Accuracy + Speed = Pick-to-Light

Aug. 1, 2002
Technological advances have increased flexibility, reduced size and brought down the cost of pick-to-light for small parts picking.
Accuracy + Speed = Pick-to-Light

Technological advances have increased flexibility, reduced size and brought down the cost of pick-to-light for small parts picking.

by Christopher Trunk, managing editor

“The most important thing about small parts picking is accuracy,” says Darin Danelski, president of Innovative Picking Technologies Inc. “When that pick-to-light panel flashes, you’re going to select the right product, and that accuracy spells savings in pharmaceuticals, assembly stations, kitting and retail fulfillment.”

Without pick-to-light in small parts picking, you must rely on the picker being always attentive, especially with similar-looking parts and part numbers. Bob Rienecke, vice president of marketing and customer service for Diamond Phoenix, finds that “light-directed picking relieves the worker from having to search between one location and another, as the light identifies where to pick from and how much to choose.”

Jim Bast, general manager for Professional Controls Corporation, says pick-to-light makes life simpler. “In many small parts picking applications, all a worker needs to know is how to read a number, count out the quantity and hit a button to extinguish a light — without a lot of training. That helps as many orderpickers are temporary staff.”

Along with simplicity comes faster orderfilling. “Pick-to-light cuts by half the time needed to pick orders and can reduce errors by 70 percent to 90 percent when compared to paper pick lists,” says Stephen Small, product manager for Diamond Phoenix Corporation. Vendors insist this isn’t just “sales talk” when it comes to improving performance. “If you study applications across industry and across vendors’ equipment, you see the same benefits when switching from paper to lights.”

Another benefit is the plunging cost of pick-to-light units. “Light units are easy to replace and are cost-effective these days,” says Jeff Hedges, director of market development for HK Systems Inc. “Now when a component wears out, it’s as easy as plug-and-play rather than rewiring a pickface.”

New ideas for pick-to-light

Technological advances are making inroads against the drawbacks inherent to orderpicking. One example is the Watch-Me zoneless picking system from Innovative Picking Technologies Inc. The system constantly changes order profiles to better balance workflow among workers, and allows workers to bypass others to pick orders from the entire picking area. “Bottlenecks occur in conventional systems when one worker is busy working a large order and another is starved for work,” says Danelski.

This kind of zoneless picking contradicts outdated thinking when zones were used to keep order in a paper-based pick line, to give workers more familiarity and accountability over inventory. But with paperless picking, the system remembers similar-looking parts so the workers don’t have to.

It seems that carrier-on-wire light units that snap into place wherever needed are now what buyers should expect. At my last report (MHM last covered pick-to-light in March 2001, “Pick-to-Light: Hot-Wired for Consumer Electronics”), snap-in-place was a relatively new idea. “For sites with frequent reslotting of new part numbers and resizing of the pickface, these plug-and-play modules are essential,” says Jim Neuner, vice president of sales for Eskay Corporation. “It also eliminates new cables and rewiring.”

“We’re supplying lights of different colors to mean different things to workers,” says Small. “We’re using area controllers to light up multiple SKUs using just one light, and are integrating RF and infrared terminals on the pickline to pick slower-moving items located in nearby rack or shelving.”

Hard-wired infrared terminals sit on cradles on the lighted gravity flow rack. A panel on the terminal tells the worker to travel to a specific location.

“We have an application at a liquor distributor that lights up wine bottles to be picked. The expensive wine sitting on separate shelving is picked using infrared devices,” says Small. The worker scans the UPC label on the expensive wine bottle before the system lets him pick, providing positive identification that the right pick was made.

Also, conveyor systems are now used to route totes from one picking location to the next, rather than routing them through the whole pick area.

In the past, pick-to-light systems were highly engineered systems. Now, off-the-shelf lights and computerized control boards are available. With the explosion of PC technology, vendors are using boards that anyone can buy and that guarantee high-speed response times for pick-to-light — a problem in the past. These boards also come with good current support and a lot of testing built in.

Hedges tells of HK Systems’ QVision product. It applies light curtains to direct orderpicking at assembly line stations, primarily in automotive. Lights direct workers to the right box to pull oftentimes similar-looking parts for building motors and transmissions. “A manufacturer might have four or five different versions of a motor, but there are typically about two dozen or so parts kept at an individual workstation,” says Hedges. “The lights keep the wrong parts from being used, saving a lot of rework later down the assembly line.”


Applying pick-to-light to the right application is key to obtaining the kind of lightning throughput described above. The rates you expect to achieve are heavily influenced by the density of picks. “It’s important to understand that if you have 1,000 part numbers and are replenishing for retail stores, the probability is that you’ll need 200 of those SKUs for a store’s order, hitting every fifth part number. That fits well with pick-to-light,” says Neuner. But if you’re picking for e-catalog fulfillment and hitting just three SKUs out of 1,000 part numbers, then Neuner finds there isn’t the kind of density needed for pick-to-light.

He says a good range is for 10 percent of your SKUs fitting into one order. “This is the sweet spot. Where your application deviates on either side of that range, you need analysis about whether pick-to-light applies,” advises Neuner.

Innovative Picking Technologies is integrating voice systems with its pick-to-light product. “Small parts picking requires a lot of dexterity, counting out small parts, screws, washers, etc. That makes it a great candidate for voice-directed picking,” says Danelski. A worker wearing a headset comes upon a light for a bin. The voice says how many to pick, and the worker acknowledges the pick verbally, making for hands-free and faster picking.

And integrating pick-to-light with WMS is an easier fit than ever. “As more companies turn to pick-to-light in fulfillment, the response time and integration with WMS are more important,” says Jack DeTate, vice president, customer solutions for Optum Inc., a WMS vendor. DeTate says there are no standards for how pick-to-light communicates with WMS with message format, syntax and command language unique to each pick-to-light vendor. To make integration easier, Optum developed the Move 7i Integrator software that allows for real-time communications for parameter order, delimiters, length and characters. “This eliminates the need to change common pick-to-light transactions,” adds DeTate.

Justifying pick-to-light

When pick-to-light is applied to carousels, Rienecke finds that a system is justified in just eight months to a year with the combined benefits of reducing worker walking time resulting in higher throughput and improved orderpicking accuracy from the lights.

Danelski described a lock manufacturer that justified its pick-to-light installation by reducing the number of wrong parts being put into lock kits. This meant fewer trips to put away wrong parts, fewer trips to pick the right ones later, and an assembly line that kept moving.

Small says that in the past, systems with 10,000 lights or more were cost prohibitive from a ROI standpoint. “But because of today’s area controllers, you can light up to 40 titles with just one pick device, so publishers with 20,000 titles can consider pick-to-light,” adds Small.

It’s clear that this technology is ready to revolutionize how small parts are picked at both manufacturing sites and distribution centers. Contact vendors to see how it can fit into your company’s plan for improving worker productivity. MHM


Contact these vendors for advice on pick-to-light:

Bast, [email protected].

Danelski, [email protected].

DeTate, [email protected].

Hedges, [email protected].

Neuner, [email protected].

Rienecke, [email protected].

Small, [email protected].

Case Histories

Carousels and Pick-to-Light Consolidate Small-Parts Operations

Southco is a world-leading supplier of specialty industrial fasteners and access hardware. The company recently consolidated its European distribution operations at Worcester, England. Diamond Phoenix was contracted to install six horizontal carousels with pick-to-light and two workstations using put-to-light technology, called Diamondware. Southco stores 8,000 SKUs, and half of them are stored in carousels. The carousel parts represent 80 percent of Southco’s business.

The carousels are arranged in two, three-carousel pods, and they bring parts for the same batch pick simultaneously to the worker. Light modules adjacent to the carousel display location and quantity to pick. The part number is also displayed as a visual check. A green button indicates the right quantity was taken from the carousel.

Once items are picked, workers take the boxes and parts to a nearby put workstation. Each blue tote represents a store’s order, and a put-to-light panel (SpeedBar) above each tote tells the worker how many items to place into the tote. Once the right number of items is placed into the tote, the worker presses the yellow order-complete button.

With the pick-to-light and carousel system, this small parts warehouse has seen significant increases in productivity. “We have integrated the European workload into our operations without having to increase workforce,” says Andy Tyler, distribution manager. “Picking errors have decreased, and we have increased the number of next-day deliveries, which makes customers happier.” Diamond Phoenix.

Pick-to-Light Increases Accuracy for Auto Parts Distribution

At Advance Auto Parts distribution center in Gallman, Mississippi, an integrated orderpicking system that combines pick-to-light (Real Time Solutions), carousels (White Systems), gantry palletizers (Alvey Systems), warehouse management software (EXE Technologies) and transport/sortation conveyors fills orders for aftermarket auto parts at more than 150 stores.

“The cost of sending the wrong item to a store is very high, especially for loss leaders during sales time,” says Randy Peters, senior product manager. “Once an order is delivered to a store, it is prohibitively expensive to bring it back to the warehouse.”

Pick-to-light for both full-case and split-case picking helps reduce orderpicking errors for retail stores. In addition, the distribution center sought to shorten delivery cycles and reduce store inventories with automated material handling systems and software.

The control software that runs the pick-to-light system (Real Time Solutions OPSv2.1) allows for better planning of batch picking. OPSv2.1 balances workloads, minimizes the time workers spend walking and increases overall orderfilling efficiency and accuracy. Because it is critical at the Gallman facility to complete the entire wave of orders at one time, the software lets managers identify and locate picker delays and send more workers to help.

The split-case, small parts picking operation features 28,000 SKUs with gravity flow rack, lighted pickfaces (EasyPick) and 28 double-stacked horizontal carousels. The fastest-moving 9,000 SKUs are housed in gravity flow rack and the remaining 19,000 in the carousels.

The flow rack consists of two 400-foot-long racks with three levels of pickfaces. Flashing lights direct workers to the right zone and SKU. Workers take items off the carousels and flow rack and put them onto waist-high takeaway conveyor. Light panels tell workers where and what quantity to pick from the carousel pods. Pick-to-light is also used with full-case items, which are also placed directly onto takeaway conveyor.

The system is sized to grow to serve 450 stores within the next five years. FKI Logistex.

Lens Distributor Sees More Productivity with Pick-to-Light

An optical lens distributor was using a conventional shelving system to both store and pick its inventory. But as the business expanded, the company ran out of space to add more shelving, and the distance workers had to walk became an issue.

The company chose nine, 20-foot-tall Industriever 3500 vertical carousels to house its inventory. This allowed for a 28 percent increase in storage capacity needed for expansion, and the carousels used just 25 percent of the previous storage footprint.

The greatest gains were made in productivity improvement once the carousels were interfaced with an inventory control system using pick-to-light technology. With the new system, the worker queues the order from the computer, and the carousel automatically rotates the right shelf to an ergonomically correct height. Light beams identify the specific tote that holds the product to be picked. Orderpicking accuracy now reaches 97 percent, and pick rates have increased threefold. Kardex.

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