You have options when it comes to connecting your sensors

When it comes to connecting I/O in factory automation settings, there are many options one can choose to build an efficient and cost-effective system. This is one area where you can reduce costs while also boosting productivity.

Single Ended Cables and Hardwired I/O

It is common in the industry for single ended cables to be run from sensors to a controller input card in a centralized control cabinet. And while this method works, it can be costly for a number of reasons, including:

  • Flying leads on single ended cables are time consuming to prepare and wire
  • Wiring mistakes are often made leading to more time troubleshooting
  • I/O Cards for PLCs are expensive
  • Long cable runs to a centralized location add up quickly especially when dealing with analog devices which require expensive shielded cables
  • Lack of scalability and diagnostics

Double Ended Cables and Networked I/O

Using double ended cables along with network I/O blocks allows for a cost-effective solution to distribute I/O and increase up time. There are numerous benefits that come along with this sort of architecture. Some of these benefits are:

  • Reduced cabling — since I/O is distributed, only network cables need to be run back to the control cabinet reducing cost and cabinet size, and sensor cables are shortened since I/O blocks are machine mounted
  • Quicker build time since standard wiring is less labor intensive
  • Diagnostics allows for quicker trouble shooting, leading to lower maintenance costs and reduced downtime

IO-Link

Using IO-Link delivers all of the strengths of networked I/O as well as additional benefits:

  • I/O Hubs allow for scalability
  • Smart devices can be incorporated into your system
  • Parameterization capability
  • Increased diagnostics from intelligent devices
  • Reduced costs and downtime
  • Increased productivity

Inductive Coupling for non-contact connection

Many people are using inductive coupling technology to provide a non-contact connection for their devices. This method allows you to pass both power and signal across an air gap making it ideal for replacing slip rings or multi-pin connectors in many applications. This provides some great options for industry to gain benefits in these areas such as:

  • Reduced wear since there is no physical connection
  • Faster change over
  • Reduced downtime due to the elimination of damaged connector pins

For more information on connectivity and I/O architecture solutions please visit www.balluff.com.

Diversity in factory automation

This blog was originally posted on the Innovating Automation Blog.

Biodiversity is beneficial not only in biological ecosystems, but in industrial factory automation as well. Diversity helps to limit the effects of unpredictable events.

Typically, in factory automation a control unit collects data from sensors, analyzes this data and, according to its programmed instruction, triggers actuators to a defined operation. In most cases, a single-channel structure consisting of sensor, logic and output perfectly fulfills the application requirements. Yet in some cases two-channel structures are preferred to increase the reliability of the control concept.

Clamping control at machine tool spindles

spindle-position-control

To monitor clamping positions of tools in machine tool spindles, several options are possible: Sensors with binary output (e.g. PNP normally open) or sensors with continuous output (e.g. 0..10V or IO-Link) may be installed. The clamping process in many spindles is controlled with hydraulic actuators. This means the clamping force can be controlled by using pressure sensors which control the applied hydraulic pressure in the clamping cylinder.

The combined usage of both position and pressure sensors controls the clamping status in a better manner than using only one sensor principle. Typically, there are three clamping situations: 1) unclamped 2) clamped without object 3) clamped with object. In tooling spindles, the clamped position is usually achieved by using springs which force the mechanics to hold and clamp the object when no pressure is applied. A pneumatic or hydraulic actuator allows the worker to unclamp the object by providing force to overcome the spring load. Without hydraulic or pneumatic pressure, the clamped position should be detected by the position sensor. When enough pressure is being built up, after a short delay, the unclamped position should be achieved. Otherwise something must be wrong.

The advantage of diversity

By using two different sensor principles (in this case pressure sensing and position sensing) the risk of so-called common cause failures is reduced. The probability of concurrent effects of environmental impact on the different sensors is diminished, thereby increasing the detection rate of failures. The machine control can immediately react if the signals of pressure and position sensors do not match, simplifying monitoring of the clamping process.

Why RFID is the VIP of 2019

The “most popular” annual lists don’t usually come out until the end of the year, but I think it is worth mentioning now three applications that have gained substantial momentum this year. With the Smart Factory concept being driven around the globe, RFID has emerged from the shadows and taken its place in the spotlight. The demand for a larger amount of data, more security, and increased visibility into the production process has launched RFID into a leading role when it comes to automation.

Machine Access Control

When considering RFID being utilized for access control, they think about readers located near doorways either outside the building or within the plant. While those readers operate much like the industrial readers, they typically cannot communicate over an industrial communication protocol like Ethernet/IP, Profinet, or IO-Link.  With an industrial access control reader one can limit access to HMIs, PLCs, and various control systems by verifying the user and allowing access to the appropriate controls.  This extra layer of security also ensures operator accountability by identifying the user.

Machine Tool ID

RFID has been used in machining centers for decades. However, it was used mostly in larger scale operations where there were acres of machines and hundreds of tools. Today it’s being used in shops with as few as one machine. The ROI is dependent on the number of tool changes in a shift; not necessarily just the number of machines and the number of tools in the building. The greater the number of tool changes, the greater the risk of data input errors, tool breakage, and even a crash.

Content verification

Since RFID is capable of reading through cardboard and plastic, it is commonly used to verify the contents of a container. Tags are fixed to the critical items in the box, like a battery pack or bag of hardware, and passed through a reader to verify their presence. If, in this case, two tags are not read at the final station then the box can be opened and supplied with the missing part before it ships. This prevents an overload on aftersales support and ensures customers get what they ordered.

While RFID is still widely used to address Work in Process (WIP), asset tracking, and logistics applications, the number of alternative applications involving RFID has skyrocketed due to an increase in demand for actionable data.  Manufacturing organizations around the world have standardized on RFID as a solution in cases where accountability, reliability and quality are critical.

 

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.

Certification of Equipment in Hazardous Areas

This post was originally published on Innovating-automation.blog.

Industrial processes often need to be carried out in a hazardous atmosphere or when hazardous materials such as explosive gases, dust or flammable liquids are present. Such substances can be ignited by sufficient energy coming from sources like electrical sparks, open flames, and hot surfaces. The equipment installed in these areas must therefore be planned such that it does not represent an ignition source. In most countries around the world, national and/or local governments enact electrical construction standards intended to prevent accidents and enhance the safety of people and property. To ensure that installed components have been designed and tested according to regulations and offer sufficient protection, testing agencies are used. They certify that a particular device meets the specifications of the special standards for hazardous locations.

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Country Certification

There are many types and categories of possible hazards in explosion hazard areas. How these areas are classified depends on in which country or region the equipment is being installed:

  • In the USA the NEC (National Electrical Code) uses two methods for classifying hazardous locations: these are based on both the class/division and the zone. Categorization into class/division is a long proven procedure in the USA. Division into zones is a newer alternate concept which is becoming more and more established. As soon as the decision is made as to which method will be used for certification, that method is consistently applied.
  • Canada is similar to the US but follows the Canadian Standards Association (CSA) electrical codes.
  • In the European Union a harmonization scheme is used to eliminate technical trade barriers. The ATEX Directive 2014/34/EU is applied to devices and protection systems for proper use in explosion hazard areas. As part of a hazard assessment the operator divides the areas into zones and selects devices for the corresponding category.
  • For the rest of the world various local regulations and standards apply. But more and more countries are turning to the uniform global standard IECEx (International Electrotechnical Commission Explosive). It is however possible that a country specifies IECEx as the basic standard while requiring additional national certifications to meet country-specific regulations.

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For a comprehensive overview about the protection classes for electrical devices you may refer to following poster and brochure (including Balluff products for hazardous areas) that can be downloaded from the Balluff Homepage – or ask your Balluff sales representative for a printed version.

 

 

Using Photoelectric Sensors in High Ambient Temperatures

Photoelectric sensors with laser and red-light are widely used in all areas of industrial automation. A clean, dust-free and dry environment is usually essential for the proper operation of photoeyes, however, they can be the best choice in many dirty and harsh applications. Examples of this are raw steel production in steel mills and further metallurgical processes down to casting and hot-rolling.

Cutting of billets at casting – Photo: M.Münzl
Cutting of billets at casting – Photo: M.Münzl

Photoelectric sensors are especially useful in these environments thanks to their long sensing distance and their ability to detect objects independent of their material.

Most photoelectric sensors are approved to work in ambient temperatures of 55 to 60 °C. The maximum temperature range of these sensors is most often limited by the specifications of the optical components of the sensor, like the laser-diodes, but by taking certain precautions photoelectric sensors can provide optimal use in much hotter applications.

Maximize the distance
In steel production many parts of the process are accompanied by high ambient temperatures. Liquid steel and iron have temperatures from 1400 to 1536 °C. Material temperature during continuous casting and hot-rolling are lower but still between 650 and 1250°C.

The impact of heat emission on the sensors can be reduced significantly by placing the sensor as far from the target object as possible, something you can’t do with inductive sensors which have a short range. Very often the remote mounting will allow the sensor to operate at room temperature.

If you intend to detect quite small objects with high precision, the maximum distance for the installation might be limited. For this purpose chemical resistant glass fibers are suitable and can handle temperatures up to 250 °C. These pre-fabricated fiber optic assemblies can be easily attached to the sensor. The sensor itself can be mounted on a cooler and protected place.

Detect Glowing Metals
If you want to reliably detect red-hot or white glowing steel parts with temperatures beyond 700 °C, you won’t be able to use standard laser or red-light sensors. Red-hot steel emits light at the same wavelength that it is used by photoelectric sensors. This can interfere with the function of the sensor. In such applications you need to use sensors which operate based on infrared light.

Add Protection

Sensor enclosure and protective cable sleeve
Sensor enclosure and protective cable sleeve

At many locations in the steel production process, the extensive heat is only temporary. In a hot rolling mill, a slab runs through a rougher mill multiple times before it continues to a multi-stage finishing mill stand to be rolled to the final thickness. After that the metal strip runs into the coiler to be winded up.
This process runs in sequence, and the glowing material is only present at each stage of production for a short time. Until a new slab runs out of the reheating furnace, temperatures normalize.

Standard sensors can work in these conditions, but you do run the risk of even temporary temperature hikes causing sensor failure and then dreaded downtime. To protect photoelectric sensors against temporary overheating, you can use a protective enclosure. These can provide mechanical and thermal protection to the sensors which often have plastic bodies. Additional protection can be achieved when a heat resistant sleeve is used around the cable.

Photoelectric sensors do have their limits and are not suitable for all applications, even when precautions are taken. Ask yourself these questions when deciding if they can be the right solution for your high temperature applications.

  • Which distance between the hot object and sensor can be realized?
  • What is the maximum temperature at this location?
  • How long will the sensor be exposed to the highest heat levels during normal operation and at breakdown?

Industrial sensors with diagnostic functionality

Self-Awareness
For monitoring functionality in industrial processes two aspects are relevant: Environmental awareness and self-awareness. Environmental awareness analyzes impacts which are provided by the environment (e.g. ambient temperature). Self-awareness collects information about the internal statuses of (sub)systems. The diagnostic monitoring of industrial processes, which are typically dynamic, is  not as critical as the monitoring of static situations. If you have many signal changes of sensors due to the activity of actuators, with each plausible sensor signal change you can be confident that the sensor is still alive and acts properly. A good example of this is rotation speed measurement of a wheel with an inductive sensor having many signal changes per second. If the actuator drove the wheel to turn but the sensor would not provide signal changes at its output, something would be wrong. The machine control would recognize this and would trigger a stop of the machine and inspection of the situation.

Inductive Sensors with self-awareness

DESINA
For level sensing applications in cooling liquid tanks of metalworking applications inductive sensors with self-diagnostics are often used. The inductive sensors detect a metal flag which is mounted to a float with rod fixation.

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Additionally, to the switching output these sensors have a monitor output which is a “high” signal when the sensor status is OK. In situations where the sensor is not OK, for example when there has been a short circuit or sensor coil damage, the monitor output will be a “low” signal.  This type of so called DESINA sensors is standardized according to ISO 23570-1 (Industrial automation systems and integration – Distributed installation in industrial applications – part 1: Sensors and actuators).

Dynamic Sensor control
Another approach is the Dynamic Sensor Control (DSC). Rather than using an additional monitoring output, this type of sensors provides impulses while it is “alive.”

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The sensor output provides information about the position of the target with reference to the sensor as well as status diagnostic of the sensor itself.

IO-Link
With IO-Link communication even teaching of defined switching distance can be realized. The IO-Link concept allows you to distinguish between real-time process data (like target in/out of sensing range) and service data which may be transferred with a lower update rate (in the background of the real process).

For more information, visit www.balluff.com.

This blog post was originally published on the innovating-automation.blog.

Press Shops Boost Productivity with Non-Contact Connections

In press shops or stamping plants, downtime can easily cost thousands of dollars in productivity. This is especially true in the progressive stamping process where the cost of downtime is a lot higher as the entire automated stamping line is brought to a halt.

BIC presse detail 231013

Many strides have been made in modern stamping plants over the years to improve productivity and reduce the downtime. This has been led by implementing lean philosophies and adding error proofing systems to the processes. In-die-sensing is a great example, where a few inductive or photo-eye sensors are added to the die or mold to ensure parts are seated well and that the right die is in the right place and in the right press. In-die sensing almost eliminated common mistakes that caused die or mold damages or press damages by stamping on multiple parts or wrong parts.

In almost all of these cases, when the die or mold is replaced, the operator must connect the on-board sensors, typically with a multi-pin Harting connector or something similar to have the quick-connect ability. Unfortunately, often when the die or mold is pulled out of the press, operators forget to disconnect the connector. The shear force excreted by the movement of removing the die rips off the connector housing. This leads to an unplanned downtime and could take roughly 3-5 hours to get back to running the system.

 

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Another challenge with the multi-conductor connectors is that over-time, due to repeated changeouts, the pins in the connectors may break causing intermittent false trips or wrong die identification. This can lead to serious damages to the system.

Both challenges can be solved easily with the use of a non-contact coupling solution. The non-contact coupling, also known as an inductive coupling solution, is where one side of the connectors called “Base” and the other side called “Remote” exchange power and signals across an air-gap. The technology has been around for a long time and has been applied in the industrial automation space for more than a decade primarily in tool changing applications or indexing tables as a replacement for slip-rings. For more information on inductive coupling here are a few blogs (1) Inductive Coupling – Simple Concept for Complex Automation Part 1,  (2) Inductive Coupling – Simple Concept for Complex Automation Part 2

For press automation, the “Base” side can be affixed to the press and the “Remote” side can be mounted on a die or mold, in such a way that when the die is placed properly, the two sides of the coupler can be in the close proximity to each other (within 2-5mm). This solution can power the sensors in the die and can help transfer up to 12 signals. Or, with IO-Link based inductive coupling, more flexibility and smarts can be added to the die. We will discuss IO-Link based inductive coupling for press automation in an upcoming blog.

Some advantages of inductive coupling over the connectorized solution:

  • Since there are no pins or mechanical parts, inductive coupling is a practically maintenance-free solution
  • Additional LEDs on the couplers to indicate in-zone and power status help with quick troubleshooting, compared to figuring out which pins are bad or what is wrong with the sensors.
  • Inductive couplers are typically IP67 rated, so water ingress, dust, oil, or any other environmental factor does not affect the function of the couplers
  • Alignment of the couplers does not have to be perfect if the base and remote are in close proximity. If the press area experiences drastic changes in humidity or temperature, that would not affect the couplers.
  • There are multiple form factors to fit the need of the application.

In short, press automation can gain a productivity boost, by simply changing out the connectors to non-contact ones.

 

Improve Your Feeder Bowl System (and Other Standard Equipment) with IO-Link

One of the most common devices used in manufacturing is the tried and true feeder bowl system. Used for decades, feeder bowls take bulk parts, orients them correctly and then feeds them to the next operation, usually a pick-and-place robot. It can be an effective device, but far too often, the feeder bowl can be a source of cycle-time slowdowns. Alerts are commonly used to signal when a feed problem is occurring but lack the exact cause of the slow down.

feeder bowl

A feed system’s feed rate can be reduced my many factors. Some of these include:

  • Operators slow to add parts to the bowl or hopper
  • Hopper slow to feed the bowl
  • Speeds set incorrectly on hopper, bowl or feed track
  • Part tolerance drift or feeder tooling out of adjustment

With today’s Smart IO-Link sensors incorporating counting and timing functions, most of the slow-down factors can be easily seen through an IIoT connection. Sensors can now time how long critical functions take. As the times drift from ideal, this information can be collected and communicated upstream.

A common example of a feed system slow-down is a slow hopper feed to the bowl. When using Smart IO-Link sensors, operators can see specifically that the hopper feed time is too long. The sensor indicates a problem with the hopper but not the bowl or feed tracks. Without IO-Link, operators would simply be told the overall feed system is slow and not see the real problem. This example is also true for the hopper in-feed (potential operator problem), feed track speed and overall performance. All critical operations are now visible and known to all.

For examples of Balluff’s smart IO-Link sensors, check out our ADCAP sensor.