For many companies, truck loading and unloading is one of the last frontiers of automation.
Consider the case of Frito-Lay. By the mid-90s, the snack food giant had long since automated operations inside its distribution centers. But when it came to loading trucks, the company still relied on manual processes, with workers spending their days inside trailers hand stacking cases of chips, nuts, cookies, crackers, and meats.
As for what was holding it back, Frito-Lay didn't feel it had much choice. Its loading requirements are somewhat out of the ordinary: Because cases of snack foods are relatively light—about five to seven pounds each—trailers tend to cube out before they weigh out. Although there were loading systems on the market, there was nothing available at the time that could match hand loading when it came to ensuring that every inch of the trailer cube was utilized.
Eventually, Frito-Lay decided to take things into its own hands. Working with a partner, it developed a semiautomated solution that includes a conveyor with a series of "arms" that lob cases onto a stack. Some 10 years later, the two partners took the technology to the next level, devising a fully automated loading solution that uses robots guided by sensors.
Today, half of Frito-Lay's distribution centers use one of the two solutions, with 15 semiautomated solutions in use at five sites and 10 fully automated solutions at four others. The result? Significant gains in productivity and a raft of ergonomic benefits.
REPLICATING THE TOSS
What sent Frito-Lay down this path was a need to boost productivity. The traditional labor-intensive process was becoming less and less appealing as volume ramped up—the company ships out 700 million cases each year. On top of that, the process required a lot of bending and reaching on the workers' part. So the company was eager to find an alternative, explains Andy Fisher, senior director of warehouse operations for Frito-Lay North America (US and Canada).
In 1995, the company approached integrator Wynright about automating the process. Fisher says Wynright was a natural place to turn for help. The two had worked together on a number of DC racking and conveyor projects since 1982, and over the years, the provider had offered many useful suggestions for improving Frito-Lay's operations. "They really knew our business and understood our [distribution centers'] wants and needs," he says.
The team of engineers and project managers assigned to the task kicked off the project by going straight to the source, observing workers as they built stacks by gently tossing cases on top of one another. After watching the workers load trucks, they then tried it themselves. Deepak Aurora, a 30-year veteran of Frito-Lay (now retired), who served as a technical liaison to Wynright, recalls, "We said to the operators, 'All right, you step aside, and we will load the truck, so that we [can] get a feeling for how difficult it is and what all the steps are.'"
Once it had a handle on the process, the team took up the question of how to replicate that gentle tossing action with technology, Fisher says. It determined that this could be accomplished by having the cases shoot off the end of a conveyor. To create the stack, workers would simply change the angle of the conveyor so that the cases would land in the right place, according to Aurora.
To test the concept, one member of the team actually stood inside a trailer holding a small piece of conveyor while other team members experimented with changing the conveyor's speed and angle. The team discovered that at a speed of 400 feet per minute, they were able to stack the cases quickly without causing damage to the product.
Once the two parties had settled on the general concept, Wynright designed a conveyor with a series of arms that shoot the cases out. An operator working inside the truck aims the equipment, which Frito-Lay nicknamed "T. Rex." The conveyor then rises up automatically, and the next case is lobbed on top of the first.
With the semiautomated solution, Frito-Lay could now load trucks twice as fast as it could via the manual process, says Fisher. The solution also offered ergonomic advantages, since workers no longer had to bend, reach, and stretch to position the boxes.
The solution worked so well for Frito-Lay that the two companies filed for a joint patent for the T. Rex truck loader. "Once the thing was designed and built, we looked at the concept and realized that it's really a unique application of available technologies—of how you can put together all these simple technologies and make them into one system that will do the job," Aurora recalls.
FROM DINOSAURS TO ROBOTS
While it was Frito-Lay that came to Wynright with the general concept for a loading system in 1995, 10 years later it was the other way around. This time, Wynright approached Frito-Lay with an idea for an upgrade. Wynright's idea was to take the worker out of the process and instead, use a mobile robot that would move into the trailer, build the load, and then back out again.
After seeing a computer simulation, Frito-Lay gave Wynright the go-ahead. Then, the real work began, recalls Tim Criswell, divisional president for Wynright Robotics. "We collaborated with Frito-Lay [to figure] out how to make that work in their environment under their economic conditions: how the cases would come in, what rate we would have to run at, what reliability we would have to run, those sorts of things," he says. "When we finished that, we took those things and did the detailed engineering and implementing."
The result was a sophisticated solution called a robotic truck loader (RTL), which builds half a stack outside the trailer then drives into the trailer and gently sets it on the floor. Each stack is built to half the trailer's height. After positioning the first stack, the robot places the second stack on top of it, then works its way across the trailer. Once the robot reaches the other end, the system moves it back one case length and it repeats the process.
The biggest challenge in turning the concept into reality was figuring out how to tell the robot where it was inside the trailer. "You can put a robot on a cart and drive it into the trailer, but it's never going to be in exactly the same position," says Criswell.
Wynright solved that by deploying advanced sensor technology. "We used a laser measurement system that would scan the environment and create a cloud of data points on the location of the trailer's floor and walls, and the existing cases," Criswell explains. "The system then analyzes the data, feeds that information to the robot, and off you go!"
According to Criswell, the robot can cube out the truck as well as—or better than—a person can because it's taller and has more reach. That allows the robot to gently place the final cases on the top of the stack instead of having to toss them. Believing they had another unique solution, Frito-Lay and Wynright once again filed for a joint patent.
Fisher reports that the RTLs have brought about significant productivity gains at the sites where they've been implemented, boosting case loading rates from 500 cases per labor-hour to over 1,100. The gains in this case are due to efficiency, not speed. An RTL can't load a truck any faster than a human can, but because a single operator can control three robots at once, it allows workers to be more productive, says Fisher. It was this ability for one person to operate multiple units that justified the cost of the automation for Frito-Lay, Aurora says.
A BLENDED APPROACH
It's worth noting that the introduction of the fully automated robotic truck loader did not make its semiautomated predecessor obsolete. Because the RTL only works with products that have a standard footprint, its application is limited to those DCs that handle nothing but Lay's potato chips and Doritos, which are shipped in standard-size returnable cartons. Facilities that ship cookies, crackers, nuts, or meats in addition to chips use the semiautomated solution.
Regardless of where they're deployed, both solutions have been a hit with workers, Fisher says. "The technicians appreciate that Frito-Lay is making their jobs better and that this has been accomplished without a reduction in manpower except by natural turnover," he reports. "They have really embraced the technology. Instead of standing in a trailer throwing cases for seven hours a day, they're pressing buttons and operating machinery. It's a higher-level [job] for them."
Fisher does acknowledge that he's received one complaint. "I had one guy come up to me and say, 'I have a problem. I find that I'm gaining a little bit of weight because I'm not as physically active as I used to be.' I said to him, 'Well, are you exercising?' He said, 'I think I'm going to have to start. At the end of the day, I'm not diving into my chair anymore. My energy level has really improved.'"