Level Detection Basics – Part 2

In the first blog on level detection we discussed containers and single point and continuous level sensing.  In this edition we will discuss invasive and non-invasive sensing methods and which sensing technologies apply to each version.  Keep in mind that when we are talking about level detection the media can be a liquid, semi-solid or solid with each presenting their own challenges.

tankInvasive or direct level sensing involves the sensing device being in direct contact to the media being sensed.  This means that the container walls or any piping must be violated leading to issue number one – leakage.  In some industries such as semiconductor and medical the sensing device cannot contact the media due to the possibility of contamination.

level_btl-sf-wThe direct mounting method could simplify sensor selection and setup since the sensor only has to sense the medium or target material properties.  Nonetheless, this approach imposes certain drawbacks, such as costs for mounting and sealing the sensor as well as the need to consider the material compatibility between the sensor and the medium.  Corrosive acids, for example, might require a more expensive exotic housing material.level_bsp_w

Invasive sensing technologies that would solve level sensing applications include capacitive, linear transducers, hydrostatic with pressure sensors.

In many cases the preferred approach is indirectly or non-invasively mounting the sensor on the outside of the container.  This sensing method requires the sensor to “see” through the container walls or by looking down at the media from above the container through an opening in the top of the container.  The advantages for this approach are easier mounting, lower cost and easier to field retro-fit.  The container wall does not have to be penetrated, which leaves the level sensor flexible and interchangeable in the application.  Avoiding direct contact with the target material also reduces the chances of product contamination, leaks, and other sources of risk to personnel and the environment.

level_bglIn some cases a sight glass is used which is mounted in the wall of the tank and as the liquid media rises it flows into the sight glass.  When using a sight glass a fork style photoelectric sensor can be used or a capacitive sensor can be strapped to the sight glass.

The media also has relevance in the sensor selection process.  Medical and semiconductor applications involve mostly water-based reagents, process fluids, acids, as well as different bodily fluids.  Fortunately, high conductivity levels and therefore high relative dielectric constants are common characteristics among all these liquids.  This is why the primary advantages of capacitive sensors lie in non-invasive liquid level detection, namely by creating a large measurement delta between the low dielectric container and the target material with high dielectric properties.  At the same time, highly conductivity liquids could impose a threat to the application.  This is because smaller physical amounts of material have a larger impact on the capacitive sensor with increasing conductivity values, increasing the risk of false triggering on foam or adherence to the inside or outside wall.

Non-invasive or indirect level sensing technologies include photoelectrics, capacitive, linear transducers with a sight glass and ultrasonics.

For more information visit www.balluff.com.

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Why everyone in manufacturing should host a Manufacturing Day Event

tourAs we wrap up our second annual manufacturing day event at Balluff (Oct 7th 2016), I am motivated to see so many kids and adults excited about manufacturing. This is an amazing industry to be a part of and as the 4th industrial revolution is upon us, we must inspire the next generation to see the light.

At Balluff’s MFGDAY event, we offered hourly time slots for attendees. During that hour, they received a plant tour and participated in hands-on labs. The tour focused on lean manufacturing work-cells, automated systems, and lot-size-one flexible manufacturing. Visitors learned how these tools are utilized at a US manufacturer to be competitive in a global market, how manufacturing technologies are utilized and how STEM education is applied in a manufacturing environment.

labThe hands-on labs were by far the favorite part for most attendees. We offered 5 hands-on labs from a speed game of flexible manufacturing to technology discovery experience about infrared light. Each lab taught the students and parents about how different sensor technologies worked and created a positive effect on the manufacturing process.

vanOutside the labs, interactive automation games were available to play and win prizes. The automated bags game was a hit with adults and kids and our RFID tag catapult game took quite a lot of skill. Everything was designed to inspire interest in manufacturing automation and help educate both adults and aspiring students to consider careers in advanced manufacturing.

Our motivation at Balluff to participate in MFGDAY is three-fold:

  • Bridge the US Manufacturing Skills Gap. Help our manufacturing community bridge the 600k+skills gap by building interest in the public for a career in manufacturing.
  • Connect with our community. We want to be involved in our community, improve outcomes for local students and support the local economy. That’s why we partnered with local schools like Gateway Community College and Cincinnati State to turn a budding interest into a solid path.
  • Motivate our employees. Talking about how awesome manufacturing is is fun. And seeing the excitement of a little kid when they can see infrared light through a cellphone camera was the highlight of many employees’ day.

As attendees left the event we asked them a few questions to gauge their interests and the effect of the day on their attitudes toward manufacturing. I am happy to report that we increased an interest in manufacturing careers by 22% in both kids and adults. Many people walked away with a better understanding of how STEM education can positively affect manufacturing careers and 90% agreed that factory automation is cool. Check out our new infographic on MFGDAY16 at Balluff and our press release has event more details.


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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/inductive.

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Harsh Industrial Environments Challenge Plant Operators

Most industrial processes do not take place in a climate-controlled laboratory or clean room environment. Real-world industrial activity generates or takes place under harsh conditions that can damage or shorten the life expectancy of equipment, especially electronic sensors.

A cross-section of industrial users was surveyed about operating conditions in their facilities. The responses revealed that plant operators are challenged by a variety of difficult environmental factors, the biggest being heat, dust/dirt/water contamination, vibration, and extreme temperature swings.


Over one-third of the industrial users surveyed reported that premature sensor failure is a problem in their operations. That is a surprisingly high percentage and something that needs to be addressed to restore lost productivity and maintain long-term competitiveness.

Many heavy industries are dependent on automated hydraulic cylinders to move and control large loads precisely. The cylinder position sensors are often subjected to damaging environmental conditions that shorten their life expectancy, leading to premature failure.

Fortunately, there are measures that can be taken to reduce or eliminate the occurrence of sensor-related downtime. Help is available in the form of a free white paper from Balluff called “Improving the Reliability of Hydraulic Cylinder Position Sensors”.

To learn more about this topic you can also visit www.balluff.us/micropulse.

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IMTS 2016 Review: IO-Link Enables Industry 4.0 Installations

We have been talking about IO-Link for a long time.  The benefits to manufacturers like “hot-swapping” a smart device.  One of the benefits for machine builder is reducing commissioning time.  So it was not surprising to me to find IO-Link on the exhibit floor at IMTS 2016, but it was surprising how much IO-Link was used on equipment and demonstrations.

Makino IO-Link I/O Hubs

On a cool demo of robotic load and unload of two machining centers from the team at Makino Machine IO-Link was used for I/O applications driving solenoids and collecting sensor inputs.

What is neat about I/O hubs regardless of the brand is the ability to collect many simple discrete sensor inputs and drive outputs over one IO-Link channel.  It can save tim dramatically over traditional hardwired applications.

Beckhoff IO-Link Master for EtherCAT

Beckhoff IO-Link Master for EtherCAT

Molex IO-Link Inter-operability

At Beckhoff they were showing their IO-Link master options for a slice in the PLC.

Molex displayed their Profinet IO-Link master and slave devices like analog converter and digital I/O hubs.  What I liked about their demo is they showed how open and easy the IO-Link technology is to integrate other company’s devices like the Balluff SmartLight.

Klingelnberg IO-Link

In the Klingelnberg booth on one of their flagship machines IO-Link masters and SmartLight were installed on the machine. IO-Link inductive positioning Smart Sensors from Balluff were used for measurement of the chucking position.

And inter-operability was also shown with multiple manufacturer’s process sensors with IO-Link installed tied back to a Profinet master.  Since IO-Link is an open standard with over 90 automation vendors, it was nice to see the inter-operability in action.

Caron Eng Demo of SmartLight

The SmartLight was shown all over the IMTS show due to Caron Engineering’s easy integration into a PC without an industrial network.  Too many booths to name had the SmartLight integrated with the Caron IO-Link Master solution.

The fact that IO-Link can be used with multiple master interfaces and options, really makes it an easy to select and universal choice for a variety of applications.


I look forward to seeing what unfolds in the two years before the next IMTS show.  I anticipate there will be a dramatic and continued adoption of IO-Link as it enables and scales Industry 4.0 and IIoT applications.

To see more or join the conversation check out #IMTS2016 on Twitter.

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Proximity Sensor Switching Distances


Diagram showing the relationship between the various operating distances of an inductive proximity sensor.

When looking at a data sheet for an inductive proximity sensor, there are usually several different specifications listed with regard to the switching distance (or operating distance). Which of these various specifications really matter to someone trying to use a prox sensor in a real-world application? How can a specifier or user decide which sensor is going to work best in their situation?

Fortunately, there is an international standard that defines sensor switching distances and spells out test methods to assure that sensor specifications from product to product and even manufacturer to manufacturer can be directly compared “apples to apples.”

This standard is IEC 60947-5-2 Low voltage switchgear and controlgear – Part 5-2: Control circuit devices and switching elements – Proximity switches.

Operating (switching) distance s

In the diagram shown here, the letter “s” refers to a given sensor specimen’s actual switching distance when tested.  It is defined as the distance (between the standard target and the sensing face of the proximity switch) at which a signal change is generated. For a normally open sensor, the target approaches the sensor axially, that is, the sensor approaches the active surface from the front (not the side). There are several subscripts used to describe different aspects of a sensor’s switching behavior.

Rated operating distance sn

… is the nominal switching distance of the sensor. It is simply used as a standard reference value. The rated operating distance is the best figure to use when comparing different sensor models to get an idea of their essential sensing distance capabilities.

Effective operating distance sr

…is the range of actual switching distances that any given proximity sensor will fall into when measured under specified conditions of mounting, temperature, and supply voltage. For well-designed and manufactured sensors, the sensor will be triggered between 90% and 110% of the rated operating distance. For example, various samples of a proximity sensor model with a rated operating distance (sn) of 8mm may deliver switch-on points anywhere between 7.2mm and 8.8mm.

Usable operating distance su

…takes into account the effects of the sensor’s full ambient temperature range (low to high) and variation of the supply voltage from 85% to 110% of the nominal voltage rating. The IEC standard requires the usable operating distance (su) to be between 90% and 110% of the effective operating distance (sr). For our example of a sensor with a rated operating distance (sn) of 8mm, the usable operating distance would fall between 6.5mm and 8.8mm. Pop quiz: why is the max of usable operating distance not 9.7mm (sr of 8.8mm * 110%)? Answer: the usable operating distance can always be less than but can never be greater than the maximum effective operating distance.

Assured operating distance sa

This is the distance of the target to the sensor where the sensor can be guaranteed to have turned on. If a target approaches within the assured operating distance, you can be confident that the sensor will detect it.  It is 90% of sr which is in turn 90% of sn, which is in effect 81% of sn. Going back to our example of a sensor with a rated operating distance (sn) of 8mm, sa would be 81% * 8mm = 6.5mm. So in essence, sa = su(min).

Differential travel H

Now when the target recedes, at what distance will the sensor switch off? All good-quality sensors have a built-in property called hysteresis, which means that the sensor will turn off when the target is further away from the sensor than the point where it turns on. This is necessary to prevent chattering and instability when the target approaches the sensor. We want the sensor to turn on and stay on, even if the target might be vibrating as it crosses the threshold of detection. For most sensors, it is defined as ≤ 20% of the effective operating distance sr. The differential travel is added to the value of sr to define the switch-off point.

In practice, for any group of sensors, the minimum value of H would be zero and the maximum value would be sr(max) + 20% of sr(max). For our example of a sensor with a rated operating distance (sn) of 8mm, 7.2mm ≤  sr  ≤ 8.8mm. So, the range of switch-off points would be 7.2mm ≤  sr+H  ≤ 10.6mm. It might sound like a large range, but for any given sensor specimen the switch-off point is never greater than 20% of that particular sensor’s switch-on point.


The good news is that you don’t have to conduct sensor tests yourself or go through all of these calculations manually to determine a sensor’s performance envelope. The sensor manufacturer provides all of these useful figures pre-calculated for you in the sensor data sheet.

Learn more about the basics of the most popular automation sensor here.

You can also learn more about other topics by visiting balluff.us/basics.

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Three Things to Know About IO-Link

IO-Link has become synonymous with the term “distributed modular I/O”. We know it is universal, smart, and easy, but what exactly is IO-Link? In a nutshell, by utilizing a standard sensor cable, the IO-Link slave device speaks point to point with an IO-Link master. The IO-Link master then combines the data with other IO-Link slave devices and communicates over an industrial network or backplane to the controller. In other words, it can be compared to a simple USB connection: for the most part, any USB device will work in any USB port, as long as the manufacturers of both devices have played by the rules when making the devices.

With that being said, here are three things to know about IO-Link:

  • Cable Length Cable Type and Length

Cable runs between master and slave can be up to 20 meters in length and typically utilize standard automation cables. Most cables, but not all, are M12 A-coded, unshielded, 3 or 4-conductor DC sensor cables.

  • Star ArchitectureStar Architecture

Since IO-Link utilizes a point-to-point serial communication, Star Topology is the only device architecture that can be constructed.

  • IO-Link PortsPort Class A vs Port Class B Devices

While most devices utilize IO-Link port Class A, output devices like valves are now being offered as IO-Link port Class B. Be sure to know if the master and/or slaves are Class A or Class B type ports. Most Balluff devices are IO-Link port Class A.

To learn more visit balluff.us/iolink

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A Simple Out Feed Solution for Progressive Stamping

Applications where sensor contact is unavoidable are some of the most challenging to solve. Metal forming processes involving over travel can also damage or even destroy a sensor causing failure and expensive unplanned downtime. Manufacturers often try to remedy this with in-house manufactured spring loaded out-feed mechanisms but those are expensive to make by experienced tool and die personnel who have more important things to do . Over the years, I’ve seen this as a pervasive problem in the stamping industry. Many of these issues can be solved with the use of a simple yet effective  sensor actuator system known as a Balluff PlungerProx.

PlungerProx solves a few key issues in Progressive stamping:

  • The flexible trigger/actuation point is fully adjustable to meet sensitive or less sensitive activation points, not possible with “fixed” systems with substantial “over travel” built into the design.
  • It is fully self-contained (minimizing any risk of sensor damage and resulting unplanned machine down time).
  • The device can be disassembled and rapidly cleaned, reassembled, and placed back in service in the event that die lube or other industrial fluids enter the M18 body that can potentially congeal during shut down periods.

See me demo this product in the following video:

For more information visit www.balluff.us.

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The Importance of Data Accessibility with IIoT

20160809_100331 (1) Typically a college student is asked two questions: “What are you studying?” and “What would you like to do with your degree?” In my case, I always answer with “Computer Science” and “I have no idea”. Lately, the field that has grabbed my interest the most is the Internet of Things (IoT). The concept of data transfer and communication between ordinary utilities is going to revolutionize the way we go about our day to day tasks. Home automation is a key example of this. We have found ways to expedite those pesky tasks that nobody enjoys doing by simply automating them.

I’ve come to realize that there is data everywhere; we just need to take the opportunity to use it. I’ve done this in a few small side projects around my apartment. Is the door locked? Are my lights on? Did the refrigerator door completely close? These are all examples of data that is useful to me at any point in time. The trick is making it available. Using a low power microcontroller and a few sensors, I’m able to host this data and view it at any point in time. IoT has the capability of effectively improving our energy efficiency, security, and productivity simply by making data readily available.

IoT screenLikewise, these same concepts apply to industrial automation. I’ve spent the last few months developing a web application to demonstrate Industrial Internet of Things (IIoT).  The web app simply hosts a live feed of data from a conveyor system. From any computer on the network, we can see crucial data such as conveyor accumulation, sensor status or even maintenance needs.  Once this data is made available, we can even automate the analysis. For example, on a conveyor, we can look at the number of packages that go by every day. A simple script that increments by one for every passing object can give a very accurate representation of day to day productivity. More intense algorithms could analyze trends in mass quantities of data return valuable results. All of this is done simply by making data continuously accessible.

According to Business Insider, by 2020, there will be 34 billion devices connected to the internet and that there will be $6 trillion spent on incorporating and integrating IoT.  As a student with a passion for technology, I see a lot of potential in this field.  So next time I’m asked what I plan on doing with my degree, I might say an IoT developer. It’s a fascinating subject that only has room to grow.

To learn more about IIoT visit www.balluff.us.

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Machine Tool Identification with RFID -Automation for Advanced Machining

When most people think of automation in manufacturing the first thing that comes to mind is usually a robot. Without a doubt, robots play an integral part in automating the production process, and let’s face it they are pretty cool. However, there is an often overlooked topic in the automation discussion and that is Automatic Data Collection (ADC), which includes barcode and RFID technology. While it doesn’t carry the “cool factor” quite as well as robotics, RFID has helped automate manufacturing, specifically machining, over the last 30 years.

How is it used?

An RFID tag is placed in the tool holder and stays put for the life of the tool. The tag essentially acts as a mini database that can be read and written to thousands of times.

What type of data is typically written to the tag?

Tool Life, Tool Chain Pocket location, Offset Data, Maintenance Info, etc. Up to 2K of info can be written and read and erased and written again. In addition, this information can be updated on the spot.

What are the benefits of using RFID in Machine Tools?

RFID Improves Quality, Increases Efficiency, and Reduces overall Costs by:

Maximizing Tool and Machine Utilization

  • Precise up-to-date tool life information
  • Accurate transfer of tool offset data
  • Continuous tracking of the tool

Minimizing Human Error

  • Eliminates human data entry
  • Automates transfer of data from presetter to machine
  • Data can be accessed directly on the plant floor as opposed to a database lookup

ToolIDRFID is a tried and true technology that will continue to have a great impact on the machining process. Organizations all over the globe are saving millions every year by utilizing this simple method of collecting and transferring data. Machine tool ID is a no-brainer when quality, efficiency, and productivity matters!

For more information or to learn more visit www.balluff.us/rfid.

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