Hydraulic Cylinder Position Feedback, Revisited

In a previous Sensortech post entitled “Hydraulic Cylinder Position Feedback“, we discussed the basic concept of hydraulic cylinder position feedback.  In case you might have missed that post, here it is for an encore appearance.

Magnetostrictive linear position transducers are commonly used in conjunction with hydraulic cylinders to provide continuous, absolute position feedback.  Non-contact magnetostrictive technology assures dependable, trouble-free operation.  The brief video below illustrates how magnetostrictive position sensors are used with hydraulic cylinders.

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Non-contact Power & Data Exchange For Assembly Automation

InductiveCouplersAssembly automation has evolved multi-fold since Ford’s first linear assembly plant. Assembly automation is of course commonly found in Automotive or heavy industries but it has found its way in small parts assembly, consumer goods and other industries that are embracing automation full on.

Typically, in assembly automation, pallets of sub-assemblies travel along the conveyor maze making stops at various stations to get further components and assemblies put on or some kind of operation is being performed on them.

Several times, inspection, measurement or other process specifics demand sensors and actuators to be on-board these pallets. A very common challenge people face in this environment is to provide power and communicate with this traveling assembly. Pin based automatic couplers and/ or manual intervention is common solution. As explained in my previous blog “Inductive Coupling for Robotic End Effectors” the pin based coupling has downfall of being susceptible to environmental elements and mechanical wear. Thus, offering a solution that requires some regular maintenance and related downtime. Manual intervention for inspection or measurement is of course time consuming and laborious activity.

Non-contact inductive coupling offers great benefits in this scenario. Typically, the base (transmitter) is mounted along the conveyor and the remote (receiver) is mounted on the moving pallets. As the pallet moves along the assembly line, the remote, when in-zone of the base, receives power and exchanges data over small air-gap with the base unit. There are three major benefits of this approach

  1. Because of magnetic induction phenomenon, these non-contact couplers are immune to dust, humidity, oil or vibrations, unlike the pin based couplers.
  2. Misalignment tolerance: Inductive couplers do not need to be in exact axial or angular alignment. They can tolerate angular or axial offsets. The amount of offset they can tolerate depends on the particulars but typically 10-20° angular offset is acceptable. So over-time when the conveyor system develops some slag, the inductive couplers won’t fail you that easily.
  3. Scalability: Inductive couplers come in various form factors and functionality that includes Power-only, input only, analog, configurable channels of inputs and outputs, and with IO-Link bi-directional communication. IO-Link inductive couplers offer the greatest benefits as they allow exchanging up to 32bytes of data bi-directionally- so in future if the I/O needs grow for your pallets, it can be easily handled.

You can always learn more about inductive couplers on Balluff’s website at www.balluff.us/inductive-couplers. You can also learn more in our Basics overview.

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How to Make Plant-based Assets Smarter

 

traceability…add RFID

Pallets, bins, shipping containers, machine tools, hand tools, calibration equipment, neumatic and hydraulic cylinders, etc, etc, etc can all be given some level of intelligence which would make life easier within the plant. Plant-based assets are truly assets because they make our job easier or they allow us to be more efficient. When workers are efficient they are more productive.

Really it all comes down to the questions that we need answered. Here are a few that I have run into in a plant:
Where are all of my pallets and shipping containers?
How much longer can I use this machine tool before the tolerances are out of range?
Has this gauge been calibrated? when? by whom? what are the parameters?
I need to re-order this part or order spare parts and the manufacturer information has been worn off. What is the serial number, when was this part manufactured, what is the location of this asset within the plant?

Ultimately, if your assets can answer a few questions your life becomes a little less complex. All of the answers are simply written to the RFID tag and when you have a question you can read the information from the tag with an RFID reader, sometimes called an interrogator for obvious reasons. It’s that simple.

For more information on RFID as a solution visit our website at www.balluff.us/rfid

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The Machine Builder’s Guide to Improving Machine Turns

controlpanelEfficiency! Efficiency ! and Efficiency!  Every day, in the industrial environments we are all focused on improving efficiencies in our plants, to be able to do things better, easier, and faster, to get more done with as little efforts as possible. Manufacturers focus their efforts to improve their production processes while machine builders are challenged to produce more machines with limited resources. Sometimes, we focus so much on the human and machine capabilities factors through process improvement initiatives such as six-sigma, KANBAN, and other methods, that we tend to overlook some easier ways that can add tremendous value to our endeavors.

“Machine turns” or “turns” is a powerful measure of productivity for the machine builders to measure their efficiency. This determines, with given resources, how many machines they can produce per year in the same space.

Recently, collecting thoughts from industry experts, reviewing various case studies, and based on personal experiences, we compiled a white paper that reveals on how distributed modular controls architecture can boost productivity in system integration and machine build processes. For over few decades, an automated system is accompanied by a huge controls cabinet hosting processors, power-supplies and terminations of hundreds, if not thousands of wires. Building this cabinet, troubleshooting it and maintaining it is laborious activity that costs money and time all across the life cycle of the system.

Distributed modular controls architecture eliminates lot of these activities, provides tools for ease of troubleshooting and ensures a scalable architecture. Most importantly, it saves valuable labor time per machine. Thus, improving the machine turns on the floor.

Balluff recently released a white paper with practical examples that identifies how machine builders and integrators can significantly impact their operations with the choice of controls architecture. The paper also provides guidance on determining the magnitude of impact you can expect, and offers recommendations on how to go-about making the change.

Request your copy here or visit www.balluff.us for more information.

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How Manufacturing Can Easily Invest in STEM Programs

I continuously hear from manufacturers, machine builders and integrators across our industry that they can’t find qualified people for the job openings they have.  Technicians or Engineers, Controls or Mechanical, all positions are in short supply and heavy demand.

“The Boston Consulting Group (BCG)’s “Made in America” research series estimates the shortage at 80,000 to 100,000 highly skilled manufacturing workers.” SHRM

In addition, according to the same study, the average age in 2013 of these workers was 56 years.  In conference presentations, I have seen segments like Steel or Metalworking show average ages up to 62.  And the demand for Science Technology Engineering & Math (STEM) jobs is only growing.

“Over the past 10 years, STEM jobs grew three times faster than non-STEM jobs, and they are projected to continue to grow by 17% through 2018, compared to 9.8% for all other occupations.” SME – Anna Maria Chávez
CEO, Girl Scouts of the USA

But…

“The United States has one of the lowest shares of college degrees awarded in science and technology.” McKinsey

This collection of data screams to me that we MUST work on encouraging our youth with an interest in manufacturing and automation.  Manufacturers have the opportunity to drive this interest even with small investments that can have a large impact.

Especially important is that we invest in programs for the K-12 level according to McKinsey as relatively few incoming freshmen choose these STEM subjects and less than half complete their degrees.

I am personally passionate about encouraging people of all ages into STEM careers and I love sharing my passion for automation.  We, at Balluff, are investing in technical labs, capstone projects and even middle school after school programs.

If you are interested in how you can get more involved in promoting STEM careers in your community, please reach out to me.

@WillAutomate on Twitter

https://www.linkedin.com/in/willhealyiii

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“Team” Spells Success In Traceability

If you’ve ever considered a traceability project, like asset tracking for instance, you’ve probably also done some homework into the different technological ways to implement it, from barcoding to using RFID (radio frequency identification). And possibly, while doing that research, you may have seen some presentations or read some articles or whitepapers that have talked about the “team” of stakeholders required to implement these projects, especially if involving the scale required for a facility, or even multiple facilities. Well if you’re a manager reading this and involved with such an endeavor, I’m writing to tell you, take this stakeholder team thing seriously.

In many respects, there are rational fears in getting a stakeholder team together in the early stages of these projects, like the conceptualization stage for example. These fears include: Blowing the project out of proportion; Creating mission creep; Even derailing the project with the others self-interests. Again, all can be valid and even come true to a certain extent, but the reality is that most, if not all of the time, these same stakeholders will also identify the potential opportunities and pitfalls that will either help build the REAL ROI case, and/or help prevent the unseen wall that will prevent success.

These stakeholders can range from operational management (warehouse to manufacturing, depending on the target), IT, financial, quality, and engineering, just to get the ball rolling. You must always be careful of allowing the project to slip into “decision by committee”, so hold the reins and have the project lead firm in hand. But by bringing their input, you stand to satisfy not only your goal, but likely the shared goals they also have, validating and strengthening the real ROI that will likely exist if traceability is the requirement. You will also likely find that along the way you will bring improvements and efficiencies that will benefit the broader organization as a whole.

Once you’ve established the goal and the real ROI, reinforced by the stakeholder’s inputs, that is the time to bring in the technology pieces to see what best will solve that goal. This is many times were the first mistake can be made. The technology suppliers are brought in too soon and the project becomes technology weighted and a direction assumed before a true understanding of the benefits and goals of the organization are understood. Considering a project manager before bringing in the technology piece is also a great way to be ready when this time comes. When you’re ready for this stage, this will typically involve bringing in the vendors, integrators and so forth. And guess what, I’m certain you’ll find this part so much easier and faster to deal with, and with greater clarity. If you have that clear picture from your team when you bring in your solution providers, you will find the choices and their costs more realistic, and have a better picture of the feasibility of what your organization can implement and support.

Not to kill the thought with a sports analogy, but a team united and pulling for the same goal in the same direction will always win the game, versus each player looking out for just their own goals. So get your team together and enjoy the sweet taste of ROI success all around.

For more information on Traceability visit www.balluff.us/traceability.

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Requirements for Sanitary Fill Level Sensors

In a previous entry here on the SensorTech blog, we discussed the concept of liquid level sensing, and the difference between discrete liquid level detection and continuous liquid level monitoring.  In this entry, we are going to talk about the requirements for liquid level sensors that are used to measure or monitor liquid products that will ultimately be consumed by humans.

In these applications, it is necessary and critical that sanitary standards be met and maintained.  Sensor designed for sanitary applications are usually designed from the ground up to meet these requirements.

Basically, there are two key criteria that come into play when considering the suitability of a sensor to be used in a sanitary environment:

  • Cleanability – Sanitary filling systems typically need to be regularly cleaned and/or sterilized to prevent the growth of potentially harmful bacteria. It is desirable in most cases that the cleaning/sterilization process be done as quickly and as easily as possible, without having to remove components (including sensors) from the system.  For this reason, many sanitary fill sensors are designed to withstand “cleaning-in-place” (CIP).  Factors such as water-tightness, and ability to withstand elevated cleaning solution temperatures come into play for CIP suitability.
  • Mechanical Sensor Design – Sensors for sanitary fill applications are usually designed such that there are no mechanical features that would allow liquid or debris to collect. Crevices, grooves, seams, etc. can all act as collection points for liquid, and can ultimately lead to contamination.  For this reason, sanitary sensors are designed without such features.  The physical make-up of the sensor surface is also important.  Exterior surfaces need to be very smooth and non-reactive (e.g. high-grade stainless steel).  Such materials also contribute to cleanability.

Consistent standards for sanitary equipment, products, and processes are defined and maintained by 3-A SSI, a not-for-profit entity that provides consistent, controlled, and documented standards and certifications for manufacturers and users of sanitary equipment, particularly in the food, beverage, and pharmaceutical industries.  Equipment that meets these sanitary standards will usually display the 3-A symbol. For more information on this solution visit the Balluff website.

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Miniature Capacitive Sensors for Small Part Detection

As discussed in a previous blog post, miniature sensors are an ongoing trend in the market as manufacturing and equipment requirements continue to demand smaller sensor size due to either space limitations and/or weight considerations. However, size and weight aren’t the only factors. The need for more precise sensing — higher accuracy, repeatability, and smaller part detection — is another demanding requirement and, often times, the actual main focus point.

This post will look specifically at capacitive sensors and how smaller capacitive sensors can lead to better detection of smaller parts.

cap1

Principle of a capacitive sensor

cap4

Parallel-plate capacitor equation

Capacitive sensors provide non-contact detection of all types of objects, ranging from insulators to conductors and even liquids. A capacitive sensor uses the principle of capacitance to detect objects. The equation for capacitance takes into account the surface area (A) of either electrode, the distance (d) between the electrodes, and the dielectric constant (εr) of the material between the electrodes. In simple terms: a capacitive sensor detects the change in capacitance when an object enters its electrical field. Internal circuitry determines if the gain in capacitance is above the set threshold. Once the threshold is met the sensor’s output is switched.

cap2

Actuation of a capacitive sensor

When looking at small part detection, the size of the capacitive sensor’s active sensing surface plays a significant part. Now there isn’t a defined formula for calculating smallest detectable object for a capacitive sensor because of the numerous variables that need to be considered (as seen in the equation above). However, the general rule for optimal sensing is that the target size should be at least equal to the size of the sensor’s active surface. The reason behind this is if the target size is smaller than the sensor’s active surface, the electric field would travel around the target and cause unreliable readings.

Taking the general rule into consideration and comparing a miniature 4mm diameter capacitive sensor to a standard 18mm diameter capacitive sensor, it’s simple to determine that the 4mm diameter capacitive sensor can reliably detect a much smaller target (4mm) than the 18mm diameter capacitive sensor (18mm).

So when looking at small part detection, the smaller the sensor’s active sensing surface is, the better its ability for small part detection. Therefore, if an application requires detection of a small part, it’s best to start with miniature capacitive sensor.

For more information on miniature capacitive sensors click here.

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Detecting Small Bubbles? Consider These Factors First

BubbleDetectionBubble or air-in-line detection is a common lab automation application. In these types of applications it’s important to know whether or not liquid is flowing through a line to ensure safe and proper function in liquid-handling processes.  As these processes utilize smaller and smaller volumes of liquid — which provides cost and time saving benefits — it becomes more and more difficult to detect the potential air pockets forming inside the line. The most common approach in detecting these minute air pockets is a through-beam, photoelectric bubble sensor.

Photoelectric bubble sensors provide non-invasive detection of fluids and air pockets residing inside a tube. They have fixed opening dimensions for standard tube sizes allowing the selected tube to sit in perfect position between the sensor’s optical components. When the sensor’s light beam is blocked by fluid (or an air pocket) inside the tube, the received signal varies and external electronics determine if the signal variation is above or below the set threshold. Once the threshold is met the sensor’s output is switched.

Detecting bubbles sounds quite straightforward and simple, but in reality the application can be somewhat complicated. Several factors should be considered for reliable detection. Listed below are a few factors to consider:

  1. Tube diameters (inner and outer)
  2. Tube transparency
  3. Liquid type(s)
  4. Liquid transparency

Tube Diameters

Tube Sensor DrawingBecause a tube acts as a lens for light to travel it’s important to factor in the tube diameters. If there is a large difference between the outer and inner diameters of a particular tube, the outcome is a relatively large tube wall. A large tube wall will allow light rays to travel from the emitter through the wall straight to the detector without passing through the inner diameter of the tube, where the liquid or bubble is present. This causes unreliable detection. By accounting for both the inner and outer tube diameters a proper determination can be made in selecting what type of sensor to use to ensure that light only passes through the inner diameter of the tube and not through the wall.

Tube Transparency

Since photoelectric tube sensors operate on the principle of light detection, light must make it through one end of the tube and out the other end. Therefore, the transparency of the tube is critical. If the tube is opaque a photoelectric sensor solution is unlikely; however, in some cases it’s possible for a photoelectric tube sensor to detect through an opaque tube.

Liquid Type(s) and Transparency

The liquid type(s) and transparency are critical when determining which photoelectric tube sensor to use. If the liquid type is non-aqueous, without factoring in its transparency, it’s best to use the principle of light refraction through the liquid. If the liquid type is aqueous and is completely transparent or semitransparent, it’s best to use the principle of light absorption through the liquid. The following table will help determine what type of sensor to use with respect to the liquid type present inside the tube.

BubbleSensingChart

Since the type of applications that require precise bubble detection range in specifications from the use of hundreds of different liquids to specialized tube dimensions, this post only touches the surface of the photoelectric sensors for bubble detection.  For more information on tube sensors, please visit the Balluff website.

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Which cable jacket is best for your application?

There are many different types of cable jackets and each jacket works well in a specific application.  The three main sensor cable jackets are PVC (Polyvinyl Chloride), PUR (polyurethane) and TPE (thermoplastic elastomer). Each jacket type has different benefits like washdown, abrasion resistant or high flexing applications.  Finding the correct jacket type for your application can extend the life of the cable.PVC

PVC is a general purpose cable and is widely available.  It is a common cable, and typically has the best price point.  PVC has a high moisture resistance, which makes it a good choice for wash-down applications.

PURPUR is found mostly in Asia and Europe.  This cable jacket type has good resistance against abrasion, oil and ozone.  PUR is known for being Halogen free, not containing: chlorine, iodine, fluorine, bromine or astatine.  This jacket type does have limited temperature range compared to the other jacket types, -40…80⁰C.

TPETPE is flexible, recyclable and has excellent cold temperature characteristics, -50…125⁰C.  This cable is resistant against aging in the sunlight, UV and ozone.  TPE has a high-flex rating, typically 10 million.

The table below details the resistance to different conditions. Note that these relative ratings are based on average performance. Special selective compounding of the jacket can improve performance.

ResistanceTo

Choosing the right jacket type can help reduce failures in the field, reducing downtime and costs.  Please visit www.balluff.us to see Balluff’s offering of sensor cables in PVC, PUR and TPE.

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