10 tips for improving piece picking
If your DC is typical, you're probably doing more piece picking today than you did a decade ago. Here are some tips for improving that part of your operation.
If you've been involved in order fulfillment for a decade or more, there's a good chance you've seen a shift in your facility's picking patterns. Over the last 10 years, many DCs—particularly in the retail sector—have found themselves picking far fewer pallets or cases and a lot more individual items or pieces. (See sidebar for a look at what's driving this trend.)
And that's no trivial change.
Compared to case or full pallet picking, piece picking is a more complex and labor-intensive operation, according to Norman E. Saenz Jr., assistant vice president at the consultancy TranSystems. Not only does it often mean more handling, but also more totes or cartons, more pick faces, more lines in the order (but fewer units per line), and certainly more work.
But if piece picking is going to become a bigger part of your operation, it's important to get it right. Here are some tips from the experts on how to pick small orders more efficiently.
1. Don't underestimate the value of slotting.
The benefits of proper slotting (the efficient placement of items in a warehouse or DC) might seem obvious—shorter travel times, reduced congestion, better use of space. Yet many companies fail to master the technique and end up paying the price in efficiency.
Good slotting isn't easy; in fact, it's an art, says Saenz. There are a lot of factors or constraints to consider—the SKU's current and future velocity, its cube, its weight, seasonality, and what else ships with it—and they often contradict one another, he explains. With so many factors to take into account, you can't just rely on intuition; a robust slotting tool is crucial for piece picking success.
2. Reslot early and often.
When it comes to piece picking, one of the most common mistakes companies make is failing to reslot in a timely fashion, says Ken Ruehrdanz of distribution equipment and systems developer Dematic. "As demand for each SKU changes, so do the pick rates and therefore, so should the slotting," he says. Skip that step and the operation is likely to see its efficiency drop over time.
How often should you reslot? It all depends on your products' life cycles, says Jack Kuchta, president of Jack Kuchta Supply Chain Advisors. If you're handling high-fashion apparel, you may need to reslot daily; machine tool companies, however, could probably get away with reslotting every year or even every five years.
How do you know when it's time to reslot? "There's no easy rule," says Kuchta. "The only way to know is to keep running a [software] program that looks at what percentage of your picks are still in the correct slot zone. When you start dropping below 80 percent, then it's time to reslot."
3. Keep it simple.
With so many picking methods to choose from—multi-order cart picking, pick and pass lines, zone picking, wave picking—how do you decide which is best for you?
"I find it useful to begin thinking about the simplest one first," says Jim Apple, partner with the consultancy The Progress Group, "and then work toward more sophisticated methods as the volume increases." Examples of simpler solutions would include multi-order cart picking and the use of parallel picking zones, while techniques like wave picking would appear at the other end of the sophistication scale.
4. Don't be afraid to mix and match technologies.
As for what's the "best" picking system for your piece picking operation, there's no simple answer. It's rare that one technology will be a good fit for all the SKUs in your facility, says Jerry Koch, director of product management at material handling solution provider Intelligrated.
For example, you may be able to get by with RF and order carts for your slower-moving SKUs, while the fast-movers might require carton flow racks combined with pick-to-light or voice technology for maximum efficiency. For that reason, says Koch, most facilities will be best served by a mix.
5. Be realistic about your needs.
When choosing a picking system, be realistic about how much accuracy you really need. Although some operations—pharmaceuticals, for instance—may require accuracy rates approaching 100 percent, that's not true of everyone. And it's important to keep in mind that perfect accuracy often requires some sacrifice in productivity.
When buying equipment, take into consideration how much an incorrect pick costs you and how much time your workers spend confirming picks, advises Steve Mulaik, partner with The Progress Group. Then weigh those costs against your need for speed.
6. Be store friendly.
In the past, companies looking to boost distribution productivity typically focused on streamlining activities inside the DC, says Ruehrdanz. Now, however, some retail leaders are finding there are far bigger gains to be made by streamlining operations at the receiving end. Store labor is often more expensive than warehouse labor, which means that anything the warehouse can do to optimize store putaway will likely have a big payoff—whether it's building pallets that correlate to a retail store's planogram or picking an order in the reverse sequence of how it will be replenished at the store. "The cost of one more selector in a distribution center is vastly smaller than the cost of adding an associate per retail store across 30 or 40 stores," says Koch.
7. Make sure your hiring practices reflect the new realities of your operation.
If your operation is doing more piece picking than in the past, you should take that into account when you hire new workers. The physical requirements for piece picking are far different from those for case-level picking, says Mulaik.
"When I go to a grocery warehouse [where case picking predominates], there are huge hulking guys slinging 30-pound cases all over the place," Mulaik observes. "The physical traits that often define success in a piece-pick operation, however, are arm and finger dexterity: peeling a pick label and applying it with one hand while the other hand drops the product into a box, grabbing a packaging invoice off a printer while you simultaneously grab a box to place the merchandise inside."
Mulaik believes this shift in emphasis from physical strength to dexterity opens the field up to more women than ever.
8. Choose equipment and technology that can grow with you.
All too often, companies fail to look down the road when choosing picking technology or equipment and end up outgrowing the system within a few years, says Intelligrated's Koch. To avoid that, Mulaik urges DC managers to select automated equipment with an eye toward flexibility. "You don't want to throw up something without thinking seriously about what may change in the next three years, or you may find that your performance is bounded," he says.
9. If you don't already have one, invest in a robust WMS.
With case or pallet picking, you might be able to get by with a basic warehouse management system (WMS)—or none at all. But that's a lot harder with a complex piece picking operation.
To support a piece picking operation, the experts say, you need a WMS with a robust slotting program. Thomas Gripman, director at The Progress Group, also recommends choosing a system that can select both the optimal size carton and the parcel carrier for each outbound shipment prior to picking. "This minimizes shipping cost, which is one of the highest cost components in an 'each' picking environment," he says. "It also allows orders to be picked directly into the shipping carton, which eliminates additional handling."
10. Don't be a copycat.
Don't design your picking operation from a magazine, says Kuchta. While case studies and best-practice examples can be an excellent source of ideas, you shouldn't apply them wholesale to your operation.
Instead, Mulaik says, explore all the options out there. "There are many more than you would think," he says. "I learn new ones every month or two, and I've been doing this for 20 years."
What's driving the trend toward smaller orders?
The obvious answer is that the growth of e-commerce has led to more customer-direct shipping. But there are other factors as well.
One is the down economy. "In the last 18 months, even brick-and-mortar retailers have started shipping eaches to their stores not only because sales volumes are down but also because there's a big drive to reduce investment in inventory at the store level," says consultant Jack Kuchta.
That push to cut inventory has led some retailers to adopt what's known as a "continuous replenishment" strategy, says Ken Ruehrdanz of Dematic. "This means replenishing the store shelf more often. In fact, some retailers replenish every store every day. The effect on the distribution center is smaller order sizes [placed] more often."
SKU proliferation also factors into the trend. "Manufacturers just can't seem to resist adding new products," says Jim Apple of The Progress Group. "Without significant top-line sales growth, each new product dilutes the volume of the rest. This creates lower stocking positions at the retail store that need to be replenished in smaller quantities."
Don't expect the trend toward smaller orders to reverse itself anytime soon. If anything—according to Mulaik—orders are getting smaller. "Some retailers this year are telling suppliers that in order to reduce transportation costs and the order size further, they want suppliers to pick 'tiny orders'—less than four units—for [their] stores," he says.
About the Author
Susan Lacefield has been working for supply chain publications since 1999. Before joining DC VELOCITY, she was an associate editor for Supply Chain Management Review and wrote for Logistics Management magazine. She holds a master's degree in English.
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