Design Your Best Picking Layout
Balancing the costs of space/equipment,
replenishment and picker time.
Every order picking operation represents a unique company
solution to the question, "How can we best pick our orders to minimize costs and
enhance shipping times?" This article will concentrate on how to tailor your
equipment, space, replenishment needs and pick areas to exactly fit YOUR operational
needs, YOUR unique product line, and YOUR order patterns and volumes.
Obtain the data on your daily and weekly order volumes,
product movement, and product cube. If this data is not available from your order
processing system, you can physically measure key product sizes, and estimate movement for
all key product groups. THIS IS THE SINGLE MOST IMPORTANT STEP IN A FACILITY REDESIGN.
With these numbers, you will be able to calculate the very best solution to the question
of "How best?"
STEP II - USE A COST CALCULATION SPREADSHEET
SPECIAL NOTE: You may request a copy of the Excel
spreadsheet that I have developed to calculate the ideal equipment/personnel mix for
operation. Use my Email listed on this site, and a free copy will be forwarded by Email.
- To understand how and why a specific pick layout should be
chosen, we must look at the TOTALS of the costs of space, equipment, replenishment and
- Calculate the cubic feet per pick to find the size of a
piece (or pack or case), and multiply this number by the number of pieces in the average
pick of this item. NOTE: The greater the cube of a pick, the more often it will have to be
replenished into any given pick slot.
- Determine the average numbers of times per day that a
picker physically passes an individual pick slot to pick an order. This number is
extremely important - (also, calculate that the larger the pick slot, the more walking
will be required, and this increases picking time.) This number need not be the same as
the number of orders picked in the whole facility. (In a future article, we will discuss
several strategies for GREATLY reducing the need to pass every pick slot with every
- Find the average number of picks per item per day.
- Multiply the cubic feet per pick by this number and you
have the cube per item per day, giving you a measure of the replenishment required.
- Finally, how many SKUs are in the slot where an individual
item is located?
Now, you are ready to provide the weighting factors for
determining your ideal layout.
INSERT - the spreadsheet
THE COST CALCULATION.
You will note that for every combination of storage
device, product cube, movement and number of orders/day, a total cost calculation is
listed on the spreadsheet. This cost is for one item for the entire year and includes the
equipment amortization , space rental, replenishments, and pick walks past the slot. It
must be emphasized that these numbers are approximate BUT also representative of the real
world operations for which they were developed.
THE SHADED AREAS DENOTE THE LOWEST COST STORAGE OPTION FOR
A PARTICULAR CUBE MOVEMENT OF AN INDIVIDUAL PRODUCT WITH A GIVEN NUMBER OF PICK TRIPS PAST
- Larger picks work better in pallet slots, due to the need
for fewer replenishments.
- Smaller items cost less to store in shelving.
- Flow rack does well with averaged size items with many pick
trips past the slots.
- Pallet rack slots do well when then there are few pick
trips required and the space is available.
IMPORTANT NOTE: Anytime that you have a varying
range of product cube and movement, you will save money by also using a matching range of
storage racks and shelving.
IMPORTANT NOTE #2: Design your layout for expected demand
TWO YEARS FROM NOW! Redoing your layout is expensive (and easily postponed). Too many
companies are picking from slots that are too small and/or nearly empty. If you need more
space or a mezzanine for additional pick area, get it NOW. It will be much less expensive
in the long run.
FINAL NOTE ON PICKER TRAVEL TIME.
Orders/day is a measure of actual pick trips past a pick
slot. There are several ways to reduce this number.
- Place all slow moving items in pick areas near (but not
on), the main high mover pick aisles. Pickers will only need to go into these slow mover
areas when they actually require a specific item. Also, this way, larger pick slots may be
used, which will require less replenishment.
- Place all products that are often picked together on the
same order, into a specific picking zone or department. Pickers will go into these
departments only when required, and make as many picks in this department as possible.
- If you use pick conveyor, be sure that it diverts into
departments ONLY when it is needed, and then make as many picks in that department as
possible (see our next article on batch picking).
REAL WORLD EXAMPLES OF PICK AREA DESIGN.
EXAMPLE I: CATALOG DISTRIBUTOR OF DENTAL SUPPLIES
Walk times past orders was reduced by picking the slow and
medium moving items into a tote on the conveyor from the far end of the pick aisles. If an
aisle had no picks, it was bypassed. Medium movers were picked more frequently than slow
movers, so they were located closer to the conveyor, minimizing walk time. The average
slow mover was passed only 50 times a day versus 150 times per day in the previous layout.
Since almost all orders have at least SOME high movers, they are passed 1000 times per
day, and placed the closest to the conveyor at the end of the aisle.
As an aside, this facility has a serious jam-up at the end
of the pick line almost every night. This jam has made it difficult to ship orders on
time. The cause? - the need for 100% checking of every order, dropped haphazardly into
cartons in the totes on the conveyor. If the orders had been batch picked, for instance16
at a time into shipping cartons, scanning or check keying every pick, this expensive and
delay-causing check/repack operation could be ELIMINATED, saving at least, $150,000
annually, based on their current number of orders per day.
EXAMPLE II: DISTRIBUTOR OF PRINTER SUPPLIES
This operation was a good example of utilizing a conveyor
with a divert ability, to bypass pick zones without picks in the order being processed.
The order is started in a carton with an order ID label on its side. The divert system
insures that the carton goes into all zones with designated picks. When all picks are
completed, the carton is checked with an inline scale to insure that all picks were made
(in addition to scanning each item as it was placed into the carton).
On the flip side, using short lengths of flow rack for
high moving items and shelving for medium and slow movers, has meant that replenishment is
a major problem, especially for larger and higher moving items such as laser printer
cartridges. Since ample space was available in this facility, I recommended that full and
1/3 pallet rack slots should be used to a much greater extent than currently practiced.
Another issue with this system was the presence of a few
extremely high moving items that appeared in 50% of all orders. If all of these high
moving items had been put into one divert zone, orders would soon begin to back up on the
conveyor. If placed into many zones, too much time in the system would be required to
process these orders. The solution was simple - duplicate-slot these high volume items
into several pick zones, always near the conveyor. When an order was diverted into that
zone, the high movers were also picked in that zone. An extra benefit of this solution was
that these high movers would require much less frequent replenishment secondary to their
multiple slot placements
EXAMPLE III. EYEGLASS FRAME DISTRIBUTOR.
Eyeglass frames are small, but expensive. This was an
ideal situation for batch picking from shelving. All the inventory for each item is kept
in the pick slot or in the overhead shelving slot. Batches of 15 (or more) orders are
picked in one picker trip with scanning of bar codes, verifying each item and package 100%
of the time. Shipping labels and packing lists are printed before picking and guide the
choice of the correct carton size based on numbers and previously calculated cube.
NOTE: In this case, the use of batch picking coupled with
the small size of each shelf facing reduces pick trips to the point where pick travel is
no longer a significant cost factor.
EXAMPLE IV: COSMETICS DISTRIBUTOR.
This unusual "paced" picking system is included
in this discussion because it highlights a situation where a fully flow-racked picking
system, coupled with a daily "micro adjustment" and a "pick- to-light"
computerized picking system, could be appropriate
Orders are cubed by the computer, cartons are labeled and
placed together on the start side of the conveyor. Pickers work on both sides of the
conveyor, picking directly into the shipping carton as directed by the system. If an order
is in danger of moving out of a picker's zone before all picks are completed, the conveyor
will stop until the pick-to-light system notifies the conveyor that the order is
The "micro-adjustment" mentioned earlier
balances the sequence in which orders are picked to keep each picker's workload as equal
as possible. The location of any given item is also changed as directed by this system.
Significantly, these orders have been placed by sales representatives and concentrate many
small cosmetic orders into fewer and larger distributor orders.
This final example shows quite dramatically how a system
can be tailored to a company's highly individual demand pattern. This is the perfect
picking solution for this unique fulfillment operation.
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Some Recent Testimonials
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you are very welcome for the references. You may not know
this but we RAVE about the suggestions you made to us for
our "Distribution Center", and how right your
suggestions were…" Dan G.,
Pres., Pipersville, PA.
forward to having you involved for our DC implementation plan
and in future endeavors as well. Your input was extremely
valuable to us".
Brent T., President Jacksonville, FL
is incredibly difficult - I would never have been able
to do this without all your great help"! Dave W.,
Owner, Chicago, IL.
I wanted to say that all your suggestions work great! Thanks so much.
Secondly, in the later part of May, we will be moving out of our current
facility into a new one. I was wondering if I gave you the layout could
you draw up a design. You told me if there were ever changes, just ask for
a new layout, so here I am. Thanks a lot!" Bob V., Owner, New Kensington, PA
know it has been a while, but we finally signed on a new
building, and are looking at a mid July move. We have three
dock highs, and two roll ups. Please do your magic and lay out
the floor space. Thanks." Rami R.,
Owner, Chatsworth, CA
renovation is going great. The large shelving is all moved and
the small shelving is about 75% in its new location. A company
is coming in Tuesday to build the new shelving...then we can
start to relocate all the product. Thanks for all the help."
Jeff L., Operations Manager, Victoria, BC, Canada.
received the final report, thanks for the summary of findings
and the recommendations. What was most valuable for us was
the process of getting to the goal and the discussions around
it… Thanks again for your help…Joachim
S., Systems Manager, New York, NY
proud to say that our first day of production in our new
location was March 6. Thank you for your work on our
behalf. Looks like we got off to a fine start in the warehouse
and picking areas. It's always a pleasure hearing from you."
Charlie T., Project Manager, Amityville, NY