This is material to supplement Warehouse & Distribution
Science, a textbook and a graduate course taught at the Georgia
Institute of Technology by John J. BARTHOLDI, III and Steven
T. HACKMAN. Everyone is welcome to use the book and materials here for
educational purposes, so long as the copyrights remain intact. You
will find more information and technical details on these topics
within the book.
Super Club Music
Super Club distributes recorded music to retail stores. Such physical distribution
of music is, of course, a dying enterprise, as it is being replaced by distribution
via the web.
The distribution of recorded music poses some special challenges. The most
noteworthy is the extremely skewed popularity among sku's: A very, very few
sku's will be very, very popular and most sku's will scarcely sell at all.
In fact, it is not unusual for 20 percent of the sku's to sell one or fewer
copies over a year.
Another challenge is that popularity is very fleeting. For example, there may be a
huge surge in popularity of a sku, perhaps because the band is currently touring
or because of an unexpected hit record (such as "The Ketchup Song" in
Europe recently). Thus, what is a popular product now may be dead in two weeks.
The market for so-called "urban music" (rap, hip-hop) is especially
volatile.
A third challenge is that there are a large number of returns in the music business.
By some estimates up to 25 percent of all recorded music is returned unsold to
the distributor. The distributor may then either send it out to another retail
store where it may be selling better, or else return it to the publisher for
destruction. All this represents double-handling. And by the time product has
been returned and re-distributed, it may be past its peak in popularity.
There is one way in which the physical distribution of recorded music is
unusually simple: The physical uniformity of the product -- all CD's are
the same physical size and most cartons are about the same size -- makes
it easy to configure storage so that it can be packed tightly to get full
use of the space.
Some interesting facts about the music business:
- There are only six major labels and no competition among them because
artists sign with the label.
- Significant new releases are generally shipped directly from the publisher
to the stores, bypassing the distribution center. Some new product is shipped
to the distribution center so it can replenish stock at stores.
- Musical tastes remain very regional. What is popular in Atlanta may look
very different from what is popular in Detroit or Los Angeles.
- Some busy times are predictable but irregular. For example, if a big name
band is touring, sales of their CD's will increase. Some busy times are not
predictable, as when sales of a popular artist increase following their death.
Some busy times are predictable and regular: The busiest recurring season in
the US is the two weeks following Christmas, when people who have received CD
players as gifts then buy CD's to play. People shopping at this time mostly
buy collections of greatest hits.
- One theory holds that cars determine the medium of distribution in
the music business! According to this line of thought, vinyl did not die
until cassette players were common in cars. Similarly, cassette is almost dead
now that cars increasingly have CD players. Will CD die because cars get MP3
players?
Super Club stores are divided in to routes and each route is visited by a delivery
truck once a week on a regular day. Each day they pick for about 8 routes, which
total about 100 stores. On average each store orders about 50 sku's and about 3
of each sku, for a total of about 15,000 pieces per day. The warehouse knows these
orders a day in advance of picking and so can plan its work in advance.
The Super Club distribution center is about 88,000 square feet (8,175 square meters)
in floor area. This is augmented slightly by a mezzanine area so that there are two
flow rack areas, one stacked atop the other.
Click on any image to enlarge it.
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Product arrives from the publisher as pallets or partial pallets.
Each pallet is stacked with cartons of CD's or, ever less frequently,
cassettes. The CD's are packed either 25 or 30 to a carton, depending
on publisher.
The bulk of the product is kept in pallet-rack, from which it is moved,
in response to demand, to either shelving (for less popular sku's)
or else flow rack (for more popular sku's).
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Most of the warehouse floor space is occupied by static-shelving, from
which about 13,000 different labels (sku's) are picked. This represents
about 90 percent of all sku's but only about 35 percent of all picks.
Order pickers push carts through the aisles, much like shoppers at a grocery
store. Since these are the less popular sku's, there is a lot of walking per
pick.
The top of the shelves are used to store "overstock" so that the
shelves can be restocked without having to travel all the way to the pallet rack
(visible at the far left).
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Here is a closer view of a typical shelf. Notice that the physical uniformity
of the sku's makes it easy to configure the shelf heights to reduce unused
vertical space (the space between the top of the product and the bottom of the
shelf above). But why is there so much empty (horizontal) space? What is the
effect on the efficiency of order-picking?
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The 48 bays of flow rack contain only about 10 percent of the sku's but
these account for about 65 percent of the picking. You can see as many
workers in this area than in all of the static-shelving area. Instead of
pushing shopping carts the pickers are operating like an assembly line,
where the products to be assembled are the customer orders.
Of the 1,000 sku's in flow rack, about 600 are steady sellers (Tony Bennett, the
Rolling Stones, Aretha Franklin, etc.) and 400 are current fast-movers.
The middle conveyor is powered and takes the completed cartons away to shipping.
On either side of the powered conveyor are passive rollers that make it easy to push
work-in-process along the assembly line.
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Here you can see completed and sealed cartons riding the powered conveyor to
shipping and open cartons (work-in-process) on the passive conveyor.
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Notice that there is no empty space on the pick face of flow rack. Why?
How does this affect picking efficiency?
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Copyright © John J. BARTHOLDI,
III. All Rights Reserved. This is material to supplement the textbook Warehouse &
Distribution Science.
Last revised: 12 Feb 2015