Shedding New Light on the problem of Scratch-Free” Coil Processing

Faced with extremely demanding stamping quality and productivity challenges, Cooper Lighting’s Monterrey Mexico stamping/
assembly facility was forced to upgrade to improved manufacturing techniques and equipment. Specifically, finding precision servo press feeding equipment to replace their outdated air feed lines across a dozen hungry mechanical presses. The end result led to a range of improvements:

• meeting ever increasing production volumes and tighter delivery schedules,
• flexibility to run as many as four to five different part numbers per shift,
• efficiency to achieve 10 to 12 coil changeovers per shift on each press, and
• processing painted or polished material surfaces with scratch-free results.

Cooper Lighting—Brief Background

The foundation of what Cooper Lighting consists of today goes back to 1956 when the Halo Lighting Company was founded to manufacture lighting fixtures. Later Halo was bought by McGraw Edison that was then purchased by Cooper Industries in 1985. Cooper Lighting was established in 1987.

From its modest beginnings of a one-room facility and six product lines, Cooper Lighting has grown to a leadership position of an international industry. Today, Cooper Lighting, headquartered in Peachtree City, Georgia, is the leading manufacturer of track and recessed lighting in North America and one of the largest fixture manufacturers of incandescent, fluorescent, H.I.D., exit and emergency, vandal resistant, sports, landscape and complex environment lighting. The company is comprised of thirteen brands with ten manufacturing facilities throughout the U.S., Canada and Mexico.

Meeting Extreme Stamping Challenges

In April 2000, Cooper Lighting launched their stamping operation in Monterrey, Mexico. From the beginning, they were 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 to increase production rates as needed to meet customer demand.  They soon realized that their inefficient air-operated coil feeds would prevent them from finding solutions to these challenges. Simply put, they had a dramatic limiting effect on SPM 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 to 600 tons. Their most recent productivity and quality successes are tied to Coe Press Equipment (Sterling Heights, MI) ServoMaster Series Feed Lines.  The lines are designed in conventional line layouts to provide the highest degree of processing speed and flexibility for their stamping operations.  The lines are configured with ServoMaster Series roll feeds, heavy-duty power straighteners, pull-off type coil reels with capacity up to 20,000#, and hydraulic traveling coil cars. The Coe ServoMaster Series roll feeds provide fast and accurate performance, replacing the old and inefficient air feeds. The feeds and straighteners are 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 hand-free threading tables with nylon covered surfaces.

Enrique Barella, Cooper Engineering Manager, explains why they specified Coe feed lines…

“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 wide 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. 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 set-up quickly is imperative.

Barella adds, “We have around 250 dies that are ran across our 12 presses…and we need them to be actively process parts 80% to 90% of the time. We need to be very flexible in our ability to change them over in a moment’s notice. For example, one single die set has the ability to run one to four different part numbers at a time (IE: 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 confidence and flexibility to get all of this done quickly.”

“Going 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 SPM performance has now been realized at Cooper Lighting’s stamping operations. Many jobs can go from 25 to 75 strokes per minute with only minimum adjustments. “If we want to increase our speed on the press,” Barrella ads, “the Coe equipment helps us with its fast set-up and adjustments. So the Coe press feeders and straighteners help us a lot, especially when we only need to adjust feed progression for a part number change.”

For one specific light reflector job, 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 correctly, 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 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…but still at higher speeds than ever before.”

On another job being produced at the time of this visit, Barella explained that there have been productivity gains specifically due to the Coe equipment that, he quotes, “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, either”

Some of the conventional lines are specified with a looping pit in order 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, he says that there must be good communication between the Coe equipment and the press. “Because we run four different brands of presses, we appreciate the fact that the Coe equipment has given us no problem integrating and communicating with any of them,” Barella states. “The Coe feed lines runs well in our progressive die stamping operations as well, because even if the press speed increases from 25 to 75 SPM, you don’t lose the progression accuracy (as you might in air feeds or other servo feeds).”

Improving their “Green Light” Processing…Even with Wide Range of Jobs/Material Types

Another way Coe Press helps Cooper Lighting to increase production efficiency is by keeping their machines running parts versus set-up time or other downtime.  Minimizing coil changeover time and optimizing set-up time are critical challenges when a new coil and/or part is introduced to a line.  The servo feeds are controlled Coe’s ServoMaster Controller that controls all servo feed functions and stores the job recipe information for each part number on a press.  “Especially important is how we achieve the fast training for new operators, as well as easy movement of jobs from one press to another,” states Barella.

To increase press uptime, coil cars are pre-staged with the next coil while the reel finishes paying out material. Once the next coil is centered and properly loaded on the mandrel, only minor set-up changes are needed for the material width, straightener roll depth settings, and passline height.

Running Tons of Smaller Coils Annually…Not a Problem Here

There are some self-observed limitations with their stamping line layout, especially in limited coil weight processing. “We can’t run big coils, because we don’t have the capacity to move them with a forklift,” says Barella. “We use a crane to unload them from a truck, but because of our space limitations, we are forced to use a forklift to move them from the storage area to the press lines. So each coil can’t weigh more than 20,000 pounds. Therefore, we load new coils, on average, 10 to 12 times per shift. The press needs to be set just right every time you load a new coil.  Also, every coil       is different…and can have problems like waviness, camber, and convex or concave center areas.

And if you don’t have a very good feed line, you will have a lot of problems with set up and obtaining accurate parts. Coe helps us to best meet these issues.”

Barella says they process roughly 360 coils per month weighing an average of 16,000 to 20,000 pounds. Cooper Lighting runs many different types of materials in the same press both in steel and aluminum. Often they just have to make sure that the rollers on the straightener and feeder are cleaned before handling the different pre-finished materials. Steel ranges in thickness from 0.023” to 0.032” and aluminum from 0.014” to 0.017”.  “We can start running the 0.032” thickness material in a press and then change to 0.026”. 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 states.

Because prefinished materials are more costly, scrap reduction is even more critical than running standard steels.  And Barella states that Coe roll feeds and straighteners help them dramatically reduce scrap levels. “For example, when we run aluminum parts through them,” he states, “we can program the equipment to stop after 1,000 strokes for a quality inspection of the die set and feeding equipment, providing 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.”

Barella mentions, “We have material that would be considered very special, like our mirrored material used for some louvers for florescent lamps. Also we have some materials with a mirror finish and a plastic cover for protection. With the adjustment we have in the Coe straighteners for the rollers, it 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.”

Better Performance Over Previous Air Feeding

When processing painted or polished materials, Coe’s servo feed technology helps them 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 excessive mis-feeds and downtime. Uptime and processing speeds were the primary factors for replacing their air feeds. Barella explained that the slit-edge of the steel can lose the clamp that holds the strip.

This allows the strip to move in the press and 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. With the servo feed equipment having a roller instead of clamps to move the coil material, “It gives you more speed, a lot more traction. So the material will run smooth, especially with aluminum parts,” mentions Barella.

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