position measurement Archives - AUTOMATION INSIGHTS

The Right Mix of Products for Recipe-Driven Machine Change Over

The filling of medical vials requires flexible automation equipment that can adapt to different vial sizes, colors and capping types. People are often deployed to make those equipment changes, which is also known as a recipe change. But by nature, people are inconsistent, and that inconsistency will cause errors and delay during change over.

Here’s a simple recipe to deliver consistency through operator-guided/verified recipe change. The following ingredients provide a solid recipe-driven change over:

Incoming Components: Barcode

Fixed mount and hand-held barcode scanners at the point-of-loading ensure correct parts are loaded.

Change Parts: RFID

Any machine part that must be replaced during a changeover can have a simple RFID tag installed. A read head reads the tag in ensure it’s the correct part.

Feed Systems: Position Measurement

Some feed systems require only millimeters of adjustment. Position sensor ensure the feed system is set to the correct recipe and is ready to run.

Conveyors Size Change: Rotary Position Indicator

Guide rails and larger sections are adjusted with the use of hand cranks. Digital position indicators show the intended position based on the recipes. The operators adjust to the desired position and then acknowledgment is sent to the control system.

Vial Detection: Array Sensor

Sensor arrays can capture more information, even with the vial variations. In addition to vial presence detection, the size of the vial and stopper/cap is verified as well. No physical changes are required. The recipe will dictate the sensor values required for the vial type.

Final Inspection: Vision

For label placement and defect detection, vision is the go-to product. The recipe will call up the label parameters to be verified.

Traceability: Vision

Often used in conjunction with final inspection, traceability requires capturing the barcode data from the final vials. There are often multiple 1D and 2D barcodes that must be read. A powerful vision system with a larger field of view is ideal for the changing recipes.

All of these ingredients are best when tied together with IO-Link. This ensures easy implantation with class-leading products. With all these ingredients, it has never been easier to implement operator-guided/verified size change.

Flexibility Through Automated Format Changes on Packaging Machines

Digitalization does not stop at the packaging industry. There is a clear trend toward more individual packaging and special formats. What does this mean for packers and packaging machine manufacturers? The variants increase for every single packer, and this leads to a decreased batch size. The packer needs highly flexible machines, which he can easily adjust to the different formats and special variants. The machine manufacturer, in turn, must make these flexible machines available. What does this format change look like? Which technologies can support the packer optimally?

There are two different format adjustment tasks to perform. One is the adjustment of guide rails, side belts or link chains so that they can be adapted to the new format. The other is the changing of parts when a new format is to be produced.

Both tasks have different demands concerning automation technology and therefore there are different solutions available.

Format adjustment

Format adjustment is the adjustment of guide rails, side belts or link chains. In order to carry out this adjustment quickly, safely and error-free, precise position information is required. This recorded position information can then be used to support manual adjustment on the display unit or it can be transferred to the PLC for fully automatic adjustment. One possible solution is to use different position measuring systems. Various standardized interfaces are available as transmission formats, including IO-Link.

Fast format changes in secondary packaging.png — Fast format changes in secondary packaging

IO-Link has ideal features that are predestined for format adjustment: sufficient speed, full access to all parameters, automatic configuration, and absolute transmission of measured values. This eliminates the need for time-consuming reference runs. Since the machine control remains permanently traceable, the effort for error-prone written paper documentation is also saved.

One example for a non-contact absolute position measuring system

BML SL1, IO-Link

A magnetic encoded position measuring system is ideally suited for position detection during format adjustment. It is insensitive to dust, dirt and moisture, offers high accuracy and a measuring length of up to 8,190 mm. Therefore, the position determination and the speed control during the change of guide rails, sidebands or link chains are no problem.

For more information read our previous blog post “Boost Size-Change Efficiency with IO-Link Magnetic Encoders and Visualization”.

Changeable part detection

When changing to a different format size, it is often necessary to not only adjust guide rails but to also replace changeable parts. Machines are becoming more and more flexible, which means that the number of changeable parts per machine is growing. It is becoming increasingly difficult for the machine operator to find the right part and even more difficult to find the correct mounting position. This conceals some avoidable sources of error. If the replacement part is installed incorrectly, it can cause machine damage, which can lead to downtime.

Therefore, a fast recognition of changeable parts is all about reliably detecting the changeable part at the correct position in the machine. It is also important to make it as easy as possible for the operator to detect possible faults before they happen via a visualization system.

One way of identifying exchangeable parts is industrial identification with RFID.

The right part at the right position

When changing a machine over to a new format you can use RFID data carriers or barcodes to ensure that the correct new parts are being used. Vision sensors also detect whether the part was installed correctly or incorrectly. These solutions help you prevent errors and machine damage, which in turn increases throughput and reduces production costs.

Implement predictive maintenance

With RFID data carriers, the operating times of each change part can be documented directly on the part itself. If a part needs to be cleaned, replaced or reworked, a notification or alarm is issued in the machine controller before fault conditions can arise. RFID data carriers also allow regular cleaning cycles to be logged.

Automate machine settings

Since you can store the individual setting parameters for the change part on the data carrier, the part itself also provides the information to the machine controller. Thus, the change part can trigger a format change in the PLC and change the production process. This is an important step toward intelligent production in the Industry 4.0 concept.

Simple visualization enables expert free operation

With an LED signal lamp, the operator can recognize the operating status of the machine quickly, easily and at a glance. Among other things, it serves to monitor the operating windows and signals whether all settings have been made correctly. The segments of the signal lamp can be configured so that one machine lamp meets a wide range of requirements.

Summary

Format adjustment involves changing guide rails, sidebands or link chains due to a new format. This can be semi-automated or fully automated on the machines. It requires displacement measuring systems whose sensors provide feedback on the respective position.

If format parts on the machine have to be replaced, it must be ensured that the correct changeable part is installed at the correct position in the machine. Industrial identification systems such as RFID are suitable for this purpose. Each changeable part is equipped with a tag and, with the help of the read/write heads, it recognizes whether the correct changeable part is installed in the correct place.

Both automation options offer the following advantages:

Short set-up times and increased system productivity
Efficient error prevention
Increased machine flexibility
Avoidance of machine damage due to wrong parts when starting up the machine
Simple visualization for the operator

To learn more about format change visit www.balluff.com.

IO-Link Measurement Sensors Solve Application Challenges

In industrial distance and position measurement applications, one size definitely does not fit all. Depending on the application, the position or distance to be measured can range from just a few millimeters up to dozens of meters. No single industrial sensor technology is capable of meeting these diverse requirements.

Fortunately, machine builders, OEM’s and end-users can now choose from a wide variety of IO-Link distance and position measurement sensors to suit nearly any requirement. In this article, we’ll do a quick rundown of some of the more popular IO-Link measurement sensor types.

(For more information about the advantages of IO-Link versus traditional analog measurement sensors, see the following blog posts, Solving Analog Integration Conundrum, Simplify Your Existing Analog Sensor Connection, and How Do I Make My Analog Sensor Less Complex?)

Short Range Inductive Distance Sensors

These sensors, available in tubular and block Scott Image1.JPG style form factors are used to measure very short distances, typically in the 1…5 mm range. The operating principle is similar to a standard on/off inductive proximity sensor. However, instead of discrete on/off operation, the distance from the face of the sensor to a steel target is expressed as a continuously variable value. Their extremely small size makes them ideal for applications in confined spaces.

Inductive Linear Position Sensors

Inductive linear position sensors are available in several block style form factors, and are used for position measurement over stroke lengths up to about 135 mm. These types of sensors use an array of inductive coils to accurately measure the position of a metal target. Compact form factors and low stroke-to-overall length factor make them well suited for application with limited space.

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Magnetostrictive Linear Position Sensors

IO-Link Magnetostrictive linear position sensors are available in rod style form factors for hydraulic cylinder position feedback, and in external mount profile form factors for general factory automation position monitoring applications. These sensors use time-proven, non-contact magnetostrictive technology to provide accurate, absolute position feedback over stroke lengths up to 4.8 meters.

Laser Optical Distance Sensors

Scott Image 4.JPG Laser distance sensors use either a time-of-flight measuring principle (for long range) or triangulation measuring principle (for shorter range) to precisely measure sensor to target distance from up to 6 meters away. Laser distance sensors are especially useful in applications where the sensor must be located away from the target to be measured.

Magnetic Linear Encoders

IO-Link magnetic linear encoders use an absolute-coded Scott Image 5 flexible magnet tape and a compact sensing head to provide extremely accurate position, absolute position feedback over stroke lengths up to 8 meters. Flexible installation, compact overall size, and extremely fast response time make magnetic linear encoders an excellent choice for demanding, fast moving applications.

IO-Link Measurement Sensor Trends

The proliferation of available IO-Link measurement sensors is made possible, in large part, due to the implementation of IO-Link specification 1.1, which allows faster data transmission and parameter server functionality. The higher data transfer speed is especially important for measurement sensors because continuous distance or position values require much more data compared to discrete on/off data. The server parameter function allows device settings to be stored in the sensor and backed up in the IO-Link master. That means that a sensor can be replaced, and all relevant settings can be downloaded from master to sensor automatically.

To learn about IO-Link in general and IO-Link measurement sensors in particular, visit www.balluff.com.

Measurement Fundamentals: Position Measurement vs. Distance Measurement

Continuous measurements on industrial machines or the materials that these machines are making, moving, or processing can be categorized into two main types of sensors: position measurement sensors, and distance measurement sensors. It’s a somewhat subtle distinction, but one that is important when evaluating the best measurement sensor for a particular application.

Position Measurement: When we speak in terms of position measurement, we’re typically talking about applications where a the sensor is installed onto a machine, and mechanically coupled to the moving part of the machine – or is installed into a hydraulic cylinder that is moving the machine – and is reporting the continuous position of the machine. In a positioning application, the questions that need to be answered are: “Where is it? Where is it now? And now?”.

Scott image1

Examples of position measurement sensors include magnetostrictive linear position sensors and magnetically encoded linear sensors. With each of these sensor types, either the sensor itself, or the position marker, is typically attached to the moving part of the machine.

Distance Measurement: Distance measurement sensors, on the other hand, are used in applications that require accurate measurement of a target that is typically no part of the machine. A good example would be an application where parts or components are moving along a conveyer belt, and the position of those parts needs to be accurately measured. In this example, it wouldn’t be practical, or even possible, to attach a sensor to the moving part. So its position needs to be measured from a DISTANCE. In a distance measuring application, the question being answered is: “How far away is it?”.

Scott image2

Examples of distance measuring sensors include photoelectric (laser) sensors and inductive distance sensors. These types of sensors are usually mounted on the machine, or in the immediate vicinity of the machine, and are aimed at a point or a path where the object to be measured is, or will be, located.

In summary, while both position and distance sensors do much the same thing – provide continuous indication of position – the applications for each are generally quite different. Gaining an understanding of the application and its requirements will help to determine which type of sensor is the best choice for the task.

For more information on position and distance measurement sensors, visit www.balluff.com.

Hydraulic Valves – Customize your Feedback

Hydraulic actuators can be used to open and close a valve’s position. In automation architectures, a linear position sensor is used within the hydraulic actuator to provide continuous position feedback.

The linear position sensor is installed into the back end of the cylinder. The sensing element resides in a cavity that has been gun-drilled through the piston and cylinder rod, extending the full length of the mechanical stroke. A magnet ring is used as a position marker and mounted on the face of the piston. As the piston (and the position marker) move, the linear position sensor provides a continuous absolute position by way of an analog or digital signal.

In some applications, a cylinder’s position may only be moving across a small portion of the overall stroke or a specific portion of the stroke. The end user could benefit from altering the transducer’s signal based on the application’s specific stroke requirements instead of the entire cylinder’s stroke, thereby maximizing available position resolution. When this situation arises, most transducer manufacturers offer the ability to customize or “teach” a modified output of the stroke via push buttons or from wiring inputs. When this is done, the process does require the cylinder (and position marker) to move to these defined locations for a “teach”.

A more user-friendly and repeatable approach for customized stroke lengths with linear position sensors is to use a graphical software package. The software can be connected
from a PC via USB to a compatible linear position sensor. Starting and ending stroke values can be precisely entered into the software and a graphical representation of the output curve is created. For a more straightforward approach, you can also drag and drop these stroke points by a click of a cursor. The file can be saved on a PC and downloaded to the transducer. In either case, the cylinder’s piston doesn’t need to be actuated.

In projects where multiple, identical actuators and linear position sensors need to be customized, the setup would only need to be done once, the file saved, and simply uploaded to all the sensors for the project. A great time-saver over manually teaching each and every sensor.

Another benefit to using software with linear position sensors is to be able to upload programs for replacement units in a safe user environment (e.g. lab station or office) and shipping them to various job sites. These different locations (or locales) can be in harsh environmental conditions (extreme cold or heat) or areas that contain ignitable or explosive gases or dusts which may be difficult to work in.

Other software features include inverting the output curves, offering position or velocity outputs, and more.

For more information on Balluff’s Magnetostrictive Linear Position Sensors, visit www.balluff.com.

Solar tracking systems and sensors

Over the last few years there has been a lot of discussion on how we will meet the global energy demand in the future. And what will be the technologies to generate it? In the end it all comes down to the levelized cost of electricity (LCOE), which is the sum of all costs of a power plant divided by the total electricity that is generated over the plant’s lifetime. All companies in the renewable energy industry focus on reaching lower LCOE compared to conventional power generation (especially gas). Their biggest advantage is that there are no costs for fuel (sun light, wind, water).

Let’s take solar power as an example. Principally there are two ways to use the sun light: First it can be converted directly to electricity (photovoltaics). Second, it can be used indirectly by generating thermal energy (concentrated solar power). In order to reach higher efficiency solar trackers are used to orient photovoltaic panels, reflectors, or mirror towards the sun. On the other hand they add costs to the system. Therefore it must be carefully calculated whether a tracker (single or dual axis) is required or not (fixed installation).

Single axis trackers are used to position photovoltaic panels, parabolic troughs or linear Fresnel collectors from east to west on a north to south orientation. Depending on the required tracking accuracy different sensors are used for this task. As most of the photovoltaic trackers use electric linear actuators, very often inductive sensors are installed on the actuator for position feedback. They are cost optimized and are a standard feature in the actuators. Another option is to use inclination sensors that are directly mounted on the rotating shaft to provide angle feedback (e.g. in linear Fresnel plants). As inclinometers are mounted on the moving part, there is cable wear that could lead to failure over time. For high end tracking, as is required in parabolic trough plants, magnetic tape systems are used as rotary encoders. A magnetic tape is mounted around the shaft and a sensor head is installed on the frame of the tracker. The sensor counts the pulses accurately and provides continuous position feedback without any wear.

Dual axis trackers are used to position concentrated photovoltaic (CPV) panels, parabolic reflectors (dish) or mirrors (heliostats). Especially in central receiver plants high accuracy is required. They need high temperatures and therefore have to focus lots of light on a central receiver on top of a tower in the middle of the heliostat field. As there is an azimuth and an elevation axis, two position feedback systems are required. The elevation angle could be solved with an inclinometer, but this does not work for the azimuth position. Again, the position could be measured with embedded rotary encoders directly on the drive. But there is again backlash, and accuracy is of highest importance as heliostats could be one mile away from the central receiver. Magnetically coded position and angle measurement systems can be mounted on both axis (azimuth and elevation) and provide direct position feedback with highest accuracy.

More information can be found in this brochure about power generation. http://asset.balluff.com/std.lang.all/pdf/binary/861522_162563_1305_en-US.pdf

Special thank you to Bernd Schneider, Industry Manger – Balluff GmbH for contributing to this post.

Direct load position sensing with secondary feedback encoders

Motion control system designers have found a way to eliminate or reduce common sources of position error, such as mechanical backlash, non-linearity, and hysteresis. The method is called direct load position sensing and it employs linear encoders as a source of secondary position feedback. Secondary feedback encoders supplement the indirect position measurement taken by a rotary shaft encoder by measuring the position of the moving load directly.

This method can save money by delivering the specified motion system performance at lower initial cost, and helps maintain system performance over time by getting around the problem of mechanical wear and tear degrading the accuracy of position measurements taken at the motor.

If you’d like to know more, there’s a White Paper available called “Motion Control Primer: Direct load position sensing with secondary feedback encoders”.

Tag: position measurement

The Right Mix of Products for Recipe-Driven Machine Change Over

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