Order picking: Beyond the basics

Want to get more out of your warehouse operations? Advanced picking techniques and technologies can improve productivity and accuracy.

By Bob Trebilcock, Editor at Large -- Modern Materials Handling, 9/16/2008

Along with accurate inventory, accurate and productive picking is key to an efficient warehouse and happy customers. After all, those cartons and pallets aren’t going to move themselves. If you want to get your product out the door and onto a truck, someone has to pick it. The fundamentals of picking include WMS -, RF- and voice-enabled picking by an operator on foot or on a lift truck.

But what if you want to move beyond the basics?

What’s the next step in picking fundamentals? “In general, you’re going to look at advanced picking techniques and technologies when you have excessive travel time, when you need to accommodate dense storage to make the most of your footprint, or when you want real-time management of a significant number of SKUs,” says Craig Bertorello, vice president of operations for TriFactor, a materials handling systems integrator.

There is a picking continuum when it comes to traditional order picking, with facilities moving from paper-driven picking to RF-directed picking, and from batch picking to wave picking to zone picking, depending on throughput requirements.  

The same isn’t true when it comes to advanced picking. “Instead, what you’re looking at is a variety of solutions that work in different situations,” says Bertorello. “You need to look at the size of the products you’re picking and the profile of your products and orders.”

Some of the most common advanced picking technologies are:

Pick-to-light. Like voice technology, light-directed increases productivity because it’s hands free. Instead of holding a scanning gun, order pickers are directed to pick locations by flashing lights along the shelves. The light bars also display the number of units to be picked from a carton. “You’re still sending an operator to a picking location, but they are more productive and more accurate than basic picking,” says Bertorello. As a general rule, lights are best in medium- to high-volume operations with medium- to high-moving SKUs.

Carousels. Vertical and horizontal carousels provide dense storage for cartons and small-to-medium size parts. What’s more, carousels eliminate operator travel time by rotating to deliver the part to the operator. “Carousels are ideal for piece picking, especially in batch picking and kitting operations,” says Bertorello. 

Automated storage and retrieval systems (AS/RS). Like carousels, unit-load and case-handling mini-load AS/RS systems provide dense storage in a small footprint. And like carousels, they deliver the items to be picked – pallets and cases – to a picker, providing real-time control of inventory and eliminating travel time. AS/RS systems also enable dynamic slotting: Rather than a large number of picking locations dedicated to an SKU, the warehouse control system can dynamically deliver product to available locations, reducing the amount of space required for picking locations.

A-frames. Want to take operators out of the equation? A-frames, which work like high-speed industrial Pez dispensers, provide fully automated picking in environments with a limited number of high-volume, fast-moving SKUs with a consistent size. Fast moving belt conveyors or totes receive product as they pass beneath the A-frames. They are most commonly used for dispensing products like lipstick and cosmetics, pharmaceuticals, DVDs and CDs.

While none are a one-size fits all solution – you’re most likely to see pick-to-light, carousels, AS/RS and A-frames used in conjunction with traditional picking – each can improve productivity, throughput and accuracy in the right situation.