Hawker XFC batteries from EnerSys are being used in a new project with automated guided vehicles (AGVs) manufactured by JBT Corporation for handling print reels and other loads at a commercial printing plant in Sheffield, UK. The Hawker XFC units were chosen by JBT Corporation because of the batteries’ compact size/shape, heavy duty performance, and quick/on-demand charging, without the need for maintenance. These features enabled the batteries to be integrated into the JBT Corporation AGVs and deliver efficient, round-the-clock operation.
AGVs are battery powered, computer controlled vehicles which operate unmanned to complete routine material movements in production plants and warehouses. There is a certain level of customization in AGVs because they are typically designed for the requirements of the specific material handling application (e.g. load weight, load dimensions, aisle width, pick up points, drop off points, hours of operation, etc.). In analyzing the specific application, AGV engineers design the AGV to safely support and move each load type while maximizing the amount of time each AGV is available to do work. To maximize AGV availability, the optimum mix of battery capacity, battery size, battery weight and battery charge frequency/time is required. This allows the operational needs of the application to be met by the minimum number of AGVs.
The equipment required by the printing plant in Sheffield is a good example of what is required in this design process. The customer produces magazines and other items for newspaper colour supplements which are wound spirally onto large, two metre diameter reels as they are printed. They wanted an automated method of moving these reels between the printing, assembly and packing areas. Each reel typically holds thousands of magazines and weighs up to 1400kg. The plant operates around the clock and the customer needed equipment that could operate almost continuously to ensure it could meet the demanding service commitments.
After assessing the flow of materials that were required to support efficient plant operation, JBT Corporation designed an AGV that would safely pick up and deliver the required loads. The existing infrastructure at the plant dictated some of the design parameters such as the maximum length and width of the AGVs. Factors such as weight and size of the loads and the need to install and access safety sensors and guidance equipment were also critical considerations. The batteries provide some of the weight that counterbalances the load but the vehicle design had only a limited amount of space on the vehicle available for the battery.
The shape and size of the compact Hawker XFC battery unit offered several advantages compared to other battery technologies. Each XFC battery is approximately 30 per cent smaller than comparable conventional units with the added advantage that it can be placed in any orientation, including upright, on its side or on its end because the dry gel electrolyte will not leak. These features allowed use of a compact and efficient battery pack made up of 12 smaller battery units in various orientations on three layers to make the most efficient use of the available battery compartment space and achieve the required 48V, 530A capacity needed.
Another critical consideration in the choice of the Hawker XFC battery was its performance in use. The AGVs are designed for almost continuous operations and battery changing or swapping – which is sometimes used on AGVs – was not preferred by the customer. The XFC battery delivers maximum performance because it stores around 30 per cent more charge than conventional units which extends the amount of time the AGV can operate before recharging. The XFC battery can be charged from around 60 per cent discharge to full capacity in under three hours when used with a Hawker Lifetech high frequency charger. This combination of battery and charger also supports intermittent or opportunity charging with shorter but more frequent charge periods – and this does not adversely affect battery performance or lifetime. It was this opportunity charging method that was utilized in this application so that the AGVs are charged for a few minutes whenever they are not being used. The AGVs are automatically commanded to navigate to one of the automatic charging points distributed throughout the site. In this way the batteries and chargers can support nearly continuous AGV operation 24 x 7.
Another attractive feature of the XFC battery is its maintenance-free and no-gassing performance. Since one of the primary goals of installing an AGV system is to increase personnel productivity, maintenance-free batteries are often preferred by customers. And typically when a standard battery is charged, it gives off gasses that must be vented from confined areas. No gassing means the AGV can be used in confined areas without the need for special venting equipment at the charging stations.
Ten AGVs were integrated by JBT Corporation into this printing customer’s operations. An on-board laser-based guidance system keeps the AGVs on the predetermined paths. The position of each AGV is also communicated to an on-site management control system so that operation of the fleet of AGVs can be continually optimized. Obstacle detection on the AGVs is supplied by additional laser based sensors which bring the AGV to a safe stop before it contacts any obstacle that might be in the AGV’s path. JBT Corporation’s laser guided AGV systems are very flexible and scalable and as the movement of materials in the printing plant grows and changes in the future, the AGV system can quickly be reconfigured and expanded to support the new requirements.