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Servo Presses

Shedding light on better stamping

By James Ward

Cooper Lighting's Monterrey, Mexico, stamping/assembly facility was faced with extremely demanding stamping quality and productivity challenges. To solve these issues, the company developed unique solutions leading to a range of improvements.

Cooper found precision servo-press feeding equipment to replace outdated air feed lines across a dozen mechanical presses. These enhancements resulted in meeting increasing production volumes and tighter delivery schedules, the flexibility to run as many as five different part numbers per shift, efficiency to achieve 10 to 12 coil changeovers per shift on each stamping press and the ability to process painted or polished material surfaces with scratch-free results.

From its modest beginnings of a one-room facility and six product lines, Cooper Lighting, headquartered in Peachtree City, Ga., has grown to a leadership position. Today, the company is the leading manufacturer of track and recessed lighting in North America and one of the largest fixture manufacturers of incandescent, fluorescent, high intensity discharge, exit, emergency, vandal resistant, sports, landscape and complex environment lighting. The company is comprised of 13 brands with 10 manufacturing facilities throughout the United States, Canada and Mexico.

Meeting extreme stamping challenges
In April 2000, Cooper Lighting launched their stamping operation in Monterrey, Mexico. From the beginning, it was faced with some extreme challenges. These included the demand to produce 10,000 or more part numbers per year, the flexibility to schedule parts from one press to another, the requirements to stamp painted or polished material surfaces without scratches, the need to improve coil changeover effectiveness and increase production rates as needed to meet customer demand. It soon realized that its inefficient air-operated coil feeds would prevent it from finding solutions to these challenges. Simply put, they had a dramatic limiting effect on stroke per minute rates, caused scratching on the painted and polished material and resulted in excessive die breakage and repairs.

Cooper Lighting's stamping area uses several types of presses: Komatsu, Clearing, Williams-White and Clearing-Niagara, ranging in tonnage from 300 tons to 600 tons. The company's most recent productivity and quality successes are tied to using Coe Press Equipment's ServoMaster Series feed lines. The lines are designed in conventional line layouts to provide the highest degree of processing speed and flexibility for its stamping operations. They are configured with ServoMaster Series roll feeds, heavy-duty power straighteners, pull-off type coil reels with capacities up to 20,000 lbs. and hydraulic travelling coil cars. The Coe feeds and straighteners were specified with polished chrome rolls to eliminate problems with scratching painted or polished material surfaces. In addition, the catenary rollers and threading surfaces are coated with Koat-a-Roll nylon materials to prevent damage to the material. Many of the lines employ hands-free threading tables with nylon-covered surfaces.

"Coe ServoMaster Series 2 roll feeds give us the capacity to run a wide range of materials at different widths and thickness and do so in a large range of materials including aluminum, steel and galvanized steel. They are easy to adjust and set up, which is very important because we need to deliver fast coil and part changes," says Enrique Barella, Cooper engineering manager. "They are also designed to feed our painted or polished materials without scratching or damaging. With 61,000 part numbers running through the plant and about 10,000 produced by stamping operations, changeover efficiency and the ability to perform feed setup quickly is imperative."

Barella adds, "We have around 250 dies that are run across our 12 presses, and we need them to actively process parts 80 percent to 90 percent of the time. We need to be very flexible in our ability to change them over at a moment's notice. For example, one single die set has the ability to run one to four different part numbers at a time (for example, ballasts at different lengths). When we need to change this die's setup by making changes inside the die, the Coe equipment gives us the flexibility to get all of this done quickly."

Faster is key
Barella states that their key need was to increase part throughput, desiring both faster processing rates and minimizing coil and job changeover times. Doubling or even tripling their past stroke per minute performance has now been realized. Many jobs can go from 25 spm to 75 spm with only minimum adjustments.

For one specific light reflector part, Barella explains that the steel must be kept at an exact length with the proper alignment going through the press. "If it's not straightened properly, it will incorrectly move inside the press, producing scrap, creating downtime and possibly breaking the die set. Therefore straightening the steel is critical." This job's output has grown from a run time of 25 spm to 70 spm. Barella says the Coe equipment ?gives them the flexibility to keep the metal level and to run at higher speeds. It also allows us to slow down the process when stamping polished or painted aluminum or steel parts to make sure they aren't getting any surface blemishes."

On another job, Barella explained that there have been productivity gains specifically due to the Coe equipment."I think we can speed up to 45 spm compared to the 25 spm we had before. So you get nearly double the production, and it's not only the speed that you gain with the equipment; it's the quality that you get with the parts, too. So there's no compromise there."

Some of the conventional lines are specified with a looping pit to store the necessary slack material for long feed lengths. This is important for smooth operation of the coil feeding system and continuous operation of the press, especially for stamping the ballast parts that have longer feed lengths. To do this there must be good communication between the Coe equipment and the press, Barella says. "The Coe feed lines run well in our progressive die stamping operations because even if the press speed increases from 25 spm to 75 spm, you don't lose the progression accuracy (as you might in air feeds or other servo feeds)," says Barella.

Another way Coe Press helps Cooper Lighting increase production efficiency is by keeping its machines running parts. Minimizing coil changeover time and optimizing setup time are critical challenges when a new coil or part is introduced to a line. The servo feeds are controlled by Coe's ServoMaster controller that regulates all servo feed functions and stores the job recipe information for each part number on a press. "Especially important is how we achieve fast training for new operators, as well as easy movement of jobs from one press to another," states Barella.

Coil mix is no problem
Barella says they process roughly 360 coils per month weighing an average of 16,000 lbs. to 20,000 lbs. Cooper Lighting runs many different types of steel and aluminum materials in the same press. Often they just have to make sure that the rollers on the straightener and feeder are cleaned before handling the different prefinished materials. Steel ranges in thickness from 0.023 in. to 0.032 in. and aluminum from 0.014 in. to 0.017 in. "We can start running the 0.032 in. thickness material in a press and then change to 0.026 in. All we need to adjust is the height of the die against the press and a little adjustment on the feeders and that's all. We don't have any big problems trying to adjust the feeder. Also, the progression of any part that we use can be adjusted on the control display, which helps us to have faster changeovers," Barella says.

Because prefinished materials are costly, scrap reduction is even more critical than running standard steels. "When we run aluminum parts, we can program the equipment to stop after 1,000 strokes for a quality inspection of the die set and feeding equipment or for a cleaning if needed. This can save a lot of scrap if there are problems with a broken punch or a part that moves out of alignment. And we can do it quickly and efficiently."

"We have material that would be considered special, like our mirrored material used for some louvers for fluorescent lamps," says Barella. "Also we have some materials with a mirror finish and a plastic cover for protection. The adjustment we have in the Coe straighteners for the rollers is so precise that we can make sure the plastic doesn't come off of the material when it goes through the feeder and straightener."

When processing painted or polished materials, Coe's servo-feed technology helps reduce scrap due to losing progression during the coil feeding process. Previous air feeds used side grippers to move the coil, often slipping and resulting in misfeeds and downtime.

For air feeders, the slit-edge of the steel can loosen the clamp that holds the strip, Barella says. This allows the strip to move in the press, lose progression and risk the possibility of a double hit. Also, because the press can speed up quickly, the feed clamps might not open and close at the correct speed. Using a roller instead of clamps to move the coil material, "gives you more speed, a lot more traction. So the material will run smooth, especially with aluminum parts," he says. FFJ

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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