Space Use in Carton Flow Rack

June 1, 2004
Recently, in two different conversations, I was asked to talk about how to optimize the use of carton flow rack, conventional flow rack installations

Recently, in two different conversations, I was asked to talk about how to optimize the use of carton flow rack, conventional flow rack installations for repack picking. I discussed this topic in a column a few months ago, and in reviewing it I noticed some additional points that you might find helpful. In these recent situations, the primary issue was that the number of SKUs continued to increase but the companies did not have the building space or money to invest in more rack. They needed more SKU facings. When a subject comes up frequently, I have found there are often many more people who are experiencing the same issue at this time. And, of course, this is a situation where there is not one simple solution, but rather many small changes that can all help. So here are a few items I suggest you implement, whether you need the space now or not.

SKUs in flow rack – Some years ago, some flow rack manufacturers published guidelines for the use of flow rack. One of the key guidelines was that, because flow rack is the most expensive static storage medium per cubic foot of merchandise, it should be used for SKUs that have the highest number of picks per day. So regularly reviewing the activity of the SKUs in flow rack to move the slow movers to shelving will help keep only the highest-activity items there and provide some available space as new items arrive. This is an important housekeeping task that is often overlooked until it becomes a major project. Another criteria that sometimes gets lost in the design of picking areas is that for any pick position, the unit of measure for stocking the location should be higher than the unit of measure being picked, i.e., pallet in/case out, or case in/piece out.

Vertical opening between shelves – There are two changes we have used to optimize the opening height on each shelf.

Like pallet rack, installers often place all the shelf decks in flow rack in a nice, neat and consistent height along a rack row, because they do not have instructions to do it differently and because it looks good that way. Yet we know that all box heights are not the same. So when SKUs are assigned to rack sections and cartons are placed on the shelves, there often are some cartons with very little space between their tops and the shelving above, while for other cartons the space is far more than needed. So, the first step to increasing the number of SKUs in flow rack is to group SKUs on a shelf with similar carton heights. I have found that this process can create space for an additional empty shelf within a section, without having the top shelf too high for the picker to reach.

A second step is to re-evaluate the method you use to open the cartons. I have found that in many warehouses the cartons in the flow rack have their flaps standing up in the air, filling the space between the carton and the next shelf. In these situations, the flaps are not only using valuable space, but they also scrape and sometimes cut the skin on the forearm of the pickers as they reach for the merchandise. You have two options here. Most warehouse workers can learn to cut the tops off cartons without damaging the merchandise, and this is the process I suggest. If you choose this method, I recommend that the stockperson do the cutting and that the cut-off carton top be replaced on the merchandise until the carton has moved to the forward position and is being picked. All warehouses are dusty environments and regardless of the speed of movement through the flow rack system, merchandise in an open carton will get dusty. The carton tops are much more effective at keeping the merchandise clean than wiping it off before shipping it to the customer.

An alternative where there is a strong resistance to cutting the tops off cartons is to have the stockperson open the carton in the conventional manner and fold the flaps back to there original position when placing the carton into the rack, and then when the carton moves to the front position the picker can pull the carton out, fold the flaps back over to the outside and then place a large rubber band around the carton. The result is the same and while the risk to the merchandise is eliminated, the picker now has another task that occasionally can be difficult. But the result is the same for space use. The flaps no longer require significant vertical space, or get in the way or scrape the pickers’ forearms as they reach into the cartons.

Long side or short side facing – Another way we have increased space use in flow rack was started with another of the guidelines provided by the vendors. We specified flow rack for repack picking to hold approximately 1-week demand per SKU lane. We then started by determining the average weekly demand for the SKUs we were going to assign to flow rack and converted that amount to a number of cartons. The next step was to determine how many cartons will fit in a lane for each SKU with the long side facing the picker or with the short side facing the picker. Often orienting the cartons with short side facing down still provides an adequate inventory level for the SKU, and I have seen instances where we created an additional SKU per shelf after the adjustments.

These are just a few ideas that you can implement to get the most out of your current investment. I encourage you to begin the process now rather than wait until Purchasing has a new surprise for you.

Don Benson, P.E., has been consulting to retail, wholesale and manufacturing organizations for more than 25 years. His practice focuses on improving the effectiveness of warehouse and distribution operations. His office is in Oakland, California. He can be reached at [email protected] or 510-482-3436.

Other articles in this series:

Improving Distribution Operations

Evaluating Vendor Shipping Performance

Improving Labor Productivity

Picking Document Design

Implement Cycle Counting

Inventory Storage

Planning Daily Operations

Another Way To Think About Change