No matter what type of steel they’re made of, the functionality of a rack is based on the type of storage system employed. There are several different options, and most of the major rack manufacturers provide their own versions of all of them. Three of the most well-known are selective, drive-in and push-back.
A selective rack system can effectively get the job done in most foodservice distribution centers. The system operates by storing one pallet per position at a time. When an order is submitted, workers drive down the aisles with a pallet jack and place the items from the order list onto the pallet. Once all of the items ordered are picked, the pallet is dropped off at the back door and awaits shipment to the customer.
These racking systems are generally lower-priced, but they make it difficult to achieve optimal product density. A poorly designed selective racking system may leave 30 to 50 percent of your storage positions empty, according to Frazier’s Oliver.
Drive-in racking systems are among the least used in grocery distribution centers; however, they do have a place in the market. One advantage to drive-in racking systems is that it allows for greater storage density than the selective rack system.
When using this model, all pallets from floor to ceiling and front to back must be the same SKU. This is because of the replenishment process, which requires lift trucks to work from the outside in. The entire row must be empty before replenishment can occur.
The most efficient racking system for grocery distribution, agrees Oliver and Flemings, is the push-back or glide-in racking system.
The rack itself sits atop a platform with wheels. The floor has railroad-like tracks embedded in it, so the racks can be pushed close to one another and eliminate the aisles between them.
“The advantages are incredible,” says Flemings. “The storage density, especially in frozen applications, is very important. For example, green beans are only grown in the summer and once harvested, they are immediately flash frozen and sent to a warehouse for storage. You can use the mobile racking system to close up the aisles where they’re stored and sell them off from October until mid next summer without having to take up large amounts of space.”
Oliver says this method of racking is the most expensive of the three, but when you’re paying by the square foot, or for each cubic foot of frozen or air conditioned air, it quickly becomes apparent how paying a premium for added storage density can pay off in the long run.
Storage is an integral part of a distribution center’s success, but it’s not the only factor that can lead to increased throughput. Utilizing automatic storage retrieval systems, or AS/RS racking, can also improve operations and productivity immensely.
In the mid-1970s the distribution industry was introduced to a new type of racking systems: AS/RS. The system uses automated cranes that run along a railroad track in the middle of the aisles and precisely picks items to place onto a pallet. The crane arm can extend out to either side of the aisle to pick up or retrieve a pallet.
Oliver says Frazier’s AS/RS was popular into the 1980s, but demand softened for awhile as conventional racking systems began to reach higher heights. Although the concept has changed little over the years, the AS/RS market has recently made a comeback across warehouses worldwide.
One advantage to using such a system is the ability to reduce your workforce and the overhead costs associated with it such as wages, employee benefits and workers’ comp claims.
“Because of the price of labor and unionization and the dialogue in the federal government with respect to healthcare, more and more companies are going to turn to automation to maintain high productivity at low costs,” says Oliver.
In addition to labor savings, using an AS/RS eliminates shrink, human error and the risk of forklift collision, while enabling more accurate inventory control.
“The capital investment for an AS/RS racking system is significant,” adds Steel King’s Larson. “The costs can be in the millions, but it’s a controlled cost that will eliminate future overhead costs,” he says.
According to Flemings, there is a specific threshold where once reached, a company should seriously consider utilizing an AS/RS.