To keep pace with market demand and maintain its leadership position in the industry, Nintendo Co. sought to upgrade the conveyor and sorting system at its North Bend, WA facility. The old system's capacity limitations prevented it from keeping pace with market demand: the system couldn't handle smaller unit sizes, nor could it keep pace with the increased volumes associated with increased sales. As part of a complete system retrofit, the company relied on Rockwell Automation control components to provide the speed, efficiency, and flexibility needed for this critical system.
A leader in the creation of interactive entertainment, Nintendo Co., Ltd., of Kyoto, Japan has sold more than one billion video games worldwide. Nintendo manufactures and markets hardware and software for its popular home video game systems, including the Nintendo 64 and Game Boy, the world's best-selling hand-held video game system.
As a wholly-owned subsidiary, Nintendo of America Inc., based in Redmond, WA, serves as headquarters for Nintendo's North American operations. The North Bend, WA, plant is the only Nintendo-owned distribution facility in the U.S., so it is essential that the facility operate at peak performance to meet market demand for Nintendo products.
Nintendo's existing conveyor system was not meeting the distribution center's throughput requirements. Because the system was more than nine years old, it relied on older controller and conveyor technology that lacked the capabilities needed to enhance workflow and increase throughput capacity. For example, the aging sortation system couldn't accurately sort boxes under 12 inches in length, a critical issue given the industry's move to smaller unit boxes. In order to accommodate newer products, the distribution facility needed to be able to process boxes as small as six inches in length.
Overview of the Distribution Process
Nintendo video game systems are delivered to the North Bend facility already assembled, with several units packed in a carton. The units are then put away into the warehouse storage system until the orders are picked. Units are shipped both to customer distribution centers and retail outlets in full pallet, full case, and mixed case quantities. Direct-to-consumer shipments also are sent from the facility year-round, with a greater concentration of shipments occurring during the holiday season.
Full pallet shipments bypass the conveyor and sortation system and are delivered directly to the appropriate shipping lane. For full case and mixed case orders, as well as direct-to-consumer shipments, the individual boxes are placed on a conveyor and sorted by shipping service level to the appropriate "takeaway" lane for loading and delivery.
Implementing a New Conveyor System
To upgrade its aging sortation and conveyor system, Nintendo turned to material handling integrator R.H. Brown Co., Seattle, WA, who then teamed with Hytrol Conveyor Co., Jonesboro, AR, and Serra Systems, Healdsburg, CA, to engineer a retrofit of the sortation system to meet the growing demands for Nintendo products.
The engineering team was determined to deliver an upgraded control system capable of meeting their operating and efficiency goals. Since several Allen-Bradley products were already in use throughout the facility, Jerry Danson, Nintendo of America's equipment manager, requested that the new system be controlled by an Allen-Bradley programmable logic controller.
"Over the years we've come to rely on Allen-Bradley control products to make sure we keep pace with consumer demand," said Danson. "As the market has changed and demand has grown for smaller units and greater volumes, we knew Allen-Bradley products were the logical choice for our control system."
The engineers considered an Allen-Bradley SLC Series Programmable Logic Controller or an Allen-Bradley ControlLogix™5550 controller. After evaluating the existing system and the controller options available, the engineering team's first and most important decision was to design a new system retrofitted with the ControlLogix5550 controller.
"The typical scan time for the SLC controller in the new system would be about 20 to 30 milliseconds," said Don Winkle, engineering manager, Serra Systems. "To meet the demands of the new system, the scan times had to be less than 10 milliseconds. With its fast processing speed, the ControlLogix controller averages a scan time of 5-6 milliseconds in the new system."
While the SLC programmable controller is designed for a broad range of industrial application customers who want a small controller with high value, performance, functionality, robustness, and Allen-Bradley reliability and support, it is best suited for discrete and factory floor process applications. The ControlLogix controller has the high-end capacity needed to handle the speed and throughput requirements specified by Nintendo. The complexity of Nintendo's application and objectives made the system an ideal choice and well-suited for the robust capabilities of the ControlLogix controller.
"With the ControlLogix platform, we gain the flexibility to program every parameter possible and still remain within the 10 millisecond time window," Winkle said. "For the SLC to meet the necessary processing times, the programming would have to be cut, which translates into fewer application features."
Variable Gap Optimization Process Speeds Throughput
To increase throughput speeds, several obstacles had to be overcome. Products are often pulled in waves to fill orders going to the same retail store, and therefore are routed to the same takeaway lane. While the main conveyor system runs at 350 ft per minute, the takeaway lanes run at only 100 ft per minute. Without making alterations to the system, boxes would either build up in the takeaway lanes or need to be recirculated through the plant, slowing system throughput and impacting delivery times.
To meet these challenges, the engineering team implemented a Variable Gap Optimization (VGO) process designed to keep the system running smoothly. The VGO process speeds or slows the conveyor in order to optimally space adjacent boxes heading for the same takeaway lane. This maximizes sorter throughput and prevents backups from developing.
At the core of the system is the ControlLogix5550 controller's fast processing capability. The VGO scanner reads the barcode of an entering box. The ControlLogix controller processes the information and assigns the box to an appropriate takeaway lane. Simultaneously, the length of the box is measured, added to the accumulated total length (linear feet) for that lane and stored in the ControlLogix controller memory. The actual gap between one box and the next is also measured. The larger the accumulated length in a lane, the more space is created between one box and a subsequent box destined for the same lane. The process allows more time for the takeaway lane to empty, ensuring that the lane has the capacity to hold subsequent boxes. When the lane accumulator empties completely, the space between boxes is set at the minimum, and the conveyor operates at full speed.
To accomplish this process, an Allen-Bradley ControlLogix5500 controller is connected to an Allen-Bradley Ultra 200 Digital Servo Drive via an analog output module. The ControlLogix controller processes the information to determine the optimal gap and commands the servo drive to either speed or slow the conveyor. The fast processing time of the ControlLogix processor, combined with the rapid response time of the servo drive, allows the system to work efficiently and minimizes the conveyor length necessary to make these speed changes.
The VGO process also increases overall system throughput by minimizing recirculation of boxes. The recirculation lane is long, so a box that needs to be recirculated can spend a substantial amount of time making its way back through the system to the appropriate lane. If a truck is packed and waiting for part of the shipment to recirculate, overall throughput can be affected significantly. In addition, the VGO process prevents the sorter from jamming and the takeaway lanes from overfilling.
Directing the Boxes to the Appropriate Shipping Lane
Once the boxes are placed on the conveyor with optimal spacing, they head to the next stage -- the shipping induction point -- for sorting. Using an Allen-Bradley PanelView™550 interface, operators assign destinations (takeaway lanes) to the bar codes stored in the ControlLogix controller. Omni-directional scanners read the label on the box, and the ControlLogix controller processes the information. Based on the information programmed via the PanelView, ControlLogix directs the box to the appropriate takeaway lane. The boxes are then loaded onto trucks and shipped to the designated retailer.
ControlLogix Multi-Vendor Interface Module Makes Device Connection Simple
To connect the scanners to the ControlLogix controller, the new system uses a ControlLogix Multi-Vendor Interface Module (MVI). The alternative to the MVI Module is an SLC BASIC Module. The MVI Module, with three ports, represents a key upgrade from the BASIC Module, which has only one port. The six scanners (three at the VGO process and three at the shipping induction point) are connected to two ports. With the capacity to store a small amount of code written in C programming language, the MVI cards can complete minor processing functions before presenting the information to the ControlLogix controller to process and evaluate.
The third port is used as a host interface, directly connecting ControlLogix5550 to the AS/400 Warehouse Management System (WMS). This enables a checks and balances system: ControlLogix sends divert verification messages to the WMS to notify the WMS that the cartons have been switched to "diverted status." All connections are made via RS232 protocol links.
Because of the programming capability of the MVI card, the system achieves substantial speed enhancements. Other benefits include a significantly minimized footprint. With the BASIC Module, Nintendo would have had to install two additional cards to the rack. Doing so would require extending the rack, taking up valuable electrical enclosure space. Using the BASIC Module also would require more power, software and maintenance, as there would be three modules instead of one to achieve the same results as those generated by using the MVI module.
Diagnostics and Troubleshooting Made Easy
The ControlLogix controller is programmed using the RSLogix5000 programming software. The RSLogix family incorporates superior diagnostics, reliable communications, an intuitive user interface and enhanced reporting options to help maximize performance and reduce development time.
"It's one of the best development environments out there," Winkle said. "It's easy to install, stable and intuitive."
RSLogix5000 also uses a Microsoft ActiveX control, TrendX™. TrendX allows users to integrate the programming software with an HMI software package such as Rockwell Software RSView32 to monitor real-time data and provide historical trending from HMI data.
"It (RSTrendX) is one of the best features of RSLogix," Winkle said. "You can run a histogram to see the internal workings of the ControlLogix controller. RSTrendX allows you to compare historical data to current data, and the troubleshooting capabilities of that feature are enormous."
Direct Remote Access Simplifies Updates and Speeds Troubleshooting
Serra Systems now has direct remote access to the system at the Nintendo facility. This allows the engineers at Serra Systems to accomplish changes or enhancements over the phone line, greatly simplifying system updates and troubleshooting.
"Direct remote access is a valuable timesaver when it comes to troubleshooting," Winkle said. "If they have a problem with the system, technicians may have to troubleshoot for a couple hours to find the problem. We know the system so thoroughly that we can often pinpoint a problem very quickly. For example, something as simple as someone unknowingly changing the parameters on the HMI could cause minor problems. Internally, they may not notice the change, but we would notice it because we know what the parameters should be."
Increasing System Throughput
The Nintendo distribution facility met its goals for the conveyor and sorting system upgrade. On average, the new conveyor system runs just slightly faster than the previous system. However, with the high delivery accuracy and low rate of product recirculation attributable to the VGO process, throughput has increased from about 80 cases per minute to about 150 cases per minute. While the old system couldn't handle boxes less than 12 inches in length, the new system can accurately sort and move boxes as small as six inches in length, routinely handling boxes in the six- to nine-inch range. With throughputs also significantly increased, Nintendo is pleased with the new system.
"The new conveyor and sorting system has allowed Nintendo to accurately and effectively expand their sorting capabilities," Winkle said. "It also has enabled them to nearly double their throughput to meet the increasing market demand for Nintendo products."
ControlLogix, PanelView, and RSLogix are trademarks of Rockwell Automation. Microsoft ActiveX and TrendX are registered trademarks of the Microsoft Corporation.
