August 29, 2017
strategy | Automation

22 million SKUs? No problem

22 million SKUs? No problem

Tracking and handling millions of new and used industrial parts might sound like the ultimate inventory challenge. But Radwell International's automated storage system makes easy work of it

By David Maloney

The first thing a visitor notices at Radwell International's new operations and distribution facility in Willingboro, N.J., is that the family-owned company operates a bit differently than most industrial distributors. Maybe it's the 47 fish tanks in the complex, the largest being 500 gallons. (The company employs a full-time fish wrangler who's charged with keeping the tanks spotless.)

Or maybe it's the employee lunchroom, where tables painted in bright Caribbean colors and adorned with beach umbrellas sit alongside pingpong tables and videogame consoles. Possibly all of these serve as distractions from the decidedly daunting task of keeping track of a catalog of 22 million stock-keeping units (SKUs). Regardless, it looks like a fun place to work.

But what may be one of the most interesting features of the new facility is the state-of-the-art automated storage system that allows it to handle the million or so parts that account for most of its daily volume. Known as the "AutoStore," the automated storage and picking system enables workers to pick nine or 10 products in the time it takes to select one product manually.


To understand the automated system's significance to the operation, it helps to know a little about Radwell's business. Radwell International is a full-service supplier of new and used industrial parts and components. Its products include parts for automation, MRO (maintenance, repair, and operations), motion control, electronic, pneumatic, hydraulic, electrical, and HVAC (heating, ventilation, and air conditioning) equipment. Its main customers are manufacturers, engineering wholesalers, and others tasked with plant maintenance and keeping production lines going.

"Our business model is based on having the right product in stock," says Todd Radwell, senior vice president of operations and production. "When a machine is down, we help customers find the critical parts they need to get it running."

The company has four basic business functions, each of which operates as a separate production group. The first unit buys surplus and used manufacturing and production equipment. The second resells components and individual parts from equipment that it strips down, much the same way an auto salvage business sells off individual car parts. Radwell is known for having the hard-to-find replacement parts that help customers keep their aging systems operating.

A third group sells an extensive catalog of new parts and components, while the fourth unit repairs malfunctioning controls, boards, sensors, servo products, and other parts used on production machines for customers. Radwell serves the automotive, bottling, pharmaceutical, plastics, chemical, and other industries, as well as clients like cruise ships and amusement parks.

The company has six U.S. facilities, plus locations in Canada, Germany, and the United Kingdom. Two of the U.S. operations are stocking locations, as is the U.K. facility. Radwell's largest operation is in Willingboro, which also houses its corporate offices. The company is growing by about 20 percent per year.


Last October, Radwell moved into a 312,000-square-foot facility in Willingboro that previously served as a pharmaceutical distribution center. In making the move, the company consolidated production and warehouse operations from two former locations. In addition to distribution space, the building contains the repair shops as well as work areas where components are broken down into parts that can be resold.

Moving into larger quarters allowed Radwell to house more inventory. The company generally takes in about five times more parts than it sells in order to maintain a wide assortment of stock. (The distributor holds a lot of inventory because manufacturing machines—which are durable goods with long useful lives—need parts long after the original manufacturer has stopped providing replacements.) At the same time, the move allowed Radwell to design a facility with better material flow than it had in its other buildings.

The centerpiece of the operation is the AutoStore, which Radwell chose for its storage density and ability to handle small parts effectively. The system's relatively small footprint also made it a good fit for the facility's space, especially since the ceiling's 30-foot clearance ruled out the use of crane-based systems.

The AutoStore houses parts in dense stacks of 16 bins that are arranged in a grid. There are nearly 50,000 bins in total, all containing a mix of small parts. Thirty-four small robots glide on aluminum rails above the stacks of bins. Each robot is equipped with a grabbing device that enables it to pick up the bin on the top of a stack, which it then moves to a different stack to reorganize the warehouse or delivers to a picking station to supply a part needed for an order.

The robots only require a deep charge of four hours each day. In addition, when they're not needed for a few minutes, they move over to charging stations to regenerate throughout the day.

Managers appreciate that the system has few moving parts, which minimizes downtime. "The robots aren't dependent on each other," says Todd Radwell. "If a robot goes down, you just take it and repair it. It doesn't stop the other robots from working."

Another key advantage of the AutoStore is its scalability. Expanding the system will be a simple matter of adding more grid, stacks, robots, and processing stations. Currently, the facility has nine stations. Most of the time, five of the stations are used for putaway, while four are dedicated to picking, but they can be easily reassigned as needs change.


Product flow through the Willingboro building varies according to the type of part and the business unit it is associated with. Radwell's business is split evenly among its three revenue-generating operations, with the sale of new parts accounting for about 35 percent of its business, used parts another 35 percent, and repairs approximately 30 percent. Parts for all operations are received at three doors, with most arriving in cartons and the remainder (mainly larger units) on pallets.

Handling inventory here is a bit different than it is at most parts suppliers, where parts are customarily stored according to SKU. Because Radwell handles such an enormous variety of parts, it would be nearly impossible to assign each SKU to its own bin. Instead, Radwell mixes the parts into bins that may contain dozens of different SKUs. The parts are effectively stored by when they are received or made available for sale.

To track such a seeming hodge-podge of parts, the company relies on its Epicor Prophet 21 warehouse management system (WMS) working in conjunction with the Swisslog "SynQ" software that manages material flow in the automated storage system.

To facilitate product movement, Radwell repurposed over two miles of conveyors and diverters to transport bins between various parts of the building, including receiving, production, AutoStore induction, and product boxing.

Parts for which the company has received advance ship notices or other documentation are placed on a conveyor and sent to one of 22 processing stations. A separate set of 40 processing stations handle bulky receipts and what are known as "blind receipts." These are items sent to the company without notice by customers hoping to sell off any parts from old equipment that may still hold value. Workers identify the parts and take photos of them for inventory purposes.

The faster-moving parts are then conveyed to the AutoStore, while bulky parts and slower-moving items head to pallet racks, where wire-guided turret trucks supplied by Crown perform putaway duties. The pallet area has 10,000 pallet positions and can hold 38,000 bins. When items in the pallet racks are needed for orders, workers gather them using order picker trucks.

The facility also has an air tube system that it can use to whisk small parts around the facility. The system consists of 31 stations where items are delivered swiftly in the air tubes, similar to systems used at drive-through bank windows.

Items that need repairs are sent to 12 stations where they are evaluated and then directed to one of 12 specific work areas for repairs by type—for example, small drives, large drives, robots, PLCs (programmable logic controllers) and controls, and circuit boards.

Products for the AutoStore are conveyed to the five input stations, where workers remove each item from the transport bin, check it, and scan it into the AutoStore software. They then place the item into an AutoStore bin that a robot has delivered to the station. Random parts are added to the bin until it is full or reaches a weight of 65 pounds. A robot then picks up the bin and deposits it in an open slot on the top of one of the stacks.

The WMS works with the SynQ software to analyze incoming orders and determine the location of bins containing the required parts. The software then assigns robots to shift bins to other locations to allow access to the desired bin.

When parts are needed for orders, the robots deliver the bins to four picking stations, which are part of the Swisslog "Click&Pick" system. A display screen shows which part or parts are needed from the incoming bin along with a picture of the item to help with identification. Most picks can be completed within 30 seconds and total orders within 90 seconds, even those requiring multiple parts from different bins. The system is capable of delivering 140 bins an hour to each processing station.

A key benefit of the AutoStore is the way it consolidates parts. The process differs from the method used in conventional warehouses, where parts must be broken down into individual orders after they are zone-picked. "With the AutoStore, all bins with parts needed for an order are delivered at the same time, so it does the picking and order consolidation in one step," says Todd Radwell.

The worker selects the parts from the AutoStore source bins into order bins. When an order is complete, the picker places the bin onto a flow rack that feeds one of nine adjacent pack stations, where orders are readied for shipment. Two robotic carton erectors from Xpak Robox build shipping cartons in six sizes. A machine from Sealed Air supplies air-filled dunnage for the cartons, while a CubiScan dimensioning system is used to measure and weigh outbound cartons.

Every outbound carton also gets a small bag of candy, which is a treat that customers have come to expect. "We started it many years ago. This is a practice that once you start, you can never stop," notes Todd Radwell.


As for how the new system is working out, initial reports are decidedly positive. Since the company began using the AutoStore, processing time has been cut significantly while volumes have steadily increased. "It has taken over about three-quarters of our daily volume and about 800 orders a day," reports Brian Janusz, global program manager at Radwell. Currently, the system operates with just four pickers on one 10-hour shift.

As for its experience working with Swisslog, the systems integrator for the project, Radwell has nothing but praise for the team. "We were a month ahead of schedule on the installation," Janusz says. "They've been a great partner."

About the Author

David Maloney
Editorial Director
David Maloney has been a journalist for more than 35 years and is currently the editorial director for DC Velocity and Supply Chain Quarterly magazines. In this role, he is responsible for the editorial content of both brands of Agile Business Media. Dave joined DC Velocity in April of 2004. Prior to that, he was a senior editor for Modern Materials Handling magazine. Dave also has extensive experience as a broadcast journalist. Before writing for supply chain publications, he was a journalist, television producer and director in Pittsburgh. Dave combines a background of reporting on logistics with his video production experience to bring new opportunities to DC Velocity readers, including web videos highlighting top distribution and logistics facilities, webcasts and other cross-media projects. He continues to live and work in the Pittsburgh area.

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