What is Warehouse Management System Part 5 - What is "Wave Management" or "Wave Planning"?
If you play “Tower Defense” games, you understand that enemies attack you in groups by waves. But why? Why don't the game designers make all the enemies attack you at once? Because that would take away the fun, the fun of strategizing, planning and executing.
Likewise, in warehouse operation, there are always many orders waiting for delivery. These orders are in a place in the warehouse management system often referred to as the “order pool”. The order pool is never constant, new orders are added every second when the existing orders are being processed. A busy warehouse always has many orders in the order pool, even after a working long weekend, you can never empty the order pool. This is a good thing, very good indeed, this means business is good!
With many orders waiting to be processed, and very often, “star” salespeople may call the warehouse requesting urgent delivery for VIP customers; So, warehouse operations need an efficient way to better manage the execution of these orders.
Imagine all these orders are enemies of different types, some are orders with large quantity but not a lot of lines (example people ordering a few pallets of mineral water), some are orders with a lot of lines but with small quantities, some orders are to be delivered today, some for tomorrow, some are local deliveries, some are overseas, some are outstations and some customers may even give you a delivery time (example, between 4 pm to 6 pm today).
Strategize, Plan and Execute. That’s the core concept of “Wave Management” in a good warehouse management system.
Wave management allows you to group orders so you can process them together. You can group them in many ways: group by route, by delivery date/time, by freight, by priority, by zone, by location or by MHE (material handling equipment) type.
No two pickers will be asked to go to the same location when there isn't enough stock for the second picker who may arrive at the location later than the first picker.
Once you have planned the waves, you “run” them – the Warehouse Management System goes through all the order lines in the wave(a group of orders) and allocate the stock based on all the rotation and picking rules. Rotation rules are rules such as First In First Out (FIFO), we will talk about picking rules(which can be fairly complex) in our next article. Because of allocation function, the WMS can then guide multiple pickers simultaneously where to pick, what to pick, and how many to pick. No two pickers will be asked to go to the same location when there isn't enough stock for the second picker who may arrive at the location later than the first picker. If you are using a Warehouse Management System such as Wave WMS, the WMS even has the flexibility for users to further configure these allocation rules.
WMS can then guide multiple pickers simultaneously where to pick, what to pick, and how many to pick.
As you can imagine, this is a process that required a lot of computing power.
As a result, you cannot compare a Warehouse Management System with another system that also processes orders, for example, a Point of Sales (POS) system, as the operation requirements are very different. A POS system scans an item barcode, display the price and record the transaction. In a WMS, before a picker is allowed to scan an item, the WMS needs to go through the entire inventory in the warehouse to determine the correct products, correct batches, correct locations of the inventory in the most efficient way for the picker to pick them.
“Run Wave” is to allocate the inventory, this means a list of tasks is determined, each with an associated location, waiting for the pickers to execute these tasks. Pickers may use different equipment - reach truck drivers who can pick inventory stored at a high level whereas pickers with hand pallet jacks may only be allowed to operate at the ground locations. A good warehouse management system considers all these constraints when running waves.
“Release wave” is to release all the tasks created by WMS during the “run wave” process. This means to get pickers to execute all the tasks. Well… mainly pickers, but read our next article for more.
Enjoy wave management – Strategize, plan and execute. Choose a WMS that allow you to do this.
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