Top 5 Automation Insights Posts from 2017

Kick off the New Year by taking a look at the top 5 Automation Insight blog posts from last year.

#5. Make sure your RFID system is future-proof by answering 3 questions

With the recent widespread adoption of RFID technology in manufacturing plants I have encountered quite a number of customers who feel like they have been “trapped” by the technology. The most common issue is their current system cannot handle the increase in the requirements of the production line. In a nutshell, their system isn’t scalable.5

Dealing with these issues after the fact is a nightmare that no plant manager wants to be a part of. Can you imagine installing an entire data collection system then having to remove it and replace it with a more capable system in 3 years or even less? It’s actually a pretty common problem in the world of technology. However, an RFID system should be viable for much longer if a few simple questions can be answered up front. Read more>>

#4. IO-Link Hydraulic Cylinder Position Feedback

Ready for a better mousetrap?  Read on…..

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…..”

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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. Read More>>

#3. External Position Feedback for Hydraulic Cylinders

The classic linear position feedback solution for hydraulic cylinders is the rod-style magnetostrictive sensor installed from the back end of the cylinder. The cylinder rod is gun-drilled to accept the length of the sensor probe, and a target magnet is installed on the face of the piston. A hydraulic port on the end cap provides installation access to thread-in the pressure-rated sensor tube. This type of installation carries several advantages but also some potential disadvantages depending on the application. Read More>>

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#2. 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 new2 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.

The 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. Read More>>

#1. What is a Capacitive Sensor?

Capacitive proximity sensors are non-contact devices that can detect the presence or absence of virtually any object regardless of material.  1They utilize the electrical property of capacitance and the change of capacitance based on a change in the electrical field around the active face of the sensor.

A capacitive sensor acts like a simple capacitor.  A metal plate in the sensing face of the sensor is electrically connected to an internal oscillator circuit and the target to be sensed acts as the second plate of the capacitor.  Unlike an inductive sensor that produces an electromagnetic field a capacitive sensor produces an electrostatic field. Read More>>

In-Cylinder Position Sensing in Electrically Conductive Hydraulic Fluids

The standard for hydraulic fluid in the industry is mineral oil, which is a dielectric medium that does not conduct electricity. Yet environmental concerns have led to the search for alternatives that are less harmful in case of leaks and spills. One development is biodegradable oils, typically with biological origins, often called “bio-oils” for short. They behave in many ways like mineral oil with a key difference in that they can be electrically conductive.

Another alternative hydraulic fluid is water-glycol mixtures, commonly known as the anti-freeze found in your liquid-cooled automobile engine. Water-glycol solutions are used for several reasons, including environmental concerns but more often conditions of extreme heat or extreme cold. They have much lower viscosity than oil, and there are several fluid power application considerations as a result, but water-glycol mixtures, like bio-oils, are electrically conductive.

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So, when it comes to cylinder position sensing, why should we care whether or not the hydraulic fluid is electrically conductive? Well, because it could come back to bite us if we put an incompatible position sensing technology into a cylinder that is filled with a conductive fluid.

I recently met an engineer who’d run into this exact situation. A hydraulic cylinder was ordered from the manufacturer with an “integrated position feedback sensor.” The feedback sensor turned out to be a resistive potentiometric type, in other words, a linear potentiometer or “pot.” The entire length of the resistive material is “wetted” inside the cylinder, along with the traveling “wiper” that moves with the piston. In typical applications with non-conductive, mineral-based hydraulic fluid, this works fine (although linear pots do tend to be somewhat fragile and do wear out over time). However, when the resistive material and wiper is wetted in a conductive liquid, all kinds of wrong start happening. The signal becomes very erratic, unstable, and lacks resolution and repeatability. This is because the fluid is basically short-circuiting the operation of the open-element linear potentiometer.

This caused quite a headache for the engineer’s customer and subsequently for the engineer. Fortunately, a replacement cylinder was ordered, this time with a non-contact magnetostrictive linear position sensor. The magnetostrictive sensor is supplied with a pressure-rated, protective stainless steel tube that isolates the electrical sensing element from the hydraulic medium. The position marker is a magnet instead of a wiper, which the sensor can detect through the walls of the stainless steel pressure tube. So, a magnetostrictive sensor is absolutely unaffected by the electrical properties of the hydraulic medium.

A magnetostrictive linear position sensor carries a lot of performance and application advantages over linear pots that make them a superior technology in most applications, but when it comes to conductive hydraulic fluids they are definitely the preferred choice.

To learn more about linear position sensors visit www.balluff.com.

Ensure Optimum Performance In Hostile Welding Cell Environments

The image above demonstrates the severity of weld cell hostilities.

Roughly four sensing-related processes occur in a welding cell with regards to parts that are to be joined by MIG, TIG and resistance welding by specialized robotic /automated equipment:

  1. Nesting…usually, inductive proximity sensors with special Weld Field Resistance properties and hopefully, heavy duty mechanical properties (coatings to resist weld debris accumulation, hardened faces to resist parts loading impact and well-guarded cabling) are used to validate the presence of properly seated or “nested” metal components to ensure perfectly assembled products for end customers.
  2. Poke-Yoke Sensing (Feature Validation)…tabs, holes, flanges and other essential details are generally confirmed by photoelectric, inductive proximity or electromechanical sensing devices.
  3. Pneumatic and Hydraulic cylinder clamping indication is vital for proper positioning before the welding occurs. Improper clamping before welding can lead to finished goods that are out of tolerance and ultimately leads to scrap, a costly item in an already profit-tight, volume dependent business.
  4. Several MIB’s covered in weld debris

    Connectivity…all peripheral sensing devices mentioned above are ultimately wired back to the controls architecture of the welding apparatus, by means of junction boxes, passive MIB’s (multiport interface boxes) or bus networked systems. It is important to mention that all of these components and more (valve banks, manifolds, etc.) and must be protected to ensure optimum performance against the extremely hostile rigors of the weld process.

Magnetoresistive (MR), and Giant Magnetoresistive (GMR) sensing technologies provide some very positive attributes in welding cell environments in that they provide exceptionally accurate switching points, have form factors that adapt to all popular “C” slot, “T” slot, band mount, tie rod, trapezoid and cylindrical pneumatic cylinder body shapes regardless of manufacturer. One model family combines two separate sensing elements tied to a common connector, eliminating one wire back to the host control. One or two separate cylinders can be controlled from one set if only one sensor is required for position sensing.

Cylinder and sensor under attack.

Unlike reed switches that are very inexpensive (up front purchase price; these generally come from cylinder manufacturers attached to their products) but are prone to premature failure.  Hall Effect switches are solid state, yet generally have their own set of weaknesses such as a tendency to drift over time and are generally not short circuit protected or reverse polarity protected, something to consider when a performance-oriented cylinder sensing device is desired.  VERY GOOD MR and GMR cylinder position sensors are guaranteed for lifetime performance, something of significance as well when unparalleled performance is expected in high production welding operations.

But!!!!! Yes, there is indeed a caveat in that aluminum bodied cylinders (they must be aluminum in order for its piston-attached magnet must permit magnetic gauss to pass through the non-ferrous cylinder body in order to be detected by the sensor to recognize position) are prone to weld hostility as well. And connection wires on ALL of these devices are prone to welding hostilities such as weld spatter (especially MIG or Resistance welding), heat, over flex, cable cuts made by sharp metal components and impact from direct parts impact. Some inexpensive, effective, off-the-shelf protective silicone cable cover tubing, self-fusing Weld Repel Wrap and silicone sheet material cut to fit particular protective needs go far in protecting all of these components and guarantees positive sensor performance, machine up-time and significantly reduces nuisance maintenance issues.

To learn more about high durability solutions visit www.balluff.com.

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.

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.

Quick field replacement for linear sensor electronics

Micropulse Transducers BTL 7 Rod-style with Rapid Replacement Module
Micropulse Transducers BTL 7
Rod-style with Rapid Replacement Module

When maintenance technicians replace linear position sensors (also known as probes or wands) from hydraulic cylinders, it can leave a terrible mess, waste hydraulic oils, and expose the individual to harmful hot fluids.  Also, the change out process can expose the hydraulic system to unwanted contaminants. After the sensor replacement has been completed, there can also be more work yet to do during the outage such as replacing fluids and air-bleeding cylinders.

Hydraulic linear position sensors with field-replaceable electronics/sensing elements eliminate these concerns.  Such sensors, so-called Rapid Replacement Module (RRM) sensors, allow the “guts” of the sensor to be replaced, while the stainless steel pressure tube remains in the cylinder.  The hydraulic seal is never compromised.  That means that during the replacement process there is no danger of oil spillage and no need for environmental containment procedures. There is also no need to bleed air from the hydraulic system and no danger of dirt or wood debris entering the open hydraulic port. Finally, there is no danger of repair personnel getting burned by hot oil.

The RRM is an option for Balluff’s BTL7 Z/B Rod Series used in applications for the lumber industry, plastic injection and blow molding, tire and rubber manufacturing, stamping presses, die casting, and all types of automated machinery where a continuous, absolute position signal is required.  Applications in industries such as Oil & Gas and Process Control are especially critical when it comes to downtime.  For these applications, this Rapid Replacement Module capability is especially advantageous.

You can learn more about linear position sensors with hazardous area approvals, by visting http://www.balluff.com/local/us/products/sensors/magnetostrictive-linear-position-sensors/

The video below shows a demonstration of the Rapid Replacement Module in action.

 

Blaise Pascal – The Ultimate Powerlifter

Our modern technological society owes a lot to the scientific work and inspiration of a 17th-century French mathematician and physicist, Blaise Pascal. Pascal was a pioneer in the fields of hydrostatics and hydrodynamics, which deal with the subject of fluid mechanics under pressure.

One of the most important physical principles he defined is known today as Pascal’s Law:

“Blaise Pascal Versailles” by unknown1

“A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.”

It is this characteristic of fluids held in containment that allows force applied to a fluid in one location to be delivered to another remote location. A well-known example would be the hydraulic brake system in a car. Mechanical pressure from the driver’s foot is transferred to the brake fluid through a master cylinder. This pressure is then instantly communicated to braking cylinders located at each wheel, causing them to apply mechanical force to press friction pads against a brake drum or rotor, thus slowing or stopping the vehicle.

In the industrial world, the compact yet incredible power of hydraulic cylinders is a constant source of awe and amazement. Through the magic of fluid power leverage via Pascal’s Law, hydraulic cylinders are capable of generating tremendous lifting forces to move massively heavy structures.

In order for such great force to be harnessed to do useful work, it must be kept fully under control. Force that is out of control is either useless or destructive. When it comes to controlling the movement of a powerful hydraulic cylinder, the piston/ram position must be continually monitored in near-real-time.

The most popular device for measuring cylinder position is called a Magnetostrictive Linear Position Sensor. Sometimes these position sensors are called LDTs (Linear Displacement Transducer) or MDTs (Magnetostrictive Displacement Transducer). All of these terms refer to the same type of devices.

BTL7

To get an idea of the power and control that is feasible with modern hydraulic cylinders and integrated cylinder position sensors, have a look at this amazing video from ALE Heavylift. The topside of a giant offshore oil platform was jacked up 131 ft (40 m) and then skidded horizontally a distance of 295 ft (90 m) to place it on top of its supports. Imagine the incredible synchronization of speed, position, and operational sequencing needed to safely lift and place such a massive structure.

For more information about magnetostrictive linear position sensors for hydraulic cylinders, visit the Balluff website at www.balluff.us.

1. “Blaise Pascal Versailles” by unknown; a copy of the painture of François II Quesnel, which was made for Gérard Edelinck en 1691. – Own work. Licensed under CC BY 3.0 via Commons – https://commons.wikimedia.org/wiki/File:Blaise_Pascal_Versailles.JPG#/media/File:Blaise_Pascal_Versailles.JPG

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.

Continue reading “Hydraulic Cylinder Position Feedback, Revisited”

Anatomy of a High Pressure Inductive Proximity Sensor

Some industrial applications will require a sensor with special properties. This type of sensor offering is needed especially when pressure comes to play. In a wide range of hydraulic cylinder and valve applications high pressure sensors are exposed to hostile environments and are subject to pressure that a standard sensor simply cannot hold up in. For example 350 bar of pressure can be detrimental to a standard sensor as it is not designed for a pressure application.

High pressure inductive sensors are designed to withstand the severe duty of a high pressure application with product features like corrosion – resistant housing materials, high strength ceramic sensing faces and special sealing techniques such as undercut housings with sealing and support rings. This is very important because not only do we need to have a sensor that can withstand pressure on the face of the sensor without damage we also need to make sure we can keep the hydraulic fluid inside the cylinder or valve where it belongs.

In the photo below you will notice the undercut area at the sensing face of the sensor along with an O-ring and supporting backing ring to make sure the application is sealed tight.

installation instruction Installation Photo

There are several common sizes for different types of cylinder and valves however the same principle applies. Below is an example of a flange mount style offering. This type of sensor takes a different design approach that is bolted to the top side of a cylinder with a sealing O-ring under the mounting point.

Strokemaster Diagram

strokemaster photo

It’s also important to know what form factor is needed when specifying a high pressure inductive sensor. Typically you will see pressure options from 50 up to 500 bar. The dimensions of the cylinder or valve will determine what type of high pressure sensor is needed.

HighPressureGroup

To learn more visit www.balluff.us.

Linear Position Sensors for Valve Actuators

Illustration of Magnetostrictive Linear Displacement Transducer (MLDT) inserted into a gun-drilled cylinder.Today’s petrochemical and process industries, like most industries, are striving to increase their capabilities of automation & control, coupled with condition monitoring, across their entire operation.  Demands for uptime are increasing and the focus on reliability through redundancy and prediction of pending maintenance requires new control and monitoring strategies.  This is nowhere more true than in the case of the sophisticated valves that form the most critical elements of the operation or process.  Operational readiness and confirmation of operation for these valves are indispensable to assure smoother and uninterrupted production…and safety.

Christian Dow has written an interesting article in Valve Magazine that highlights the benefits of linear position sensors when installed in the hydraulic actuators of these valves.  The benefits mentioned in the article don’t apply just for valves, though.  Many of the advantages can be obtained for almost any application where a hydraulic cylinder is the prime mover.