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Enhancing Precision and Efficiency in Life Sciences Manufacturing Via Sensing Tech

The life sciences industry has stringent quality demands for its manufacturing processes due to the nature of its products, which directly impact human health and life. These demands include but are not limited to regulatory compliance, quality control and assurance, sterility and cleanliness, precision and accuracy, traceability, and product stability. The life sciences are also no exception to any other industry in the necessity for continuous improvement and efficiency in their manufacturing processes. As such, businesses in this sector constantly seek out automation solutions to satisfy these demands, with potential use cases for a range of sensing technologies. This industry makes extensive use of the most common sensing technologies, including capacitive, photoelectric, and inductive sensors.

Capacitive sensors

Capacitive sensing relies on the capacitance (the ability to store an electric charge) of material or media to provide an accurate and reliable detection reading. When an object approaches a capacitive sensor, it will interfere with the electrical field of the sensor: If the object is a conductor, it will absorb some of the field’s energy; if it is a dielectric (non-conductor), it will cause a displacement of the electrical field. You can then detect and measure the change. This principle allows capacitives great versatility in sensing applications, some of the most sophisticated applications using certain sensors that can ignore multiple layers of material or media. This is especially useful in the life sciences industry, as many businesses in the sector have complex manufacturing processes that provide challenges for certain automation solutions, such as media-level detection. Standard capacitive sensors can also be useful for general part and product detection as well, depending on the material.

Potential life science applications include:

    • Bioreactor level detection
    • Packaging fill level detection
    • Product count detection
    • Waste/reagent tank level detection

Photoelectric sensors

Photoelectric sensors use light to detect objects and have the following three primary categories:

    • Through-beam sensors, which use an emitter and receiver to determine object presence by the absorbance or amplification of the emitted light
    • Diffuse beam sensors, where the emitter and receiver are in the same housing and light reflects off the object
    • Retro-reflective beam sensors, which operate similarly to diffuse but use a fixed special reflector to send polarized light back to the receiver

In addition to these categories and several product variants in each category, photoelectrics come in a variety of housing options that provide great versatility in sensing applications.

Businesses in the life sciences industry can capitalize on photoelectric sensing technology for highly precise measurements and specialized sensors for liquid detection through certain containers and vessels. Photoelectrics can also easily be applied for part and consumable detection.

Potential life science applications include:

    • Pipette volume detection
    • Product cap detection
    • Packaging film detection
    • Liquid presence in clear tubing

Inductive sensors

Inductive sensors use a coil to generate an electromagnetic field from the sensor head. This field induces eddy currents in objects that come within range of this field, specifically metallic objects. This will cause a change in the magnetic field, which the sensor will measure and detect. Businesses that operate in the life science industry don’t exclusively deal with liquid, media-level, and plastic part detection. Many are also suppliers of sophisticated equipment and instrumentation designed for specific tasks, and these devices must operate reliably through daily cyclical usage, where inductive sensors can ensure they are secure and operate correctly while in use by scientists and technicians.

Potential life science applications include:

    • Centrifuge lid closure detection
    • Robotic arm positioning
    • Device speed detection

Applying a few of the most common sensing technologies can satisfy various demands for businesses within the life sciences industry. Companies across all industries share several needs when it comes to gauging the perfect solution for their automation needs, but those in this industry are additionally reliant on highly accurate and precise sensing, sensors that are exceptional in quality and reliability and are customizable to their specific application.

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Flush, Non-Flush, or Quasi-Flush: Choosing the Right Proximity Sensor for Optimal Object Detection

Proximity sensors are aptly named for their ability to detect objects in close proximity. They are not suitable for detecting objects across a room or on a conveyor belt. Their focus is on detecting objects up close and personal. Inductive proximity technology allows detection from physical contact with the sensor head to a few millimeters away. When choosing the right type of inductive proximity technology, several factors must be considered. Let’s start at the beginning.

Inductive proximity sensors may seem magical, but they operate based on specific magical characteristics. To prove my point, show them (and try to explain them) to a kid. Imagine an invisible electromagnetic field surrounding the sensors. This field can only be disrupted by a metal target. Different metals can affect this field at varying distances, depending on the type of metal and the sensor used. In simple terms, the sensor can detect if an object is a metal and, to some extent, the type of metal– all without touching the object physically.

Now that we’ve covered the basics, let’s focus on understanding the characteristics of the magical electromagnet field, its impact on sensing range, mounting, and the risks of sensor and/or part damage.

You may have heard the terms flush or non-flush used for inductive proximity sensors. I’ll throw one more into the mix: quasi-flush.

Non-flush mounting

Non-flush mount proximity sensors offer the longest range – the air gap between the target and the sensing head. This can be a good thing or a bad thing, depending on the situation. For precise positioning requirements, the extra range might cause issues. However, if precision is unnecessary, the extended ranges could be beneficial as objects might come into range slightly differently. One major downside of non-flush sensors is their susceptibility to damage. Typically, several millimeters to half an inch of the sensing head is exposed, increasing the risk of shearing off the sensor head or damaging the object you are detecting.

Flush mount proximity

With flush-mount proximity, you gain some protection for both the sensor head and the object being detected, but it comes with a trade-off of reduced sensing range. This is because the shape of the electromagnetic field coming out of the sensing head is focused to avoid triggering the mounting block or other hardware.

Quasi-flush mounting

If you are looking for a Goldilocks solution, consider quasi-flush mounting. With this style of sensing head, you recess the sensor into a mounting block, which helps focus the electromagnet field a bit more, thereby adding more field length compared to a flush mount. It is important to ensure your mounting block has a bevel around the sensing head to avoid false triggers of the output.

So, when deciding which type to use, I recommend using flush or quasi-flush sensors for any target that may come into contact with the sensing head. This choice will prolong the sensor’s life and better ensure proper target triggering. Non-flush sensors are great when you need a larger gap between the target and the sensing head, and precision is not a big issue.

In closing, proximity sensing is designed to be a non-contact form of object detection, specifically metal objects. The goal is to avoid any contact with the sensing head, although we’re aware that object/sensor collisions can happen.

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Automation Insights: Top 10 Blogs From 2023

In 2023, the industrial automation sector experienced significant advancements and transformative trends, shaping the landscape of manufacturing and production processes. Listed below are our top 10 blogs highlighting some of these advancements, from streamlined changeover processes using RFID to machine safety levels determined through risk assessments and a proactive approach to unplanned downtime using condition monitoring. Other blogs explored UHF RFID considerations, communication protocol analysis, camera selection guidance for engineers, machine safety practices emphasis, and discussions on IO-Link and MQTT benefits for automation projects.

    1. Using RFID Technology for Rapid Changeover

In today’s tight economy, marked by high inflation and supply chain issues, the need to enhance product flexibility has become increasingly important. Most manufacturing lines these days are set up to run multiple work orders of the same product type based on specific requirements. The goods produced at the manufacturer line are still the same, but the package size can change. The raw materials that start the process might be the same, but other component parts and tools on the machine that help with the different packaging sizes must be replaced. The process of converting one product line or machine to another is known as changeover. This blog explores how Radio Frequency Identification (RFID) technology can revolutionize changeover by eliminating manual verification and adjustments.

Read more.

    1. Understanding Machine Safety: The Power of Risk Assessments

My last blog post was about machine safety with a focus on the different categories and performance levels of machine safety circuits. But I just briefly touched on how to determine these levels. By default, we could design all equipment with the highest-level category and performance levels of safety with an abundance of caution, but this approach could be extremely expensive and not the most efficient.

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    1. Getting Started With Condition Monitoring

Unplanned downtime is consistently identified as one of the top manufacturing issues. Condition monitoring can offer a fairly simple way to start addressing this issue and helps users become more proactive in addressing and preventing impending failures of critical equipment by using data to anticipate problems.

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    1. Sensing Ferrous and Non-Ferrous Metals: Enhancing Material Differentiation

Detecting metallic (ferrous) objects is a common application in many industries, including manufacturing, automotive, and aerospace. Inductive sensors are a popular choice for detecting metallic objects because they are reliable, durable, and cost-effective. Detecting a metallic object, however, is not always as simple as it seems, especially if you need to differentiate between two metallic objects. In such cases, it is crucial to understand the properties of the metals you are trying to detect, including whether they are ferrous or non-ferrous.

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    1. Considerations When Picking UHF RFID

If you’ve attempted to implement an ultra-high frequency (UHF) RFID system into your facility, you might have run into some headaches in the process of getting things to work properly. If you are looking to implement UHF RFID, but haven’t had the chance to set things up yet, then this blog might be beneficial to keep in mind during the process.

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    1. Comparing IO-Link and Modbus Protocols in Industrial Automation

In the realm of industrial automation, the seamless exchange of data between sensors, actuators, and control systems is critical for optimizing performance, increasing efficiency, and enabling advanced functionalities. Two widely used communication protocols, IO-Link and Modbus, have emerged to facilitate this data exchange. In this blog, I’ll analyze the characteristics, strengths, and weaknesses of both protocols to help you choose the right communication standard for your industrial application.

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    1. Exploring Industrial Cameras: A Guide for Engineers in Life Sciences, Semiconductors, and Automotive Fields 

In the bustling landscape of industrial camera offerings, discerning the parameters that genuinely define a camera’s worth can be a daunting task. This article serves as a compass, steering you through six fundamental properties that should illuminate your path when selecting an industrial camera. While the first three aspects play a pivotal role in aligning with your camera needs, the latter three hold significance if your requirements lean towards unique settings, external conditions, or challenging light environments.

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    1. Focusing on Machine Safety

Machine safety refers to the measures taken to ensure the safety of operators, workers, and other individuals who may encounter or work in the vicinity of machinery. Safety categories and performance levels are two important concepts to evaluate and design safety systems for machines. A risk assessment is a process to identify, evaluate, and prioritize potential hazards and risks associated with a particular activity, process, or system. The goal of a risk assessment is to identify potential hazards and risks and to take steps to prevent or mitigate those risks. The hierarchy of controls can determine the best way to mitigate or eliminate risk. We can use this hierarchy, including elimination, substitution, engineering, and administrative controls, and personal protective equipment (PPE), to properly mitigate risk. Our focus here is on engineering controls and how they relate to categories and performance levels.

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    1. Why Choose an IO-Link Ecosystem for Your Next Automation Project?

By now we’ve all heard of IO-Link, the device-level communication protocol that seems magical. Often referred to as the “USB of industrial automation,” IO-Link is a universal, open, and bi-directional communication technology that enables plug-and-play device replacement, dynamic device configuration, centralized device management, remote parameter setting, device level diagnostics, and uses existing sensor cabling as part of the IEC standard accepted worldwide.

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    1. Using MQTT Protocol for Smarter Automation

In my previous blog post, “Edge Gateways to Support Real-Time Condition Monitoring Data,” I talked about the importance of using an edge gateway to gather the IoT data from sensors in parallel with a PLC. This was because of the large data load and the need to avoid interfering with the existing machine communications. In this post, I want to delve deeper into the topic and explain the process of implementing an edge gateway.

Read more.

We appreciate your dedication to Automation Insights in 2023 and look forward to growth and innovation in 2024.

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Remote Power Through Inductive Coupling

Inductive couplers are reshaping industrial connectivity by enabling wireless power and data transmission across air gaps. In this blog, I explore the mechanics behind inductive couplers, from magnetic fields facilitating power transfer to bidirectional data communication. I’ll look at applications like end-of-arm tooling, rotary indexing tables, and rapid die change systems to discover how inductive couplers enhance flexibility, durability, and reliability in manufacturing. Additionally, I’ll review the benefits of this technology, poised to revolutionize wireless connectivity in industrial settings.

Inductive couplers: what they are and how they work

Inductive couplers transmit power and data wirelessly without physical connection over an air gap. They are used in various industrial applications such as end-of-arm tooling, rotary indexing tables as well and rapid die change.

Inductive couplers consist of two components: a base (transmitter) and a remote (receiver). The base is connected to a power source and a controller. The remote is attached to a load, such as a hub powering sensors or actuators. Power and data are transferred when the base and remote are in range and aligned on a common axis.

The base generates a magnetic field by passing a current through a coil. The magnetic field induces a voltage in the coil of the remote, which powers the load. The power transfer is based on the principle of electromagnetic induction, which states that a changing magnetic field creates an electric potential difference across a conductor.

The data transfer is also based on electromagnetic induction but with a different frequency and modulation scheme. The base and the remote can communicate bidirectionally by modulating the amplitude, frequency, or phase of their currents. The data signals are superimposed on the power signals and can be decoded by the controller.

Applications that can benefit from inductive coupling

Inductive coupling finds valuable applications in various scenarios, such as:

End-of-arm tooling: Inductive couplers can power and control robotic arms, grippers, or tools, without limiting their mobility or functionality. They can also enable wireless charging of autonomous robots or drones. This technology’s contribution also extends to:

    • Increased flexibility in robot movements. Since there are no physical connections, the robot can move freely without worrying about cable management or connector wear.
    • Improved durability in harsh industrial environments, as inductive couplers are typically sealed and resistant to dust, dirt, and moisture.
    • Fast tool change on robots. Since there’s no need to manually disconnect and reconnect cables, tool changes can be done quickly and efficiently.
    • More reliability than pin-based connector systems, especially for low power sensors. They can create a more stable connection, reducing the risk of signal loss or interruption.

Rotary indexing tables: Machine tool positioning devices used to move parts in programmed, increments so they can be machined or assembled. During operation, the table rotates around a central axis, stops at a predetermined location, remains in that position while an operation is performed, and then rotates to the next position. Powering sensors on a rotary indexing table can be achieved through various methods, but the most efficient way is using inductive coupling which allows for the transfer of power and data without physical contact. it is particularly useful in applications where the rotary indexing table must be able to move in complex ways.

Rapid die change: The quick die change system includes a combination of a die transfer arm, die clamp, die lifter, operation box, and power pump. Through the combination of automated equipment, the product changeover time, production start-up time, or adjustment time of the mold can be minimized. Users can quickly change the mold and clamp the mold, reduce mold change time, produce a variety of small quantities, and reduce inventory and output.

Inductive coupling can be advantageous for die change in industrial automation. Stampers can integrate inductively coupled connector systems to enable rapid die change. This technology can be used for joining die segments, easing the changeout of transfer arms, and communication during transfer functions.

Disadvantages of pin style connectors. Soldered connections can be sensitive to both corrosion and vibration. The filler metal used for the soldering connection will degrade over time and can cause connection failures.

Slip rings are often used in automated assembly lines and packaging machinery, where continuous rotation is required for the system to efficiently operate. They are also used in the food and beverage industry, wind turbines, factory automation, robotics, radars, medical imaging equipment, monitoring equipment, and many others.

Despite their versatility, slip rings come with a complex construction, which includes components such as rings and brushes. These components require regular inspection, cleaning, and maintenance to ensure optimal performance. Failure to maintain slip rings and brushes properly can result in poor electrical contact, increased resistance, and reduced motor efficiency.

The presence of slip rings and brushes introduces additional points of potential wear and tear, requiring inspection, cleaning, and replacement when necessary. This increased maintenance requirement can result in higher downtime and maintenance costs compared to other motor types.

What are the benefits of using inductive couplers?

Inductive couplers offer several advantages that make them a preferred choice in various applications. One key benefit is their flexibility, as they can be easily installed and reconfigured without the need for complex wiring or connectors. Unlike traditional methods, inductive couplers allow for misalignment of up to 15-20 degrees of angular offset or 2-4mm of axial offset while still maintaining functionality.

Another notable advantage is their reliability, as they are immune to wear and tear, corrosion, vibration, or dirt that may affect the performance of standard mechanical contacts. With both the base and remote components fully encapsulated, typically featuring an IP67 protection class, environmental concerns are effectively mitigated.

Additionally, inductive couplers enhance safety by eliminating the risk of electric shocks, sparks, or short circuits commonly associated with exposed conductors or contacts. They also reduce the electromagnetic interference that can affect signal quality or damage electrical components.

Overall, the use of inductive couplers brings about a combination of flexibility, reliability, and safety, making them a valuable choice in various industrial and technological settings.

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Boosting Sensor Resilience in Welding With Self-Bunkering Inductive Proximity Sensors

A welding cell will press the limits of any sensor placed in its proximity. Avoiding weld spatter, magnetic fields, extreme temperatures, and impact damage are common challenges in a harsh welding environment. And when sensors fail in these conditions, it can significantly disrupt production uptime. To prevent such disruptions, manufacturers explore more robust sensor mounting solutions, such as proximity mounts, bunker blocks, and other protective devices to shield sensors from these harsh conditions. The self-bunkering inductive proximity sensor plays a key role in alleviating the issues, especially in situations where other accessories are not an option due to limited space.

Weld spatter and magnetic field resistant

In many welding applications, the substantial currents involved can generate heightened magnetic fields, making a welding cell vulnerable to interference. This interference can lead a basic proximity sensor to trigger, even though a part may not be present. The self-bunkering proximity sensor is designed to resist magnetic fields, allowing it to work much closer to the welding surface than a typical inductive sensor. Additionally, the sensor comes with a polytetrafluoroethylene (PTFE) weld coating, allowing for easy removal of the spatter buildup with abrasive tools like a wire brush.

Guard against heavy impacts

Again, the self-bunkering inductive proximity sensor is built for rugged environments. It features a thick, strong one-piece connector body and super thick brass housing to buffer the internal electronics from external impacts and conductive heat. It also includes a deflection ring and a non-brittle, ferrite-free coil carrier to protect the sensor face from direct impacts, disperse shock, and safeguard internal sensing components. The wide-radius corners offer stress relief at the major junction points of the connector body and housing.

Withstand extreme temperatures

With a ceramic PTFE-coated face plate, the sensor can resist up to 2200°F weld spatter burn through from the front. The rest of the body, coated with PTFE and paired with an extra-thick brass housing, provides protection for the sensor up to 300°F. This means that if the sensor is properly maintained, its lifetime should be quite a bit longer than a standard inductive sensor.

Don’t replace, defend

The core components of the proximity sensor can be destroyed if any of the three critical failures – conducted heat, impact, or spatter – occur in combination. To prevent this, the product incorporates a collection of design measures intended to create a virtually impenetrable shield around the internal critical components.

In summary, the self-bunkering inductive proximity sensor is a key solution to combat the challenges sensors face in harsh welding environments that will ultimately disrupt production. Its resistance to magnetic fields and ability to withstand heavy impacts and extreme temperatures, especially in situations with limited space, ensures the protection of the critical sensor components and extended sensor lifespan.

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Overcoming Challenges in Metal Detection: The Power of Factor 1 Sensors

Standard inductive proximity sensors are used across the automation industry for metal detection applications and are generally reliable in these operations. But issues arise when switching from steel to other metals like copper, brass, or aluminum. A standard inductive sensor may encounter problems in such scenarios. Due to the reduction factor, the standard inductive sensor detects these different metals at different distances. If you had a sensor mounted and set up to sense a steel material but switched to copper, for example, the copper material might be out of the sensor’s range due to this difference in reduction factor, resulting in a missed reading. Factor 1 sensors were created to eliminate this problem.

Reduction factor

The reduction factor is the root cause of variable distance readings with a standard inductive sensor. But what exactly is it? The standard operating range of an inductive proximity sensor is determined by its response to a one-millimeter-thick square piece of mild steel. Other metals like copper and aluminum deviate from this standard range due to differences in material properties. For example, copper has a reduction factor of around 0.4, so it can only be detected at 0.4 times the standard operating range of an inductive proximity sensor.

We can save for later the details of why this occurs, but the key point here is that different material properties cause different reduction factors, which result in different switching distances. The table below shows these different reduction factors and switching distances. Factor 1 sensors take all these variable reduction factors and equalize them to a standard operating distance. This means that you can read anything from copper to steel at the same range, reducing the possibility of missed readings and eliminating the need for repositioning sensors whenever a material change occurs.

When to use Factor 1 sensors

Factor 1 sensors are well-suited for any process that involves different metals. Whether it is automated welding or a packaging conveyor, the factor 1 sensor will keep the material switching ranges uniform. But why is this such a big advantage?

Think about the time spent having to adjust sensor distances. Not only is the task annoying, it also takes up time. Having factor 1 sensors in place will increase the uptime of these processes and eliminate the need for sensor adjustments.

One last benefit to note about factor 1 sensors is that they are inherently weld field immune. The internal construction of the sensor prevents it from being affected by the electromagnetic field generated during welding. This additional immunity allows the sensor to survive in these welding conditions where a typical sensor might fail if it comes in proximity to the weld field.

In the end, you know your application best, but if any of the above benefits resonate with you, it’s time to start thinking about factor 1.

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Choosing the Right Sensor for Measuring Distance

Distance-measuring devices help with positioning, material flow control, and level detection. However, there are several options to consider when it comes to choosing the correct sensor technology to measure distance. Here I’ll cover the three most commonly used types in the industrial automation world today, including photoelectric, ultrasonic, and inductive.

Photoelectric sensors

Photoelectric sensors use a light source, such as a laser or light-emitting diode, to reflect the light off an object’s surface to calculate the distance between the face of the sensor and the object itself. The two basic principles for how the sensor calculates the distances are the time of flight (TOF) and triangulation.

    • Time of flight photoelectric distance measurement sensors derive the distance measurement based on the time it takes the light to travel from the sensor to the object and return. These sensors are used to measure over long distances, generally in the range between 500 millimeters and up to 5 meters, with a resolution between 1 to 5 millimeters, depending on the sensor specifications. Keep in mind that this sensor technology is also used in range-finding equipment with a much greater sensing range than traditional industrial automation sensors.

    • In the triangulation measurement sensor, the sensor housing, light source, and light reflection form a triangle. The distance measurement is based on the light reflection angle within its sensing range with high accuracy and resolution. These sensors have a much smaller distance measurement range that is limited to between 20 and 300 millimeters, depending on the sensor specifications.

The pros of using photoelectric distance measurement sensors are the range, accuracy, repeatability, options, and cost. The main con for using photoelectric sensors for distance measurement is that they are affected by dust and water, so it is not recommended to use them in a dirty environment. The object’s material, surface reflection, and color also affect its performance.

Photoelectric distance measurement sensors are used in part contouring, roll diameter measurement, the position of assemblies, thickness detection, and bin-level detection applications.

Ultrasonic sensors

Ultrasonic distance sensors work on a similar principle as photoelectric distance sensors but instead of emitting light, they emit sound waves that are too high for humans to hear, and they use the time of flight of reflecting sound wave to calculate the distance between the object and the sensor face. They are insensitive to the object’s material, color, and surface finish. They don’t require the object or target to be made of metal like inductive position sensors (see below). They can also detect transparent objects, such as clear bottles or different colored objects, that photoelectric sensors would have trouble with since not enough light would be reflected back to reliably determine the distance of an object. The ultrasonic sensors have a limited sensing range of approximately 8 meters.

A few things to keep in mind that negatively affect the ultrasonic sensor is when the object or target is made of sound-absorbing material, such as foam or fabric, where the object absorbs enough soundwave emitted from the sensor making the output unreliable. Also, the sensing field gets progressively larger the further away it gets from the sensing face, thus making the measurement inaccurate if there are multiple objects in the sensing field of the sensor or if the object has a contoured surface. However, there are sound-focusing attachments that are available to limit the sensing field at longer distances making the measurements more accurate.

Inductive sensors

Inductive distance measurement sensors work on the same principle as inductive proximity sensors, where a metal object penetrating the electromagnetic field will change its characteristics based on the object size, material, and distance away from the sensing face. The change of the electromagnetic field detected by the sensor is converted into a proportional output signal or distance measurement. They have a quick response time, high repeatability, and linearity, and they operate well in harsh environments as they are not affected by dust or water. The downside to using inductive distance sensors is that the object or target must be made of metal. They also have a relatively short measurement range that is limited to approximately 50 millimeters.

Several variables exist to consider when choosing the correct sensor technology for your application solution, such as color, material, finish, size, measurement range, and environment. Any one of these can have a negative effect on the performance or success of your solution, so you must take all of them into account.

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Capacitive, the Other Proximity Sensor

What is the first thing that comes to mind if someone says “proximity sensor?” My guess is the inductive sensor, and justly so because it is the most used sensor in automation today. There are other technologies that use the term proximity in describing the sensing mode, including diffuse or proximity 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 these sensors detect objects that are in close proximity to the sensor without making physical contact. One of the most overlooked or forgotten proximity sensors on the market today is the capacitive sensor.

Capacitive sensors are suitable for solving numerous applications. These sensors can be used to detect objects, such as glass, wood, paper, plastic, or ceramic, regardless of material color, texture, or finish. The list goes on and on. 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, when the sensor touches the medium, or indirectly when it senses the medium through a non-metallic container wall.

Capacitive sensors overview

Like any other sensor, there are certain considerations to account for when applying capacitive, multipurpose sensors, including:

1 – Target

    • Capacitive sensors can detect virtually any material.
    • The target material’s dielectric constant determines the reduction factor of the sensor. Metal / Water > Wood > Plastic > Paper.
    • The target size must be equal to or larger than the sensor face.

2 – Sensing distance

    • The rated sensing distance, or what you see in a catalog, is based on a mild steel target that is the same size as the sensor face.
    • The effective sensing distance considers mounting, supply voltage, and temperature. It is adjusted by the integral potentiometer or other means.
    • Additional influences that affect the sensing distance are the sensor housing shape, sensor face size, and the mounting style of the sensor (flush, non-flush).

3 – Environment

    • Temperatures from 160 to 180°F require special considerations. The high-temperature version sensors should be used in applications above this value.
    • Wet or very humid applications can cause false positives if the dielectric strength of the target is low.
    • In most instances, dust or material buildup can be tuned out if the target dielectric is higher than the dust contamination.

4 – Mounting

    • Installing capacitive sensors is very similar to installing inductive sensors. Flush sensors can be installed flush to the surrounding material. The distance between the sensors is two times the diameter of the sensing distance.
    • Non-flush sensors must have a free area around the sensor at least one diameter of the sensor or the sensing distance.

5 – Connector

    • Quick disconnect – M8 or M12.
    • Potted cable.

6 – Sensor

    • The sensor sensing area or face must be smaller or equal to the target material.
    • Maximum sensing distance is measured on metal – reduction factor will influence all sensing distances.
    • Use flush versions to reduce the effects of the surrounding material. Some plastic sensors will have a reduced sensing range when embedded in metal. Use a flush stainless-steel body to get the full sensing range.

These are just a few things to keep in mind when applying capacitive sensors. There is not “a” capacitive sensor application – but there are many which can be solved cost-effectively and reliably with these sensors.

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Choosing Between M18 and Flatpack Proxes

Both M18s and flatpacks are inductive or proximity sensors that are widely used in mechanical engineering and industrial automation applications. Generally, they are similar in that they produce an electromagnetic field that reacts to a metal target when it approaches the sensor head. And the coil in both sensors is roughly the same size, so they have the same sensing range – between 5 to 8 millimeters. They also both work well in harsh environments, such as welding.

There are, however, some specific differences between the M18 and flatpack sensors that are worth consideration when setting up production.

M18

One benefit of the M18 sensor is that it’s adjustable. It has threads around it that allow you to adjust it up or down one millimeter every time you turn it 360 degrees. The M18 can take up a lot of space in a fixture, however. It has a standard length of around two inches long and, when you add a connector, it can be a problem when space is an issue.

Flatpack

A flatpack, on the other hand, has a more compact style and format while offering the same sensing range. The mounting of the flatpack provides a fixed distance so it offers less adjustability of the M18, but its small size delivers flexibility in installation and allows use in much tighter fixes and positions.

The flatpack also comes with a ceramic face and a welding cable, especially suited for harsh and demanding applications. You can also get it with a special glass composite protective face, a stainless-steel face, or a steel face with special coatings on it.

Each housing has its place, based on your detection application, of course. But having them both in your portfolio can expand your ability to solve your applications with sensor specificity.

Check out this previous blog for more information on inductive sensors and their unlimited uses in automation.

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Inductive Sensors and Their Unlimited Uses in Automation

Inductive sensors (also known as proximity sensors or proxes) are the most commonly used sensors in mechanical engineering and industrial automation. When they were invented in the 1960s, they marked a milestone in the development of control systems. In a nutshell, they generate an electromagnetic field that reacts to metal targets that approach the sensor head. They even work in harsh environments and can solve versatile applications.

There are hardly any industrial machines that work without inductive sensors. So, what can be solved with one, two, three, or more of them?

What can you do with one inductive sensor?

Inductive sensors are often used to detect an end position. This could be in a machine for end-of-travel detection, but also in a hydraulic cylinder or a linear direct drive as an end-of-stroke sensor. In machine control, they detect many positions and trigger other events. Another application is speed monitoring with a tooth wheel.

What can you do with two inductive sensors?

By just adding one more sensor you can get the direction of rotational motion and take the place of a more expensive encoder. In a case where you have a start and end position, this can also be solved with a second inductive sensor.

What can you do with three inductive sensors?

In case of the tooth wheel application, the third sensor can provide a reference signal and the solution turns into a multiturn rotary encoder.

What can I do with four inductive sensors and more?

For multi-point positioning, it may make sense to switch to a measurement solution, which can also be inductive. Beyond that, an array of inductive sensors can solve identification applications: In an array of 2 by 2 sensors, there are already 16 different unique combinations of holes in a hole plate. In an array of 3 by 3, it would be 512 combinations.