We all bring our bias to a warehouse layout design project - forklift people are thinking about aisle size and throughput, rack people about structural versus roll formed or selective rack versus double deep versus pushback and conveyor people talking about pick modules, sortation equipment and the like.
Customers also bring their preferences to the table, the most common one being “We have always done it this way and we just want some more of the same”. But if we are going to design the right warehouse layout, there are two key elements that must be looked at right from the start – a) what is the inventory that we are going to store, and b) how does it come in, move through the warehouse and ship out?
Someone who manufactures truckloads of palletized bottles of water is a completely different animal than a parts distribution center with 10,000 or more SKU. The first may be able to avoid rack altogether if they can bulk stack sufficient quantities of pallets within their facility, while the second will need many different types of rack and shelving and has the potential for a conveyor and sortation system. This is where an inventory analysis comes into play.
The other thing to look at is the total number of pallets to be stored and the physical space available. Usually when we do warehouse layout design work we’ll start with a standard rack solution to see the pallet count we can get. If we can fit everything in that we need with that, our work is done – there is no justification for high density storage if you don’t need it. Of course it is also important to factor in future growth and expected occupancy when considering the total pallet requirement.
There are exceptions to the rule, but in general we find that if we match the inventory to the storage type, we end up with 3 or 4 types of storage systems. Shelving or carton flow for small box quantities, selective rack for items with 1-5 pallets per product, pushback rack for items with 6-50 pallets per product, and perhaps drive-in, pallet flow rack or bulk storage for those SKU having high volumes. These types of solutions give the best mix of selectivity, high density, productivity and cost per pallet.