IO-Link Hydraulic Cylinder Position Feedback

Ready for a better mousetrap?  Read on…..btl_io-link

Some time ago here on Sensortech, we discussed considerations for choosing the right in-cylinder position feedback sensor.  In that article, we said:

“…….Analog 0-10 Vdc or 4-20 mA interfaces probably make up 70-80% of all in-cylinder feedback in use…..”

And while that 70-80% analog figure is still not too far off, we’re starting to see those numbers decline, in favor a of newer, more capable interface for linear position feedback:  IO-Link.  Much has been written, here on Sensortech and elsewhere, about the advantages offered by IO-Link.  But until now, those advantages couldn’t necessarily be realized in the world of hydraulic cylinder position feedback.  That has all changed with the availability of in-cylinder, rod-style magnetostrictive linear position sensors.  Compared to more traditional analog interfaces, IO-Link offers some significant, tangible advantages for absolute position feedback in hydraulic cylinders.

Connectivity

First and foremost, the story of IO-Link is that it offers easy, simple connection of sensors and IO to nearly any industrial network.  You can read more about that here.

Simplicity

Another big advantage of IO-Link is the ability to connect sensors to the network using standard, simple, unshielded M12 connectors and cables.  Compared to analog systems, which require shielded cabling, and sometimes unusual or proprietary connectors, connecting IO-Link sensors to the network is simpler, and usually less costly.

Visibility

Unlike their traditional analog counterparts, position sensors with IO-Link offer built-in diagnostic capabilities.  Sensor status can be monitored over the network, greatly simplifying troubleshooting and fault detection.

Flexibility

This is where IO-Link position sensors really start to shine.  Traditional analog position sensors provide one thing: position feedback in the form of an analog signal (obviously).  IO-Link position sensors provide position feedback, of course…but wait, there’s more.  In addition to position feedback, IO-Link sensors can provide velocity/speed information, temperature, and differential position (the difference between two position magnets).  And the best part?  All of this functionality can be freely configured over the network.  Plus, sensor configurations can be stored and subsequently downloaded to a replacement sensor if necessary.

Suitability

It’s worthwhile to point out that IO-Link linear position sensors are ideal for most positioning or position monitoring applications.  Just as with analog sensors though, they’re probably not suitable for high-performance closed-loop servohydraulic motion control applications.  In those applications, interfaces that are capable of providing super-fast, deterministic data, such Synchronous Serial Interface (SSI) or even Ethernet/IP are more suitable.

To learn more visit www.balluff.us

You can also learn more in this overview flyer.

Posted in IO-Link, Linear Position and Distance Measurement | Tagged , , , , | 1 Comment

Basic Color Sensor Overview

PrintIn the past, color sensors emitted light using red, green and blue LEDs’. The sensors were then able to distinguish colors using the RGB components of the reflected light back to the sensor’s receiver. As technology has progressed true color sensors have been developed that not only can compare colors but measure them more accurately than the human eye.

Color sensors are based on diffuse technology and can be compared to a fixed focus or convergent sensor because of the focused light spot. Unlike color contrast sensors that only detect the difference between two colors based on brightness, color sensors can detect a wide range of colors.

cielabTrue color sensors typically use white LED’s which allow for a greater color spectrum evaluation. Combine this with the CIELAB color system which is one of the most versatile color systems and the result is a color sensor that equals or exceeds the human eye. The CIELAB color system is a three-dimensional independent infinite representation of colors. The L component for lightness and a and b components for color are predefined absolute values. Lightness varies from black (0) to the brightest white (100). Color channel a varies from green negative 100 to red positive 100. Color channel b varies from blue negative 100 to yellow positive 100 with gray values at a=0 and b=0.

Due to the technology, color sensors can check only a small spot of color but can check this spot amazingly fast – up to 1.5 kHz in case of the Balluff’s fiber optic BFS 33M which also has a range of 400mm. Unlike a color sensor camera, which will focus on the object’s surface pattern and may cause false readings the true color sensor will ignore patterns thus providing more accurate color detection. In addition the true color sensor will have more outputs than the color camera.

Smart color cameras are working with RGB but could work also with HSV color models. They could be used to check larger areas for the same color or color codes on a part, but have slower update rate of 50 Hz. Special cameras for faster applications are available in the market but at higher costs. It is important that the light source for the smart color cameras be a white light with a standardized white balance, and that this light must kept constant for all checks to avoid errors.

The sophistication on the front end of the color sensor can be much more advanced and still remain a cost effective option for industrial use due to the fact that a camera requires a much larger processing system. The more sophisticated the sensors are in the camera the more robust the processor must be in order to process or map the data into an image.

To learn more visit www.balluff.us.

You can also request a digital copy of our Photoelectric Handbook here.

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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.

Posted in All posts, Cables and Connectors, Inductive Proximity Sensors, Object Detection Sensors, Sensor Accessories | Tagged , , , , , , , , | Leave a comment

3 Smart Applications for Process Visualization

Stack lights used in today’s industrial automation haven’t changed their form or purpose for ages: to visually show the state (not status) of the work-cell. Since the introduction of SmartLight, I have seen customers give new meaning to the term “process visualization”. Almost every month I hear about yet another innovative use of the SmartLight. I thought capturing a few of the use-cases of the SmartLight here may help others to enhance their processes – hopefully in most cost effective manner.

smartlightmodesThe SmartLight may appear just like another stack-light.  The neat thing about it is that it is an IO-Link device and uses simply 3-wire smart communication on the same prox cable that is used for sensors in the field. Being an IO-Link device it can be programmed through the PLC or the controller for change of operation modes on demand, or change of colors, intensity, and beeping sounds as needed. What that means is it can definitely be used as a stack light but has additional modes that can be applied for all sorts of different operation/ process visualization tasks.

Use Case #1: Stack Light Mode for Operation Status – The number of segments can be programmatically changed from 1 to the max segment number provided by the light (up to 5 in a five-segment SmartLight). Colors can be changed to red, blue, green, orange, yellow, white, or any other color of choice. This is the most traditional application of the SmartLight.

Use Case #2: Format Change Indicator – Many of our customers use the level mode to provide feedback to the operators when they are making adjustments to the machine. For example: red might indicate that the machine is out of alignment, yellow might mean the machine is getting closer to the specified alignment, and green might mean the machine is in the zone of alignment. Using the SmartLight in this fashion helped our customers save time in product changeovers because the operators didn’t have to come out of the cell to view the alignment status on a small HMI.  When the alignment of the machine is complete, the SmartLight can be programmed to switch back to the status indication mode or whatever mode of operation desired.

smartlightgifcroppedUse Case #3: Run Light Mode for Maintenance Indication – In this mode there are two colors – one color for the background and another color for the running segment. Along the assembly line where there are multiple work cells continuously processing raw materials in lock-step operation, downtimes are extremely costly. The standard status indicator will only indicate a problem at the work cell when the system stops, but it will not indicate a lack of raw material, for example. The moment the stack light turns red, the operator or the maintenance person is rushed to the site to first figure out what’s wrong before solving the problem. In Run Light mode, the SmartLight can be programmed to indicate different colors for the running segment and the background to show that attention is required at the cell. For example, as long as the running segment is running the machine is operational, but the background color can be changed to indicate raw material shortage, the need for mechanical adjustment of the machine, or the need for some electrical maintenance. Using a SmartLight, whoever is rushing the cell has a very good idea of what is required of them to get the system back up and running.

There are several more applications we want to share. Before we do that, we want to hear from you! Do you have a unique application for the SmartLight? Share your story with us here.

You can also learn more by visiting our website at www.balluff.us.

Posted in All posts, Industrial Networking, IO-Link | Tagged , , , , , , , , | 1 Comment

Stop the Scrap

steelmanufacturingIn the current era of steel production, steel manufacturers employ a continuous process during the casting phase of production. The molten steel is solidified during this process by a continuous casting machine. The processes include feeding the liquid steel through a series of rollers to cool the material and slowly form into the next shape of production (e.g. slabs, round, etc…). In this process, the rollers are positioned using hydraulic cylinders that include linear position sensors as closed loop feedback devices. The outputs of these sensors are closely monitored and are critical to the steel quality. Because of the harsh environment of the continuous casting process, the life span of these sensors can be cut short. If the sensor’s output becomes unstable and begins to fail, the continuous casting process cannot simply stop quickly. The steel quality during this sensor failure mode will most likely become scrap, costing the steel mill tens of thousands of dollars.

btl7-t-redundant-seriesFor maximum reliability, a linear position sensor with 2 or 3 times redundancy can be utilized to provide position feedback of hydraulic systems. Such sensors employ 2 or 3 independently-operating sensing elements and processing circuitry . The extra feedback signals can be monitored through an automation system. When the outputs are compared, a failure could be identified early and the automation system could switch over to the reliable output maintaining the quality of steel. No scrap! During the next possible scheduled stoppage in the manufacturing process, the sensor could be replaced.

For more information on Balluff solutions for the metallurgy industry, start here.

For more information, visit www.balluff.com.

Posted in All posts, Linear Position and Distance Measurement | Tagged , , , , , , , , , | 1 Comment

Reliable Part Exit/Part-Out Detection

Walk into any die shop in the US and nine out of ten times, we discover diffuse reflective sensors being used to detect a large part or a small part exiting a die. Many people have success using this methodology, but lubrication-covered tumbling parts can create challenges for diffuse-reflective photoelectric sensing devices for many reasons:

  1. Tumbling parts with many “openings” on the part itself can cause a miss-detected component.
  2. Overly-reflective parts can false triggering of the output.
  3. Dark segments of the exiting part can cause light absorption. Remember, a diffuse sensors sensing distance is based on reflectivity. Black or dark targets tend to absorb light and not reflect light back to the receiver.
  4. Die lube/misting can often fog over a photoelectric lens requiring maintenance or machine down time.

The solution: Super Long Range Inductive Sensors placed under chutes

Most metal forming personnel are very familiar with smaller versions of inductive proximity sensors in tubular sizes ranging from 3mm through 30mm in diameter and with square or “block style” inductive types (flat packs, “pancake types”, etc.) but it is surprising how many people are just now discovering “Super Long Range Inductive Proximity” types. Super Long Range Inductive Proximity Sensors have been used in metal detection applications for many years including Body-In-White Automotive applications, various segments of steel processing and manufacturing, the canning industry, and conveyance.

Benefits of Using A UHMW Chute + Super Long Range Inductive Proximity Sensor in Part Exit/Part-Out Applications:

  1. It is stronger and quieter than parts flowing over a metal chute, readily available in standard and custom widths, lengths and thicknesses to fit the needs of large and small part stampers everywhere.
  2. UHMW is reported to be 3X stronger than carbon steel.
  3. UHMW is resistant to die lubes.
  4. UHMW allows Super Long Range Inductive Proximity Sensors to be placed underneath and to be “tuned” to fit the exact zone dimension required to detect any part exiting the die (fixed ranges and tunable with a potentiometer). The sensing device is also always out of harm’s way.
  5. Provides an option for part detection in exiting applications that eliminates potential problems experienced in certain metal forming applications where photoelectric sensing solutions aren’t performing optimally.
A Two-Out Die with Metallic Chute

A Two-Out Die with Metallic Chute

Not every Part Exit/Part-Out application is the same and not every die, stamping application, vintage of equipment, budget for sensing programs are the same. But it’s important to remember in the world of stamping, to try as consistently as possible to think application specificity when using sensors.  That is, putting the right sensing system in the right place to get the job done and to have as many technical options available as possible to solve application needs in your own “real world” metal forming operation.  We believe the UHMW + Super Long Range Inductive System is such an option.

You can learn more in the video below or by visiting www.balluff.us.

Posted in All posts, Inductive Proximity Sensors, Object Detection Sensors | Tagged , , , , , , , , | 1 Comment

Putting Linear Encoders Out of Sight and Out of Mind

Linear encoders can do a lot to improve factory automation. When used as secondary feedback they can greatly enhance the precision of motion control systems. They can act as a feedback device for automatic size change, and they can be used in gauging applications.

However, they can be troublesome to maintain. Most linear encoders are made from a glass strip or rod that is etched with index marks and read optically. These kinds of encoders can achieve very high accuracy…with high price points to match. However, a consistent problem in many factory automation environments is the mechanical fragility of the glass scale encoder. They can be easily broken by shock, vibration, or impact. The presence of dirt and liquids can also interfere with proper operation. Repair costs can become a problem, not to mention the cost of carrying the spare parts needed to cope with long lead times for replacements.

bml-s1fDepending on the resolution and accuracy class required, one alternative to these issues is the magnetic linear encoder. Today’s magnetic encoders can achieve resolution to 1 μm and accuracy to ±5 μm. Rather than index marks on glass, the scale consists of magnetic poles precisely located on a ferromagnetic strip of tape. A magnetic read head glides over the tape and outputs digital position signals. The magnetic system is much more tolerant of shock and vibration, and can tolerate most kinds of liquids and dirt. The main caveat is ferrous particles or chips; these can accumulate on the magnetic strip and cause position deviations.

Most magnetic linear encoders offer incremental signals, but a new option is absolute position over an SSI or BiSS-C serial interface. This allows the encoder to report position upon power-up, without the need for a time-wasting homing or reference run. This can be helpful in situations like a power outage, where it may not be possible to re-home the machine without damaging work in process and/or breaking tooling.

To learn more visit www.balluff.us.

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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.

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3 Tips for Reducing Downtime

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.

sacraficialcableCables 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.

hdc_cablesA 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..

gizmo4A 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.

 

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Identification technology for Work In Process applications is evolving

wipI have had countless conversations over the years regarding barcode vs RFID. Most of those discussions I explained that both technologies have their own unique set of features and benefits and it is rarely the case where they are competing. I still stand by that general argument except when it applies to Work In Process applications. Looking back over the last four to six years there is evidence of a major evolution from barcode to RFID in the production process.

I guess the next question is why is this happening? I am not sure I have the definite answer, but there are a couple consistent factors that tend to come up when we are installing RFID in place of barcode:

Automation – True automation means there are no manual processes. When an operator has to pull a trigger on a barcode scanner the scan is not automated. Even with fixed barcode readers the barcode will sometimes need to be presented to the reader by an operator holding the part. With fixed RFID scanners the part is automatically scanned even without a direct line of sight and even in poor lighting conditions.

ROI – At first glance a barcode solution may seem to be more cost effective than RFID. However, things that need to be taken into account when going the barcode route are: specialized lighting, data management, longevity of the barcode in a harsh environment, etc. With RFID the tags can be read in complete darkness, the data can be managed locally, and the tags are built to survive harsh conditions. In addition, the cost of paper RFID labels has become manageable in the last couple years.

This is definitely something I will be keeping my eye on going forward. With a renewed focus on automation, identification technology will become more and more important as we move toward true automation.

To learn more about industrial RFID systems visit www.balluff.us.

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