4 Ways To Take The Pain Out Of Warehouse Slotting

Ask any consumer goods warehouse or distribution operations manager how they feel about inventory slotting, and chances are you’ll get a groan, grimace, or heavy sigh in response. That’s because — while the labor efficiency and picking productivity benefits of warehouse slotting are widely understood — the amount of work it requires, particularly in a conventional facility, can be overwhelming.

What is Warehouse Slotting?

The inventory slotting process includes continuously assessing and classifying each stock keeping unit (SKU) in existing inventory based on order and pick frequency. 

Depending on its velocity, each SKU is deemed a fast, medium, or slow (A, B, or C, respectively) mover. Then, each is assigned to a specific location within the facility depending on how often it is picked. 

• Fast (A) movers go in forward pick zones, closest to packing and outbound shipping. This reduces the amount of walking associates must do in order to retrieve them and fill orders. Replenishment stock typically sits nearby in reserve storage for easy access as needed.
• Medium (B) movers, which are ordered less often than fast movers, are kept in an accessible area. They require some travel to access, but not an extensive amount.
• Slow (C) movers, or those that are rarely required to fill orders, go in the least accessible area of the facility.

What Are The Benefits of Inventory Slotting?

In addition to helping place inventory by the rate at which it moves through an operation, slotting can also direct the placement of an item to improve picking ergonomics. That results from putting the fastest moving or the heaviest items at the most ergonomically accessible level (typically waist high to minimize frequent bending or reaching). 

Slotting can also ensure placement of items commonly ordered together (toothbrushes and toothpaste, for example) in close proximity to each other. Additionally, inventory slotting can disperse the most popular products across multiple picking zones. This minimizes congestion as pickers fill orders.

And yet, despite the advantages, warehouse slotting still requires effort. Both the process of determining how to redistribute products and the actual act of moving them around take time and manpower.

For many operations managers, it’s a daunting thought to add an internal housekeeping task to the herculean effort it takes just to move stuff out the door. This particularly true for those who struggle to keep up with increasing supply chain disruptions. Not to mention volatile consumer demands, rapidly shifting SKU velocities, labor shortages, rising wages, and more.

However, those market challenges are further complicated by the current lack of available warehouse space as capacity shortages continue. With square footage at a premium and a limited workforce, it’s become more important than ever to maximize and optimize every inch of space. Slotting provides a reliable means to that end.

Ready. Set. Slot.

Depending on the level of automation within an operation, warehouse slotting can be a challenging process. Here are a few ways to take out some of that pain:

1. Invest in warehouse slotting software. 

It is possible to determine SKU velocity on paper or with a spreadsheet for smaller facilities handling fewer items. However, larger operations with higher SKU counts will benefit from software. 

There are specific warehouse slotting software programs available to help streamline the process. Whether standalone or integrated as a module to a warehouse management system (WMS), the software first analyzes each item’s order frequency. Then, it assesses the current floor plan to determine and assign a specific location for each SKU. 

Further, software performs the slotting analysis performed automatically and continuously in real-time. This allows managers to focus on other priorities. 

2. Work slotting into picking and putaway moves. 

One of the benefits of allowing warehouse slotting software to analyze and determine the optimal location for inventory is that it can also interleave the moves among other assigned tasks. 

Whether associates carry with a paper pick list, a radio-frequency scanner or tablet, or a voice-directed picking system, the movement of a SKU from one location to another simply becomes part of their sequence of travel. That is, they re-slot inventory as they perform picks and putaways through the facility. 

3. Collect accurate SKU data. 

Having accurate inventory data is critical to this process. Operations picking eaches and cases will need to populate their inventory database with dimensional data about every item individually. 

Details include how many eaches fit into a case, the case dimensions, how many cases fit in a given storage position or on a pallet, and so on. This can be accomplished at the point of receiving with a tape measure. However, it is more efficient and accurate with an automated dimensioning system. 

Based on the information, the warehouse slotting software can more accurately pinpoint the optimal location for each SKU based on its unit size.

4. Let the automated system slot for you. 

If your operation has an automated storage and retrieval system (AS/RS), either crane- or shuttle-based, the integrated control software will interface with the WMS. Based on that information, the AS/RS determines the optimal storage location of a given SKU within the system and makes moves accordingly. 

In most operations with an AS/RS, the fastest moving items often reside outside of the system in a forward pick zone. This maximizes their pick speed. But medium movers (and sometimes slow movers) within the automation will sit closer to or further away from the retrieval mechanism’s dispensing point depending on their velocity. Either way, placement optimization requires no human intervention.

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