When the topic of welding comes up we know that our application is going to be more challenging for sensor selection. Today’s weld cells typically found in tier 1 and tier 2 automotive plants are known to have hostile environments that the standard sensor cannot withstand and can fail regularly. There are many sensor offerings that are designed for welding including special features like Weld Field Immune Circuitry, High Temperature Weld Spatter Coatings and SteelFace Housings.
For this SENSORTECH topic I would like to review Weld Field Immune (WFI) sensors. Many welding application areas can generate strong magnetic fields. When this magnetic field is present a typical standard sensor cannot tolerate the magnetic field and is subject to intermittent behavior that can cause unnecessary downtime by providing a false signal when there is no target present. WFI sensors have special filtering properties with robust circuitry that will enable them to withstand the influence of strong magnetic fields.
WFI sensors are typically needed at the weld gun side of the welding procedure when MIG welding is performed. This location is subject to Arc Blow that can cause a strong magnetic field at the weld wire tip location. This is the hottest location in the weld cell and typically there is an Inductive Sensor located at the end of this weld tooling.
So as you can see if a WFI sensor is not selected where there is a magnetic field present it can cause multiple cycle time problems and unnecessary downtime. For more information on WFI sensors click here.
Sensors in welding cells are subject to failure because, although they are intended to be non-contact devices, they tend to be located directly in the middle of the welding process. Conditions such as damage by direct mechanical impact, erosion by hot welding slag, false tripping by accumulated slag, and high intermittent heat cause conventional sensors to fail at an excessive rate. In a previous blog post we discussed our three-step protection process.
Properly bunkering and protecting sensors will prolong their service life and reduce downtime. Ideally, this strategy is implemented during the design and construction of the weld cell by the equipment builder in response to buyer demands for increased process reliability. But what about currently existing production equipment that originally was built to a lower standard that is plagued with issues? It can be very difficult for a plant to find the time and personnel resources to go back and address problematic applications with better sensor mounting solutions. The job of retrofitting an entire weld cell with proper sensor protection can take two experienced people up to eight hours or more.
Continue reading “Sensors Reduce Downtime in Welding Applications”
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.
Continue reading “Ceramic-faced Sensors Stand up to Welding Processes”