Everyone is looking for quick tricks of the trade. Sensor failure can prove to be costly in any environment. One of the easiest ways to avoid unnecessary downtime would be to add a mounting bracket plus prox mount to the machine to extend the life of a sensor.
What is a prox mount?
It has a quick release tube mounted into a tubular bracket to change out a sensor easily. The sensor is assembled into the prox mount tube and locked into place with a compression ring and metal nut. The prox mount and sensor assembly is then mounted and adjusted as with any tubular sensor, but the prox mount will remain in place on future sensor replacement tasks.
Mounting accessories are geared toward extending sensor performance in harsh industrial conditions involving chemical attack, debris accumulation, shock/vibration/impact, and high temperatures. The brackets act as protection, as well as mounting for the sensor to extend the life of the sensor. Adding a prox mount to it add another layer of protection as well as reducing down time due to the quick release to change a sensor.
Mounting brackets are a simple solution to decrease installation costs by screwing in the bracket on the machine. They are also prolonging sensor life expectancy by giving it an added layer of protection. Add in the prox mount for a faster option to reduce unplanned downtime with the quick release of the sensors. This helps increase the overall performance and utility of sensors.
Every time I enter tier 1 and tier 2 suppliers, there seems to be a common theme of extreme sensor and cable abuse. It is not uncommon to see a box or bin of damaged sensors along with connection cables that have extreme burn-through due to extreme heat usually generated by weld spatter. This abuse is going to happen and is unavoidable in most cases. The only option to combat these hostile environments is to select the correct components, such as bunker blocks, protective mounts, and high temperature cable materials that can withstand hot welding applications.
In many cases I have seen standard sensors and cables installed in a weld cell with essentially zero protection of the sensor. This results in a very non-productive application that simply cannot meet production demands due to excessive downtime. At the root of this downtime you will typically find sensor and cable failure. These problems can only go on for so long before a culture change must happen throughout a manufacturing or production plant as there is too much overtime resulting in added cost and less efficiency. I call this the “pay me now or pay me later” analogy.
Below are some simple yet effective ways to improve sensor and cable life:
Whether it’s through preventative maintenance or during planned machine downtime, reducing downtime is a common goal for manufacturers. Difficult environments create challenges for not just machines, but also the components like sensors or cables. Below are three tips to help protect these components and reduce your downtime.
Cables don’t last forever. However, they are important for operations and keeping them functional is vital. An easy way to help reduce downtime and save money is by implementing a “sacrificial cable” in unforgiving environments. A sacrificial cable is any cable less than two meters in length and placed in situations where there is high turnover of cables. This sacrificial cable does not have to be a specialty cable with a custom jacket. It can be a simple 1 meter PVC cable that will get changed out often. The idea is to place a sacrificial cable in a problematic area and connect it to a longer length cable, or a home-run cable. The benefits of this method include: less downtime for maintenance when changing out failures, reduced expenses since shorter cables are less expensive, and there is less travel for the cable around a cell.
A second way to help reduce downtime is consider your application conditions up front. We discussed some of the application conditions to consider in a previous blog post, but how can we address these challenges? Not only is it important to choose the correct sensor for the environment, but remember, cables don’t last forever. Choosing the appropriate cable is also key to reducing downtime. Welding environments demand a cable that weld beads will not stick to and fuse the cable to the sensor. There are a variety of jacket types like silicone, silicone tube, or PTFE that prevent weld debris from accumulating on the cable. I’ve also seen applications where there is a lot of debris cutting through cables. In this case, a stainless steel braid cable would be a better solution than a traditional cable. Fitting the right protection to the right application is crucial..
A third tip to help reduce your machine downtime is to simply add protection to your existing components. Adding protection, whether it is a protective bracket or a silicone product, will help keep components running longer. This type of protection can be added before or after the cell is operational. One example of sensor protection is adding a ceramic cap to protect the face of a sensor. You can also protect the connection by adding tubing to the cable out version of the sensor to shield it from debris. Mounting sensors in a robust bracket helps protect the sensor from being hit, or having debris cover the sensor. There are different degrees of changes that help prolong operations.
Metalforming expert, Dave Bird, explains some of these solutions in the video below. To learn more you can also visit our website at www.balluff.us.
In any continuous manufacturing process such as steel production, increased throughput is the path to higher profits through maximum utilization of fixed capital investments. In order to achieve increased throughput, more sophisticated control systems are being deployed. These systems enable ever-higher levels of automation but can present new challenges in terms of managing system reliability. Maintenance of profit margins depends on the line remaining in production with minimal unexpected downtime.
It is essential that control components, such as sensors, be selected in accordance with the rigorous demands of steel industry applications. Standard sensors intended for use in more benign manufacturing environments are often not suitable for the steel industry and may not deliver dependable service life.
When specifying sensors for steel production applications, some environmental conditions to consider include:
High temperatures exist in many areas of the steel-making process, such as the coke oven battery, blast furnace, electric arc furnace, oxygen converter, continuous casting line, and hot rolling line. Electronic components are stressed by elevated temperatures and can fail at much higher rates than they would at room temperature. Heat can affect sensors through conduction (direct transfer from the mounting), convection (circulating hot air), or radiation (line-of-sight infrared heating at a distance). The first strategy is to install sensors in ways that minimize exposure to these three thermal mechanisms. The second line of defense is to select sensors with extended temperature ratings. Many standard sensors can operate up to 185° F (85° C) but high temperature versions can operate to 212° F (100° C) or higher. Extreme temperature sensors can operate to 320° F (160° C) or even 356° F (180° C).
Don’t forget to consider the temperature rating of any quick-disconnect cables that will be used with the sensors. Many standard cable materials will melt or break down quickly at higher temperatures. Fiberglass-jacketed cables, for example, are rated to 752° F (400° C).
Shock and Vibration
Steel making involves large forces and heavy loads that generate substantial amounts of shock under normal and/or abnormal conditions. Vibration is also ever-present from motors, rollers, and moving materials. As with heat, look for sensors with enhanced specifications for shock and vibration. For sensors with fixed mountings, look for shock ratings of at least 30 G. For sensors mounted to equipment that is moving (for example, position sensors on hydraulic cylinders), consider sensors with shock ratings of 100 to 150 G. For vibration, the statement of specifications can vary. For example, it may be stated as a frequency and amplitude, such as 55 Hz @ 1 mm or as acceleration over a frequency range, such as 20 G from 10…2000 Hz.
Don’t forget that the quick-disconnect connector can sometimes be a vulnerability under severe shock. Combat broken connectors with so-called “pigtail” or “inline” connectors that have a flexible cable coming out of the sensor that goes to a quick-disconnect a few inches or feet away.
The best way to protect sensors from mechanical impact is to install them in protective mounting brackets (a.k.a. “bunker blocks”) or to provide heavy-duty covers over them. When direct contact with the sensor cannot be avoided, choose sensors specifically designed to handle impact.
Another strategy is to use remote sensor actuation to detect objects without making physical contact with the sensor itself.
Corrosion and Liquid Ingress
In areas with water spray and steam, such as the scale cracker on a hot strip line, corrosion and liquid ingress can lead to sensor failure. Look for stainless steel construction (aluminum can corrode) and enhanced ingress protection ratings such as IP68 or IP69K.
When All Else Fails…Rapid Replacement
If and when a sensor failure inevitably occurs, choose products and accessories that can minimize the downtime by speeding up the time required for replacement.
Strategies include quick-change sensor mounts, rapid-replacement sensor modules, and redundant sensor outputs.
In the case of redundant sensor outputs, if the primary output fails, the system can continue to operate from the secondary or even tertiary output.
Recently I came across this link on control engineering’s website and I just had to share it. They have created an app that organizes and summarizes all the available useful apps for an engineer on the go. From Autocad/Solidworks reference tools to basics on engineering topics to standards document references they have collected the perfect library for you to find the tools you need and maybe didn’t know existed. And in the long run I think the goal is to make us more productive, even when sitting in baggage claim waiting for our toolbox. As for me, I can’t wait until April when I can trade in my blackberry and get my iphone to give this app a spin.
Take a look at their offering, let me know what you think. What apps are you using today for your designs? What apps do you wish were out there for engineers? Which apps should I download first?
Correspondingly tiny mounting brackets = inherently low mass
Totally self-contained electronics = zero space taken up by separate amplifier
Miniaturization of sensors allows no-compromise installation in compact tooling
Additional tooling sensors enhance the level of high-end machine automation/control that can be achieved
Stay tuned to this space for more precision sensing challenges and solutions. Miniaturized sensors are also available in photoelectric, capacitive, magnetic cylinder, ultrasonic, and magnetic encoder. Click here to see the whole mini family.
Plural of Giz-mo. A noun. Defined as a gadget, one whose name the speaker does not know. Customers call us and ask for this or that “gizmo” all the time! I think we should consider creating a product category simply called “GIZMOS”.
I like to call these things “Enablers” because these devices are very much helping hands that optimize the function of sensors. A sensor of any brand and manufacturer performs only as well as it’s mounted, matching the fixture to the demands of the application at hand. But how often does this happen in a price-driven world? They often end up in below-par mounting that fails with regularity, in both pristine environments as well as in hostile environments. Some examples:
Here’s one example below. These inductive proximity sensors in plastic brackets, showing an exposed coil on one, with corroded mounts on the sensor caused by being beaten to death during parts loading and heat.
With a few “Gizmos” like an application-specific quick change mount, some care in gapping the sensor and guarding the cable/connector system, it could look much different. Check out the examples below.
Photoelectric sensors can suffer the same fate. In this case, a plastic bodied photoelectric sensor, originally used to replace a fiber optic thru beam pair also suffered abuse. With a little extra beefy mounting, these photoelectric sensors can be expected to last a long time without failure.
When installing sensors into a harsh environment, for example a weld cell application, protecting the sensor is a crucial step in the installation process. These sensors are exposed to extreme heat, weld slag and sometimes impact. In order to reduce sensor usage, the sensor needs to be protected from the harsh area of exposure. This can be achieved by using a complete sensor protection method that includes proper sensor selection such as sensors that have a weld slag resistant coating, proper mounting and cable protection. If you follow these steps the end result will be longer sensor life.
Identify form factor (size of sensor)
Output polarity (DC 3wire PNP, NPN etc.)
Identify special sensor characteristics (Slag resistant coating, SteelFace, F1 etc.)
Select your mechanical protection system (ProxMount etc.)
WeldRepel tubing and wrap
So, by simply implementing the three step total solution into your harsh or extreme application you can protect and lengthen the life of the sensors and cables providing less downtime. For more information on the total solution, check out this whitepaper on Increasing Sensor Life and Production Productivity.
I recently had the opportunity to attend Hannover Fair in Germany and was blown away by the experience… buildings upon buildings of automation companies doing amazing things and helping us build our products faster, smarter and cheaper. One shining topic for me at the fair was the continued growth of new products being developed with IO-Link communications in them.
All in all, the growth of IO-Link products is being driven by the need of customers to know more about their facility, their process and their production. IO-Link devices are intelligent and utilize a master device to communicate their specific information over an industrial network back to the controller. To learn more about IO-Link, read my previous entry, 5 Things You Need to Know about IO-Link.
“Downtime” is never a good word in any manufacturing facility. It means something has malfunctioned or broken, parts are not being made, production is reduced, and money is being lost. In some cases this downtime may be caused by a physically damaged inductive proximity sensor. If this failure mode is happening on a regular basis to the same location, it may be time to look at the advantages a prox mount can provide.