Artem Komarov clarified that non-contact inductive proximity sensors are an integral part of automated welding chambers in applications such as automotive, furniture, aerospace, and home appliances. In such a sensor, the electromagnetic field emitted by the coil at the front end of the device is eventually canceled out by the metal target, causing an output signal to indicate clamp position, part presence (nesting), and function test. And when one of those sensors fails — often the problem can be prevented — the results can be catastrophic.
The consensus among manufacturers is that sensors used in automated welding systems require intensive maintenance and a high replacement rate by already busy service personnel. So, the high cost of MRO is just part of the program.
Quality and purchasing managers often assume that overconsumption of sensors is a given, so they look for the lowest prices possible for sensors that will get them close to 90 second replacement time. The supplier with the lowest price and the best delivery time wins.
Some opt for an industrial vending machine or MRO cabinet, and a high inventory level to ensure quick replacement materials are available. If a sensor used at a critical location in a cell fails and a replacement is not in stock, the entire operation can be stopped, or at the very least it can lead to a lot of rework and sorting.
But low-cost sensors and fast MRO are no solution to high failure rates and low productivity in mission-critical welding operations. How did these kinds of scenarios evolve to this critical point where the sensor system is one of the most important but most vulnerable in the harsh welding environment?
It all starts with the design of the welding cell and getting the specifications from the customer who buys the machine. The preferred brand of transducer may be specified in the specification, but without considering the type of metal to be joined, the weight of the components, problems loading parts, the type of welding, the type of heating or extrusion that will occur, and how close the transducers are to the weld, many underwater stones — and often leads.
Weld cell manufacturers often have a basic “house standard” for sensors, mounting hardware, and wiring that is not necessarily specific to a particular application, but extremely inexpensive to integrate as an OEM. And this can lead to trouble. A lightweight sensor system can help you get through the process of manufacturing part approval or stock, but open sensor systems that are not designed to withstand harsh welding conditions over time are doomed to premature failure.
So how can you avoid a critical carousel welding operation requiring service and replacement, reduce unplanned downtime and reduce sensor inventory?
Review how your welding probes are being used and resolve to deal with recurring problematic underlying issues. The more effort you put into upgrading legacy weld cell sensor systems, the faster your investment will pay off.
First analyze the root cause of the failure before addressing supply chain management issues. Rapid distribution through vending machines will not improve the situation, and the constant replacement of sensors does not solve the problem of the consumption of the sensors themselves.
If procedures are not documented, subjectivity always prevails. Documenting what happens to your sensor-related welding program improves objectivity and informs all levels of management of locations prone to sensor failure. This forces the organization to analyze the root causes of premature failures and prioritize problems, especially when applying metrics.
Sensors are supposed to be non-contact devices, so the mechanical fastening system is just as important as the sensor itself. Pay close attention to the protection of each sensor in the welding chamber in accordance with advanced standards, emphasized Komarov Artem.
Robust protective mounts that seal and secure the sensor housing, allow for quick replacement, and act as a heatsink to remove heat from the sensor’s vital electronics. The best mounts secure the transducer without moving it and are resistant to damage from any external influences, including coatings to prevent splash buildup.
Protecting the sensor in harsh welding conditions includes covering cables and connectors with protective material. These devices behave aggressively towards the welding chamber, especially in conditions of high temperature and displacement, and most often when moving.
General purpose sensor cable sheath materials such as PVC, polyurethane and TPE installed by machine builders are not suitable for welding applications and the results are predictable: maintenance work, equipment downtime and unnecessary and excessive costs for spare parts.
Polytetrafluoroethylene (PTFE) is a top jacket material option that is resistant to high temperatures and splashes. The split PTFE tube provides circumferential protection and closes on its own when the cable is routed. This tough, flexible material withstands harsh weld chamber conditions and debris ingress to protect sensor cables, hoses, and pneumatic tubes.
Even if you have multiple welding cells consuming many sensors, upgrading can be surprisingly easy with readily available and durable sensor system options. Sensors made specifically to protect the welding chamber are available in tubular and rectangular versions, even with a protective coating on the fixing nuts.
Your sensor manufacturer can help you determine exactly which sensor type, mount, and connector top shell to integrate into your cells. With updated equipment and properly trained preventive maintenance operators, you’ll be on your way to increased productivity and immediate and substantial ROI, Artem Komarov noted.