Distance Measurement with Inductive Sensors

When we think about inductive sensors we automatically refer to discrete output offerings that detect the presence of ferrous materials. This can be a production part or an integrated part of the machine to simply determine position. Inductive sensors have been around for a long time, and there will always be a need for them in automated assembly lines, weld cells and stamping presses.

We often come across applications where we need an analog output at short range that needs to detect ferrous materials. This is an ideal application for an analog inductive proximity sensor that can offer an analog voltage or analog current output. This can reliably measure or error proof different product features such as varying shapes and sizes. Analog inductive sensors are pure analog devices that maintain a very good resolution with a high repeat accuracy. Similar to standard inductive sensors, they deal very well with vibration, commonly found in robust applications. Analog inductive proximity sensors are also offered in many form factors from M12-M30 tubular housings, rectangular block style and flat housings. They can also be selected to have flush or non-flush mounting features to accommodate specific operating distances needed in various applications.

Application Examples:

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For more specific information on analog inductive sensors visit www.balluff.com.

Where Did You Find That Sensor?

I recently visited a customer that has a large amount of assembly lines where they have several machine builders manufacturing assembly process lines to their specification. This assembly plant has three different business units and unfortunately, they do not communicate very well with each other. Digging deeper into their error proofing solutions, we found an enormous amount of sensors and cables that could perform the same function, however they mandated different part numbers. This situation was making it very difficult for maintenance employees and machine operators to select the best sensor for the application at hand due to redundancy with their sensor inventory.

The customer had four different types of M08 Inductive Proximity sensors that all had the same operating specifications with different mechanical specifications. For example, one sensor had a 2mm shorter housing than one of the others in inventory. These 2mm would hardly have an effect when installed into an application 99% of the time. The customer also had other business units using NPN output polarity VS PNP polarity making it even more difficult to select the correct sensor and in some situations adding even more downtime when the employee tried to replace an NPN sensor where a PNP offering was needed. As we all know, the NPN sensor looks identical to the PNP offering just by looking at it. One would have to really understand the part number breakdown when selecting the sensor, and when a machine is down this sometimes can be overlooked. This is why it is so important to standardize on sensor selection when possible. This will result in more organized inventory by reducing part numbers, reducing efforts from purchasing and more importantly offering less confusion for the maintenance personel that keep production running.

Below are five examples of M08 Inductive sensors that all have the same operating specifications. You will notice the difference in housing lengths and connection types. You can see that there can be some confusion when selecting the best one for a broad range of application areas. For example, the housing lengths are just a few millimeters different. You can clearly see that one or two of these offerings could be installed into 99% of the application areas where M08 sensors are needed for machine or part position or simply error proofing a process.

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For more information on standardizing your sensor selection visit www.balluff.com

 

Solve Difficult Sensing Applications with Ultrasonic Technology

When reviewing or approaching an application, we all know that the correct sensor technology plays a key role in reliable detection of production parts or even machine positioning. In many cases, application engineers choose photoelectric sensors Image1as their go-to solution, as they seem more common and familiar. Photoelectric sensors are solid performers in a variety of applications, but they can run into limitations under certain conditions. In these circumstances, considering an ultrasonic sensor could provide a solid solution.

An ultrasonic sensor operates by emitting ultra-high-frequency sound waves. The sensor monitors the distance to the target by measuring the elapsed time between the emitted and returned sound waves.

Ultrasonic sensors are not affected by color, like photoelectric sensors sometimes are. Therefore, if the target is black in color or transparent, the ultrasonic sensor can still provide a reliable detection output where the photoelectric sensor may not. I was recently approached with an application where a Image2customer needed to detect a few features on a metal angle iron. The customer was using a laser photoelectric sensor with analog feedback measurement, however the results were not consistent or repeatable as the laser would simply pick up every imperfection that was present on the angle iron. This is where the ultrasonic sensors came in, providing a larger detection range that was unaffected by surface characteristics of the irregular target. This provided a much more stable output signal, allowing the customer to reliably detect and error-proof the angle iron application. With the customer switching to ultrasonic sensors in this particular application, they now have better quality control and reduced downtime.
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So when approaching any application, keep in mind that there is a variety of sensor technologies available, and some will provide better results than others in a given situation. Ultrasonic sensors are indeed an excellent choice when applied correctly. They can measure fill level, stack height, web sag, or simply monitor the presence of a target or object. They can also perform reliably in foggy or dusty areas where optical-based technologies sometimes fall short.

For more information on ultrasonic and photoelectric sensors visit www.balluff.com.

Precision Pneumatic Cylinder Sensing

When referring to pneumatic cylinders, we are seeing a need for reduced cylinder and sensor sizes. This is becoming a requirement in many medical, semiconductor, packaging, and machine tool applications due to space constraints and where low mass is needed throughout the assembly process.

These miniature cylinder applications are typically implemented into light-to-medium duty applications with lower air pressures with the main focus being precision sensing Image 2with maximum repeatability. For example, in many semiconductor applications, the details
and tolerances are much tighter and more controlled than say, a muffler manufacturer that uses much more robust equipment with slower cycle times. In some cases, manufacturing facilities will have several smaller sub-assemblies that feed into the main assembly line. These sub-assemblies can have several miniature pneumatic cylinders as part of the process. Another key advantage miniature cylinders offer is quieter operation due to lower air pressures, making the work place much safer for the machine operators and maintenance technicians. With projected growth in medical and semiconductor markets, there will certainly be a major need for miniature assembly processes including cylinders, solenoids, and actuators used with miniature sensors.

One commonality with miniature cylinders is they require the reliable wear-free position detection available from magnetic field sensors. These sensors are miniature in size, however Image 1offer the same reliable technology as the full-size sensors commonly used in larger assemblies. Miniature magnetic field sensors play a key role as speed, precision, and weight all come into play. The sensors are integrated into these small assemblies with the same importance as the cylinder itself. Highly accurate switching points with high precision and high repeatability are mandatory requirements for such assembly processes.

To learn more about miniature magnetic field sensors visit www.balluff.com.

Evolution of Magnetic Field Sensors

When I visit customers, often a few minutes into our conversation they indicate to me they “must decrease their manufacturing downtime.” We all know that an assembly line or weld cell that is not running is not making any money or meeting production cycle times. As we have the conversation regarding downtime, the customer always wants to know what new or improved products are available that can increase uptime or improve their current processes.

A major and common problem seen at the plant level is a high amount of magnetic field sensor failures. There are many common reasons for this, for example low-quality sensors being used such as Reed switches that rely on mechanical contact operation. Reed switches typically have a lower price point than a discrete solid state designs with AMR or GMR technologies, however these low-cost options will cost much more in the long run due to inconsistent trigger points and premature failure that results in machine downtime. Another big factor in sensor failure is the operating environment of the pneumatic cylinder. It is not uncommon to see a cylinder located in a very hostile area, resulting in sensor abuse and cable damage. In some cases, the failure is traceable to a cut cable or a cable that has been burned through from weld spatter.

Below are some key tips and questions that can be helpful when selecting a magnetic field sensor.

  • Do I need a T- or C-slot mounting type?
  • Do I need a slide-in or a drop-in style?
  • Do I need an NPN or PNP output?
  • Do I need an offering that has an upgraded cable for harsh environments, such as silicone tubing?
  • Do I need a dual-sensor combination that only has one cable to simplify cable connections?
  • Do I need digital output options like IO-Link that can provide multiple switch points and hysteresis adjustment?
  • Do I need a single teachable sensor that can read both extended and retracted cylinder position?

Magnetic field sensors have evolved over the years with improved internal technology that makes them much more reliable and user-friendly for a wide range of applications. For example, if the customer has magnetic field sensors installed in a weld cell, they would want to select a magnetic field sensor that has upgraded cable materials or perhaps a weld field immune type to avoid false signals caused by welding currents. Another example could be a pick and place application where the customer needs a sensor with multiple switch points or a hysteresis adjustment. In this case the customer could select a single head multiple setpoint teach-in sensor, offering the ability to fine tune the sensing behavior using IO-Link.

If the above tips are put into practice, you will surely have a better experience selecting the correct product for the application.

For more information on all the various types of magnetic field sensors click here.

Project Uptime – Pay Me Now or Pay Me Later

Back when I worked in the tier 1 automotive industry we were always trying to find time to break into our production schedule to perform preventative maintenance. The idea for this task was to work on the assembly machines or weld cells to improve sensor position, sensor and cable protection and of course clean the machines. As you all know this is easier said than done due to unplanned downtime or production schedule changes, for example. As hard as it is to find time for PM’s (preventative maintenance) it is a must to stay ahead and on top of production. PM’s will not only increase the production time, but it will also help maintain better quality parts by producing less scrap and machine downtime due damaged sensors or cables.

If you have read any of my previous posts you have probably noticed that I refer to the “pay me now or pay me later” analogy. This subject would fall directly into this category, you have to take the time to prevent machine crashes and damaged sensors and cables on the front side rather than being reactive and repairing them when they go down. It has been proven that a properly bunkered or protected proximity sensor will outlast the machine tooling when best practices are executed. It’s important to take the time and look at the way a sensor is mounted or protected or acknowledge when a cable is routed in harm’s way.

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PM’s should be an important task that is part of a schedule and followed through in any factory automation or tier 1 production facility. In some cases I have seen where there is a complete bill of material (BOM) or list of tasks to accomplish during the PM time. This list will help maintenance personnel and engineering know what to look for and what are the hot spots that create unplanned downtime.  This list could also indicate some key sensors, mounting brackets and high durability cables that can improve the process.

For more information on a full solution supplier or products that can improve and decrease downtime click here.

Put Out the Fire

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.

Example of bad bunkering. Sensor face not protected. Plastic brackets and standard cables used.
Example of bad bunkering. Sensor face not protected. Plastic brackets and standard cables used.

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:

Example of properly bunkered sensors with bunker block and silicone wrapped cable
Example of properly bunkered sensors with bunker block and silicone wrapped cable
  • Apply flush sensors vs. non-flush sensor in fixtures
  • Bunker the flush sensors to protect the face of the sensor (Let the bunker block take the spatter)
  • Apply sensors with special coatings to combat weld spatter
  • Apply sensors with steel faces for added insurance against contact damage
  • Apply high temp cables such as full silicone high durability offerings
  • Protect cables with silicone tubing and high temperature weld jackets
  • Wrap cables with weld repel tape to insure spatter will not penetrate the ends of the cable

If these simple steps are followed, uptime and efficiency will result in increased productivity with immediate improvements and positive results.

For information on welding improvements visit our website at www.balluff.us.

Angle Sensing & Tilt Detection Solutions

When an application calls for angle sensing or tilt detection there are a few choices including fluid based and MEMS technology Inclination sensors. For this blog entry we will focus on the MEMS technology. MEMS offerings have the option of one or two axis with up to 360° of measuring range. They provide an easy means of directly detecting positions without making contact enabling continuous feedback of rotational movements along the axis. The precise position control and continuous positioning of rotational movements are critical in many applications making them reliable solutions where accurate positioning is a must.

Sensors based with the MEMS technology operate by taking a capacitance differential and converting it to an analog signal. This analog signal is relative to the angle of the sensor in the application. The compact housing sizes are also a great feature offering various mounting options for a wide range of applications.

constructionequipmentMEMS Inclinations sensors can be used in various types of applications. Inclination sensor typically have  robust IP67 ratings making them ideal for tilt protection for cranes, hoists, tractors, expandable mechanical arms and other types of mobile agricultural machines. The Inclination sensor controls and monitors efficient operation verifying the correct positioning needed for reliable operation.

It is not uncommon to see MEMS style inclination offerings used in the renewable energy market. You can commonly see applications where inclination sensors are mounted directly to a rotating shaft to provide angel feedback for Fresnel Solar Panels.

inclinationsensorProduct Features:

  • Compact housing
  • Low temperature drift
  • Contact Free operation
  • High repeat accuracy
  • Precise analog measurement
  • Shock resistant

Applications:

  • Cranes
  • Hoist/Boom Trucks
  • Lifts
  • Mobile Implements
  • Shaft rotation
  • Solar Power

For more information on inclination sensors visit www.balluff.us.

Three Common Mistakes When Selecting a Sensor

Balluff Globalprox inductive proximity sensorsIn a previous post we addressed things to consider when selecting a sensor. Inductive sensors are solid performers when the correct options are selected. However, the best option to accommodate a given application condition are often overlooked. Here are three common mistakes I’ve seen time and time again:

  1. Choosing Flush instead of Non-Flush mounting specifications – or vice versa
    A flush offering can be embedded into a metal bracket or mounting block without false triggering and output. A Non-Flush offering will need a free zone at the sensing face so the sensor does not false trigger from the metal in the mounting block itself.
  2. Selecting an Inductive Sensor that is not the best choice for detecting your material
    For example if the target is aluminum selecting an all metal sensor (Factor 1) offering would be the best choice since there is no reduction in the sensing range on the non-ferrous material.
  3. Selecting a sensor that is not fit for your application conditions
    If the sensor is applied in a hostile application such as welding then a sensor with special coatings is required to combat the weld spatter that is present in this type of application.

The number of options available can be overwhelming but selecting the right sensor for your application can lead to reduced downtime by preventing sensor failure. You can learn more about Inductive Proximity Sensor technologies by visiting balluff.us.

Simplifying wiring with sensors and Multiple Interface Blocks

When machine builders build assembly machines for their customers they want to keep the wiring as clean and clear as possible for an attractive machine but more importantly the ease of troubleshooting in the event of a failure. Simplifying connections with unnecessary cables and splitters not only makes it easier for the maintenance technicians to trouble shoot but it also saves the company money with unneeded product and components to inventory and maintain.

V-Twin sensor with one cable
V-Twin sensor with one cable

In the past it was common practice to wire sensors and cables all the way back into a terminal box located in sections of an assembly line. This could be very difficult to track down the exact sensor cable for repair and furthermore in some cases five meter cables or longer would be used to make the longer runs back to the terminal box. The terminal boxes would also get very crowded further complicating trouble shooting methods to get the assembly lines back up and running production. This is where Interface Blocks come in and can provide a much cleaner, effective way to manage sensor connections with significantly decreasing downtime.

For example: If our customer has a pneumatic cylinder that requires two sensors, one for the extended position and one for the retracted positon. The customer could run the sensor cables back to the Interface Block. This sometimes is used with a splitter to go into one port to provide the outputs for both sensors only using one port. Now we can take this a step further by using twin magnetic field sensors (V-Twin) with one connection cable. This example eliminates the splitter again eliminating an unneeded component. As you can see in the reference examples below this is a much cleaner and effective way to manage sensors and connections.

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For more information visit www.balluff.us.