Contrast and more

25. November 2016

Flexible adjustment is everything

With the latest trends for smaller production runs leading to customized mass-produced items and therefore a higher frequency of job-changing, an adaptive packaging machine must be able to cope with an irregular product infeed, while also being able to adjust to different formats. This adaptation is made possible with sensors and actuators. All packaging shapes and sizes are possible with just one machine.





Contrast sensors KTM: mini, easy, speedy, robust

Fast, software-supported format changes can reduce downtime and optimize material utilization and packaging processes.

In packaging machines, it is primarily contrast sensors that are used for recognizing marks. KT contrast sensors from SICK detect even the smallest contrasts at the highest speeds, such as print marks on foils or packaging. They detect minute grayscale variations between the mark and the background on matte, shiny, or transparent surfaces.


Fast format change via IO-Link

To give an example, when the contents of the packaging change from orange to apple flavor, the colors of the packaging materials often change too. This means that the contrast sensor has to be taughtin again for optimal recognition of the marks. If multiple sensors are built into a machine, this will take a lot of time. But if the formats are stored in the sensor as jobs, they can be simply called up when needed. In this way, all contrast sensors in the machine are given the same setting automatically, e.g., transmission color and switching threshold.

Once parameters have been taught in the contrast sensor, they are stored in the controller as “jobs”. Should the format change, the corresponding “job” is simply recalled. This saves time and money.


IO-LinkThe IO-Link connection also has other advantages. IO-Link enables constant data diagnostic. The sensor’s “quality of teach” function returns a value that is indicative of process reliability. If the value falls below a certain level, a “safety message” can be output via the controller, for example. If the value changes while the process is in progress, the “quality of run” function reports back immediately.


Smart sensor functions offer additional advantages

Along with conventional print mark detection, the sensor will soon be able to provide additional information via IO-Link thanks to new automation functions.

A smart contrast sensor with the additional integrated “print mark counter” function detects and counts the print marks on film rolls. If it is given the number of print marks per roll, the sensor will indicate how much film is still on the roll at any point in time. This signifies that a roll-change will take place at the right time. The conveyor speed of the packaging material can easily be determined and controlled by using the contrast sensor’s “speed monitoring” function.

Additional integrated functions allow you to produce new and higher-quality information beyond print mark detection together with the customer, depending on the desired application.


  • Using the KT at Harro Höfliger “The integrated IO-Link interface can be used to access the parameter settings for the KT contrast sensor. This speeds up and simplifies format changes. We are able to use the IO-Link functionality flexibly for diagnostic purposes in the preliminary stages to ensure that critical packaging materials are detected reliably,” explains Rainer Bauer, Controls Engineering at Harro Höfliger Verpackungsmaschinen GmbH. Harro Höfliger is a leading global manufacturer of high-quality production and packaging lines. It specializes in system solutions for the pharmaceutical and medical industries, with a focus on customerspecific machines.







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