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Intelligent photoelectric sensors: safe detection efficient automation

Supplier: SICK Pty Ltd By: Wilhelm Schürmann, Business Unit Manager for Photoelectric Sensors and Fibers, SICK AG, Waldkirch
16 April, 2018

Photoelectric sensors that offer optimum detection performance are designed specifically for their area of application.

Efficient automation is always also a question of safe object detection. Photoelectric sensors that offer optimum detection performance are designed specifically for their area of application, meet high technology and quality standards, and support intelligent automation functions are proving their worth as reliable and cost-effective solutions that are worth investing in for a wide and challenging range of applications.

In most cases, the primary aim of object detection is to maximise the productivity of machines, systems, and processes. The clear demand for maximum performance is matched by the versatility of the requirements set by the vast scope of object properties, ambient conditions, installation situations, or automation and communication preferences. As a global technology and market leader for optoelectronic sensors, SICK offer by far the most comprehensive portfolio of photoelectric sensors on the market – and can thus rise to meet virtually any challenge across the industry and indeed the world.

Reliable not random: Detecting all manner of different objects

SICK's wide portfolio enables it to make a promise to find a solution every time. Suitable photoelectric sensors with the widest possible range of characteristics are available for object detection. The optical appearance of objects can be dark, patterned, transparent, or shiny. Perforated or uneven object surfaces are also a factor in the selection of sensors, as is the distance of the objects at close and long range, or their detection through gaps and openings. High-speed processes require a “rapid eye”; and certain object shapes (contact pins on semiconductor components, for example) call for a special “sharp eye”. Regardless of whether an individual object property is to be considered in isolation or some features are to be considered together, SICK's portfolio of photoelectric sensors will be able to provide at least one suitable solution for virtually any application. This is made possible by SICK's SIRIC® optoelectronic ASIC technology. Photoelectric sensors with SIRIC® offer maximum optical durability to LED illumination, ambient light, and emitted light from other sensors, as well as supporting both extended sensing and scanning distances and enhanced operating reserves. SIRIC® photoelectric proximity sensors also impress with the best background suppression in this sensor class. The highly integrated chip technology makes it possible to reduce the size of the components without impairing detection performance. By applying the auto-collimation principle, the photoelectric sensors can be relied upon to detect objects even through small gaps and openings, and avoid blind zones at close range.

Sensor equipment: A great deal of standard and many additional options

SIRIC® provides the basis for the standard design and dimensioning of the optics and electronics of the photoelectric sensors. Users can choose light sources in the form of infrared transmitters for detection tasks with high sensing distances, PinPoint and laser LEDs, e.g., for small objects and high-speed processes, or blue light for the detection of materials that absorb light (solar wafers, for example). The shape of the object determines the shape of the light spot on the object: dot, line, double line, or light beam is possible. Photoelectric proximity sensors also differentiate between standard or V optics and can even be used to scan flat, transparent objects such as smartphone displays. SICK's ClearSens technology can be relied upon to detect transparent objects, and sensors with AutoAdapt functionality can track the switching threshold automatically, thereby significantly extending the maintenance-free availability time of the sensors.

Should the wide variety of sensors that are available as standard not be sufficient, the platform of SICK photoelectric sensors can be customised to meet technical and budgetary requirements – even at short notice should this be dictated by requirements. Within the SICK organisation, a clearly defined process is followed, from application analysis through to series delivery. Light sources and detection principles can be adapted to suit the material, optical appearance, surface, and shape of the object(s) to be detected. The operating software can be customised or even programmed based on an application. System default settings can be adapted to meet specific electrical integration requirements. The connectivity and the pin assignment of the electrical interfaces are also open for special solutions. For both standard and special devices alike, a suitable sensor solution is almost always available immediately in stock or can be produced quickly.

Best performance: A proprietary standard in any setting

Where the quality and performance of photoelectric sensors are concerned, SICK measures itself not against the market standard but by its own specifications, which are much more demanding. To a significant extent, these specifications are the result of seven decades of experience and knowledge of the requirements to be met by sensors in daily practice. SICK has developed its own test processes as it strives to meet expectations in product creation. These processes are used to simulate physical, chemical, photo biological, and climatic factors, for example, or to measure electromagnetic durability. The internal test guidelines and standards for all such tests set the bar significantly higher than legal minimum requirements and market standards. As such, the sensors can rise to any challenge; even in the most adverse application conditions, they can be relied upon for maximum availability both in and for machines and systems. In ambient light, direct sunlight, mirroring, and reflective conditions, SICK optical sensors retain a clear view – even if dust, window, and moisture are to be contended with. Almost without exception, the sensors are temperature-resistant from -40 °C to +60 °C. The sensors are setting new standards for shock and vibration resistance, and EMC values are significantly above minimum legal requirements: they are based on the strictest international standards (IEC 61000-6-2, for example). Compliance is also assured with the requirements of general standards including those governing EC conformity, Underwriters Laboratories (UL) safety requirements, or the safety requirements of EU Directive 2011/65/EU on the restriction of the use of certain hazardous substances in electrical and electronic equipment. For sensors that are used in the injection area of production and packaging systems in food processing, beverage filling, or the manufacture of pharmaceutical products in accordance with the specifications of EN 1672-5.3.2, SICK also takes its lead from the recommendations of the European Hygienic Engineering & Design Group (EHEDG) and the specifications of EN 1935/2011, as befits good manufacturing practice.

Models optimise the distribution of space in a mounting location

Large working clearances, detection from near distance, compact machine designs, restricted mounting space, mobile machine structures, restricted accessibility once installed – there are many factors that affect the ideal model and size of optoelectronic sensors. So it's good to know that SICK's sensor portfolio can meet these selection criteria to the fullest possible extent. The photoelectric sensors are available in a wide range of different housings – made from metal or plastic, from miniature to “roomy”, cylindrical, cuboid, or as fibres, in slim and flat versions, with M3 threaded female connectors through to M4 longitudinal holes. If it is likely to contact with aggressive products or cleaning agents, sensors made from stainless steel, from highly resistance VISTAL™ glass-fibre-reinforced plastic, or with Teflon coating, for example, are ideal. Optional accessories including universal clamping systems, mounting brackets, clamping and alignment brackets, and protective devices extend the options for optimum distribution of space. The same applies to the scope of the electrical connectivity. Extending from the 3-wire cable through rotating male cable connectors and beyond to 4-pin male cable connectors, it too is extended by additional special options. With all of this in place, nothing stands in the way of optimum mounting and electro-technical integration. The portfolio also makes particular allowance for the operational capability of the sensors once they have been installed; with teach-in knob, potentiometer, or light/dark switch on the device, external teach-in via the control cable, or remote configuration via IO-Link, all standard operating scenarios are catered for. 

Photoelectric sensors as smart automation providers

Intelligent opto-sensors do much more than just supplying a switching signal – they support various automation functions directly in the sensor and can be integrated into modern automation networks with the assistance of the global communication standard IO-Link. The shifting of what were control functions to photoelectric sensors and their distribution in a network have a direct effect on machine productivity and the efficiency of processes. The option of flexible sensor adjustment via the automation system is of particular benefit for machines which frequently switch between formats, configurations, or product variants. Machines and systems in the packaging industry find this feature especially useful, as the ability to download parameters directly from a control system to any number of sensors simultaneously saves time, prevents errors, and can be documented at any point. High-speed meters are ideal tools in systems that require reliable and convenient metering or speed/velocity measurement. Time measurement is another function that IO-Link can be used to implement. This function optimises processes whose aim is to use accurate time recording to determine lengths, control numbers of cycles, separate objects, or carry out efficient slip control. Remote de-bouncing also proves useful in applications that involve large numbers of interference signals for reasons related to processes or the environment (in systems used in the woodworking industry, for example).

Variance means versatility

A variety of housing formats and materials, different detection principles and optical technologies, as well as versatile mounting, connection, and operating options,  characterise the significant variance of SICK's photoelectric sensor portfolio. The standard sensors, along with the special versions based on them, offer integrators and users alike countless possibilities for detecting objects of all types. The detection reliability, durability, and availability are aligned with the actual requirements of practical applications and often go way beyond market standards. The option to integrate opto-sensors equipped with automation engineering intelligence into networks that are not dependent on controllers or fieldbuses maximises availability and process efficiency, while at the same time delivering future-proof technology.