Getting material handling right

In 1993 the folks at Osram Sylvania wanted to make room on the shop floor by installing a centralized material handling system. So they called Conair and said what they wanted - dryers, hoppers, blenders, loaders. And Osram got it. "What we realized," says Tom Nolan, senior process engineer, "was that we thought we knew what we wanted. We didn't. We should have gotten what we needed." Osram Sylvania was also confounded by another factor: Its market shifted gears. The system wasn't designed to keep up.

Osram Sylvania, based in Seymour, IN, has 50 presses, ranging from 350 to 2000 tons. Using 26 grades of engineering resins - polycarbonate, nylon, PET, polythalate carbonate, acrylic - Osram Sylvania molds car and truck headlamps, lenses, and taillights. The plant ships about 60,000 units a day. The presses gobble up a lot of resin, and because many of the headlamp applications require optical-quality molding, material temperature and moisture levels are tightly controlled.

Prior to 1993, the automotive headlamp industry was a relatively stable one. With product and design lives lasting about five years, it was easy for Osram Sylvania to run the same material in the same mold on the same press for months on end, sometimes years on end. Very little happened year-to-year in the automotive industry that dictated real change.

With such predictability, Osram decided a centralized material handling system was the way to go. Instead of sliding gaylords up next to the press, why not pull resin from a silo outside, dry it centrally, and then distribute it on demand? So Osram's engineers picked a corner of the plant and decided the new system would go there. Thinking it knew what this system needed, Osram called Conair (Franklin, PA) and ordered the equipment - dryers, hoppers, weigh blenders, loaders, and controllers. Conair complied and installed the equipment.

Nolan says the equipment ran - and continues to run - well. The system, however, was plagued by three overlooked items. First, each dryer serves two hoppers, so that for every dryer that went off-line, two hoppers went off-line. Second, because of the low ceiling in the corner of the plant, the weigh blenders were nudged into the rafters, making maintenance difficult. Third was "spaghetti junction," the junction plate that evolved into a maze of hoses and valves that looked like a snake pit. Nolan says they worked long and hard to overcome these hurdles.

Market Changes

But there was one change that Osram could not have planned for and Conair could not fix: market metamorphosis. After 1993, the auto industry changed the way it designs and makes headlamps. Instead of discrete and separate parts for the headlight and turn signal, designers merged the two into one modular unit. Such designs required more material and larger presses. Resin demand increased; and the hoppers and the dryers couldn't keep up.

And on top of that, says Nolan, design cycles changed from five years to two to three years. The stability Osram previously enjoyed vanished. Runs shortened and material changes became more frequent. Osram adjusted as best as it could, prospered, and in 1996 added 135,000 sq ft. Nolan was determined this time to install another centralized material handling system, one that could handle current capacity and future growth.

To start, Osram put the new system closer to the center of the expanded space. "The old system was shoe-horned into the corner of the plant," he says. The 30 presses (350 to 2000 tons) that were to fill the space would be placed around the new system. Next, says Nolan, Osram admitted that Conair knew more about material handling than it did. Instead of specifying particular equipment, Osram gave its requirements in terms of resin volume, resin demand, material type, material variety, number of presses, press capacity, and other factors. Conair then designed a system to meet all of those requirements.

The end product is a steel-lattice structure, about 120 by 30 ft, with stairs leading up to the mezzanine level approximately 10 ft off the ground where the dryers and hoppers are mounted. From there you can climb a short ladder to a catwalk that runs behind the hoppers; here you can easily read, access, and maintain the weigh blenders. The hoppers poke through the mezzanine floor of the structure, lower than the old version, and can pull from gaylords on the floor, or from one of eight silos outside. Conair says the new system was particularly challenging because of the long distances material has to move - up to 500 ft. The system also allows material purging, another challenge given the long distances.

The new system has hoppers of the following sizes: eight at 2000 lb, three at 1000 lb, two at 750 lb, one at 500 lb, two at 350 lb. And each has its own dryer. Nolan says he deviated from Conair's recommendations in one area - he ordered the next largest size for each hopper. Summer weather in Indiana makes drying nylon difficult; he wants the extra capacity to stay ahead of the humidity. The weigh blenders have two hoppers and weigh and mix virgin and regrind. Osram typically mixes 10 to 20 percent regrind. If there's a problem with any of the equipment, an alarm sounds on the device and on Nolan's PC in his office.

Making Connections

To replace "spaghetti junction," Osram installed Conair's vertically aligned fantail manifolds. Hoses for each press drop from the ceiling and can be attached to any valve on the selector plate. Each hose and valve has an electrical interlock. When a hose and valve are mated, the controllers check to make sure the correct material is going to the correct press. If not, an alarm is generated.

The elbows on the pipes that move the material through the plant use Conair's Pneumatic Erosion Guard (PEG), an electroless chrome plating that's supposed to last longer and leak less, especially when moving abrasive material such as nylon. Nolan says the PEG system is considerably more expensive, but if it saves him or someone else from having to replace leaking elbows 35 ft off the plant floor, it's worth it.

At the press, residence time is kept to three to 10 shots. The only space taken up beside the press is a vacuum pump that pulls material from the hoppers. The old system had one pump for every 10 presses; the new system has a pump for every three presses. All material use data are automatically sent to Nolan's PC where he can extract numbers for rates and volumes by material type.

Nolan says the system saves about 25 percent in floor space between each press. On top of that, the molder has an automated material handling system that can meet current and future capacity requirements. At $1.2 million, Osram finds it's worth it. "But the biggest difference," says Nolan, "is that we got the right one in first."