Other Voices: Slotting…Fighting for Position

Proper slotting can increase the efficiency of your warehouse

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Editor’s Note: The following column by Peter L. Zurowski Jr., application consultant, Bastian Solutions, is part of Modern’s Other Voices column. The series, published on Wednesdays, features ideas, opinions and insights from end users, analysts, systems integraters and OEMs. Click on the link (/article/how_to_submit_a_column_to_other_voices) to learn about submitting a column for consideration.

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In the material handling world, there are some pretty obvious warehousing techniques: warehouse management system (WMS) implementation, conveyor/system upgrades or even through building expansions. But there are also some great techniques which we often glaze over but that can give our processes a significant boost with minimal cost.

One technique is proper slotting, or the positioning of SKUs within your warehouse.  Many of you probably understand that slotting is important and possibly have had your distribution center or warehouse initially slotted.  However, there are some questions that you should be asking to ensure you are properly positioning products.

1. What are the true benefits to proper slotting?
2. Can simple spreadsheet models handle my warehousing needs?
3. What do I consider when slotting?  (SKU-type, velocity, etc.)
4. How often should I re-slot?
5. Should I outsource this process?
6. And many others…

To fully understand what proper slotting can do for you, let’s see if we can briefly look at some of the benefits.

Why Slot?

Depending on your picking methodology, your warehouse employees can spend upwards of 60% of their time walking to and from picking mediums.  This is why we often see the highest pick rates found in technologies where product comes to the operator, such as goods-to-person solutions that alleviate the need to walk.  If we can minimize the time given to this non-value added process, we find tremendous increases in rates and through-put.

Proper slotting allows for:

• Increased picking efficiencies
• Labor reductions through increased productivity
• Lowered storage footprint
• Decreased operating costs
• Higher on-time and more accurate shipping
• Better customer service

There are a number of slotting packages on the market, and you need to be careful when selecting one or even creating one simply through a spreadsheet.
Often times, spreadsheets only consider the product’s movement (rate); in other words, if the SKU is an A, B or C mover.  A-class movers are the most popular items while C-class movers are the slowest (“dogs”).  If you merely look at velocity, then other pertinent information could go unnoticed, such as product families.  For example, if your highest mover is a cell phone, then more than likely you would sell an additional charger, holster or protector case.  Those extra items could all be B-class movers but would be coupled with the cell phone (A-class) for ease in picking.
Other slotting considerations include:

• Slotting by size (to maximize cube)
• Balancing picking zones by spreading SKU mover class types over picking operators
• Slotting to shelf level (A-class movers on the middle shelves for ergonomic purposes)
• Etc.

Where spreadsheets fall apart, software picks up.

The market has some very powerful slotting packages that allow for rules to be put in place that use those scenarios as constraints.  Typically, the software quickly computes multiple iterations to solve for a best case scenario.  You want to be sure that you can find a package that:

1. Allows you to import your product data easily.  Data would contain not only SKU velocity, but dimensions, product family types, storing medium, full case versus split case modules and pallet information to name a few.
2. Data can be easily extrapolated.  Most slotting tools will have the ability to export to Excel or print summaries.  Some have the ability to use AutoCAD system files to show heat maps of your system for an additional level of understanding. 

3. Storage types can be easily defined.  As a user, you will need to have the ability to add pick modules, bays, levels, location heights/widths/lengths, pallet storage, or flow racking to name a few.

4. Interprets order information.  The software should analyze orders to better understand your SKU profiles.

Finally, a question that we are often asked is, “How often should a warehouse re-slot?”  This could be a loaded question, as every situation is truly unique.  Although, we find that centers which look at slotting at least every six months maintain significant gains.

Also, if you have a slotting tool readily available, you could take advantage of dynamic slotting.  Dynamic slotting, often tied into your WMS, allows for continual re-slotting as trends change over time.
What are some of the slotting techniques you’ve used in the past?  What works best for your facility? Let us know.

About the Author

Bob Trebilcock
Bob Trebilcock, editorial director, has covered materials handling, technology, logistics and supply chain topics for nearly 30 years. In addition to Supply Chain Management Review, he is also Executive Editor of Modern Materials Handling. A graduate of Bowling Green State University, Trebilcock lives in Keene, NH. He can be reached at 603-357-0484.

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