Opto-electronic sensors for detection of transparent objects

19. April 2016

Detecting with ‘(through)sight’ – automating with foresight

Transparent plastic packaging, bottles made of glass or PET, ampoules, pipettes, flat, tubular, and hollow glass, films for securing loads on pallets: In many manufacturing processes, automators must cope with transparent objects. In order that these objects are detected reliably, SICK has developed a special sensor portfolio for factory automation. It excels due to outstanding optical performance, intelligence in terms of evaluation technology, and automation-related flexibility. When detecting transparent objects, use of this portfolio allows solving varied tasks reliably and efficiently.




Many paths, one goal: the right choice of sensor

The sensors from SICK are designed in a way that they cope with the most diverse applications in a changing industrial environment – making possible future-proof solutions. In each case, the application and its secondary conditions specify which sensor solution delivers the optimum detection results. Depending on the requirement focus, different sensor solutions suggest themselves. The optimized optical performance of SICK’s sensors opens up a broad spectrum of applications that enables reliable detection of nearly every type of transparent object: from thin film and the PET bottle all the way to transparent packaging.




Sensors from SICK meet the highest requirements in terms of ruggedness and resistance to media

The sensors of the WL9G-3 product family in the glass-fiber reinforced VISTAL® plastic housing and the WL12G-3 product family in the sturdy zinc die casting feature extreme mechanical ruggedness and resistance vis-à-vis a large variety of cleaning and disinfecting agents. The WLG4S Inox and the WLG4S Hygiene are intended for use in wet areas of the food and pharmaceutical industries.



They stand out due to their perfectly seal-tight stainless steel housing and their washdown and hygiene design, respectively, implemented consistently throughout.


Instances of “poor eyesight” compensated automatically



In a harsh, dirty environment, these photoelectric sensors stand the test with integrated switching threshold adjustment. This CTA feature (CTA = continuous threshold adaption) is made possible by using special ASIC technologies from SICK. In a relatively clean environment, photoelectric retro-reflective sensors such as the WL8G, WL11G-2, and the WLG190T provide sufficiently large functional reserves for prolonged, maintenance-free continuous operation.




The sensors can be accommodated in the furthermost corner


If space is too scarce at the place of detection but the evaluation unit needs to be easily accessible nonetheless, WLL180T fiber-optic sensors are well suited. The GRL18SG and MHL15 product families with their short M18 threaded housings also provide extremely space-saving installation Solutions.


IO-Link makes integrated intelligence usable

With Smart Sensor solutions, including IO-Link, SICK offers outstanding means for optimizing automation technology in machines and plants. For instance, the WL9G-3, WL12G-3, and WLG4S-3 photoelectric sensors feature an integrated IO-Link option even in the standard version. In case of the WLG4S-3, this is available in the Inox and Hygiene versions as well.




Using this technology, the sensors transmit digital output states, digitalized analog values, as well as numerous functional and service data. Doing so makes it possible to perform preventative maintenance on facilities during operating breaks, thus avoiding unplanned machine downtimes. Moreover, the photoelectric sensors offer additional IO-Link functions, e.g. electronic debouncing in case of multiple signals, time measurement, and product tracking by means of time stamp. In this way, important tasks that had to be programmed and executed in the automation system before were transferred to the lowest field level within the automation pyramid.




Detection of transparent objects using opto-electronic sensors requires a special degree of optical performance, intelligence in terms of evaluation technology, and automation-related flexibility. The sensor portfolio from SICK, designed for detecting transparent objects, fulfills these requirements.



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