Planning a Warehouse
Every warehouse has unique problems, but planning for a
new one calls for basic decisions. Going through the planning process may help
make better use of your existing space.
by Leslie Wood
Space Utilization
Before putting time
and effort into planning a
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new building, take some basic steps to increase the
space available in the current warehouse.
• Get rid of
any junk equipment that has found a home there.
• Use JIT
deliveries and shorter runs to reduce inventories.
• Use racks. There
are many types of racks. Become familiar with them and their applications
before making any decisions. They can increase storage capacity, but they are
expensive and may not gain you as much space as expected. Analyze the potential
space gained and the financial benefits.
The Layout: Inventory Analysis
Arrange the
warehouse to fit the nature of the inventory. If it will store large quantities
of few SKUs, many deep rows are needed. If the inventory will be small
quantities of many SKUs, mostly shallow rows with many faces is more practical.
A simple
spreadsheet analysis calculates how many rows of varying depths and how many
racks are needed. From this it calculates the area needed for storage and
aisles. Space for docks, offices and future expansion are not included.
The analysis is
based on a “snapshot” of current inventories, modified to include
future changes. Although individual SKUs may vary from week to week, the mix of
deep and shallow rows is surprisingly stable and one period can be very
representative. The height pallets can be stacked depends on the weight of the
product, strength of the packaging, building height, etc.
Aisles
Aisle width depends
on the type of lift trucks used. Aisles should be wide enough for trucks to
make a single turn into the row. Making them too narrow will save space but
slow down the store-and-retrieve operations and result in greater damage. Cross
aisles can reduce travel times but take up valuable space. Balance the two.
Rows
Design rows wide
enough to allow drivers to carry loads in and out without causing damage. Lift
trucks fitted with side shifters allow drivers to move loads a few inches from
side to side so they can work in narrower rows.
Docks
The number of
shipping doors needed depends on how long it takes to load and unload trailers,
the number of trailers handled, and how many shifts are worked. The dock is the
busiest and most dangerous part of the warehouse. Don’t squeeze down the
space.
Material handling
Lift trucks are the
basic means of handling pallets. They come in many shapes and flavors. There
are clamp trucks and fork trucks and push-pull trucks. There are
counterbalanced trucks, stand-up trucks, straddle trucks, swing mast trucks,
narrow aisle trucks, very narrow aisle trucks... The list goes on and on. Work
with reputable dealers. Explain your situation and let them advise you.
When they recommend
products (most often, their own), ask to visit sites with similar applications
and request demonstrations in your own facility. If things become too
confusing, hire an experienced, independent consultant to advise you.
Conveyors are a
common means of delivering cases of product from manufacturing to the warehouse.
They are expensive to install and maintain but can be less costly to operate
than drivers on lift trucks. Whether or not a conveyor system is justifiable
depends on the amount of material, the composition of the inventory and the
distance that the products have to be moved.
Automatic guided
vehicles (AGVs) are an alternative to conveyors. They are most economical when
hauling product over long distances.
Software
Over the last 10
years, there has been an explosion of software available for managing
warehouses. Designers promise it will reduce inventories and labor costs while
improving customer service, inventory accuracy and storage capacity. What they
may not say is that it can take over your operation, tying up a quarter of your
workforce to satisfy its demands for more and more information.
You do need a means
of tracking your inventory and the software that fits your needs can bring most
of the promised savings, but beware of bells and whistles that sound good. They
can become a cacophony when you try to implement them.
Picking
Orderpicking is the
most labor-intensive operation in the warehouse. The objective is to get the
correct product to the customer in the shortest time while maintaining high
productivity.
Whether you are
picking individual parts from cases, picking cases from a pallet or picking
full pallets, specialized equipment is available. Again, work with suppliers,
study the options and ask to see demonstrations.
Whatever the type
of picking, making the most frequently picked SKUs the most accessible will reduce
picking times.
There are many more
decisions that will confront you than we could cover in this article: where is
the best location; should you lease or buy; do you need a central distribution
center; etc. Do not become overwhelmed. Take them one at a time and they will
fall into place.
About the author
Leslie Wood is the
founder of Les Wood Associates (www.lwassoc.com), a North Andover, MA-based
consulting firm that has provided industrial engineering services to
manufacturers and warehouses since 1989.
Previously, he was director
of industrial engineering for Sweetheart Plastics. He has held similar
positions in other industries including telecommunications, semiconductors,
electronics, machine shops.
Reach Les Wood at
(978) 681-8705 or by e-mail: lesw@lwassoc.com.
Slotting Optimization as High-Return Project
In recessionary
times, distribution and supply chain managers are looking for short payback
projects to optimize their operations. Many companies are delaying implementing
broader-based supply chain initiatives such as warehouse management and supply
chain process management (visibility, event management, process integration) in
favor of lower cost, faster return continuous improvement projects. Inventory
slotting optimization is a good starting point.
Slotting
optimization is an execution-focused process using software with advanced
algorithms to improve product-to-location assignments within the distribution
center. Slotting can be undertaken on a one-time basis; however, its real power
rests in its use on a continual basis — either on weekly, monthly or
seasonal periods.
Is your company a
candidate for slotting? Consider
four indicators:
• Do
burdensome replenishment volumes adversely affect your ability to complete pick
waves on time, pick accurately or productively?
• Does travel
time account for more than half of your pick/replenishment labor time?
• Are your
pick rates not in line with industry best practices?
• Do your
pick and replenishment productively levels decrease when you enter a new
season?
If the answer is
“yes” to any of these questions, your facility may be a candidate
for a slotting optimization project.
While many of these
ills can be cured using common sense and a good industrial engineer the
complexities of today’s distribution center operations has lead to the
introduction of slotting software packages. Slotting software integrates logic
for pick sequence, path and reach optimization. The solutions consider and
optimize multiple storage modes, product configuration, velocity and balancing
criteria. If these packages can be integrated with WMS a more powerful nearly
automated slot optimization effect can be created.
Slotting projects
can typically return gains of 10 percent to 15 percent or more based on:
• Reduced
golden zone reach time;
• Reduced
travel time;
• Reduced
stockout conditions and long replenishment cycles;
• Improved
pick productivity;
• Pick line
balancing;
• Reduced
accidents through better ergonomics;
• Reduced
product damage through reduced handling;
• Slot
integrity.
Slotting projects
can typically be completed in 2-6 weeks, based on availability of data.
This “Two
Minute Tip” is by Rodney Goulet, senior consultant, eSYNC International,
and Paul Maurer, partner, Streamsoft LLC. E-mail them at:
rodney.goulet@esync.com and pmaurer@streamsoft.net.
