Sizing + Storage + Velocity = Inventory Slotting Success

The following article represents findings from a recent teleconference conducted by Steve Trommer, vice president at Trommer and Associates, an Akron, OH-based facility planning company, who described the methods used for effective slotting or profiling prasctices.

The purpose of profiling, or slotting, your inventory is more than just making sure that heavy items are not located in the back of the warehouse or on the highest shelf. It’s also meant to evaluate the size, the storage media, the mix, and the velocity of product being stored in the facility in order to maximize productivity, order accuracy, and customer service.

To ensure your slotting project will be a success, you need to understand some basic factors:

Sizing Obtaining the accurate cube and weight of each product is critical. Many companies do not maintain an accurate database that includes dimensional information and product weight. If you have this information, you are already ahead of the game. You can obtain this information manually, at receiving, by checking inbound shipments. Manual data collection is time-consuming and a risky option, as various personnel may have differing opinions on the correct dimensional requirements. The best solution is to collect data electronically using a device such as the CubiScan from Farmington, UT-based Quantronix. This device accurately collects the weight and cubic data of each item.

Storage Once you’ve acquired the cube and weight of the products, you need to determine the storage media. A detailed understanding of the number of locations available within the facility means knowing the characteristics of each type of storage medium and the physical dimension of all the storage media that will be used.

If you are dealing with pallet or flow modules you need to know the depth of the lanes and the possible combinations of width and height of the lanes in each zone. Pallet racking, decked racks, and shelving need to be defined in order to relate product cube to available storage cube. Look for the width and depth of the shelf and the number of various heights and quantities of each storage position.

When selecting storage media and types of product to be stored within, some simple rules apply. When using shelving, locate fast movers closer to the main aisle or the conveyor systems and slower items farther away or on second levels of mezzanines. Pallet flow is used for high-cube fast movers of case-pick quantities. Carton flow modules are well suited for fast- and medium-moving inner pack picks or each picks from cartons. For medium movers of high-cube product, decked racking is a good choice.

Velocity By looking at the inventory over three to six months, or ideally over a 12-month time frame, you can develop an inventory movement analysis. If your business is highly seasonal, you should evaluate the inventory based on those seasonal times of change in inventory. When the analysis is completed, determine the amount of inventory that is to be dedicated to each type of storage media within the facility. This can be broken down further based on the family groupings of the inventory. Knowing the total pieces moved in a three- , six- , or 12-month time frame, you can convert total pieces to total daily piece movement.

Spend time evaluating the movement analysis to better define family groupings and how product is ordered and picked within your facility. You may need to also review order history to better understand the movement of product through the facility. Establish the methodology of how items are stored within the facility, how many cartons and tiers are stored per pallet, how many cartons have inner packs, and how are these items processed and picked.

Product mix Your operation may require keeping like groups together, allowing for ease of picking for those items that are often sold together. Some items may need to be grouped in a particular storage area because of a kitting operation. There are many combinations of solutions for product mix and storage rules. Many times working alongside a picker for a day provides insight into how product is moved through the facility. Understand the order filling requirements of the product to reduce problems of incorrect product mixing.

Completing the task
With the daily piece movement completed, convert the movement to the number of inner pack and pallet quantities moved in a day. This will help identify the number of storage locations required. Determine the percentage of inventory to allocate to each of the storage media types. To gain efficiency from slotting the inventory, decide on the number of days of product to be held in a pick location. This will help minimize the amount of replenishments required on a day-to-day process. Once you have established the cube of the inventory, you can determine the amount of space the inventory will occupy within the storage media..

Jon Paul is the vice president of sales and marketing for Willoughby, OH-based Morrison Co., ( a distributor of material handling equipment.