One giant leap for cold storage

Dairy Foods, Feb, 1992

"The processing and packaging operations at our Landover, Md., dairy plant were state-of-the-art," Dave Larson, Giant Food vice president of manufacturing, told Dairy Foods' Plant Operations Editor Jack Mans during a recent visit to the facility. "But our cold storage system was antiquated."

To correct the situation, Giant signed a $7.4-million contract with Advanced Warehouse Automation Inc. (AWA) of Helsinki, Finland, and Cannon Equipment Co., Cannon Falls, Minn., in December 1989 for an automated cold storage system. The system includes automated storage and retrieval cranes, high-rise storage racks and computer controls from AWA, as well as cart and dolly equipment, conveyors and other material handling components from Cannon. Installation began in March 1991, and the system became operational this past December.

"The total cost of the project was about $15 million," says Larson, "including a 15,000-square-foot building addition and renovation of the existing cooler. We estimate it will have a five-year payback."

The new system offers numerous benefits:

* Continuous, accurate, up-to-date inventory control;

* Balanced rotation of product in storage (so there is no accumulation of aging product);

* Improved product protection during storage and handling;

* Efficient space utilization (the full height of the cooler is used);

* Reduced operating costs;

* Automated handling (which minimizes worker exposure to difficult working conditions);

* Reduced delivery errors; and

* More efficient distribution.

Computer controls the operation

Giant Food's automated cold storage system handles product on carts and dollies interchangeably. The system has an operating rate of 60,000 cases on dollies and 1,800 carts per 16 hours, for a total storage capacity of 330,000 gallons. Two computers operate simultaneously to provide redundant memory and control in case one should malfunction. The facility also has a standby 500 KVA generator and an automatic power supply that will come on stream if there is ever a power outage.

The computer accounts for products in four categories: cartloads, dolly loads, caseloads and individual items. However, only cartloads and dolly loads enter the system initially. Caseloads are broken down from fully loaded dollies inside the system at a rate of 1,300 cases per hour.

Bottles are delivered from production to the cooler at rates of up to 24,000 gallons per hour. Automatic cart loaders place 80 gallons or 180 half-gallons on five wire shelves on the carts. Automatic casers pack fractional containers and byproducts in standard dairy cases. These cases are stacked five high by automatic stackers. Automatic dolly loaders place the four stacks (20 cases) on each dolly. The system also includes a dolly/case stack unloader for empty units, and dolly washers.

As fully loaded carts and dollies enter the cold storage system on infeed conveyors, an operator enters their contents into the computer. From this point onward, the computer tracks the quantity, date code and location of each item.

Flow-thru channels

The computer assigns each cart and dolly to one of the 14 sorting buffer channels on the lowest level. The infeed crane then transfers them to computer-assigned channels in the upper two tiers of the "flow-thru" storage racks. Up to eight carts or dollies can be carried on the crane at one time and placed in appropriate channels.

Product is accumulated in the flow-thru channels on the two upper levels of the storage racks. The channels run the entire length of the three-tier system. The fully loaded carts and dollies enter the racks on the one side and exit on the other side. In any channel, there is normally only one product of a single date code stored at any given time.

To unload product, the automated retrieval crane receives its picking quantities and product locations from the computer. Carts and dollies removed from the racks are placed on an output conveyor system that transports them to a lateral transfer cart. This places the carts and dollies into shipping channels that accumulate product for each truck load.

An accumulating channel in each of the two upper levels of the storage racks oppose one another and operate independently of the flow-thru storage channels. The accumulating channels are used to replenish product in the manual order picking channels on the lowest level, or for reassigning product in storage. One set of channels has a reverse orientation, with product moving from the retrieval side back to the infeed side. The opposing channel feeds product in the same direction as the flow-thru channels.

While product can be accumulated in these channels the carts and dollies are indexed in a different fashion than those in the flow-thru storage channels. Here, a set of three ratchet assemblies operates independently of the infeed and retrieval cranes. A single cart or dolly can be indexed through an accumulating channel without the push and pull of the infeed and retrieval cranes.