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The story behind the light curtain on the press brake

A new brake with a built-in light curtain keeps workers safe and boosts productivity at one of the world’s largest chicken housing manufacturers

Figure 1
Toby Domingues, sheet metal department supervisor; Nick Millard, manufacturing manager; and Jill Mullis, press brake lead, pose in front of a 110-ton SafanDarley E-brake that has helped to boost bending productivity at Alaso, a Lakeland, Fla.-based manufacturer of commercial chicken housing systems.

When economic pundits talk about the inconsistent performance of the U.S. housing sector, they aren’t talking about chicken housing. That business is doing just fine.

In Lakeland, Fla., Alaso knows this firsthand because it is one of the world’s largest fabricators of automated chicken housing. If you had eggs this morning, the source of those eggs might be living in one of Alaso’s fabrications.

These housing systems can be a sight to behold. One “chicken house,” as Nick Millard, Alaso’s manufacturing manager, called it, can be 500 feet long, 60 to 80 ft. wide, and up to 12 tiers high. (Tiers refer to the number of levels in each row. Typically, these facilities are arranged into four to five rows of multitiered-stacked cages, similar to the floors of a building. Tiers are separated by manure-collecting belts that take the waste from the hens above, allowing the hens below to remain healthy and clean.) Large facilities can house anywhere from 50,000 to 1 million hens.

Plenty of engineering and G90 galvanized steel go into these systems. In some of them, everything is automated. That includes delivery of chicken feed, medications, and water; removal and disposal of manure; and collection of eggs. In these larger systems, human hands may never touch an egg.

“Our company looks very heavily into the safety and well-being of the animal, as well as the ease of flock management and production efficiency for the end user. We want to minimize the amount of labor and maximize production output,” Millard said.

An Interest in Boosting Productivity

Alaso also has the same concern for its own employees and business. It wants to ensure that its employees stay safe and productive as the manufacturer continues to build its business. (Alaso is recognized as one of the highest-volume international exporters in Polk County, one of Florida’s largest counties.)

One good example of this was Alaso’s move to roll forming about 10 years ago. Management recognized that it could increase production output if it were able to capitalize on a forming process that took advantage of housing components that were consistent in length and had similar bend patterns—and also happened to be difficult to bend in a press brake. Roll forming fit the bill.

One part that was shifted to roll forming was feed troughs, which were made up of four sections, each 8 ft. long, 14.25 in. wide, and 20 gauge thick. (Alaso primarily works with steel that is as light as 22 gauge and as thick as 10 gauge.)

“If you can imagine bending that 10,000 times per order, you realize that’s a lot of work,” Millard said.

Alaso recently shifted some of the housing supports away from the press brakes to roll forming. Again, these were high-volume, light-gauge parts, 8 ft. long and 7 in. wide.

Figure 2
The incorporation of the light curtain control in the 35-ton SafanDarley E-brake is important because operators are typically dealing with smaller parts, and the precision bends require hands to be near the bending window. The light curtain keeps the operator safe during production.

“It took a long time to do those parts in the press brake. It’s so much faster to put them on the roll former,” said Jill Mullis, a guiding force in the press brake area of Alaso’s Lakeland facility.

Even with the gradual migration of parts from the brake to the roll forming line, press brake bending remains a key part of the fabrication process at Alaso. That’s why the company has 12 press brakes, including eight CNC models. It has even torn down and rebuilt two older hydraulic press brakes, incorporating new hydraulics and new controller technology.

“We know no matter how much roll forming that we will bring into the facility, being that we are making a sheet metal designed product, we are never going to get away from press brakes,” Millard said. “So we started to look for better technology.”

That led them to consider electric press brakes, and they found what they were looking for at the 2013 FABTECH® tradeshow in Chicago.

Maximizing Safety and Output

Having rebuilt two press brakes, Millard said that as the team considered new bending technology, it wanted to stay away from hydraulics if it could. He said that maintenance time increases with each passing year of a hydraulic brake’s life, and they wanted to avoid that hassle.

Additionally, they wanted a brake with the latest safety system technology.

“If we are looking to pick up speed, we don’t want to do it at the cost of safety for our employees,” he said. “In other words, I don’t want you to work fast and haphazardly. I want you to be able to work fast and even safer than you did before.”

When Millard first saw the SafanDarley electric press brakes, he noticed something different about them. The servo, belt-driven system was fast, but that wasn’t exactly it. It was the integrated safety system. The light curtain technology wasn’t simply added to the press brake after it was manufactured. It didn’t protrude from the machine like some odd sheet metal growth.

After watching the brakes in action, Millard also noticed something else. The operators were using the light barrier technology to control the press brake. He saw that as an immediate advantage for a press brake operator who normally might have to use a foot pedal over a shift.

“Sometimes hanging on one foot for eight hours a day while you are trying to press a foot pedal with the other foot can grow tiresome,” he said.

So just how does an operator use a light curtain to operate a press brake? It begins with a switch from a foot pedal operation to light barrier control. With the latter mode of operation, the operator simply brakes the light curtain to signal the ram to come down.

For instance, the operator can wave his or her hand into the focus area of the light curtain, and the ram will proceed down to a predetermined height that is millimeters above a pinch point. With another wave of the operator’s hand, the ram is instructed to come down and complete the bend. It then retreats so that a new blank can be put into place or the part can be removed and reset for the next bend. This entire bending process takes place over a second or two; hydraulic brakes may need several seconds to complete the forming action.

So why doesn’t the light curtain simply shut down the bending job when a human hand enters the bending window? The light curtain is able to keep tabs on the bending area while also allowing other movement in the press brake window because the sensors focus on an area of about 30 mm, or a little over 1 inch, where the bending takes place.

When the light curtain does pick up an unauthorized presence in that bending window, the ram stops within 80 milliseconds. A hydraulic system simply can’t match the ram control that an electric press brake’s servomotors provide.

The Alaso team liked what they saw and purchased two SafanDarley E-brakes, one with 110-ton capacity (see Figure 1) and the other with 35 tons. The latter is designed for small parts that require multiple, precise bends and came with a chair and a worktable that mounts to the front (see Figure 2).

“You never have to touch a foot pedal, and you are never going to pinch your fingers because the brake won’t actuate if your hand is in it,” Millard said. “It knows when you are there.

“The operators can put out more parts than they could with any other machine.”

Old School Meets New Tool

Millard’s enthusiasm wasn’t universally shared on the shop floor after the new brakes were installed. Mullis, a 30-year veteran of sheet metal manufacturing, summed it up succinctly: “At first I didn’t want to leave my old press brake. I’m old-school.”

Millard recognized the leap of faith that was required to move from a tried-and-true production technology to a new way of bending.

“It’s counterintuitive to put a part in a machine, move your hands, and have the press brake bend the part. You feel like you should push something to make a part, especially after operating a press brake for years and years,” he said.

But Millard insisted that Mullis, who is the lead press brake operator, start using the light curtain and encourage the others in the department to do the same. After about a month, everyone had shifted away from the foot pedal.

“It’s a big deal. The safety is a big deal,” Mullis said. “If people don’t get hurt, the more work you are going to get done.

“It’s also been a lot better for my feet,” she added. “For as long as I’ve been doing it, my feet aren’t what they used to be.”

Mullis said that the light curtain feature really comes in handy for parts with multiple bends. With the proper programming for the most sensible pinch point stops for the ram, the press brake operator can zip from one bend to the next until job completion.

Even when working with larger parts, which might pose somewhat of a problem because the operator has to hold the part and can’t afford to let go of it, Mullis found a way to use the light curtain. She attached magnets to the backgauges so that the larger parts would stick to the machine. That way she could continue to use the light barrier as a control.

“It just goes to show you that when someone likes something so much, they’ll figure out a way to use it,” Millard said.

Mullis said that she likes to train new personnel on the SafanDarley press brakes because she knows that they are safe. She has a deep respect for what such a powerful machine can do to an arm or finger that might get caught between the ram and a die, so she’s glad that the new brakes’ light curtains offer a sense of reassurance for new operators. In addition, the brakes’ graphical controls clearly spell out what the operator needs to be doing to complete a bending job per work instructions. When inexperienced operators have to look at an older press brake control interface that has nothing but numbers and axes, they can struggle.

The Numbers Tell the Story

Since installation of the press brakes, Millard has kept an eye on their performance. Actually, Alaso logs and tracks production time for all shop floor operations, which simplifies future technology investment decisions, but in this case it was helpful to see if the actual numbers were going to support the visual evidence that more parts were making their way through the bending department than before.

Millard said he looked specifically at long-run jobs, which call for 1,000 parts or more. These jobs account for about half of all the work being done in the shop.

Just by looking at those particular jobs, Millard said he noticed production speed increases from 18 to 22 percent. The eye did not deceive. The new bending technology and the employees’ willingness to use it were making a difference.

The controls on the new brakes also were helping to save time between jobs. Mullis said she started to use the memo function on the controllers to leave specific instructions for operators before they began any bending job. Memos might include guidance on why the part requires a specific punch or die or any other processing details to help other operators fully understand how to process each part.

Not only does the memo include the work instructions, but it also makes a note of who created the instructions and the date the memo was created. That’s important, according to Millard, because if Mullis wrote the memo, that’s the gospel in that bending department. Mullis has written the program, mastered it, and had engineering approve it.

“An individual can fire up the memos and read in detail how that part is supposed to be processed. That gives me confidence that the way that Jill first set up the job will be the way that it is run the next 10,000 times,” Millard said.

He added that work continues to optimize fabricating processes in other areas of the plant. This means parts are headed to the customer meeting all the tolerances and per agreed-upon delivery dates, and Alaso is able to further invest in production technology to keep up with customer demands and remain ahead of global competitors. Millard said that also might mean a larger electric press brake down the road.

In the case of the chicken and the housing, the electric press brake comes first.

Alaso, 863-606-0033, www.alaso.com

SafanDarley/Capital Machine

Technologies, 800-635-7777,

www.capitalmachine.com

About the Author
The Fabricator

Dan Davis

Editor-in-Chief

2135 Point Blvd.

Elgin, IL 60123

815-227-8281

Dan Davis is editor-in-chief of The Fabricator, the industry's most widely circulated metal fabricating magazine, and its sister publications, The Tube & Pipe Journal and The Welder. He has been with the publications since April 2002.