Save a fortune in unplanned machine down time
By Dave Bird, Business Development Manager, Balluff
 Not many welding sensor locations fall in the continuous -20° to 70°C operating range or avoid weld spatter. |
In weld cells across the country a wide variety of sensors from various manufacturers are used to indicate clamping position, parts presence (nesting), and feature validation in different welding scenarios both in and outside of the automotive industry.
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Many agricultural, HVAC, furniture, medical, aerospace and appliance manufacturers who form and weld metal components all live in an unfortunate paradigm.
The paradigm is the general acceptance by a manufacturer that “…sensor systems used in welding applications require intensive maintenance and high rates of replacement. High MRO costs are simply part of the program.”
We’ve had quality managers from a varied industry base call and say, “I need the lowest possible price for these five-to-six “high runner” sensor models from your company. If I can’t get my arms around solving the problem of excessive sensor consumption, then I might as well hunt for the lowest possible price while we work towards a sensor change out time to under the thirty-seconds. The guy with the lowest price and best delivery wins.”
Cheap sensors and fast MRO delivery is not the answer to lower cost and high productivity in a critical welding operation.
How did these kinds of scenarios evolve to this point?
It begins with weld cell design and/or specification from the customer buying that machine.
A preferred brand of sensor might be specified in the Bill of Material, but unless a great deal of thought goes into the type of metal being joined, the weight of components, parts loading issues, the kind of welding being done (MIG, TIG, laser, resistance, etc.), and where or how close sensors are located in proximity to the weld, many pitfalls can result.
Often weld cell manufacturers have a basic “house standard” for sensors, mounting hardware, and connectivity that’s not necessarily application specific (for example, general application sensors mounted in lightweight plastic cuff mounts), but extremely inexpensive to integrate on the OEM level.
If so, you’re in for trouble. A lightweight sensor system might get you through PPAP or runoff, but exposed sensor systems that aren’t designed to withstand the rigors of robust manufacturing like welding are destined for premature failure from day one.
Inductive proximity sensors are generally designed to function for more than 100,000 hours when used under manufacturer’s stated conditions, but how many welding sensor locations fall in the continuous -20° to 70°C operating range or avoid weld spatter, heavy impact, elevated ambient and burst temperature extremes due to the weld process? Not to mention flex on connectors that cause premature failure – especially if the exit geometry isn’t done properly – and slag accumulation.
So how can a critical welding operation get off the high maintenance/high replacement merry-go-round?
Here’s the roadmap to complete reversal of the Weld Cell paradigm, dramatically decreasing unplanned machine down time, reducing the number of required sensor replacements in inventory, and substantially increasing profit for your organization:
- Re-examine how your welding sensors are being used and make a commitment to get your arms around the core issues. Rapid ROI can be realized and is in direct proportion to the level of commitment to upgrade those weld cell sensor systems.
- Analyze Root Cause of Failure first before attacking supply-chain management issues. Rapid dispensing through vending machines merely band aids the situation and constantly replacing sensors does not address sensor consumption itself.
Audit Your Welding Sensor System, Cell By Cell
 Your sensor supplier can help you audit your sensor “hot spots” point-by-point in every welding cell, a complete report can be generated which establishes the road map for beginning a sensor system upgrade. |
Unless procedures are documented, subjectivity always prevails; documentation of what’s going on with your sensor-related welding program turns subjectivity into objective thinking and makes all levels of management in the organization aware of heavy sensor failure-prone locations and forces the organization to analyze the root causes of premature failure and which problem to focus on first.
Your sensor supplier can help you audit your sensor “hot spots” point-by-point in every welding cell, a complete report can be generated which establishes the road map for beginning a sensor system upgrade.
Bunker All Inductive Proximity Sensors
Sensors are supposed to be non-contact devices. Heavy protective steel and/or nickel-plated brass mounts that encapsulate the sensor body provide a means of rapid change-out and act as a heat sink to dissipate heat away from vital sensor electronics.
They can also guarantee proper gapping between the sensor face and the target. The mechanical mounting is as important as the sensor itself.
Choose the most appropriate application-specific sensor for each location in the cell. Pay close attention to protecting each and every sensor in you weld cell.
Use The Most Robust Sensor Connector Jacketing Material
TPE (thermoplastic elastomer) connector jacketing material provides a high level of flex, heat, weld slag and nick resistance yet strips like PVC.
 When the cables exit in a sharp right angle towards the J-box or MIB under heat, flex and stress, the connector will always prematurely break at the strain relief. |
Follow Proper Exit Geometry
Most OEM weld equipment integrates only one style of sensor connector – a straight version. When the cables exit in a sharp right angle towards the J-box or MIB under heat, flex and stress, the connector will always prematurely break at the strain relief.
Your upgrade to right angle sensor connectors will ensure long life. Add bright status and power LED’s to your connector selection; in a dark cell these provide a means of quick check by maintenance people, making their sensor function checks faster and easier.
Protect All Connectors With Silicone Over-Jacketing
This silicone material guards the effects of weld slag and spatter. Spatter bounces off and refuses to stick to its surface; even molten aluminum doesn’t bother it.
This material is available in large sheets in order to deflect weld berries in large surface area situations against attack on valve banks, large collections of cables, air lines, hydraulic lines, exposed end effectors on robots and weld pedestals.
Seal & Guard Your Entire Weld Sensor System
Fine weld spray can find its way in the tiniest of spots, especially in openings of the silicone over-jacketing. Sealing with clear self-fusing wrap (which allows LED to be seen), paying attention to detail, and anticipating where weld debris will concentrate, the system becomes even stronger and more robust.
Start A Preventative Maintenance Training Program
Training will ensure that your newly upgraded system will be maintained properly and guarantee continued positive performance. Conducting a pro-active PM on the system makes everyone aware of such things as how to repair nicked over-jacketing, and keeps people abreast of Industry’s Best Practices which continually evolve. Continuous Improvement never ends.
Add Metrics To The System Upgrade
 Sealing with clear self-fusing wrap (which allows LED to be seen), paying attention to detail, and anticipating where weld debris will concentrate, the system becomes even stronger and more robust. |
Corporate management needs to know how much money is saved through the weld cell upgrade. In most instances, hundreds of thousands of dollars in reduced unplanned machine down time in one or two major weld cells can be realized within the first 12 months. When material replacement cost savings are added into the mix, the results are always staggering.
Involve Your Sensor Manufacturer Rep
That representative consulting with your own staff can come to a conclusion as to exactly what sensor type (point-by-point), what protective heavy duty mounting and what type of connector with over-jacketing – properly sealed to the maximum – should be integrated into the new machine build to minimize the risk of falling back into the Weld Cell Paradigm again.
All of these solutions are off-the-shelf, readily available, and at your disposal. Even if you have multiple, high sensor system consumption welding cells, the upgrades can be surprisingly simple and can be methodically, systematically, and transparently transformed into high productivity units, that produce immediate substantial ROI.
For more information, see www.balluff.com