Inside the Automated Warehouse
The traditional functions of a warehouse are well known. Unlike its predecessors, however, the modern warehouse is an assemblage of highly evolved automation technologies, making it a core part of the supply chain.
Today's warehouse activities include crossdocking, palletizing, kitting, tagging, and identifying products, as well as storing them in the most time- and space-efficient manner possible. As a result, warehouse automation now has a direct bearing on supply chain efficiency.
"The warehouse is the last frontier for reducing long-term distribution and logistics costs," says Dan Labell, president, Westfalia Technologies, a warehousing systems planner and implementer headquartered in York, Pa.
Tools of the Trade
Because Westfalia stays ahead of the curve on major warehouse automation trends, a look at the tools it offers to help companies reduce cost and speed product flows has broad implications for warehouses in general.
Robots. Robots play a major role in the materials handling systems Westfalia designs and recommends. The company uses articulating arm robots manufactured by KUKA Robotics Corporation, a global manufacturer of industrial robots, and by Fuji Yusoki, a leading robotic palletizer manufacturer.
Westfalia programs the robots, but an operator can adjust settings and add patterns if they are not too sophisticated. The robots are programmed primarily to do palletizing, but also are used to de-palletize layers.
Westfalia also uses robots to de-palletize and re-palletize layers on its new layer storage/retrieval system, which is designed to automatically create "rainbow pallets"—different layers of SKUs on each pallet.
AS/RS Systems. Westfalia manufactures its own Automated Storage and Retrieval systems (AS/RS), writes its own software, and builds its own conveyors and controls.
"Our compact, high-density systems save a tremendous amount of floor space," Labell notes. "AS/RS systems can be built much higher than in conventional warehouses, which saves still more floor space."
In addition, AS/RS systems save labor, are 99.9-percent accurate, and do not damage product, Labell says. Westfalia's systems can handle up to 8,000-pound loads of paper and other heavy products, as well as standard weight pallets.
These computer-controlled systems provide instant access to a tremendous amount of information, which warehouse and logistics managers can retrieve through web links. "We designed our software to be user friendly; even non-computer-literate people can learn it very quickly," Labell notes.
Layer forming palletizers. Layer forming palletizers are often used in high-speed applications, and in conjunction with handling bags when pattern quality is important.
How do layer forming palletizers compare with robotic palletizers? A layer forming palletizer can square each layer before it is stripped onto the pallet (this applies to bags only). A robot cannot.
A robot is far more flexible, however, because it can handle multiple production lines at once. Robots can also quickly pick up multiple cases/bags at one time, but will not match the speed of the very high-speed lines often found in the beverage industry, for example.
"Deciding between layer forming palletizers and robotic palletizers depends on the application," Labell says. "For a warehouse with slow rates and multiple lines, a robot is likely the better solution. If the rates are very fast, and there is only one line, layer forming may be a better option. The trend, however, is toward robotic palletizing."
Whether dealing with robots or layer forming palletizers, safety is always an issue, according to Labell. A layer forming machine or robot cannot access certain areas, for example. The robotic palletizing cell is extremely dangerous when not guarded properly with laser protection devices or safety fences. Lock-out/tag-out procedures are typically implemented to ensure humans are not inside a robotic palletizing cell during operations.
Forklifts. Automated warehouse systems typically use forklifts to load trucks, but sometimes use counterbalanced trucks to move product received from the outside, or if the manufacturing facility is not coupled to the warehouse. These trucks are usually equipped with RF equipment so the truck operator can communicate information back to the Warehouse Management System (WMS).
Conveyors. Westfalia's Air-Chain conveyors use one motor for lengths of up to 100 feet, and require no electric controls to accomplish zero-pressure accumulation, similar to a traffic jam concept. The lack of controls required, plus the fact that only a two-horsepower motor is needed for up to 20 zones (100 feet), make the conveyors cost effective.
Westfalia uses right angle transfers and turntables when it wants to transport pallets in different directions while maintaining or changing the pallet orientation. "When using a turntable, for example, the pallet orientation will not change, because you are rotating the pallet 90 degrees, then continuing to convey it," Labell says.
Transfer cars. Companies use transfer cars to consolidate multiple pickup or dropoff locations—such as palletizing lines—into one or two in-feed lines to an AS/RS. A small computer, called the Programmable Logic Controller (PLC), controls all the machinery. The PLC can be easily programmed to respond to conditions detected by sensing devices such as photoeyes and proximity sensors.
RFID. RFID can be implemented at the pallet level, case level, or unit level. The medium to long-term trend is to have RFID tags at the unit level, so every item a consumer purchases can be tracked. This is still fairly cost prohibitive, but most industry experts agree that unit-level RFID tagging will continue to grow.
RFID readers can be easily integrated into any AS/RS to identify pallets and the product on a pallet. This data can be used later as the product moves through the rest of the supply chain.
"RFID is another way to identify a product without having visual reference to it," Labell notes.
Pallets. Plastic pallets continue to grow in popularity. As they become more automation friendly, they are easier to move on conveyers. Though more expensive to purchase than wooden pallets, when used in a captive system, plastic pallets hold up more effectively and cut costs in the long run. Plastic pallets are also used often in food applications where cleanliness is an important issue.
Reducing cost and product processing time is the goal of an automated warehouse. But how does Westfalia measure the effectiveness of its tools and technologies?
"We have a justification analysis tool that determines the internal rate of return and net present value," explains Labell. "It is important to use discounted cash flow techniques to analyze projects that have a life of 20 years or more. Most companies never go back to a conventional warehouse once they own and operate an automated one that works correctly.
"Unfortunately some automated warehouse systems do not have the necessary quality to handle the work cycles they are burdened with," Labell adds. "Companies tend to view these systems negatively when they create problems."
Because there are serious quality differences between AS/RS systems, it is critical to buy the highest-quality system, recommends Labell.
"Our Storage/Retrieval Machines (S/RM) are often the most important piece of equipment in the plant because if they fail, the customer is not able to ship product," he says. "This is particularly true of warehouse automation systems that have only one S/RM, which is the case for approximately 20 percent of our customers."
Westfalia offers many automation tools and techniques to help warehouses achieve reductions in cost and processing time. For warehouse automation to be most effective, tools and technologies such as Westfalia's must be coupled with efficient use of integrated information and a well-trained, capable warehouse staff.