Assembly in Action: Sensors Improve Frame Welding Productivity
Dana Corp.'s Structural Solutions Division (St. Marys, Ontario) manufacturers frames for Ford Motor Co.'s (Dearborn, MI) F-150 truck line. Currently, Dana supplies frames for both the previous F-150 model on a replacement basis, and for Ford's 2004 F-150, which boasts a more rigid chassis than the previous model. In order to win and maintain these kinds of contracts, Dana has to produce high-quality frames at the lowest possible cost. That means no-defect frame welds that are precisely made at the fastest line rate achievable.
In past years, Dana has worked with Balluff Inc. (Florence, KY) to improve both the automated and manual welding operations that go into its production process. As part of that program, Balluff removed the system's original sensors and replaced them with 18-millimeter Proximax tubular-style sensors equipped with Duraplast-coated faces and Teflon-coated bodies. These sensors operate at a longer range and at higher temperatures, making them especially effective in harsh welding environments. They are also highly resistant to slag buildup.
Recently, Dana installed a new, completely automated production line to manufacture frames for the current F-150 model. Unfortunately, once the initial debugging process was complete and production was in full swing, it became evident that the frame weld function was not up to Dana's standards. As with the previous mixed-mode line, high temperatures, weld slag and physical contact with parts were taking a toll on the sensors originally specified and installed on the line-to the point where unplanned downtime rose dramatically because the sensors were prematurely failing.
To solve the problem, Glenn Rounds, maintenance general foreman at Dana's St Marys plant, installed a range of Balluff products that were better suited to the environment created by the line's welding stations.
For example, Dana installed a number of Factor 1 Q40 block-style proximity sensors, which operate at a greater range and allowed the company to move the sensors further away from the welding activity. By doing so, the company reduced the ambient heat and slag buildup that the sensors were exposed to, greatly reducing the sensors' failure rate. In addition, because they are weld field-immune, the Factor 1 sensors can operate in strong magnetic fields, such as those found in harsh welding environments.
Dana also installed a number of Teflon-coated Prox Mount mounting systems, which help combat slag buildup. Using this approach, the sensor is inserted within the mount and quickly locked into place with a plastic ring and metal nut. The resulting assembly is then adjusted as with any other inductive sensor. Because the outside surfaces of the mount are of Teflon, slag takes longer to build up, and even after it does, the sensors are easily removable over a much longer period of time without needing to physically remove the slag. The mounts also help the sensors withstand occasional frame contact as the line is operating.
"As a result of the Balluff sensor retrofit program on our new F-150 welding system, we have significantly better overall productivity on our entire frame line," Rounds says. "We're much more efficient now. There is much less unplanned downtime, which means less maintenance and service hours, and resulting overtime."
For more on weld-immune sensors visit www.balluff.com.