Lift trucks or automation?

It's not an either or proposition. Even in highly automated facilities, lift trucks are almost always part of the equation.

"In the mid-1960's, Sara Lee opened the most automated plant in the country," says Bob Footlik, president, Footlik & Associates (847-328-5644). "Lo and behold, at the end of the line, a lift truck took the pallet from a conveyor and loaded it into a trailer."

Nearly 40 years later, the lift truck is still a key link between the dock doors and the pick-up or drop-off locations in any automated system. "The lift truck is the vehicle for transporting product to and from areas of automation," says Paul Psarcik, senior manager, Sedlak (330-908-2244). "Even an automatic guided vehicle [AGV] needs to be loaded and unloaded. A lift truck is a tool to support the automation."

Striking the right balance between automated systems and lift trucks usually comes down to three considerations: the need for flexibility, the cost of labor and the relative cost of equipment.

Both lift trucks and automation have their plusses and minuses. That's why so many operations include a mix of the two.

"Even in an automated facility, there's no good automation system to unload a trailer for you," says Jeff James, systems consultant, Forte Industries (513-398-2800). "And when it comes to putting away a pallet or replenishing a pick face, the lift truck is still the best way to go in most situations."

The flexibility to handle spikes in throughput, seasonal demand or future growth is another reason for mixing lift trucks with automation. "With a lift truck, you have limitations like aisle size and traffic," says Sam Flanders, president, Warehouse Management Consultants (603-868-6767). "But if your business changes, you can order ten more lift trucks for delivery overnight. Lift trucks are just extremely flexible."

On the other hand, there are things that lift trucks don't do well. "A lift truck is not capable of retrieving one carton," says Footlik. "That's a place where automation can come into play."

It's also a place where hybrid solutions, like a wire- or rail-guided truck might be a solution. "A man-up vehicle under computer control can move the fork truck to the next location or direct the operator where to take the vehicle for the next pick," says Footlik. "That allows a degree of flexibility that isn't possible with an AS/RS."

In fact, providing flexibility is one of the important ways a lift truck enhances an automated system.

"Automation works best in repetitive operations with well-defined throughputs," says Geoff Sisko, senior vice president, Gross & Associates (732-636-2666). "The more you try to accommodate surges in throughput, the more expensive it gets."

For instance, a facility with high labor costs can use automated equipment for routine, predictable operations. "If your WMS knows your demands for the next day, you can automate part of the order fulfillment process by automatically pre-staging inventory in an AS/RS," says Sisko. "That might very well be cheaper than doing that manually with a lift truck or man-up truck."

On the other side, lift trucks can handle the unpredictable sides of an operation, says Footlik. That might include transporting non-standard product, inventory from a specials area, or filling hot orders.

In other areas, a combination of lift trucks and automation works better than a completely automated system. Sisko cites a company that installed a completely automated solution to feed a manufacturing line. Pallets stored in an AS/RS were delivered to the line by an AGV. Later, an AGV took away finished goods and returned empty pallets to the AS/RS.

Too often, however, employees sat idle waiting for the AGV to take work-in-process or finished goods to the next station.

"The company is now mechanizing part of the operation with lift trucks to increase throughput," Sisko explains.

In addition, the company is installing racks in a forward pick area and using the AS/RS to provide space-saving reserve storage. In place of the AGVs, pallet conveyor will route product through the facility. Lift trucks will deliver pallets from the conveyor to the various processes.

"The lift trucks are the flexible interface between the operations and the automated devices," Sisko says.

Coming up with the right mix of trucks and automation is also a matter of labor and equipment costs. Other factors also come into play. "In addition to the cost of labor and the time it takes for a lift truck to pull and deliver a pallet, there are other things, like congestion in the aisles," says Flanders. "Finally, there's the cost of how long it takes automation to complete the function on average. Since automation is more expensive up front, there has to be a driving reason to spend that extra money."

How a company looks at those costs may also tip the equation more in favor of lift trucks over automation. "A lift truck can typically be leased or rented, which means it's an operating expense," says Pisarcik. "Installing an AS/RS or adding a conveyor line is a capital expense, and those are harder to get approved."

Even when the equipment and labor costs point in the direction of automation, it can be difficult for some to justify. "A lift truck is easy to justify because everyone knows what they do," says Flanders. "That's not the case with automation, where you might be putting your career on the line to justify a project."