While flow meters typically are used to provide actual flow rate data as part of process control, AW-Lake was instrumental in the development of an innovative aircraft painting system that uses Coriolis flow technology to provide an early warning of depleted paint supplies to ensure system performance of an automated airframe painting process.
The automated painting system was a joint development by engineers and technicians at ABB Robotics and an OEM airframe manufacturer in which overhead cranes lower uncoated aircraft wings into two very long spray booths, then orients them end-to-end. A service booth is located in the middle of the spray booths. Two ABB six-axis robots are mounted on three-axis gangways that travel along the wings on either side. In addition to moving up or down, the robots swing out over the wing to provide complete access to all upper wing surfaces. The wing is mounted to elevators that raise or lower it so that the robots can have access to paint the bottom of the wings. Primer, color coats, and topcoat paint are applied while the other wing is being prepped in the second booth.
ABB was tasked to add additional colors and a method to detect air in the paint supply lines which occur just prior to running out of paint. Paint depletion during operations can result in an extreme expense in downtime to rework the wing. Several methods can detect the presence of air in a paint line, but none were compatible with Class I, Division 1, EX environments. That is when engineers at ABB reached out to AW-Lake Company for help.
AW-Lake Engineers Create Solution using TRICOR Coriolis Meters
AW-Lake application engineers proposed using their TRICOR Coriolis metering technology to detect the presence of air bubbles by monitoring the specific gravity of the paint. When the pressure vessel begins to run empty, a downward spike in specific gravity occurs as air is introduced into the paint stream. This serves as an early detection method to avoid over-agitation and out-of-paint conditions. In addition, the meter provides high-accuracy flow verification when used in conjunction with the servo driven paint gear pumps. This eliminates a manual flow calibration procedure, saving both paint and time. The system can now track paint usage by paint type and color for VOC compliance.
Flow Meters Interface with Wireless Telemetry System
Another innovation offered by AW flow meters was the integration of SignalFire Wireless Telemetry’s Modbus-to-Ethernet converter module so that the five flow meters associated with each robot are networked to a single high-speed wireless telemetry system.
This wireless solution eliminated thousands of feet of Ethernet wiring in the C1D1 EX area. Full diagnostics and meter configuration are possible from the safety of an overlooking control room.
AW-Lake enabled ABB to fulfill one aspect of their contract that no other solution offered – the ability to prevent paint defects from air bubbles in paint due to over agitation and/or running out of paint. This capability dramatically improves system quality and uptime. The Return on Investment of the flow meters was estimated to easily be less than one year, when considering costs from rework, paint pump calibration time, and process validation.
