WAREHOUSE REDESIGN

 

 

It can be said that the warehouse redesign process is more art than science and more common sense than theory. The primary objective

of warehouse redesign are to:
• Use space efficiently
• Allow for the most efficient material handling
• Provide the most economical storage in relation to costs of equipment, use of space, damage to material, handling labor and

operational safety
• Provide maximum flexibility in order to meet changing storage and handling requirements
• Make the warehouse a model of good housekeeping

Eight steps are required to make this happen:

1. Measure the space you have to work with
2. Define the fixed obstacles (columns, walls, doors, clearances, etc.)
3. Understand the product stored and handled
• Define storage condition zones
• Throughput/replenishment requirements
• Unit handling loads
4. Establish the material flow paths
5. Determine auxiliary facility requirements (offices, dock staging, hold and inspection, etc.)
6. Generate alternatives
7. Evaluate alternatives
8. Recommend and implement improvements

All alternatives must consider not only space, but also material handling, and impacts on labor. If too much of the right product

exists in the warehouse in sporadic waves, the following should be considered as alternatives:

Bulk Storage: Appropriate for large unit load quantities of single products that are stackable or for low clearance areas (under 20

feet) for stackable product. This type of storage is ideal as large quantities of single SKUs may be stored in large blocks.
Portable Rack: Like bulk storage, but used for non-stackable product. Portable racks allow both the utilization of vertical cube in a

warehouse and the added advantage of being re-configurable for any product mix. The disadvantages for this alternative are the high

cost and the storage space required for portable rack components not in use.

Creative Ways to Create More Space

Too much of the right product can be handled with simple storage methods, but what happens when there is just too much inventory—right

or wrong—of a mixture of products in variable quantities in the warehouse?
The classic warehouse is a mixture of bulk storage and wide aisle selective (10 to12 feet) pallet rack. This design works well when

fast moving items arrive in large quantities and are stored in bulk, while medium and slow moving items are stored in pallet rack.

However, due to product proliferation and shrinking customer order quantities, many warehouses have lower quantities of all individual

products are stored, creating a space shortage as less dense pallet rack configurations are installed to handle ever-increasing pick

face requirements.

Vertical Cube Utilization

To increase the number of pick faces and storage density, the first step is to ensure that the facility’s entire vertical cube is

effectively utilized. Vertical cube includes all space above loads, total building clearance, space above cross aisles, space above

work and pick areas, and space above docks.
Within the rack, the opening height should be approximately six inches larger than the load height to facilitate easy and safe loading

and unloading of product. A quick formula to check this is to take a sample of unit loads stored in the warehouse and divide a typical

vertical bay of product height by the clear height in that area of the building. If the space is utilized less than 50 percent, a

great opportunity for improvement exists. If the space is utilized between 50 to 75 percent a moderate opportunity for improvement

exists. A well-designed facility will have approximately 75 to 80 percent vertical utilization. In order to recapture lost space, the

location opening sizes should be changed to meet the existing unit load dimensions. This means creating multiple opening heights and

implementing a re-warehousing program to move partial slow moving pallets into shorter locations.
If product is received and stored in less than one-half pallet loads, decked rack and case flow rack locations should be considered.

Typically, the pallet accounts for 10 percent of the storage requirement of a unit load. By hand stacking cases on decked rack or into

case flow rack, the pallet is removed from storage. The density of the pick faces then increases dramatically by narrowing the pick

face dimension from a pallet width down to a single case width. Both decked rack and case flow rack may be utilized with pallet rack

to optimize vertical cube utilization. It is often found that gains of 20 to 50 percent in vertical utilization can be obtained by

simply moving a few beams and adding a small amount of decking or case flow rack.

Tunnel Rack

Another often under utilized space is the area over cross aisles. This area can be converted to storage space in back-to-back rack

sections, also referred to as “tunneling the rack.” In a warehouse with 20- to 24-foot clearance with four levels of storage,

generally the top two levels of rack may be tunneled. This will improve unit load storage capacity by 5 to 10 percent. When tunneling

over aisles, it should be noted that pallet decking or netting should be added to prevent falling cases from reaching the floor. To

tunnel existing rack, custom measured and fit beams must be purchased to fit the space between existing sections of rack which often

vary by up to an inch in length. Tunneling of rack should be done in conjunction with forklift training to ensure operators are moving

with the fork mast down.

Rack Over Docks

Docks poorly utilize vertical cube as the majority of activity occurs in the lower 10 feet of space. A good opportunity exists to

place racking over the dock doors for storage of pallets or other packaging materials. Another potential gain in the dock area is for

the long-term storage of staged materials in rack rather than on the floor for shipments that have been pre-picked and are awaiting

final release.

Mezzanines

In operations such as direct-to-consumer or small order fulfillment, most items are picked from broken case pick lines and then packed

into shipping containers at secondary pack stations. These areas generally require low clearance, but are often located in the general

warehouse building. One method to regain the space in these areas is to build a mezzanine structure above these work areas or to move

the work areas to the mezzanine. This will yield roughly 50 percent vertical space utilization improvements, but is an expensive

option that reduces future flexibility.
Properly designed mezzanines can be used for anything from bulk storage areas, to process areas, to value-added service areas (VAS). A

large pharmaceutical distributor recently added two such mezzanines to create space for additional packaging materials and

refrigerated storage. The first mezzanine was utilized for two days of corrugate storage on the lower level and the upper level was

used for order inspection, invoice printing and final packaging. The second mezzanine was designed for refrigerated packaging

materials on the upper level and a consolidated manifesting operation on the lower level. The additional space was required to handle

increasing small quantity shipments of vaccines to doctors and small clinics. The addition of the mezzanines extended the life span of

the existing DC an estimated two years before relocation will be required.
All physical changes in a warehouse incur a cost, while only being a part of the ultimate solution. After creating the ideal location

types and sizes for the present operating requirements, a program must be put in place to review and adjust the storage plan on a

regular basis.

Making the Most of What You Have

The implementation of any single or combination of changes discussed will create additional space in a warehouse, but every warehouse

has specific operational requirements that must be addressed. If space is the only concern, labor efficiency, safety and throughput

will suffer and create even greater problems. Companies can make a lot of improvements but must realize that no change made is the

ultimate solution. Change is constant. Uncovering ways to optimize existing warehouse operations while preparing for business changes

must become primary concerns for company management. The flexibility to handle both long-term projections and short-term need is what

make operations world-class.