IO-Link Boosts Plant Productivity

In my previous blog, Using Data to Drive Plant Productivity, I categorized reasons for downtime in the plant and also discussed how data from devices and sensors could be useful in boosting productivity on the plant floor. In this blog, I will focus on where this data is and how to access it. I also touched on the topic of standardizing interfaces to help boost productivity – I will discuss this topic in my future blog.

Sensor technology has made significant progress in last two decades. The traditional transistor technology that my generation learned about is long gone. Almost every sensor now has at least one microchip and possibly even MEMs chips that allow the sensor to know an abundance of data about itself and the environment it which it resides. When we use these ultra-talented sensors only for simple signal communication, to understand presence/absence of objects, or to get measurements in traditional analog values (0-20mA, 0-10V, +5/-5V and so on), we are doing disservice to these sensors as well as keeping our machines from progressing and competing at higher levels. It is almost like choking the throat of the sensor and not letting it speak up.

To elaborate on my point, let’s take following two examples: First, a pressure sensor that is communicating 4-20mA signal to indicate pressure value. Now, that sensor can not only read pressure value but, more than likely, it can also register the ambient temperatures and vibrations. Although, the sensor is capable of understanding these other parameters, there is no way for it to communicate that information to the higher level controller. Due to this lack of ambient information, we may not be able to prevent some eminent failures. This is because of the choice of communication technology we selected – i.e. analog signal communication.

For the second example, let us take a simple photoeye sensor that only communicates presence/absence through discrete input and 0/1 signal. This photoeye also understands its environment and other more critical information that is directly related to its functionality, such as information about its photoelectric lens. The sensor is capable of measuring the intensity of re-emitted light, because based on that light intensity it is determining presence or absence of objects. If the lens becomes cloudy or the alignment of the reflector changes, it directly impacts the remitted light intensity and leads to sensor failure. Due to the choice of digital communication, there is no way for the sensor to inform the higher level control of this situation and the operator only learns of it when the failure happens.

If  a data communication technology, such as IO-Link, was used in these scenarios instead of signal communication, we could unleash these sensors to provide useful information about themselves as well as about their environment. If we collect this data or set alerts in the sensor for the upper/lower limits on this type of information, the maintenance teams would know in advance about the possible failures and prevent these failures to avoid eminent downtime.

Collecting this data at appropriate frequencies could help build a more relevant database and demonstrate patterns for the next generation of machine learning and predictive maintenance initiatives. This would be data driven continuous improvement to prevent failures and boost productivity.

The information collected from sensors and devices – so called smart devices – not only helps end users of automation to boost their plant’s productivity, but also helps machine builders to better understand their own machine usage and behaviors. Increased knowledge improves the designs for the next generation of machines.

If we utilized these smart sensors and devices at our change points in the machine, it would help fully or partially automate the product change-overs. With IO-Link as a technology, these sensors can be reconfigured and re-purposed for different applications without needing different sensors or manual tunings.

IO-Link technology has a built in feature called “automatic parameterization” that helps reduce plant down-time when sensors need replaced. This feature stores IO-Link devices’ configuration on the master port as well as all the configuration is also persistent in the sensor. Replacement is as simple as connecting the new sensor of the same type, and the IO-Link master downloads all the parameters and  replacement is complete.

Let’s recap:

  1. IO-Link unleashes a sensor’s potential to provide information about its condition as well as the ambient conditions, enabling condition monitoring, predictive maintenance and machine learning.
  2. IO-Link offers remote configuration of devices, enabling quick and automated change overs on the production line for different batches, reducing change over times and boosting plant productivity.
  3. IO-Link’s automatic parameterization feature simplifies device replacement, reducing unplanned down-time.

Hope this helps boost productivity of your plant!

Rise of the Robots: IO-Link Maximizes Utilization, Saves Time and Money

Manufacturers around the world are buying industrial robots at an incredible pace. In the April 2020 report from Tractia & Statista, “the global market for robots is expected to grow at a compound annual growth rate (CAGR) of around 26 percent to reach just under 210 billion US dollars by 2025.” But are we gaining everything we can to capitalize on this investment when the robots are applied? Robot utilization is a key metric for realizing return-on-investment (ROI). By adding smart devices on and around the robot, we can improve efficiencies, add flexibility, and expand visibility in our robot implementations. To maximize robot utilization and secure a real ROI there are key actions to follow beyond only enabling a robot; these are: embracing the open automation standard IO-Link, implementing smart grippers, and expanding end-effector application possibilities.

In this blog, I will discuss the benefits of implementing IO-Link. Future blog posts will concentrate on the other actions.

Why care about IO-Link?

First, a quick definition. IO-Link is an open standard (IEC 61131-9) that is more than ten years old and supported by close to 300 component suppliers in manufacturing, providing more than 70 automation technologies (figure 1). It works in a point-to-point architecture utilizing a central master with sub-devices that connect directly to the master, very similar to the way USB works in the PC environment. It was designed to be easy to integrate, simple to support, and fast to implement into manufacturing processes.

Figure 1 – The IO-Link consortium has close to 300 companies providing more than 70 automation technologies.

Using standard cordsets and 24Vdc power, IO-Link has been applied as a retrofit on current machines and designed into the newest robotic work cells. Available devices include pneumatic valve manifolds, grippers, smart sensors, I/O hubs, safety I/O, vacuum generators and more. Machine builders and equipment OEMs find that IO-Link saves them dramatically on engineering, building and the commissioning of new machines. Manufacturers find value in the flexibility and diagnostic capabilities of the devices, making it easier to troubleshoot problems and recover more quickly from downtime. With the ability to pre-program device parameters, troublesome complex-device setup can be automated, reducing new machine build times and reducing part replacement times during device failure on the production line.

Capture Data & Control Automation

Figure 2 – With IIoT-ready IO-Link sensors and masters, data can be captured without impacting the automation control.

The final point of value for robotic smart manufacturing is that IO-Link is set up to support applications for the Industrial Internet of Things (IIoT). IO-Link devices are IIoT ready, enabling Industry 4.0 projects and smart factory applications. This is important as predictive maintenance and big-data applications are only possible if we have the capabilities of collecting data from devices in, around and close to the production. As we look to gain more visibility into our processes, the ability to reach deep into your production systems will provide major new insights. By integrating IIoT-ready IO-Link devices into robotic automation applications, we can capture data for future analytics projects while not interrupting the control of the automation processes (figure 2).

Buying a Machine Vision System? Focus on Capabilities, Not Cost

Gone are the days when an industrial camera was used only to take a picture and send it to a control PC. Machine vision systems are a much more sophisticated solution. Projects are increasingly demanding image processing, speed, size, complexity, defect recognition and so much more.

This, of course, adds to the new approach in the field of software, where deep learning and artificial intelligence play a bigger and bigger role. There is often a lot of effort behind improved image processing, however,  some people, if only a few, have realized that part of it can already be processed by that little “dummy” industrial camera.

I will try to briefly explain to you in the next few paragraphs how to achieve this in your application. Thanks to that, you will be able to get some of these benefits:

  • Reduce the amount of data
  • Relieve the entire system
  • Generate the maximum performance potential
  • Simplify the hardware structure
  • Reduce the installation work required
  • Reduce your hardware costs
  • Reduce your software costs
  • Reduce your development expenses

How to achieve it?  

Try to use more intelligent industrial cameras, which have a built-in internal memory sometimes called a buffer. Together with FPGA (field programmable gate array) they will do a lot of work that will appreciate your software for image processing. These functions are often also called pre-processing features.

What if you have a project where the camera must send images much faster than the USB or Ethernet interface allows?

For simple cameras, this would mean using a much faster interface, which of course would make the complete solution more expensive. Instead, you can use the Smart Framer Recall function in standard USB and GigE cameras, which generates small preview images with reduced resolution (thumbnails) with an extremely accelerated number of frames per second, which are transferred to the host PC with IDs. At the same time, the corresponding image in full resolution is archived in the camera’s image memory. If the image is required in full resolution, the application sends a request and the image is transferred in the same data stream as the preview image.

The function is explained in this video.

Is there a simpler option than a line scan camera? Yes!

Many people struggle to use line scan cameras and it is understandable. They are not easy to configurate, are hard to install, difficult to properly set and few people can modify them. You can use an area scan camera in line scan mode. The biggest benefit is standard interface: USB3 Vision and GigE Vision instead of CoaXPress and Cameralink. This enables inspection of round/rotating bodies or long/endless materials at high speed (like line scan cameras). Block scan mode acquires an Area of Interest (AOI) block which consists of several lines. The user defines the number of AOI blocks which are used to create one image. This minimizes the overhead, which you would have instead when transferring AOI blocks as single images using the USB3 Vision and GigE Vision protocols.

The function is explained in this video.

Polarization has never been easier

Sony came with a completely new approach to — a polarized filter . Until this new approach was developed, everyone just used a polarization filter in front of the lens and combined it with polarized lighting. With the polarized filter, above the pixel array is a polarizer array and each pixel square contains 0°, 45°, 90°, and 135° of polarization.

 

What is the best part of it? It doesn’t matter if you need a color or monochrome version. There are at least 5️ applications when you want to use it:

  • Remove reflection – > multi-plane surfaces or bruise/defect detection
  • Visual inspection – > detect fine scratches or dust
  • Contrast improvement -> recognize similar objects or colors
  • 3D/Stress recognition -> quality analysis
  • People/vehicle detection -> using your phone while driving

Liquid lens is very popular in smart sensor technology. When and why do you want to use it with an Industrial camera?  

 

Liquid lens is a single optical element like a traditional lens made from glass. However, it also includes a cable to control the focal length. In addition, it contains a sealed cell with water and oil inside. The technology uses an electrowetting process to achieve superior autofocus capabilities.

Benefits to the traditional lenses are obvious. It doesn’t have any moving mechanical parts. Thanks to that, they are highly resistant to shocks and vibrations. Liquid lens is a perfect fit for applications where you need to observe or inspect objects with different sizes and/or working distances and you need to react very quickly. One  liquid lens can do the work of multiple-image systems.

To connect the liquid lens, it requires the RS232 port in the camera plus a DC power from 5 to 24 Volt. An intelligent industrial camera is able to connect with the camera directly and the lens uses the power supply of the camera.

 

Tire Manufacturing – IO-Link is on a Roll

Everyone working in the mobility industry knows that the tire manufacturing process is divided up into five areas throughout a large manufacturing plant.

    1. Mixing
    2. Tire prep
    3. Tire build
    4. Curing and molds
    5. Final inspection

Naturally,  conveyors, material handling, and AGV processes throughout the whole plant.

All of these areas have opportunities for IO-Link components, and there are already some good success stories for some of these processes using IO-Link.

A major opportunity for IO-Link can be found in the curing press area. Typically, a manufacturing plant will have about 75 – 100 dual cavity curing presses, with larger plants having  even more. On these tire curing presses are many inputs and outputs in analog signals. These signals can be comprised of pressure switches, sensors, pneumatic, hydraulic, linear positioning, sensors in safety devices, thermo-couples and RTD, flow and much more.

IO-Link provides the opportunity to have all of those inputs, outputs and analog devices connected directly to an IO-Link master block and hub topography. This makes it not only easier to integrate all of those devices but allows you to easily integrate them into your PLC controls.

Machine builders in this space who have already integrated IO-Linked have discovered how much easier it is to lay out their machine designs, commission the machines, and decrease their costs on machine build time and installations.

Tire manufacturing plants will find that the visual diagnostics on the IO-Link masters and hubs, as well as alarms and bits in their HMIs, will quickly help them troubleshoot device problems. This decreases machine downtime and delivers predictive maintenance capabilities.

Recently a global tire manufacturer getting ready to design the curing presses for a new plant examined the benefits of installing IO-Link and revealed a cost savings of more than $10,000 per press. This opened their eyes to evaluating IO-Link technology even more.

Tire Manufacturing is a perfect environment to present IO-Link products. Many tire plants are looking to upgrade old machines and add new processes, ideal conditions for IO-Link. And all industries are interested in ways to stretch their budget.

 

Non-Contact Inductive Couplers Provide Wiring Advantages, Added Flexibility and Cost Savings Over Industrial Multi-Pin Connectors

Today, engineers are adding more and more sensors to in-die sensing packages in stamping applications. They do so to gain more information and diagnostics from their dies as well as reduce downtime. However, the increased number of sensors also increases the number of electric connections required in the automation system. Previously, the most common technique to accommodate large numbers of sensor in these stamping applications was with large, multi-pin connectors. (Figure 1)

Figure 1
Figure 1: A large multi-pin connector has been traditionally used in the past to add more electronics to a die.

The multi-pin connector approach works in these applications but can create issues, causing unplanned downtime. These problems include:

    1. Increased cost to the system, not only in the hardware itself, but in the wiring labor. Each pin of the connector must be individually wired based on the sensor configuration of each particular die. Depending on the sensor layout of the die, potentially each connector could need to be wired differently internally.
    2. A shorter life span for the multi-pin connector due to the tough stamping environment. The oil and lubrication fluids constantly spraying on the die can deteriorate the connectors plastic housings. Figure 1 shows the housing starting to come apart. When the connector is unplugged, these devices are not rated for IP67 and dirt, oil, and/or other debris can build up inside the connector.
    3. Cable damage during typical die change out. Occasionally, users forget to unplug the connectors before pulling the die out and they tear apart the device. If the connector is unplugged and left hanging off the die, it can be run over by a fork truck. Either way, new connectors are required to replace the damaged ones.
    4. Bent or damaged pins. Being mechanical in nature, the pin and contact points will wear out over time by regular plugging and unplugging of these devices.
    5. A lack of flexibility. If an additional sensor for the die is required, additional wiring is needed. The new sensor input needs to be wired to a free pin in the connector and a spare pin may not be available.
Figure 2
Figure 2: Above is a typical set up using these multi-pin connectors hard-wired to junction boxes.

Inductive couplers (non-contact) are another solution for in-die sensors connecting to an automation system. With inductive couplers, power and data are transferred across an air gap contact free. The system is made up of a base (transmitter) and remote (receiver) units. The base unit is typically mounted to the press itself and the remote unit to the die. As the die is set in place, the remote receives power from the base when aligned and exchanges data over a small air gap.

The remote and base units of an inductive coupler pair are fully encapsulated and typically rated IP67 (use like rated cabling). Because of this high ingress protection rating, the couplers are not affected by coolant, die lubricants, and/or debris in a typical stamping application. Being inherently non-contact, there is no mechanical wear and less unplanned downtime.

When selecting an inductive coupler, there are many considerations, including physical form factors (barrel or block styles) and functionality types (power only, input only, analog, configurable I/O, IO-Link, etc…). IO-Link inductive couplers offer the most flexibility as they allow 32 bytes of bi-direction data and power. With the large data size, there is a lot of room for future expansion of additional sensors.

Adding inductive couplers can be an easy way to save on unexpected downtime due to a bad connector.

fig 3
Figure 3: A typical layout of an IO-Link system using inductive couplers in a stamping application.

Reduce Packaging Downtime with Machine Vision

Packaging encompasses many different industries and typically has several stages in its process. Each industry uses packaging to accomplish specific tasks, well beyond just acting as a container for a product. The pharmaceutical industry for example, typically uses its packaging as a means of dispensing as well as containing. The food and beverage industry uses packaging as a means of preventing contamination and creating differentiation from similar products. Consumer goods typically require unique product containment methods and have a need for “eye-catching” differentiation.

The packaging process typically has several stages. For example, you have primary packaging where the product is first placed in a package, whether that is form-fill-seal bagging or bottle fill and capping. Then secondary packaging that the consumer may see on the shelf, like cereal boxes or display containers, and finally tertiary packaging or transport packaging where the primary or secondary packaging is put into shipping form. Each of these stages require verification or inspection to ensure the process is running properly, and products are properly packaged.

1

Discrete vs. Vision-Based Error Proofing

With the use of machine vision technology, greater flexibility and more reliable operation of the packaging process can be achieved. Typically, in the past and still today, discrete sensors have been used to look for errors and manage product change-over detection. But with these simple discrete sensing solutions come limitations in flexibility, time consuming fixture change-overs and more potential for errors, costing thousands of dollars in lost product and production time. This can translate to more expensive and less competitively priced products on the store selves.

There are two ways implementing machine vision can have a benefit toward improving the scheduled line time. The first is reducing planned downtime by reducing product change over and fixturing change time. The other is to decrease unplanned downtime by catching errors right away and dynamically rejecting them or bringing attention to line issues requiring correction and preventing waste. The greatest benefit vision can have for production line time is in reducing the planned downtime for things like product changeovers. This is a repeatable benefit that can dramatically reduce operating costs and increase the planned runtime. The opportunities for vision to reduce unplanned downtime could include the elimination of line jams due to incorrectly fed packaging materials, misaligned packages or undetected open flaps on cartons. Others include improperly capped bottles causing jams or spills and improper adjustments or low ink causing illegible labeling and barcodes.

Cost and reliability of any technology that improves the packaging process should always be proportional to the benefit it provides. Vision technologies today, like smart cameras, offer the advantages of lower costs and simpler operation, especially compared to the older, more expensive and typically purpose-built vision system counterparts. These new vision technologies can also replace entire sensor arrays, and, in many cases, most of the fixturing at or even below the same costs, while providing significantly greater flexibility. They can greatly reduce or eliminate manual labor costs for inspection and enable automated changeovers. This reduces planned and unplanned downtime, providing longer actual runtime production with less waste during scheduled operation for greater product throughput.

Solve Today’s Packaging Challenges

Using machine vision in any stage of the packaging process can provide the flexibility to dramatically reduce planned downtime with a repeatable decrease in product changeover time, while also providing reliable and flexible error proofing that can significantly reduce unplanned downtime and waste with examples like in-line detection and rejection to eliminate jams and prevent product loss. This technology can also help reduce or eliminate product or shipment rejection by customers at delivery. In today’s competitive market with constant pressure to reduce operating costs, increase quality and minimize waste, look at your process today and see if machine vision can make that difference for your packaging process.

Why In-Die sensing is a must

Metalforming suppliers are facing unprecedented challenges in today’s marketplace. As capital becomes scarce, and competition for business increases, the impact of a die crash or production run of bad parts could make the difference in whether they survive. Companies must protect their most critical assets, the presses and dies. Presses, dies, and various press room automation systems are the lifeblood of the supplier, and their costs can run into multiple millions of dollars in capital investment.

Sensor-driven error-proofing and die protection programs reduce downtime, ensure production is maximized, and prevent costly capital equipment repairs. Sensor implementation can prevent most die crashes and defective parts production if utilized correctly.

The vast majority of expensive press and die damage occurs due to failure to implement or the misapplication of sensing devices through a die protection program. There is a relatively inexpensive way for metal formers to protect their most critical assets in terms of dollar value and revenue creation. Stamping companies need to focus on two main areas to reduce costly repairs and production:

Feed-in and feed-through: You have to ensure the metal is in the press before the start of the cycle, and that it is feeding through properly. Once the cycle has completed, you must make sure the finished part is out of the stamping area. The type of stamping you do will determine the various points where you will need to incorporate sensors.

Part and slug ejection: During the stamping process, scrap material will be left that needs to be removed before the next cycle. Failure to ensure this will leave material inside the press, which can affect product quality or cause significant damage to the press, die, or both.

There are multiple additional processes within the press operation that can improve overall operational efficiency, but the two above should be the first steps toward implementing a successful program.

Multiple sensing devices can help you meet these requirements as well as a variety of suppliers and options you can choose from. It is essential that your personnel are trained on the various sensor technologies, and you are aligned with a supplier that understands the industry, your processes, and the variety of dies and materials you produce.

Many suppliers can provide you with sensing parts, but only a few are industry experts and can serve as both a consultant and parts supplier. You may need to invest a little more to get the expertise necessary to implement a sensing program upfront. Still, it will pay dividends for years to come if you focus upfront on the products that will reduce the downtime related to premature component failure or misapplication of sensor components.

Also, since most suppliers outsource the design and build of their dies, it is critical that your sensor solution partner is involved in new die design, with both your internal team as well as your die supplier. In addition, successful die protection programs entail rigid specifications for die sensing to help reduce their spare parts footprint and maximize the performance of their sensing devices.

 

How to Take Advantage of IO-Link Parameter Data

IO-Link data packets contain parameter data of an IO-Link slave device that is acyclic and is only transferred when read or write is requested by the machine controller. Having parameter data available on a device is not new or groundbreaking; however, the main advantage of IO-Link parameter data is that it is directly accessible by the machine controller, and it is dynamic, meaning you do not have to take the device offline to change its parameters or configuration. Parameter data determines how flexible or configurable an IO-Link slave device is. Its content will be different from device to device and manufacturer to manufacturer, a differentiator when choosing the right device for your application. We all know that not all IO-Link devices are created equal.

So how can you take advantage of parameter data?

Automatic machine configuration

Imagine if your machine could automatically configure itself upon first power-up? Yes, it is possible. Because IO-Link parameter data is accessible by the machine controller, i.e., the PLC or PAC, one can write a routine/program that first verifies the correct device is connected to the correct port of the IO-Link master, request a parameter read, compare the parameter content to the desired configuration in the program, and overwrite the current device parameter set if necessary. Why would someone do this? Well, if you are an OEM machine builder building ten of the same machines for one end customer, it would be a worthwhile investment in programming development to have IO-Link devices configured automatically. This method would eliminate the need for manual machine parameterization and result in cost savings. Examples of typical configuration would be changing the pin assignment of an IO-Link freely configurable discrete input/output hub as an input or an output, machine home position or offset of an IO-Link linear transducer, set points of an IO-Link pressure transducer, set points of an IO-Link laser distance sensor, and so on.

Recipe change

Another way to take advantage of IO-Link parameter data is to have the machine controller automatically change device configuration based on recipe change. This would eliminate the need for an operator to manually change device parameters, thus saving time and minimizing human error, especially if the device is not easily accessible by a human.

Maintenance

Having direct access to device parameters by the machine controller also enables OEMs to simplify their machines’ serviceability. For component replacement, all the maintenance personnel would have to replace a damaged device with a new device and walk away, eliminating the need for specialized training, software, or hardware.

Some manufacturers add special functions to their IO-Link masters to enable automatic backup and restoration of IO-Link slave device parameters, making replacement of components as easy as plug and play. This function would eliminate the need for OEMs to create custom programs or logic in their PLCs to restore parameter sets on a device automatically.

How to

So how would I do this? Because parameter data is accessible by the machine controller, implementation of auto configuration differs based on what brand of controller you are using. I will mention a few of the most popular.

  • Allen Bradley – For the Allen Bradley family of PLCs, you would use an explicit  instruction to read and write IO-Link device parameters.
  • Siemens -For the Siemens family of PLCs, you would use a standard function block named “FB_IOL_CALL”.

As you can see, every PLC or machine controller manufacturer and their flavor of IDE (Integrated Development Environment) will have their unique way of accessing IO-Link device parameter set. It is best to consult with both manufacturers and review IO-Link devices and PLCs to better understand how to set the read and write parameters of an IO-Link slave device.

Conclusion

Having direct access to device parameters and being able to change them without taking the device offline or needing special software or hardware, and implement it at a device level is game-changing. It opens doors for time and cost savings in design, integration, operation, and serviceability of machines. It is different from what we are used to, so don’t be afraid to think outside of the box and jump in with both feet.

 

How Lower-Priced Cables Can Cost More and Cause Downtime

Cable selection is an important step when it comes to creating a system to yield the most uptime. Sensors tell a machine when to start and stop or begin the next process. The time to replace and rewire the cable are costly, but small in comparison to the costs associated with the unplanned downtime a failed cable can cause. That is why it is so important to make sure you are selecting the right cable for the job.

There are three cable jacket materials that are the most commonly used: polyvinyl chloride (PVC), polyurethane (PUR), and thermoplastic elastomer (TPE). Each material has its own strengths and weaknesses, allowing them to work better in certain applications than others. When selecting cables, you must consider all factors and conditions such as the temperature rating, whether the cable will have contact with any chemicals, how much will the cable be moving, will it encounter weld spatter, vibrations, etc. Once you have this information you can start to look for what cable will work best for you.

Polyvinyl Chloride (PVC)
PVC is the most general cable jacket. It usually has the lowest price, it’s durable and offers a decent temperature range. This is the cable jacket you will see in most standard automation applications, but it isn’t built for harsher environment conditions. PVC does not perform well with weld spatter and can’t handle high heat; it also does not have the best chemical resistance compared to other cable material options.

Polyurethane (PUR)
The PUR jacket is a step up from PVC in most areas. It provides a higher abrasion resistance and better chemical resistance but has a lower temperature range. PUR jackets are mostly used in areas with lots of oils and chemicals or in a cable carrier due to its higher abrasion rating.

Thermoplastic Elastomer (TPE)
TPE jacketed cables deliver a higher temperature rating, are more flexible, offer great chemical resistance, and can resist weld spatter. These cables work in weld cells, high-heat applications, cable carriers, and much more. Because of the higher performance, TPE jacketed cables tend to have a higher price point than PVC and PUR but will last longer and can be used effectively in a variety of environments.

There are many other cable jacket options available that are more application specific than the three mentioned above. Cables with silicone or FEP jackets will have higher temperature ranges than even TPE and can more effectively resist weld spatter. Steel-jacketed cables provide great protection from abrasion and constant vehicle traffic or any falling objects that could cut through a standard jacket. There are also TPE-V cables that are made for the Food and Beverage industry that have all the necessary certifications and can undergo many washdown cycles.

A key to reducing downtime and MRO costs is selecting the right cable for the application. Choosing a lower-priced cable can costs your more in the long run. Using a PVC cable in a weld cell will cost you much more in replacements costs and downtime than would be spent on using a slightly more expensive silicone cable designed to last 4 times longer in that environment. Don’t be blinded by initial costs; instead, focus on the needs of your application and you will see the benefits.

Capacitive Prox Sensors Offer Versatility for Object and Level Detection

When you think of a proximity sensor, what is the first thing that comes to mind? In most cases it is probably the inductive proximity sensor and justly so because they are the most widely used sensor in automation today. But there are other types of proximity sensors. These include diffuse photoelectric sensors that use the reflectivity of the object to change states and proximity mode of ultrasonic sensors that use high frequency sound waves to detect objects. All of these sensors detect objects that are in close proximity of the sensor without making physical contact.

One of the most overlooked proximity sensors on the market today is the capacitive sensor. Why? For some, they have bad reputation from when they were released years ago as they were more susceptible to noise than most sensors. I have heard people say that they don’t discuss or use capacitive sensors because they had this bad experience in the past, however with the advancements of technology this is no longer the case.

Today capacitive sensors are available in as wide of a variety of housings and configurations as inductive sensors. They are available as small as 4mm in diameter, in hockey puck styles, extended temperature ranges, rectangular, square, with Teflon housings, remote sensing heads, adhesive cut-to-length for level detection and a hybrid technology that is capable of ignoring foaming and filming of liquids. The capability and diversity of this technology is constantly evolving.

Capacitive sensors are versatile in solving numerous 1applications. These sensors can be used to detect objects such as glass, wood, paper, plastic, ceramic, and the list goes on and on. The capacitive sensors used to detect objects are easily identified by the flush mounting or shielded face of the sensor. Shielding causes the electrostatic field to be short conical shaped much like the shielded version of the inductive proximity sensor. Typically, the sensing range for these sensors is up to 20 mm.

Just as there are non-flush or unshielded inductive sensors, there are non-flush capacitive sensors, and the mounting and housing2 looks the same. The non-flush capacitive sensors have a large spherical field which allows them to be used in level detection. Since capacitive sensors can detect virtually anything, they can detect levels of liquids including water, oil, glue and so forth and they can detect levels of solids like plastic granules, soap powder, sand and just about anything else. Levels can be detected either directly with the sensor touching the medium or indirectly where the sensor senses the medium through a non-metallic container wall. The sensing range for these sensors can be up to 30 mm or in the case of the hybrid technology it is dependent on the media.

The sensing distance of a capacitive sensor is determined by several factors including the sensing face area – the larger the better. The next factor is the material property of the object or dielectric constant, the higher the dielectric constant the greater the sensing distance. Lastly the size of the target affects the sensing range. Just like an inductive sensor you want the target to be equal to or larger than the sensor. The maximum sensing distance of a capacitive sensor is based on a metal target thus there is a reduction factor for non-metal targets.

As with most sensors today, the outputs of a capacitive sensor include PNP, NPN, push-pull, analog and the increasing popular IO-Link. IO-Link provides remote configuration, additional diagnostics and a window into what the sensor is “seeing”. This is invaluable when working on an application that is critical such as life sciences.

Most capacitive sensors have a potentiometer to allow adjustment of the sensitivity of the sensor to reliably detect the target. Today there are versions that have teach pushbuttons or a teach wire for remote configuration or even a remote amplifier. Although capacitive sensors can detect metal, inductive sensors should be used for these applications. Capacitive sensors are ideal for detecting non-metallic objects at close ranges, usually less than 30 mm and for detecting hidden or inaccessible materials or features.

Just remember, there is one more proximity sensor. Don’t overlook the capabilities of the capacitive sensor.