give it a try.
Slow and steady is a good strategy for the tortoise racing against the hare, but it’s a pretty ineffective plan for a metal fabricating business.
Everywhere that a metal fabricator looks, the pace is picking up. Customers laugh at seven-week lead-times, might tolerate three- to four-week turnarounds, but truly desire delivery within two weeks in many instances. The emergence of solid-state laser cutting machines has radically changed the economics of blank preparation; these devices can slice through thin-gauge metal at speeds unmatched by more traditional CO2 laser technology, creating plenty of work for downstream processes.
In some instances, metal fabricators need to speed up their own production processes in an effort to get parts out the door as quickly as possible and receive payment that much sooner. With two harsh recessions fresh in the minds of most, these metal fabricators know that the more cash they have on hand, the better off they will be for the next downturn. Unless they win the lottery, getting paid promptly is the easiest way to boost those cash reserves.
These trends have resulted in fabricators’ endeavoring to increase product velocity in their shops. The term looks like a buzzword, but it actually carries real weight with those aware of the changing competitive landscape around them. These fabricators will tell you that quality is a given, but speed is the factor that ultimately may determine winning or losing an increasing number of jobs.
Unfortunately, press brakes are a huge impediment for these manufacturing operations seeking to speed up production (see Figure 1). Robotic bending has advanced, but robots are nowhere close to replacing human press brake operators on a wide scale. Additionally, metal fabricators are likely to hold on to or purchase older press brake technology because these old pieces of iron are still able to do most bending jobs—albeit at a much slower pace.
That’s where bending software is making a significant difference. Computer-aided manufacturing (CAM) software is helping to remove a lot of waste from part design, bending program creation, and part try-out. It doesn’t immediately address the time it takes for a ram to go up and come down to bend the sheet metal, but that simple process doesn’t represent the biggest opportunity for improvement. It’s all about making the front-end activities associated with bending as efficient as possible.
In a world where 3-D modeling is as prevalent as it has ever been, some metal fabricating shops still don’t have the advanced CAM software that enables them to smoothly transitions files from the design department to the shop floor. They have to take their time to prep the file before sending it on its way.
Imagine receiving a 3-D file, deconstructing it to create a flat pattern that can be used to program the press brake, and then basically re-creating the 3-D geometry as the press brake operator figures out how to bend the part. Depending on the complexity and number of jobs that have to be created from scratch in this manner, a shop can be adding several unnecessary hours of programming time that is typically automated with most modern CAM programs for press brakes.
“Ultimately, it’s a step that is not necessary. You already have the 3-D file. This is what I want to manufacture. You should be able to send that file over to your manufacturing department or a job shop to create that component,” said Doug Wood, sales and services director for manufacturing software developer Radan. “When they get the 3-D model, they calculate the blank based on their tooling, calculations, and formulas. Working with 3-D data is a much more efficient process than taking 2-D DXF or DWG files and basically localizing that flat based on the shop environment that is ultimately going to bend those parts.”
Most bending software programs can receive native files from most 3-D modeling CAD packages on the market. Some actually can work with the native formats right inside their own software environment. That translates into a fabricator being able to receive a 3-D model, plugging it into the bending software, and having the bending process for the press brake operator and a flat pattern created in a manner of minutes.
Offline programming and virtual simulation—these are the most obvious benefits of bending software. Because of the offline programming for the press brake and the ability to see the part being made, the machine operator can focus on making parts for which the fabricator will get paid. The operator’s time isn’t spent forming tryout pieces that no one is interested in buying.
“If you are programming live at the press brake, you are programming on the most expensive PC there is,” said James Lindsey, product manager, SigmaTEK Systems.
Consider a fab shop that doesn’t use advanced CAD/CAM software for offline programming of the press brake. This shop relies on a press brake operator to look at the part, determine the correct bend sequence, and figure out the proper values and calculate the tooling requirements. If the press brake operator is good, he might be able to nail down the proper bending procedure with two or three test parts. That’s when everything works out well. The same scenario easily can involve several more parts before the right bend sequence is found.
“If it is taking you 30 minutes to a couple of hours to figure out how to bend a part, you are taking your machine out of production for that long,” Lindsey said. “If I’m able to take 80 to 90 percent of that work load offline and do it in a simulation program, that machine is eligible to make money now instead of costing me money.”
Of course, with a simulation program, a programmer actually can determine if the part can be bent successfully before it ever hits the shop floor (see Figure 2). This is particularly helpful for those companies working with less-experienced press brake operators.
“You can see bad things that are going to happen before the parts get out to the floor,” Lindsey said. “You can see where the fingers aren’t going to retract out of the way during a bend, or you might have to use a gooseneck tool instead of a straight tool because a flange is going to come up and hit the punch. You are able to see the simulation and the collision detection very easily.”
Simulations are getting so sophisticated that they are taking into account machine accessories such as lift aide and sheet followers and part features such as embosses. These items, too, are accounted for in the collision detection simulation, according to Wood.
Metal fabricators that have press brake software with a CAM system that also programs laser cutting and punching machines get an additional layer of sophisticated operation, Wood added. For instance, a part programmer can view a simulation, recognize what part edges he plans to gauge off, potentially avoid placing a tab in a location that could affect backgauge positioning on the press brake, and alter the nest on the laser cutting machine in a matter of seconds.
“That’s where having that connectivity between the press brake software and the laser cutting and punching machine software pays off,” Wood said. “You can make those types of changes on-the-fly.”
Bending simulation software takes into account tooling as well (see Figure 3). The company’s tooling libraries are reflected in the software, so the virtual world matches up with the real world on the shop floor.
It sounds like common sense, but the fact is that machine programmers are not always on the same page as the press brake operators. Every metal fabricator has a story about how a rushed press brake job hit the shop floor only to enter a holding pattern because tooling for the press brake operator to start the “hot” assignment wasn’t ordered.
Several bending software programs also keep up with the press brake tooling offerings from the major manufacturers. If a part programmer is creating a job and finds out that the shop doesn’t have the right tool to make all of the bends, the software can access a supplier’s tooling library, find the right tool, and incorporate that into the simulation.
The parts programmer also can assign certain bending jobs to a press brake and the tooling typically found in that press brake. In this situation, a press brake operator only has to set up his equipment once for a series of jobs because the bending software has optimized the jobs for that particular press brake, according to Anupam Chakraborty, vice president, Metamation Inc.
“The lean part of bending now becomes very effective because your setup time has not increased,” he said.
With so much focus on getting as much efficiency as possible on the shop floor, a metal fabricator sometimes can overlook front-office activities. Efficiency there is as important as anywhere else in a fabricating operation.
Consider the quoting process. Familiar with the phrase “first in, first to win”? Well, it’s not a phrase used to describe punching time clocks. The fabricator that can turn around a request for quote in a matter of hours can emerge as the winner of those jobs that have a tight time frame for completion.
For instance, an OEM might need hundreds of parts fabricated and delivered in three weeks, so it contacts a local fabricator. With hardly any time to waste, the OEM sends the files to the fabricator, expecting a quote as soon as possible. Bending software turns what could be an overwhelming manual task into a much simpler one.
“In these cases, if you have the right CAD/CAM tools, you’ll know how many bends are going to be there, how much timing is going to be involved, and what the material utilization is,” Chakraborty said. “This will give you a much more informed decision to predict how much the job will cost. And you can quote to the customer accordingly—and faster.”
There’s no time to waste in today’s metal fabricating business, and a shop’s bending operations can be the biggest eater of time if it’s not careful. Bending software can help tremendously. For those shops that have been reluctant to change, it’s only a matter of time before they are forced to.