When it comes to picking, there’s no one-size-fits-all approach. For many businesses, using two (or more) picking processes in parallel is the most efficient approach.
Here are the most common picking methods for e-commerce warehouses
One order at a time
This is the simplest option if:
- You have a small number of orders, which are all different.
- Your orders are physically too large to be batch picked (this method is explained below).
You get a single order, you pick, pack, and ship it – and then grab the next order and repeat. This can be done with paper pick tickets or mobile devices. The obvious downside of this approach is the time it takes to fulfill orders individually, yet for smaller or start-up e-commerce businesses it may make the most sense.
Order queue picking makes sense if:
- You have many pickers and the items to be picked are close to the pickers or are too large to batch
You still fulfill one order at a time, but the main factor is the use of a digital system that funnels one order at a time per picker. The order queue method does this in real-time while ensuring there are no duplicates, no missed orders, and no delays in the orders being shipped – not the case in paper-based systems.
Multiple orders of the same item
This method makes sense if:
- You run flash sales, do pre-orders,or have big releases with a lot of orders for the same item
This method has you picking many orders that are exactly the same at the same time, then boxing or bagging them. As the items are all the same, it doesn’t matter which orders go to which customer and the weights are all identical.
You can implement this method by printing just the shipping label and not including an invoice. or by printing the label and invoice on the same page. Don’t print a separate invoice and label and then have to match them – it’s time consuming and introduces an error-prone step.
Batch picking involves picking groups of orders (batches) at the same time, which reduces the number of times your picking staff go to the same product storage bin. I’ll take you through the two main types:
- Single-item batch, where orders that contain a single, same item are picked at the same time.
- Multi-item batch, where many orders are picked at the same time, no matter how many items they have.
Use order management system (OMS) software to group your orders in the most efficient picking sequence.
For many e-commerce companies, the majority of their orders have a single line item (even if people are ordering multiples of that item). If your e-store has a lot of these single item orders, then increase efficiency by picking them all in a single-item batch.
Single-item batch picking is done in two steps, picking and packing.
In the picking step, pickers get a list of items for orders with just one item and they’re routed intelligently through the warehouse to minimize walking time. Using a wheeled cart or a carried tote, they collect the items until the cart or tote is full or all the single item orders have been filled.
In the packing step, all of the items that were picked are deposited in the packing area. The first item is grabbed, scanned or otherwise selected, then you generate your invoice and your shipping label, bag or box then item, and then grab the next item and repeat.
Multi-item batch picking is the most complex picking method. It involves picking many orders at the same time (and these orders have multiple line items). There is no second check, so it’s very important not to make mistakes.
Multi-item batch also involves the two steps of picking and packing. There can be many pickers and many packers. Typically, there are more pickers than packers, unless your packing process is especially time-consuming.
The picker takes a cart with multiple totes (plastic bins) or final shipping boxes. Each tote or box represents a single order and is identified with a barcode, often called a License Plate Number (LPN). Reusable totes are more common than shipping boxes and the number of totes or boxes will generally be between three and 30, (I’ll touch on this a bit further down).
The picker walks the warehouse once and picks all the items into the correct totes or boxes.
At the first location, the picker selects the order item, confirms that it is the right one by scanning its barcode and puts it into the totes or boxes representing orders that need that item. Then the picker goes to the next location, collects the item into the right totes or boxes and repeats the process until all the orders on the cart are fully picked.
The picker doesn’t waste walking time by picking one order completely and then picking the next order. Instead, they pick different orders into different totes or boxes until all the cart’s orders are complete in a pass through the warehouse.
Once the picks are complete, the totes or boxes are offloaded onto a conveyor which goes to the packing stations.
At the packing stations, the first available packer takes the tote or box and scans its LPN (the barcode). The LPN brings up a list of what items were picked into the tote or box and the order information. If a tote, rather than a final shipping box is used, the packer puts the items into a final shipping box.
The invoice is then printed and put in the shipping box. The box is weighed, sealed, and the postage label is printed and applied to the package.
That order is now shipped!
You’ll notice that the packer didn’t need to do a second pick of finding the correct items for each order. This saves time and eliminates an error-prone step. You’ll also notice that there is no second verification step – because during the first step, the picker scanned the items and the tote they were placed in. Eliminating a second sort at the packing stage avoids another opportunity for error. The typical error rate for this single verification process is less than 1 in 1,000. You can do a second verification, with the packer also scanning the items, if you ship high-value items like expensive watches, jewellery and electronics.
Deciding on boxes versus totes – and how many you’ll need
The decision on whether to pick into totes or boxes depends on what shipping boxes or envelopes you use to ship your orders. If most (or all) of your orders go in the same size shipping box or envelope, then picking directly into that box or envelope makes sense. If you use a variety of shipping boxes or envelopes, it’s best to pick into totes.
To figure out the number of totes to pick at a time, you need to determine the size of the totes to use and how many will fit on your cart.
You want to use totes that are large enough to contain all the items from a typical, large shipment. Don’t include orders that go in multiple boxes or on pallets when figuring out your tote sizes, as these will be picked one at a time, not via the batch pick process.
You want a cart that holds the maximum number of totes while giving pickers easy access to them. When fully loaded, the cart should be easily navigable around the warehouse. When selecting a cart, avoid those:
- That are too unwieldy to move easily around your warehouse.
- With high shelves that your shorter pickers can’t use.
- That are too heavy to be easily moved around the warehouse by weaker pickers.
If you have uneven or pitted floors, make sure that the cart wheels handle the floor.
The last commonly used pick methodology is a wave pick. In a wave pick, you pick many orders at a time and then do a second pick to separate items into their individual orders. Wave picking has gone out of favour because it takes more time and introduces more errors than a combination of single-item batch and multi-item batch.
I hope that taking you through the most common picking methods provided some useful information. Use one or a combination of picking techniques to meet your businesses’ needs and enjoy increased efficiencies and a near zero per cent error rate.
Get a fuller picture of how you can create a more efficient, labour-saving fulfillment process.Read this
Aaron Rubin founded and was the CEO of a mid-size e-commerce company for 14 years. After struggling to find a warehouse management solution (WMS) that provided the efficiency, accountability and ease of use needed at a reasonable cost, he founded ShipHero, a robust WMS for e-commerce small-to-mid-size businesses. ShipHero is a Canada Post partner.