Don't let capacity limitations keep you from meeting market demand.

Nintendo Enhances Performance of its Conveyor Sortation System

Nintendo's High-Speed Sorter Utilizes Logix Solution Control Products From Rockwell Automation to Increase Speed and Boost Throughput by more than 85 Percent

In order to keep pace with market demand and maintain its leadership position in the industry, Nintendo Co. sought to upgrade its conveyor and sorting system at its North Bend, Wash., facility. The old system had capacity limitations that 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 a control and information system solution approach from Rockwell Automation to provide the speed, efficiency and flexibility needed for this critical system.

Background

Nintendo Co., Ltd., of Kyoto, Japan, is the acknowledged worldwide leader in the creation of interactive entertainment and has sold more than one billion video games worldwide. Nintendo video game systems are delivered to the North Bend distribution facility already assembled with several units packed in a carton. After arrival the units are 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. 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.

Challenge

Nintendo's existing conveyor system was not meeting the distribution center's throughput and work flow requirements. The aging 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, Nintendo needed to expand the capabilities of the facility to process boxes as small as six inches in length. An upgrade would enable the system to run faster and more efficiently.

Solution

To upgrade its aging sortation and conveyor system, Nintendo turned to Material Handling Integrator R.H. Brown Co., Seattle, Wash., who then teamed with Serra Systems, Healdsburg, Calif., to engineer a retrofit of the sortation system which would 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. Nintendo has come to rely on Rockwell Automation to deliver Quality, support and tightly integrated control systems. Because of this, Jerry Danson, equipment manager, Nintendo of America, requested 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 Control-Logix™ 5550 controller. After evaluating the existing system and the controller options available, one of the engineering team's most important decisions was to design a new system retrofitted with the Allen-Bradley ControlLogix controller. To meet the demands of the new system, the selected processor needed a scan time of less than 10 milliseconds. With its fast processing speed, the ControlLogix averages a scan time of 5-6 milliseconds in the new system.

Results

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 feet per minute, the takeaway lanes run at only 100 feet per minute. Without making alterations to the system, boxes would either build up in the takeaway lanes or need to be re-circulated through the plant, slowing system throughput and impacting delivery times. Given these challenges, the engineering team developed a solution that would eliminate backups in the takeaway lanes.

A new process improves throughput

They implemented a Variable Gap Optimization (VGO) process designed to keep the system running smoothly. For example, 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 fast processing capability of the ControlLogix. The VGO scanner reads the barcode of an entering box. The ControlLogix 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 for that lane and stored in the ControlLogix memory. The actual gap between one box and the next box 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. This 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 completely empties, the space between boxes is set at the minimum, and the conveyor operates at full speed.

To accomplish this process, a ControlLogix is connected to an Allen-Bradley Ultra 200 Digital Servo Drive via an analog output module. The ControlLogix 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, combined with the rapid response time of the servo drive, allows the system to work efficiently and minimizes the amount of conveyor length necessary to make these speed changes.

The VGO process also increases overall system throughput by minimizing the recirculation of boxes. To accommodate the previous sorter and control system, the recirculation lane is long. If a box needs to be recirculated, it can take a substantial amount of time to make its way back through the system and down the appropriate lane. In a scenario where 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 in optimal spacing measurements, the boxes head to the next stage of the system — the shipping induction point where the boxes are sorted. Using an Allen-Bradley PanelView 550 interface, operators assign destinations (takeaway lanes) to the bar codes that are stored in the ControlLogix. Omni-directional scanners read the label on the box, and the ControlLogix processes the information. Based on the information from 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, the new system uses a ControlLogix Multi-Vendor Interface Module (MVI). 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 to process and evaluate. The third port is used as a host interface, directly connecting ControlLogix 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.

Diagnostics and Troubleshooting Made Easy

The ControlLogix is programmed using the RSLogix 5000 programming software. RSLogix incorporates superior diagnostics, reliable communications, an intuitive user interface and enhanced reporting options to help maximize performance and reduce development time. RSLogix 5000 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. RSTrendX allows you to compare historical data to current data providing troubleshooting capabilities.

Direct Remote Access Simplifies Updates and Speeds Troubleshooting

Troubleshooting can now occur at the Nintendo facility via direct remote access. This allows the engineers at remote locations to accomplish changes or enhancements over the phone line, greatly simplifying system updates and troubleshooting in a timesaving manner.

Increasing System Throughput

The Nintendo distribution facility met its goals with the upgrade of the conveyor and sorting system. 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, the 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."