Dematic supplies sortation system to JCPenny

JCPenney Debuts Integrated Sortation System with the World’s Longest Sorter at Its New California Distribution Center

Ultra-precise merge gapping, parallel diverting sortation with linear induction motors, modular variable-speed functionality and single-point system control – JCPenney’s new Lathrop, California DC with its Integrated Sortation Sub-System (ISS) technology including a 980-foot long single-unit continuous sorter from Dematic, is processing up to 165,000 cases per day at 99.9 percent accuracy.

by Jim McMahon

In July of 2007, JCPenney opened its sixth Retail Logistics Center (RLC) in the United States. The new distribution center, located in Lathrop, California, not far from Oakland, is essentially a cross-dock facility for handling primarily import containers. At the DC the containers are broken down, and the cases shipped out to one of 13 of the company’s regional Store Support Centers (SSC) located throughout the U.S. This distribution center is unique because it is JCPenney’s first DC to utilize a sortation technology called Integrated Sortation Sub-System® (ISS), developed by Dematic.

The prime characteristic of ISS is that it approaches the entire sortation subsystem as a singular unit, fully integrated with a single point of control, and permitting the flexibility for all sections of the system to run at independent, variable speeds to optimize component throughput requirements and maximize operational and energy efficiencies. The system encompasses a number of cutting-edge DC components such as precision merge gapping to within one inch between boxes, high-speed, parallel-divert sliding shoe sortation, and air-cooled linear induction motors (LIM) for oil-less, pneumatic-less, and very quiet sortation.

With its 20,000 linear feet of conveyor, and 980-foot long, single-unit sliding shoe sorter – the longest continuous sorter in the world – the Lathrop DC is moving up to 165,000 cases per day through the facility. The high-tech automation, from receiving to shipping and everywhere in between, means a typical case only spends six minutes in the DC and is only touched twice (unloading at receipt and loading at shipping) in the process, before it is on its way to one of the company’s regional Store Support Centers.

J.C. Penney Company, Inc. (JCPenney) is one of America’s leading retailers, operating 1,093 department stores throughout the United States and Puerto Rico, as well as one of the largest apparel and home furnishing sites on the Internet,, and the nation’s largest general merchandise catalog business. JCPenney offers a wide array of national, private and exclusive brands which reflect the company’s commitment to providing customers with style and quality at a smart price. The company’s private brand retailing accounts for nearly 50 percent of its merchandise mix.

Headquartered in Plano, Texas, JCPenney has 155,000 associates, with 2007 revenues of $19.9 billion. The company has positioned itself to be the preferred shopping choice of Middle America.

The Need for an Additional Retail Logistics Center
In addition to the new Lathrop Retail Logistics Center, JCPenney’s logistics network includes five other RLCs located in Buena Park, California; Statesville, North Carolina; Haslet, Texas; Forest Park, Georgia; and North Bergen, New Jersey. The company also operates a network of 13 regional Store Support Centers, each servicing 60 to 130 stores; four Direct Distribution Centers (DDC) which fulfill orders for catalog and customers; and four Retail Distribution Furniture Warehouses (DFW).

“Prior to Lathrop being built, JCPenney received all West Coast container shipments at its Buena Park RLC in Southern California, arriving through the Port of Long Beach,” says Kevin Williams, Facility Manager at JC Penney’s Lathrop RLC. “Increasingly, more merchandise was being received from overseas and through the Buena Park facility, stretching the throughput limits of the DC. It became apparent to us that it was time to build another RLC to carry some of the load of inbound containers, and the decision was made to build another distribution center in the Bay Area. Lathrop allows us to route inbound goods through the Port of Oakland. The added capacity of the DC, and the port diversification, has helped us reduce transportation time for our direct imports. It has also allowed us to mitigate potential risks – an earthquake in Southern California would have stopped everything in the Buena Park RLC.”

Lathrop’s primary function is to receive and sort imported merchandise for routing to JCPenney’s Store Support Centers across the country. Ninety percent of all merchandise received at the RLC is from overseas in containers. Ten percent of the merchandise is from local suppliers in the area, which is merged in with the container merchandise at the RLC’s receiving docks Once received at the SSCs, they cross-dock the merchandise and ship it out to the individual JCPenney retail stores. The same distribution procedure is followed by JCPenney’s other five RLCs and 13 SSCs.

“JCPenney had two criteria for the Lathrop DC,” says Mike Harding with Dematic. “One, high throughput, capable of handling at least 150,000 – 200,000 cartons per day over two shifts; and two, it had to be built fast, within six months. Dematic was brought in to design and build out the entire material handling facility. Of JCPenney’s 18 existing distribution centers at the time, two of them were running almost exclusively on Dematic equipment, so it was not unusual for JCPenney to bring in Dematic to engineer and build this one as well.”

“Dematic was awarded the contract in February, 2007,” continues Harding. “JCPenney secured the lease on Lathrop in March, and the 436,000 square-foot DC went live in July. In essence, Lathrop was an existing structure that was completely built out. Some additional construction had to be done to accommodate additional shipping capability. To say the least, it was a project on a fast track.”

Integrated Sortation Sub-System:
Providing a 20 Percent Increase in Throughput Efficiency

It was on this project that Dematic introduced JCPenney to its new high-speed sortation technology called Integrated Sortation Sub-System, or ISS for short.

The philosophy behind ISS is to treat the entire sortation subsystem – composed of separate components like the pre-merge, merge, gapping and sortation – as one machine fully integrated from a single point of control. The ISS system is constantly adjusting speeds based on: (a) how much volume is coming through this sub-system upstream of the merge; (b) how much volume is coming off of the sorter; and (c) how much volume is enroute from the pre-merge through the sorter. From a speed-setting viewpoint, however, the sorter acts as the master device that everything else in the sub-system follows. It is the prime variable-speed unit in the subsystem – the system is watching how fast the sorter is going and all the other sub-system equipment adjusts to it.

ISS is characterized by system-wide, distributed, variable-speed control, which is uniquely based on how much product is being fed into the system, and how much product is moving out. Unlike any other system, it will automatically adjust its speed incrementally as required.

ISS is further characterized by an exclusive use of belts throughout the system and an absence of rollers, which increases package control; precision gapping; and high-speed, parallel-divert sliding shoe sortation. Dematic’s ISS is capable of providing 20 percent increased efficiency while maintaining comparable conveyor throughput speeds.

Needless to say, JCPenney found this approach to sortation an ideal match for its new high-speed, high-volume, cross-dock facility at Lathrop.

“The system adjusts its speed according to the volume of cartons being handled,” continues Williams. “The infeeds adjust their speed automatically depending on the volume of cartons moving through them to the sorter. The sorter also automatically adjusts its speed according to the volume of cartons it is carrying and offloading. The system is totally interlinked and integrated.”

Power Unloading through Merge, with Precision One-Inch Gapping between Cartons
From the moment the ASN’s (Advanced Shipping Notice) are received and the containers, or trucks, arrive at one of the 17 receiving docks, JCPenney knows exactly what is coming in. Within six minutes the cartons have been received, routed through the sortation subsystem and 20,000 linear feet of conveyor, and exited the facility. Here is an overview of how the system that Dematic designed and built for JCPenney works:

Power Unloading – A power loader is moved into the container or truck to unload it, and immediately each carton is assigned to a specific JCPenney store and given a UPC code while it is still on the conveyor.

Pre-Merge Accumulation – It is possible that hundreds of cartons from a container could be destined to a specific store. This posed a problem, as a conventional merge trying to handle this volume of cartons going to the same store would have caused effective throughput issues on the sorter.

To handle this, Dematic designed a zipper merge, so that cartons destined for the same store are not entered into the sortation subsystem in a continuous line. The zipper merge shuffles the deck, so to speak, so the chances of having a high number of cartons, like 100 cartons going to the same location in a continuous line, is reduced.

Main Merge – Cartons are arriving at the main merge via three lanes from the pre-merge accumulation at the rate of 15 cartons per minute (CPM) per lane. The cartons are being accepted at a slower rate entering the merge and being output at 45 CPM. At this point the sorter and the merge are tied together, and the Integrated Sortation System is now in play. The ISS is monitoring multiple aspects of the sortation subsystem to speed up and slow down sections of the system automatically based on the input rates. To do this, however, the entire system between the merge and the sorter needs to be on variable frequency drives to be able to precisely speed up and slow down the conveyors as required. Variable-frequency drives control the rotational speed of AC electric motors by controlling the frequency of the electrical power supplied to the motor.

“We have variable speed on the whole sorting subsystem,” says Tim Wood, Manager of Logistics Facilities Engineering for JC Penney. “We can dial in whatever speed we want. If we know it is a slow day we will run the conveyors at 300 feet per minute. If it is a heavy day we can run them at 550 feet per minute. This helps save electricity and it really helps on the wear and tear of the equipment. Running a conveyor at 300 feet versus 550 feet makes a big difference in maintenance.”

Precision Gapping – The cartons exiting the main merge are moving at 45 CPM. But, after the main merge, everything needs to run at sorter speed. The Lathrop sorter is running at 238-plus CPM, a significant difference. Enter Dematic’s C-L300 GU gapper system which closes the gaps between cartons to a remarkable 1” to 2”. Typical gapping on almost all other systems is 12” to 14” between cartons. This reduction in air space allows the system to get more cartons closer together before entering the sorter.

The gapper is using variable frequency AC drives in the gapping function, as are used throughout the entire sortation sub-system, to provide precision control of its belts. Each motor is driving a zone (belt) independently, so there is no gear reduction, giving very good control over the ratio from the speed of one belt to the next. This means more precise gapping.

The system also uses horizontal array sensors for gapping in place of the traditional PPI (Pixels per Inch) used in digital camera image sensors, which enables the gapping process to be even more precise. It uses a solid state photo eye array with a very small 2mm pitch between photo eyes for the length of the gapping device, which is watching each package in real time. Because the system is tracking the packages and tracking the gapping between packages in real time, it can adjust the speed of the belts to manipulate the gap much more precisely.

World’s Longest Single-Unit, Continuous Sorter with Parallel Diverts and Powered by LIM
Parallel Divert Sortation with Linear Induction Motors – Lathrop’s sorter is a 980-foot long, single-unit sliding shoe sorter, the longest continuous sorter in the world. The sorter is quite different from typical sortation equipment with angled diverts that rotate the boxes to facilitate discharge to the takeaway conveyors. When a package is rotated, essentially it becomes longer because one corner falls back, this means there is a bigger gap created between packages. The Dematic S-L300 sorter, which was put into place at Lathrop, does not need to rotate the boxes, allowing it to divert cartons with tighter 1” to 2” gaps between the conveyed product, as was previously set by the gapper. The take-away is designed to complete the rotation to the correct orientation, using gravity and power rollers that rotate and realign the packages.

Because the packages are closer together, the sorter can run at a slower speed, yet handle the same volume of packages that another sorter would handle having to run at a much faster speed – 20 percent higher speed to be exact. Consequently, Lathrop’s sorter can process the same number of cartons at 540 feet per minute (FPM) compared to the industry standard of 650 FPM. And with a more gentle handling because of the lower speed.

A unique feature of the S-L300 sorter is its use of linear induction motors (LIM), which are electro-magnetic drives that move a magnetic field across the face of the drive and move the aluminum slats of the sorter without mechanical contact. There is an air gap between the electromagnet and the slats. The air-cooled LIM drive-units are mounted and centered on cross member supports and are evenly spaced along the sorter track, and propel the sorter slats without any moving parts. The sorter has no belts, drive chains, gears or sprockets, no air lines or compressors requiring maintenance, no filters to clean, and no oiling.

“One of the big features for us is the linear induction motors,” explains Wood. “Dematic designed 50 of them into this sorter. They engineered it so that if the system were to lose two or three of them, the sorter will still run. With our other sorters, if a motor/gearbox drops, our whole sorter is down until we get it fixed, and these motors are 30 hp and weigh about 400 pounds. Not real easy to pull off and put a new one back on, and not usually positioned in a great place either. On this sorter all of the LIMs are easily accessible, and that also makes a big difference with maintenance down the road.”

Outbound Lanes – Exiting the sorter are 51 outbound lanes to shipping and multiple outbound lanes are designated for each SSC. The cartons, labeled for specific JCPenney stores, are loaded into trucks with power loaders.

Web-Based System Monitoring
The sortation subsystem is controlled via a PC-based controller that handles all of the tracking, diverting and manages all induction, and controls various PLCs throughout the sortation subsystem. The PC controller communicates with JCPenney’s host system.

The entire Lathrop sortation system has a web-based graphic monitoring system. Called the Dematic GMSI system manager, it allows users to access records, faults and alarms, and monitor the status of the system from a single user point, local or remote. Multiple users can access the system at any time.

99.9 Percent Throughput Accuracy,70 Percent Reduction in Maintenance
JCPenney’s new Lathrop facility is a marvel of logistics ingenuity. The system delivers a product accuracy rate of 99.9 percent. Operating at a 20 percent reduction in speed to move the same volume of throughput as compared to conventional systems means less wear on the system, less repairs, and a longer operational life. It also means reduced energy usage, and less maintenance – approaching a 70 percent reduction.

“This DC is performing exceptionally well,” continues Williams. “It is also very quiet, much quieter than any other sortaion system I have used before. We have had the system in place now for 15 months and it has had no difficulties. The system helps meet our business objectives serving our needs into the future.”

For distribution centers opting to operate at a lowered cost of ownership, the JCPenney Lathrop DC is certainly a model to emulate.

About Dematic Corp. - Based on a rich tradition of over 70 years of worldwide industry expertise in creating logistics results and more than 10,000 systems installed worldwide, Dematic Corp is the world’s leading supplier of logistics automation solutions, systems and service.

Beginning with Rapistan’s rich history from gravity conveyors to automated, modular conveyor and sortation solutions, Dematic now offers a full range of engineered and highly configurable system solutions that optimize warehousing and distribution operations. With Dematic, companies can reduce distribution costs, maximize overall logistics efficiencies, and increase the operating speed of their supply chain.

Dematic is a global company with operations in 22 countries around the world. Its North American headquarters is located in Grand Rapids, Michigan. For genuine Rapistan conveyor system parts, or more Dematic information, visit

Jim McMahon writes on logistics automation.

His feature stories have appeared in hundreds of industrial and high-tech publications throughout the world and are read by more than 5 million readers monthly.