There are numerous factors that affect product consistency. It begins with raising livestock on the farm and continues into the packing and processing plant.

For Excel Corp.'s pork plant in Beardstown, Ill., the responsibility for product consistency begins when carcasses are broken down. "So much money is made or lost when carcasses are broken down that ounces make a difference," says Steve Alloway, specification superintendent at the Beardstown plant. "That's why consistency and meeting specifications are critical," he adds.

Excel's Beardstown plant is a two-shift operation that processes more than 15,000 hogs a day into fresh pork commodities, such as hams, loins, spareribs and bellies. Earlier this year, when the Wichita, Kan.-based company was looking for new ways to maintain and improve product consistency, it chose a statistical process control method to identify and correct problems.

The shift to statistical process control required management and operators to learn new methods and new skills. And the company is seeing improved consistency results because of the new system.

Shelly Melroe, a senior research statistician for Cargill Red Meat Group, which manages Excel, says the statistical process control program is helping management to objectively understand what equipment and systems are capable of doing. "It clearly shows when specifications can't be met with available resources," she says. "It clearly shows when the specifications can be met."

In the breaking area, where Excel implemented the statistical control process, carcasses arrive from the cooler suspended by chain. When they arrive at the breaking table, an automatic cut-down knife drops the carcasses on a conveyor where eight operators use circular and scribe saws to cut them.

Although the cuts are guided by lasers, variations are inevitable because of differences in the carcasses, Alloway says.

The statistical process control program reduces the variation in cuts, bringing them as close to specifications as possible, he adds.

Technical service supervisors pull 10 samples from the conveyor hourly and measure them on each side for length of shoulder scribe, rib scribe, neck bone and aitchbone.

The data—along with information on who took the measurements, date, time, operator and causes—is entered into a computer with software supplied by Portland, Ore.-based Northwest Analytical Inc. Supervisors use the software to generate control charts that show whether the cuts are within database-control limits and specification tolerances.

"The software makes it easy to interpret the data," Alloway says. "When we spot a trend that's hugging the upper or lower end of our tolerances, we can identify the problem and work with the operator on a solution."

There were several obstacles to overcome before Excel felt confident enough to put the statistical process control method into operation. Among them:

• In the course of implementing the statistical process control program, employees noticed discrepancies in carcass measurements.

They discovered that when two different employees took measurements on the same carcass—or when one employee took two different measurements—the outcomes were different.

Excel executives found that measurements taken while the carcasses were in motion were unreliable, Alloway says. Excel solved the problem by having employees take samples off the conveyor and place them on a stationary table for measurements.

• Employees had to overcome their reluctance to statistics.

"Most people didn't like math in school, and when they hear the word 'statistic,' they tune out," Alloway says.

But the software helps employees overcome any uneasiness. "We input the measurements and the program produces the chart," he says. "There are no complex statistical formulas to compute."

Alloway believes that the statistical process control will help Excel reduce the variations in cuts, leading to better products for its customers, although the company does not have enough data yet to quantify the reduction.

"But we can see the results in the consistency we're achieving on the charts," he says.

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