Real-world flexibility in packaging lines

Prepared Foods, May, 1991 by Rick Lingle

* Changeovers are one of manufacturing's necessary evils.

"Processors do everything they can not to have to change over a production line," says jim Fisher, director of operations for Request Foods (Holland, Mich.), manufacturer of frozen meals for foodservice operations. "The scheduler or planner holds a big key to manufacturing productivity. Poorly scheduled changeovers ca cripple the plant floor."

Fisher notes that plant floor production momentum and operator enthusiasm suffer at least a temporary setback during a changeover.

Regardless, changeovers-stopping production of one product formulation or package size and starting another-are a given for most food processors. And trends point to even more changeovers in the future.

Sterling Anthony, a management consultant and president of Sterling Anthony Inc., Detroit, notes two major market trends that indicate more line changeovers ahead: * uncertain or shorter new product life cycles; and * greater incentives for decreased product inventories.

"In general, equipment capacity is being utilized less in terms of continuous runs," Anthony says.

"Two-thirds of our clients in the food industry are looking for increased flexibility," says Colleen Staton, president of Key Automation and Design Inc. (St. Paul, Minn.), which specializes in packaging machinery and facilities planning. "Line flexibility is a huge concern when expanding with new products or when running different package sizes to meet changing marketing demands."

Staton sees fewer dedicated fines nowadays, partly because many food plants want to run a full product array in regionally located plants, especially those producing perishable foods. This strategy greatly reduces distribution costs.

Aside from proper scheduling and operator enthusiasm, the greatest factor in changeover efficiency on the packaging line is the equipment itself. Is your machinery adept at change, like a chameleon to its surroundings, or is it more like an immobile dinosaur that operators and maintenance personnel must struggle with?

The following tour along a packaging line should shed some light on the shadowy world of changeovers.

One of the main lines at Request Foods produces 2-lb. trayed meals in nine varieties. Fisher believes filler changes represent Request's biggest bottleneck, although he says a well-trained operator can do the changeover in 10 minutes.

Fisher likes the easy operation of fillers with electronic controls, but thinks electronic systems are not durable enough withstand the rigors of the plant floor. Instead, Request uses air-piston fillers.

A major jam and jelly manufacturer avoids middle-of-shift changeovers at all costs and even tries to restrict between-shift changeovers to different size containers. Nonetheless, it listed changeover capability high among its criteria for filler selection. When the firm purchased a filler, it spent tens of thousands of extra dollars to have a filler equipped with finger grippers that enabled it to run five different size containers, from 10-oz. through 18-oz. Such changeovers on conventional fillers are not easy, if possible at all.

One type of machinery seems ideally suited for changeovers: form-fill-seal equipment. Staton believes FFS systems lend themselves particularly well to changeovers since changeovers can be done "on the fly" as needed.

That's true at the Hiland Potato Chips plant in Des Moines, Iowa, where seven vertical FFS units handle 10 different size packages from 0.5 to 16 oz. Changeovers are rapid, less than 15 minutes when a change in film width is necessary and considerably less for other changeovers involving the same product. The only limit to product or flavor changeovers is the time it takes to wipe the product contact surfaces with dry cloths.

Staton says that in conjunction with servo (electronics)-controlled systems, menu-driven software packages also play an important role.

Experts agree that metal detectors and checkweighers present few changeover problems, mainly because they are electronic systems with little or no mechanical interfacing. With a metal detector, changeovers simply involve digital keypad changes-as long as the product fits through the aperture or opening.

The programmable storage capability of these systems is tailor-made for multi-product processing lines. One supllier's metal detector stores up to 60 different product setups and their parameters for instant recall and minimal changeover slowdowns.

Further downstream is the cartoner, where the odds of a changeover bottleneck are as great as anywhere in the packaging line. Staton pegs cartoner changeover time from a half-hour to two hours or more, the exact time depending on the skills of the maintenance staff.

It seems that changeovers by machinery setting alterations are inherently better than those that rely upon the skills of a plant's maintenance personnel.

Staton prefers cartoners that changeover via a handwheel, rather than those that require a wrench. "The user-friendly ones are equipped with scales mounted as reference guides," she says. Consider robots