Inductive proximity sensors in a welding environment face a variety of hazards. Hot metal particles – called weld spatter – are ejected from the welding process and can melt or burn their way through unprotected plastic sensor faces. Built-up weld spatter (often called weld slag) can eventually cause a sensor to trigger on falsely. If the slag can’t be removed, the sensor has to be replaced.
One solution to these issues is sensors made with tough ceramic faces. The ceramic face stands up to the hot weld spatter without melting, and doesn’t provide a good surface for slag adhesion. Even if slag does build up on a ceramic face, it can typically be removed during maintenance without the need for sensor replacement.
Sensors in a welding environment are also subjected to impacts from part loading. In the case of a ceramic-faced sensor, what happens if a ball of weld spatter is sitting on the face and then a heavy part is loaded on top of it? Could the ceramic face crack? Given enough force, it certainly could. But ceramic sensors can be designed to withstand a reasonable amount of force without damage.
This video demonstrates impact testing of a ceramic-faced sensor by a test weight having a ball-shaped tip. The ball-shaped tip simulates a ball of weld spatter sitting on the sensor face, which is suddenly impacted by a part being loaded on top of it. In this test, the ceramic face has sufficient resilience to withstand the impact without sustaining damage.