Palletized Automation with Inductive Coupling

RFID is an excellent way to track material on a pallet through a warehouse. A data tag is placed on the pallet and is read by a read/write head when it comes in range. Commonly used to identify when the pallet goes through the different stages of its scheduled process, RFID provides an easy way to know where material is throughout a process and learn how long it takes for product to go through each stage. But what if you need I/O on the pallet itself or an interchangeable end-of-arm tool?

Inductive Coupling

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Inductive coupling delivers reliable transmission of data without contact. It is the same technology used to charge a cell phone wirelessly. There is a base and a remote, and when they are aligned within a certain distance, power and signal can be transferred between them as if it was a standard wire connection.

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When a robot is changing end-of-arm tooling, inductive couplers can be used to power the end of arm tool without the worry of the maintenance that comes with a physical connection wearing out over time.

For another example of how inductive couplers can be used in a process like this, let’s say your process requires a robot to place parts on a metal product and weld them together. You want I/O on the pallet to tell the robot that the parts are in the right place before it welds them to the product. This requires the sensors to be powered on the pallet while also communicating back to the robot. Inductive couplers are a great solution because by communicating over an air gap, they do not need to be connected and disconnected when the pallet arrives or leaves the station. When the pallet comes into the station, the base and remote align, and all the I/O on the pallet is powered and can communicate to the robot so it can perform the task.

Additionally, Inductive couplers can act as a unique identifier, much like an RFID system. For example,  when a pallet filled with product A comes within range of the robot, the base and remote align telling the robot to perform action A. Conversely, when a pallet loaded with product B comes into range, the robot communicates with the pallet and knows to perform a different task. This allows multiple products to go down the same line without as much changeover, thereby reducing errors and downtime.

Why Sensor & Cable Standardization is a Must for End-Users

Product standardization makes sense for companies that have many locations and utilize multiple suppliers of production equipment. Without setting standards for the components used on new capital equipment, companies incur higher purchasing, manufacturing, maintenance, and training costs.

Sensors and cables, in particular, need to be considered due to the following:

  • The large number of manufacturers of both sensors and cables
  • Product variations from each manufacturer

For example, inductive proximity sensors all perform the same basic function, but some are more appropriate to certain applications based on their specific features. Cables provide a similar scenario. Let’s look at some of the product features you need to consider.

Inductive Proximity Sensors Cables
 

·         Style – tubular or block style

·         Size and length

·         Electrical characteristics

·         Shielded or unshielded

·         Sensing Range

·         Housing material

·         Sensing Surface

 

·         Connector size

·         Length

·         Number of pins & conductors

·         Wire gage

·         Jacket material

·         Single or double ended

 

Without standards each equipment supplier may use their own preferred supplier, many times without considering the impact to the end customer. This can result in redundancy of sensor and cable spare parts inventory and potentially using items that are not best suited for the manufacturing environment. Over time this impacts operating efficiency and results in high inventory carrying costs.

Once the selection and purchasing of sensors and cables is standardized, the cost of inventory will coincide.  Overhead costs, such as purchasing, stocking, picking and invoicing, will go down as well. There is less overhead in procuring standard parts and materials that are more readily available, and inventory will be reduced. And, more standardization with the right material selection means lower manufacturing down-time.

In addition, companies can then look at their current inventory of cable and sensor spare parts and reduce that footprint by eliminating redundancy while upgrading the performance of their equipment. Done the right way, standardization simplifies supply chain management, can extend the mean time to failure, and reduce the mean time to repair.

Size Matters When Selecting Sensors for Semiconductor Equipment

As an industry account manager focusing on the semiconductor industry, I’ve come to realize that when it comes to sensors used in semiconductor production equipment, size definitely matters. A semiconductor manufacturing facility, better known as a fab or foundry, can cost thousands of dollars per square foot to construct, not to mention the cost to maintain the facility. Therefore, manufacturers of equipment used to produce semiconductors are under pressure to reduce the footprint of their machines. As the equipment becomes more compact, it becomes more difficult to incorporate optical sensors that are needed for precise object detection.

A self-contained optical sensor that includes the optics along with the required electronics is often much too large. There simply isn’t enough space for mounting in the area where the object is to be detected. An alternative method is to use a remote amplifier containing the electronics with a fiber optic cable leading to the point of detection where the light beam is focused on the target. However, there are some drawbacks to this method that can be difficult to overcome. There are instances where the fiber optic cable is too large and not flexible enough to be routed through the equipment. Also, a tighter beam pattern is often required in semiconductor equipment for precise positioning. To provide a tighter beam pattern with fiber optics, it is necessary to add additional lenses. These lenses increase the size, complexity and cost of the sensor.

1The most effective way to overcome the limitations of fiber optic sensors is to use very small sensor heads connected to a remote amplifier by electric cables, as opposed to fiber optic cables. The photoelectric sensor heads are exceptionally small, and because the cables are extremely flexible they can easily accommodate tight bends. Therefore, these micro-optic photoelectric sensors are particularly well suited for use in semiconductor equipment. The extremely small beam angles and sharply defined light spots are ideal for the precise positioning required for producing semiconductors. No supplementary lensing is required.

2An excellent example of how this micro-optic sensor technology is utilized in semiconductor equipment is for precision wafer detection needed for automated wafer handling. At the end of a robot arm used for wafer handling there is a very thin end-effector known as a blade. By utilizing a very tightly controlled and focused light spot, the sensor can detect wafers just a few μm thick with extreme precision.

3The combination of extremely small optical sensor heads with an external processor unit (amplifier) connected via highly flexible cables is a configuration that is ideal for use in semiconductor production equipment.

 

Photoelectric Methods of Operation

Photoelectric sensors vary in their operating principles and can be used in a variety of ways, depending on the application. They can be used to detect whether an object is present, determine its position, measure level, and more. With so many types, it can be hard to narrow down the right sensor for your application while accounting for any environmental conditions. Below will give a brief overview of the different operating principles used in photoelectric sensors and where they can be best used.

Diffuse

Diffuse sensors are the most basic type of photoelectric sensor as they only require the sensor and the object being detected. The sensor has a built-in emitter and receiver, so as light is sent out from the emitter and reaches an object, the light will then bounce off the object and enter the receiver. This sends a discrete signal that an object is within the sensing range. Due to the reflectivity being target-dependent, diffuse sensors have the shortest range of the three main discrete operating principles. Background suppression sensors work under the same principle but can be taught to ignore objects in the background using triangulation to ensure any light beyond a certain angle does not trigger an output. While diffuse sensors can be affected by the color of the target object,  the use of a background suppression sensor can limit the effect color has on reliability. Foreground suppression sensors work in the same manner as background suppression but will ignore anything in the foreground of the taught distance.

diffuse

Retro-reflective

Retro-reflective sensors also have the emitter and receiver in a single housing but require a reflector or reflective tape be mounted opposite the sensor for it to be triggered by the received light. As an object passes in front of the reflector, the sensor no longer receives the light back, thus triggering an output. Due to the nature of the reflector, these sensors can operate over much larger distances than a diffuse sensor. These sensors come with non-polarized or polarizing filters. The polarizing filter allows for the sensor to detect shiny objects and not see it as a reflector and prevents any stray ambient light from triggering the sensor.

retroreflective

Through-beam

Through-beam sensors have a separate body for the emitter and receiver and are placed opposite each other. The output is triggered once the beam has been broken. Due to the separate emitter and receiver, the sensor can operate at the longest range of the aforementioned types. At these long ranges and depending on the light type used, the emitter and receiver can be troublesome to set up compared to the diffuse and retro-reflective.

throughbeam

Distance

The previous three types of photoelectric sensors give discrete outputs stating whether an object is present or not. With photoelectric distance sensors, you can get a continuous readout on the position of the object being measured. There are two main ways the distance of the object is measured, time of flight, which calculates how long it takes the light to return to the receiver, and triangulation, which uses the angle of the incoming reflected light to determine distance. Triangulation is the more accurate option, but time of flight can be more cost-effective while still providing good accuracy.

Light type and environment

With each operating principle, there are three light types used in photoelectric sensors: red light, laser red light, and infrared. Depending on the environmental conditions and application, certain light types will fare better than others. Red light is the standard light type and can be used in most applications. Laser red light is used for more precise detection as it has a smaller light spot. Infrared is used in lower-visibility environments as it can pass through more dirt and dust than the other two types. Although infrared can work better in these dirtier environments, photoelectric sensors should mainly be used where build-up is less likely. Mounting should also be considered as these sensors are usually not as heavy duty as some proximity switches and break/fail more easily.

As you can see, photoelectric sensors have many different methods of operation and flexibility with light type to help in a wide range of applications. When considering using these sensors, it is important to account for the environmental conditions surrounding the sensor, as well as mounting restrictions/positioning, when choosing which is right for your application.

For more information on photoelectric sensors, visit this page for more information.

Do Your Capacitive Sensors Ignore Foam & Condensation for True Level Detection?

Capacitive sensors detect any changes in their electrostatic sensing field. This includes not only the target material itself, but also application-induced influences such as condensation, foam, or temporary or permanent material build-up. High viscosity fluids can cause extensive delays in accurate point-level detection or cause complete failure due to the inability of a capacitive sensor to compensate for the material adhering to the container walls. In cases of low conductive fluids such as water or deionized water and relatively thin container walls, the user might be able to compensate for these sources of failure. Potential material build-up or condensation can be compensated for by adjusting the sensitivity of the sensor, cleaning of the container, or employing additional mechanical measures.

However, this strategy works only if the fluid conductivity stays low and no other additional influencing factors like temperature, material buildup, or filming challenge the sensor. Cleaning fluids like sodium hydrochloride, hydrochloric acid, chemical reagents, and saline solutions are very conductive, which cause standard capacitive sensors to false trigger on even the thinnest films or adherence. The same applies for bodily fluids such as blood, or concentrated acids or alkaline.

Challenges of this type of application are not obvious. This is especially true when the sensors performed well in the initial design phase but fail in the field for no obvious reason. An example of this would be when the sensors on the equipment are setup with deionized water however, the final process requires some type of acid  Difficult and time-consuming setup procedures and unstable applications requiring frequent readjustment are the primary reasons why capacitive level sensors have been historically avoided in certain applications.

Today, there are hybrid technologies employed in capacitive sensors for non-invasive level detection applications that would require little or no user adjustment after the initial setup process. They can detect any type conductive water based liquid through any non-metallic type of tank wall while automatically compensating for material build-up, condensation, and foam.

This hybrid sensing technology helps the sensors to distinguish effectively between true liquid levels and possible interferences caused by condensation, material build-up, or foaming fluids. While ignoring these interferences, the sensors still detect the relative change in capacitance caused by the media but use additional factors to evaluate the validity of the measurement taken before changing state. These sensors are fundamentally insensitive to any non-conductive material like plastic or glass, which allows them to be utilized in non-invasive level applications.

These capacitive sensors provide cost-effective, reliable point-level monitoring for a wide array of medical, biotechnology, life sciences, semiconductor processes, and other manufacturing processes and procedures. This technology brings considerable advantages to the area of liquid level detection, not only offering alternative machine designs, but also reduced assembly time for the machine builders.  Machine designers now have the flexibility to non-invasively detect almost any type of liquid through plastic, glass tubes, or other non-metallic container walls, reducing mechanical adaption effort and fabrication costs.

Discrete indication tasks like fluid presence detection in reagent supply lines, reagent bottle level feedback, chemical levels, and waste container overfill prevention are now a distinct competence for capacitive sensors. Reagents and waste liquids are composed of different formulas depending on the application.  The sensing technology has to be versatile enough to compensate automatically for changing environmental or media conditions within high tolerance limits. Applications that require precision and an extraordinary amount of reliability, such as blood presence detection in cardiovascular instruments or hemodialysis instruments, medical, pharmaceutical machine builders, equipment builders for semiconductor processes can rely now on these hybrid capacitive sensors

Top 5 Insights from 2019

With a new year comes new innovation and insights. Before we jump into new topics for 2020, let’s not forget some of the hottest topics from last year. Below are the five most popular blogs from our site in 2019.

1. How to Select the Best Lighting Techniques for Your Machine Vision Application

How to select the best vision_LI.jpgThe key to deploying a robust machine vision application in a factory automation setting is ensuring that you create the necessary environment for a stable image.  The three areas you must focus on to ensure image stability are: lighting, lensing and material handling.  For this blog, I will focus on the seven main lighting techniques that are used in machine vision applications.

READ MORE>>

2. M12 Connector Coding

blog 7.10_LI.jpgNew automation products hit the market every day and each device requires the correct cable to operate. Even in standard cables sizes, there are a variety of connector types that correspond with different applications.

READ MORE>>

3. When to use optical filtering in a machine vision application

blog 7.3_LI.jpgIndustrial image processing is essentially a requirement in modern manufacturing. Vision solutions can deliver visual quality control, identification and positioning. While vision systems have gotten easier to install and use, there isn’t a one-size-fits-all solution. Knowing how and when you should use optical filtering in a machine vision application is a vital part of making sure your system delivers everything you need.

READ MORE>>

4. The Difference Between Intrinsically Safe and Explosion Proof

5.14_LIThe difference between a product being ‘explosion proof’ and ‘intrinsically safe’ can be confusing but it is vital to select the proper one for your application. Both approvals are meant to prevent a potential electrical equipment malfunction from initiating an explosion or ignition through gases that may be present in the surrounding area. This is accomplished in both cases by keeping the potential energy level below what is necessary to start ignition process in an open atmosphere.

READ MORE>>

5. Smart choices deliver leaner processes in Packaging, Food and Beverage industry

Smart choices deliver leaner processes in PFB_LI.jpgIn all industries, there is a need for more flexible and individualized production as well as increased transparency and documentable processes. Overall equipment efficiency, zero downtime and the demand for shorter production runs have created the need for smart machines and ultimately the smart factory. Now more than ever, this is important in the Packaging, Food and Beverage (PFB) industry to ensure that the products and processes are clean, safe and efficient.

READ MORE>>

We appreciate your dedication to Automation Insights in 2019 and look forward to growth and innovation in 2020!

 

 

Inductive Coupling: A Simple Solution for Replacing Slip Rings

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Figure 1: Inductive coupling for power and data exchange

In the industrial automation space, inductive sensors have grown very popular , most commonly used for detecting the proximity of metal objects such as food cans, or machine parts. Inductive coupling, also known as non-contact connectors, uses magnetic induction to transfer power and data over an air gap.

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Figure 2: Slip ring example

While inductive couplers have many uses, one of the most beneficial is for replacing a traditional slip-ring mechanism. Slip-rings, also known as rotary connectors, are typically used in areas of a machine where one part rotates, and another part of the machine remains stationary, such as a turn table where stations on the indexing table need power and I/O, but the table rotates a full 360°. This set up makes standard cable solutions ineffective.

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Figure 3: Inductive coupling replacing the slip-ring

A slip ring could be installed at the base of the table, but since they are electromechanical devices, they are subject to wear out. And unfortunately, the signs for wearing are not evident and often it is only a lack of power that alerts workers to an issue.

An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base of a coupler could be mounted at the base of the table and the remote end could be mounted on the rotating part of the table.

Additionally, slip rings are susceptible to noise and vibration, but because inductive couplers do not have contact between the base and the remote, they do not have this problem.

Inductive couplers are typically IP67-rated, meaning they are not affected by dirt or water, or  vibrations, and most importantly, they are contact free so no maintenance is necessary.

Learn more about Balluff inductive couplers www.balluff.us.

Environmental Impacts – Choosing the Right Sensor for the Conditions

Last week’s blog spoke about reducing waste and downtime by implementing LEAN manufacturing procedures. This involves taking a proactive approach to improving efficiencies. This post will focus on selecting the right part for the job to reduce failure rates that lead to avoidable machine downtime and increased costs.

Hardly a day passes by where we are not contacted by a desperate end-user or equipment manufacturer seeking assistance with a situation of sensors failing at an unacceptably high rate.  Once we get down to the root cause of the failures, in most cases it’s a situation where the sensors are being applied in a manner which all but guarantees premature failure.

Not all sensors are created equal.  Some are intentionally designed for light-duty applications where the emphasis is more on economic cost rather than the ability to survive in rough service conditions.  Other sensors are specifically designed to meet the challenges of specific application environments, and as a result may carry a higher initial price.

Some things to think about when choosing a sensor for a new application:

  • What kind of environmental conditions will the sensor be exposed to?  For example:
    • Very low or very high temperatures
    • Constant exposure to or immersion in liquid
    • Continuous vibration
    • Extreme shock
    • Disruptive electrical noise (hand-held radios, welding fields, etc.)
    • Chemical contamination
    • Physical abuse or impact
    • Abrasion
    • High pressure washdown procedures
    • Exposure to outdoor conditions of UV sunlight, rain, ice, temperature swings, and condensing humidity
  • Is it possible to relocate the sensor to move it away from the difficult condition?
  • Is the sensor technology the best choice given the kind of application environment that it must operate in?
  • Is there a way to protect the sensor from exposure to the worst of the damaging effects?

When you reach for a catalog or jump on the internet to look for a sensor, it’s a good practice to just stop a moment first and make a list of the environmental challenges that the sensor could face.  Then you will be prepared to make an appropriate selection that best meets your expected application conditions.

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Heavy metal parts being loaded into a welding cell can damage specialty nut detection sensors designed to stick through a hole in a part.  Plunger probes are a better solution.

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Unprotected and non-bunkered sensors in damage prone areas result in premature sensor failure.

Mini Sensors Add Big Capabilities to Life Science Applications

1Miniaturization is one of the essential requirements for medical instruments and laboratory equipment used in the life science industry. As instruments get smaller and smaller, the sensor components must also become smaller, lighter and more flexible. The photoelectric sensors that were commonly used in general automation and applied in life science applications have met their limitations in size and performance.

2.jpgSensors used in these complex applications require numerous special characteristics such as high-quality optics, unique housing designs, precise LEDs with the best suited wavelength and the ability to be extremely flexible to fit in the extremely small space available. Sensors have been developed to meet the smallest possible installation footprint with the highest optical precision and enough flexibility to be installed where they are needed. These use integrated micro-precision optics that shape and focus the light beam exactly on the object without any undesirable side-effects to achieve the reliability demanded in today’s applications.

Previously many life science applications used conventional plastic fiber optic cables that were often too large and not flexible enough to be routed through the instruments. An alternative to the classic fiber cables is a “wired” fiber with precision micro-optics and extremely flexible cables with essentially no minimum bending radius and no significant coupling losses. Similar to a conventional fiber optic sensor, an external amplifier is required to provide a wide variety of functionalities to solve the demanding applications.

These sensors can be used in applications such as:

  • Precise detection of liquid levels using either attenuation or refraction with a small footprint
  • Reliable detection of transparent objects such as microscope slides or coverslips having various edge shapes
  • Detection of transparent liquids in micro-channels or capillaries
  • Reliable detection of individual droplets
  • Recognition of free-floating micro-bubbles in a tube that are smaller than the tube diameter and that cannot be seen by the human eye
  • Recognition of macro-bubbles that are the diameter of small tubes

For more information on photoelectric sensors that have the capability to meet the demands of today’s life science applications visit www.balluff.com.

Make Clear Water Visible to Your Sensors

In some industries such as life sciences it is necessary to detect clear water or clear liquids in a container or tube. This is even more challenging when the diameters of the tube are small, and the tube thickness is nearly as large as the stream of liquid.

The attenuation or gradual reduction of the intensity of the light beam in water and air can be directly compared. The attenuation of light in water can be attributed to light entering water at any angle other than at a right angle and can be refracted. The measurement of light through a tube is different because not only is the light attenuated by the liquid, but depending on where the light passes through the tube it can be refracted, diverted and or focused. As a result, the signal differences can be low.

Attenuation is typically the first choice if the liquids are opaque or colored. The requirements of the shape of the light beam and the alignment of the sensor add more complication to the application. The attenuation effect appears weaker in clear liquids. The principle does not work with reflective sensors since reflection is a surface effect and the light must pass through the liquid.OPTO_appl_08_sw-water

From spectral analysis it’s has been determined that the attenuation characteristics of water are heavily dependent on the wavelength of the light that is conducted through it. Sensors were developed for such applications. Typically, these sensors utilize LED’s in the upper infrared range of 1,450 nm. At this wavelength water literally absorbs the light and becomes opaque making detection more simplified and reliable.

This principle even works for fine capillaries and microchannels. Liquid detection can be very precise depending on the sensor size and the effective light beam. Light beams as small as 0.4mm can provide high resolution for small thin tubes typically found in microfluidics applications.

Versions of these sensors exist for applications that involve less transparent or semi-transparent vessels. Light at the 1450nm wavelength can pass through these containers or tubes and can be attenuated by the water. The main factor is that enough light makes its way through the walls of the container.

Through-beam sensors were developed for applications such as detecting clear liquids. These sensors are also available in extremely small dimensions and usually require an amplifier, or they can be supplied in a rugged fork sensor housing. The required sensor dimensions conform to the geometry of the vessel or container.

For more information on sensors for these types of applications contact your local Balluff representative or contact us at www.balluff.com.