Until I started setting up a high volume warehouse I never gave much consideration to routes and pick methods. I quickly learned though after choosing the wrong picking method that this can have a gigantic impact. Once I found the right one for my operation the challenge became keeping the pickers busy throughout the workday instead of trying to catch up and get everything out. Since I learned through trial by fire I thought maybe I could write a brief overview to help others that might be trying to figure this out themselves.
Picking By Order: This is what we did in my first warehouse because we were dealing with maybe 20-60 orders a day. When that’s all you’re doing there’s no need to get too sophisticated. You would typically just take your stack of packing slips and grab the items as they come up in the stack. Nothing fancy or complicated here and works fine for smaller warehouses.
Wave Picking: Wave picking is the next step up. It starts you with the oldest order and then routes you through the warehouse base don order age and location. You can enter how many you want to pick into the gun typically and it will keep you going until you’re done. Most warehouse management systems can also split up the pickers into zones so that you aren’t running across the whole warehouse for each wave. When you think about how a warehouse should logically work this is usually what comes to mind. What I learned the hard way though is that this is not the most efficient way to pick. If you are shipping 50-300 orders a day it makes the most sense, it’s also your best path if you ship multiple items in a single box. If you ship more volume though batch picking is the way to go.
Batch Picking: Batch picking is picking based on SKU groupings. It ignores the order age and just has you pick however many of that item that you need overall. So instead of being sent to bin A.2.3 over and over throughout the day as you make new waves to pick in order of age, you’ll just grab all the items from A.2.3 that are outstanding the one time you are there. It’s guided purely by geography. You can also integrate zones to gain even greater efficiency. We were able to more than double our volume per picker when we switched from wave picking to bath picking. Having known how much faster this method is would have saved me months worth of headaches. I would even suggest that if you think you have to pick by wave because your orders have multiple line items, make sure you care doing that math and watching your pre-fulfillment cancellation rate. If you are struggling with your leadtime because the warehouse can’t get the item out within a day you might be better off changing the method and shipping each item on it’s own to prevent delays. Depending on your current level of efficiency you might gain more in retrained revenue than you lose in extra shipping costs.
Finally regardless of which method you use you should then drop the items at one central shipping area. I learned that printing shipping labels in the warehouse aisles as orders are picked sounds awesome but is actually a massive cause of wasted time. Not only did it slow down our pickers but the misshipment rate doubled! So keep shipping and picking separate.
Hope I can save some of you the time I spent learning this in practice!