Slotting the forward-pick area of a warehouse
A fast-pick or forward pick area is one from
which it is most efficient to pick, but which must be restocked
from a reserve or overflow or bulk storage area. Here are some
examples of forward pick areas:
- Carton flow rack that is restocked from bulk storage
- The ground floor of pallet rack that is restocked by moving
pallets down from higher levels
- Carousels, A-frames, or any other specialized equipment
that must be replenished from elsewhere in the warehouse
The following schematic shows the flow of material through and
the economics of a forward-pick area.
The forward-pick area is the most important real estate in a
warehouse because it is the most convenient from which to pick.
Moreover, it may represent considerable capital investment for
special equipment. How large should it be? What should be stored
there? In what amounts?
To get maximum value from a forward area, one must stock it
with the right skus. These are not simply the most popular,
because volume-ordered matters as well. A sku that is ordered in
larger volumes will have to be restocked more frequently than a
sku that is of identical popularity but ordered in smaller
volumes. To minimize labor costs we must account for
both picking and restocking.
Almost all warehouses store product in the forward pick area
according to one of two philosophies:
- Give each sku the same amount of space; or
- Store the same time supply of each sku (for example, store
3-weeks supply of each sku)
You may be surprised to learn that these are equivalent in
that they require the same total work (restocks) to maintain the
foward pick area—furthermore, you can do better, sometimes
Our book shows how to minimize total labor (picking
plus restocking) by careful choice of what to store in the
forward-pick area and in what quantities. Furthermore, these
models have been realized in software that you can run from their
respective web pages.
There are three programs: One is specifically for storing
pallets and other unit-loads (which require a different model of
labor). The other two are for storing less-than-pallet
- To slot pallets
- Use this to optimally slot skus into the ground floor of
pallet rack or into pallet flow rack. This program is
specifically for pallet or other unit-load storage.
- To slot cartons and/or pieces
- Use this to slot skus into carton flow rack or bins or
shelving. This program will handle only a single forward-pick
area but it accounts for all detail, including the geometries
of storage containers and shelves. It will determine the best
shelf heights and will show exactly where every carton should
be placed: in what orientation, how many lanes, and high they
should be stacked.
- To allocate SKUs among multiple types of storage
- Use this to decide which skus should be picked from flow
rack, which from carousels, from shelving, bulk storage, etc.
This program is most appropriate for high-level design: It
tells from which storage mode each sku should be picked. (but
it does not tell exactly how to arrange the shelves because it
has no model of geometry).
What sets these programs apart
- The programs are provided as services over the internet and so
you always have the latest version, and with no need to worry
- Your data stays on your machine. The computational engines
come to you.
- The slotting is computed by mathematical optimization
rather than simplistic rules. Furthermore, the mathematical models
and optimization technologies are fully documented in our book.
- The programs are fast: Once you have the data, they will
compute optimal slotting strategies within seconds, even for
tens of thousands of skus. This enables you to quickly evaluate
- After running the programs, the economics of each decision
are fully auditable, so that you can understand exactly why the
optimization engine made the choices it did. No mysteries.
- You may use these programs freely, but
please note that the user assumes all responsibility. See the
accompanying license and disclaimers
When to use the programs
These programs will be essential if you are reorganizing your
warehouse or part of it or if you are buying new storage
equipment. They can also suggest incremental adjustments that you
can use as regular maintenance.
How to use the programs
You start each program by clicking on a button on its web page
(but the program runs on your computer and your data remain on
The basic steps of use appear as numbered tabs in each program
and are as follows.
- Load a table of sku descriptions.
- Describe the labor economics (estimated costs of picking,
- Start the optimization.
- Examine summary statistics.
- Examine and save the detailed results.
The most time-consuming part of using these programs is getting the required data.