Food Engineering

The Quest for Efficiency

March 26, 2003
Line optimization is a journey, not a destination

A disciplined approach to bottleneck identification can have big payoffs in line efficiencies. Source: Alcoa CSI Inc.


Articulated arm robots are helping bring the efficiencies of automated palletizing to processors who don’t have the production volumes necessary to justify a gantry system. Source: Alvey Systems Inc.
NO MATTER HOW EFFICIENT A FOOD PLANT IS, THERE’S always room for improvement. Consider the Tennessee Bun Co. The Dickson, Tenn.-based foodservice supplier was founded in 1997 with the objective of being the most automated bakery possible. “You look for anyplace you can put in automation to eliminate a guy,” notes chief engineer Richard Cary, and there aren’t a lot of people left at this point.

Five operators can be found in the makeup area, and another seven are downstream from the oven, primarily in the packaging department. For a line that is capable of producing 1.5 million buns a day, that qualifies as skeletal. “We’re down to the minimum without killing us,” Cary chuckles.

Plants that effectively manage their assets are natural proving grounds for new-to-the-market products. DuPont Performance Lubricants gravitated to Tennessee Bun to demonstrate the efficiencies possible with Krytox, a line of synthetic lubricants originally developed for the aerospace industry. With its ability to perform at extreme operating temperatures and an inert composition that won’t support bacterial growth, DuPont managers decided it was time to target the food industry. The lubricant was certified as safe for incidental food contact by NSF, and a plant environment with temperatures above 250º was sought as a proving ground.

The 700 ft.-plus chain that drives Tennessee Bun’s oven band through a 450º heat zone qualified, so a trial was arranged. An automatic chain oiler with a drum pump lubricates the chain after 10 hours of run time. Efficiency gains were to be measured against lubrication savings only. Given the premium price Krytox commands, that would mean oiling the chain once every six to seven days, according to Cary. “We check to make sure the unit is oiling right, but other than that, there’s no labor involved in chain lubrication.”

So far, the lubricant has only meant a reduction in lubrication to a three to five day cycle—an impressive improvement, but not efficient as the test was constructed. Undeterred, DuPont technicians analyzed the situation and determined the weak link was not the lubricant itself but the delivery system. It blasts oil onto the chain, flooding the surface but failing to soak the pins where it is needed most. The solution may lie in a precision delivery system from Lincoln Industrial. Known as Orsco, the system delivers minute quantities of lubricant in continuous or pulsed mode. Quantities as small as 0.015 cc (half a drop) are dispensed precisely with the desired pressure.

By switching to the new delivery system, chain lubrication should only be required every seven or eight days, according to Gregory A. Bell, senior technical service engineer at the Krytox lab. “With sealed bearings, it might go three to five years without lubrication.”

Unlike the ester hydrocarbon oil it replaced, Krytox won’t oxidize when exposed to extreme heat. Oxidation causes oil to evaporate and break down, resulting in the formation of tar and varnish. “Once carbon forms, you have to scrape or hammer it off,” explains Geri Walker, president of Baking Technology Systems Inc., which designed and installed the oven and proofing systems at Tennessee Bun. “Preventing the residue from forming is what we’re really trying to get at.”

Some bakeries swap out 100-ft. sections at a time of the oven chain, cleaning the carbon from one section before exchanging it for another section with carbon buildup. The process can be continuous, depending on frequency of lubrication. A 40º increase in oven operating temperature can mean a four-fold increase in lubrication frequency. Chain cleaning is by nature inefficient, so any reduction in that activity means increased efficiency.

Lubricating conveyor drive chains and bearings that perform near fryers, ovens and cookers can be a nightmare. DuPont is demonstrating that increased efficiencies can cost justify its Krytox lubricants. Source: DuPont Performance Lubricants.

Improving technology

“The best can always be improved,” says Walker, summing up his philosophy on efficiency. Tennessee Bun’s ovens were state of the art when installed, but technology keeps advancing, and upgrades are necessary to remain efficient. A few years ago, he retrofitted the bakery’s oven with a humidity control system that controls exhaust flow to maintain consistent humidity within the oven. Relative humidity can range from 20 to 80 percent, Walker says, depending on water release from the dough and the amount of combustion within the oven, and that has a dramatic affect on the bake. The control system maintains humidity at a 40 percent set point.

Vision systems hold great potential in boosting bakery efficiency. Walker’s firm is working with Georgia Tech and Flowers Bakeries on a system that feeds back data on seed distribution, bun color and other quality parameters.

Efficiency often is equated with automation, and automation requires production scales that are realized only by the largest food and beverage companies. That’s the case with automated carousel systems for order picking in boxed beef operations. These alternatives to manual order-picking started to appear in the plants of Iowa Beef and Swift & Co. a decade ago, but they remain out of reach for small to mid-sized packers, notes Ken Thouvenot, vice president of project management and marketing at Alvey Systems in St. Louis.

“The equipment can be downsized, but the software that drives them remains pretty much the same, so scalability has been a problem in making the systems cost effective for the smaller guys,” says Thouvenot. In the meantime, the order-picking speed of the systems has improved 50 percent since the early 1990s.

In a packing house, a carousel might have as many as 100,000 positions to accommodate individual boxes of beef. The positions are distributed throughout 20 stacks, with a picking robot serving each level in the stack. As shipping orders come in, the software system picks the various primal cuts on a first in, first out basis, filling the order without the need for any workers to enter the freezer until the entire order is assembled.

“Twenty years ago, the controls and servo drivers that make automated inserter/extractor technology possible didn’t exist, so all this work was done manually,” says Thouvenot. “Our first installation was around 1993, and each robot probably picked four cases a minute. Now they pick six cases for each stack, so that’s an extra 80 cases a minute overall.”

Sidebar: Lights, cameras, action!

If Francis Ford Coppola was an engineer, he’d probably be directing Alcoa Closure Systems International’s Line Efficiency Improvement Program (LEIP).

Armed with a dozen or more high-speed video cameras and a multiplexer editing unit, field technicians from Indianapolis, Ind.-based Alcoa CSI swoop into beverage plants to conduct a critical analysis of where and why bottlenecks occur on a line. The filler and capper are the focal point, but delays elsewhere in the system cause most of the slowdowns and delays, and identifying them is the objective in those thousands of feet of videotape, explains David Weyenberg, technical services manager and one of the creators of LEIP.

The cameras roll for about 40 hours of production time, and the editing process produces a comprehensive overview as well as up-close-and-personal looks at individual containers’ journey through the system. The result is an action plan of corrective steps involving “low-hanging fruit all the way to replacing antiquated equipment and the likely payback,” says Weyenberg.

“People in the plant just aren’t armed with the data to quantify the cost of inefficiencies,” he adds. “This analysis makes it easy to justify a capital project.”

The camera’s unflinching eye exposes processing as well as equipment issues, such as operators out of position for optimal servicing. The multiple angles lay bare problems in one area that are not apparent to people in another. “There are a certain number of buffers built into any system, so people on the other side of the wall are unsure when there’s downtime in another area and how much of an effect it has on their efficiency,” Weyenberg says.

Alcoa traditionally has worked with soft drink bottlers and brewers with bottling line speeds of up to 2,400 units a minute, but its Texas division is bringing the firm increasingly into the food segment, working with clients like Kraft and Aurora Foods. The line speeds are slower—“If you’re bottling 375 units a minute, you’re really moving,” he notes—but the bottlenecks often are similar, and the cameras capture them all.