Safety Photocell, Light grids and light curtain are non-contact protective devices that secure access and dangerous areas. With the optoelectronic safety devices, the light beam is interrupted as soon as the danger area is entered. For these applications we present here the innovations of the Schmersal group ago like three new light barriers series.

Light barrier Schmersal

 

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Safety light curtains/light grids in Ex version

Schmersal light curtain28.07.2023 | Schmersal has a new series optoelectronic protective devices developed. The EX-SLC/SLG440 safety light curtains/grids in the Ex version are designed with the types of protection EX d (gas atmospheres), EX t (dust atmospheres) and EX op is (optical radiation). This makes the light curtains particularly suitable for protecting access to potentially explosive areas in industrial production, especially for zones 1 and 21.

In many production areas there is one increased risk of explosion such as in the chemical industry, refineries or paint shops and wherever flammable coating materials are processed. In applications where bulk materials are processed, such as in the animal feed or recycling industry and in wood or grain processing plants, there is a risk of a dust explosion. A dangerous, explosive cloud of dust can occasionally form here during normal operation.

For all these applications, the safety light curtains/grids SLC/SLG440 in Ex version developed. The devices can be installed in potentially explosive gas and dust atmospheres of zones 1/21 and 2/22 category 2GD. They secure danger points and areas as well as machine access. If one or more beams are interrupted, the hazardous movement is brought to a standstill.

The curtains/grids are Atex certified, IECEx, Inmetro and CCC Ex certifications to follow. The optical sensors are housed in a protective housing made of shatterproof glass with metal caps. The safety light curtains for Finger, hand and body recognition are available in variants with a resolution of 14 and 30 mm and ranges of 0,3 to 20 m. The waterproof and dustproof devices achieve protection class IP66 and IP67 and are suitable for outdoor use.

Safety light barrier for the food industry



09.03.2023 | Schmersal introduces the new safety light barriers Series SLB440 before. This is particularly suitable for hygiene-sensitive applications in the packaging and packaging industry Food industry as for dairy farming and meat processing. A single-beam light barrier from the SLB series is very compact with a diameter of 62 mm and a height of 115 mm. They are therefore ideally suited for use on deep-drawing machines for packaging, as well as on cutting devices or other tight installation spaces.

The SLB440 light barrier was based on the safety light curtain and light grid SLC/SLG 440 IP69 constructed. Both have proven themselves in the food and packaging industry for several years. The new single-beam photocell can also cope with the demanding environmental conditions such as cleaning.

The well thought-out detail construction gives the light barrier protection class IP69. The external and internal seals of this non-contact protective device (ESPE) withstand the very high requirements and frequent cleaning with foam, lye, high pressure or superheated steam.


Safe field box with reduced wiring effort


The BWS light barrier series was Hygienic Design specifications constructed. The sealing caps, cable entry, pressure equalization membrane and fastening parts of the SLB440 light barrier are made of stainless steel (V4A). The transparent protective tube is made of polycarbonate (PC). It has a high resistance to detergents and withstands heavy mechanical loads.

If, for example, the cleaning lances accidentally hit the housing of the SLB440 IP69 during high-pressure cleaning in food production, the robust protective tube reliably protected. The material ensures high process reliability with a long service life for the safety light barriers. The material resistance of these components is verified by the independent test laboratory Ecolab approved.

The BWS series has one integrated evaluation with two safety outputs for direct connection to the higher-level controller. Additional features include an integrated set-up aid and a simple connection option with a 12- or 4-pin M5 plug. The light barrier achieves performance level PLe, type 4.

Schmersal is exhibiting at the Hannover Messe 2023.

Safety light grid with integrated Bluetooth interface

The Schmersal Group contributes for the first time Safety Light Curtain with an integrated Bluetooth interface. The SLC440 / COM with Bluetooth BLE is an optoelectronic security system which, thanks to a Bluetooth interface, provides all status and diagnostic data about the operating status of the device on smartphones or tablets in real time.

Live demonstration at SPS 2019 in Nuremberg

27.11.2019/2019/XNUMX | Guido Gutmann, Key Account Manager, Safety Control GmbH, Schmersal Group, Mühldorf presents the new one at the SPS XNUMX in Nuremberg SLC440/COM safety light grid SLC440 / COM with Bluetooth interface for diagnosis. 



10.05.2019/440/XNUMX | The Bluetooth interface of the SLCXNUMX/COM enables easy commissioning via smart phone or tablet thanks to the integrated set-up aid. Thanks to the possibility of storing the data, these can be used e.g. B. can also be used for documentation purposes for recurring inspections and in the sense of predictive maintenance.

The Communication The data on smartphones / tablets (Android, IOS) is made possible via an app developed by the manufacturer. BLE stands for Bluetooth Low Energy, a radio system for the near-field range for data transmission with secure transmission technology.

To date, only diagnostic tools based on NFC technology have been available on the market. While NFC tools only offer a range of a few centimetres, the Bluetooth BLE interface achieves a range of up to 5 m 100x greater range. Therefore, the BLE interface is particularly advantageous when the optoelectronic security system is located in a relatively inaccessible place. In addition, Bluetooth BLE allows more uses since most smartphones or tablets have Bluetooth, but not all have NFC. The safety light grids can be used worldwide.

Application reports for safety light curtains and light grids

To protect people and machines Is available for optoelectronic security devices such as light curtains, light grids and light barriers numerous applications. While the light barrier is suitable for processing centers, rack lines, transfer aisles or palletizing devices, light grids are used in the Robotic, on presses or die-casting machines. The following two examples from the food industry and laser technology make it clear that the sectors can also be very diverse.

Light grids pass practical tests at Coppenrath & Wiese

11.08.2020 | Coppenrath and Wiese uses hygienically encapsulated safety l in its production plants and packaging machineslight grid and light curtains. Together with Schmersal, the manufacturer of deep-frozen baked goods successfully tested the mechanical stability of the protective covers and subsequently declared them to be the company's internal standard.

Schmersal light grids


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For the machine safety in food production, special regulations apply, which result in particular from Hygiene requirements surrender. Conventional safety switching devices can be used in the food technology not be used. Here the opening for the actuator represents a dead zone. Dirt settles in it despite thorough cleaning. Objects in food production are cleaned with high-pressure water jets, superheated steam or other highly effective media. This influences the service life of the switching devices.

Light grids and light curtains in hygienic design

Schmersal safety light grilleIn food production are therefore common security sensors used, which have matching surfaces and an encapsulated housing. They monitor the position of protective doors and protective flaps.

If you go one step further, you completely do without separating protection systems. Rather, the danger area with optoelectronic protective devices such as safety light grids and light curtains. These safety switching devices offer additional advantages. They allow a clear view of the machine's working area and increase flexibility in the process.

When using a safety light grid, the optical sensors must be protected against the harsh cleaning processes. The Safety Control Ltd in Mühldorf, the Schmersal Group's competence center for optoelectronic protective devices, has developed a series of light grids and light curtains for these applications. The SLC / SLG 440 series complies with protection class IP69.

Material for the protective housing

Compared to the basic version, the light grid/light curtain series has a protective housing with a long service life and high availability. Fixing parts, sealing caps and cable entries are made of stainless steel V4A. It made sense to use the thermoplastic material PMMA for the transparent protective tube. The polymethyl methacrylate is highly resistant to cleaning agents.

Customary housing are often made of this material, which, however, is susceptible to stress cracks under mechanical stress. That is why the developers opted for polycarbonate (PC). It also ensures a very high mechanical load capacity. The resistance to detergents has been tested and proven by the Ecolab laboratory.

The protective tube made of polycarbonate has been used in applications of the Milk processing and bottling plant, how resistant it is to the intensive cleaning agents. The protective tube is secured against the sensor unit with sealing caps and a sealing concept on the outside and inside. The encapsulated safety sensors are very space-saving. With a diameter of just 50 mm, they can be integrated into the machine design, even if installation space is tight.


Safety control protects the sausage processing plant 


During the Food production it can happen that the housing of the safety light grids and light curtains are subject to high mechanical stress, such as from cleaning lances or contact with transport aids. The transparent housing must not splinter in such cases. If it does happen, contamination will result, which would result in a production stop or even a recall.

Test series with targeted damage

In some areas of baked goods production, Coppenrath and Wiese use hygienic, optoelectronic protective devices and prefer the Schmersal SLC/SLG 440 IP69 series for this purpose. In a series of tests with Stephen Richter, Schmersal's regional manager, the baked goods producer examined the protective cover in terms of stability and breaking strength. 

In the first test the test technicians hit several housings on solid objects such as a vice or table. Even after hitting it with a hammer, there was no protective cover for the light grid chips. Only scratches on the surface were created. In the second test the experts clamped the light curtain housings in a vice while applying a load until their diameter reduced to around 30% of the original value (picture above). The severe deformation caused the transparent protective tubes to become cloudy, but did not lead to chipping. At the third test the testers machined the protective tubes with a pointed center punch. They were able to knock crater-shaped cones into the case, but no splinters were released from the protective cover either.

Tests with comparable protective covers for safety light curtains on the market invariably caused chipping, which is unacceptable in food production. In this respect, the tests at Coppenrath and Wiese were all the more convincing. As a result of the test series, the technicians from Coppenrath and Wiese haveSLC 440 series Defined IP69 as the standard for corresponding applications and included it in the tender documents for new systems. The conversion of existing systems is also being examined.

Light grids with additional functions

Basis of the tested safety sensors in the Hygienic Design are the standard series SLC / SLG 440 or 440 COM. They offer useful additional functions such as double acknowledgment and contactor monitoring. Thanks to integrated beam suppression, moving parts can be guided through the protective field without triggering a stop signal. 

The measured values can be transferred to a PC via the contamination indicator an optical warning message is issued when the sensor signal becomes weaker. In this way, the user can forestall an unplanned system downtime. Sensor pairs support the user with an optical set-up aid when installing the light curtains. Parameterization is very easy without external tools.

For Communication and diagnostics, the safety light grids were equipped with an integrated Bluetooth interface fitted. This means that status and diagnostic information is available to the user in real time via an app. With the extensive system information, service cycles and recurring inspections can be planned. This function is also used to localize sporadic shutdowns of the safety outputs caused by dirt on the Surface can be caused.

Safety light curtain for laser marking system at Rofin-Sinar

22.09.2015/XNUMX/XNUMX | The laser specialist's marking division Rofin Sinar has in the course of the redesign of its laser marking system "Combiline Advanced" also adapted the safety concept. For example, monitor now security curtains from Schmersal the danger area in the loading area of ​​the machine. Due to their high reaction speed, the safety distance could be kept small. You can find out more about this in this user report:

Schmersal safety light curtain Rofin Sinar


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Schmersal safety light curtain installationThe Rofin Sinar Group positions itself worldwide as a technology leader in the field industrial laser. It is active in three business areas:

The area Macro offers its customers systems for industrial material processing, for example of automotive sheet metal parts with high-performance lasers. The business area Microphone focuses on the laser processing of small and very small parts down to the µm range. The business area marking headquartered in Bergkirchen is one of the world's market leaders in laser marking.

The precise, non-contact and durable Labeling of almost all materials with the laser has established itself in many areas of industrial production.

From the chainsaw to microchip

The company manufactures a large number of laser systems. The spectrum ranges from compact diode-pumped Nd:YAG and Nd:YVO4 lasers with wavelengths of 1064, 532 and 355 nm up to CO2-laser systems, which ensure precise and fast marking results on various inorganic and organic materials.

These lasers are used by system builders in production lines integrated. In addition, complete laser systems are also manufactured in Bergkirchen – with a strong upward trend. The user can choose from a portfolio of different series.

This ranges from compact table unit with a footprint of 60 x 60 cm up to the Combiline Advanced series, which is designed for 24-hour operation and the marking of workpieces of different sizes and weights. These machines mark, among other things, saw blade rails of chainsaws, components of high-quality precision watches, car labels, Photovoltaics-modules, Medical Technology-Components and Semiconductor-Microchips.

Redesign of the protective devices

The Combiline Advanced-Systems are also available in the RT version with rotary table. This variant offers the advantage that the user can already clamp the next component while another is being marked. The rotary table is divided into two halves by a bulkhead so that the laser processing takes place safely (laser protection class 1) in the work area of ​​the system. A risk that must be secured separately is the risk of crushing and shearing during the movement of the turntable, which has a diameter of either 800 or 1000 mm. 

When this series recently underwent a redesign, those responsible also checked how to optimize the protective equipment. Joseph Pfaffinger, Head of Systems and Software Engineering: “We first evaluated different types of safety switching systems such as safety mats and optoelectronic protection devices. It quickly turned out that the safety light curtains are still best suited for the turntable.” This safety device stops the movement of the turntable if the operator reaches into the danger zone.

Safety light curtain with quick response

Schmersal Rofin SinarAfter this fundamental decision, a safety light curtain with a clearly defined property was sought. Stephen Albrecht, as the designer responsible for the safety technology of the systems: "The distance between the safety light curtain and the danger area should be as small as possible for reasons of ergonomics. This results in the requirement that the light curtain responds very quickly and the entire system works with a short run-on time.”

Under this condition, various safety light curtains were tested. The new SLC 440 series from Schmersal proved to be the most suitable. electrical engineer John Jorias: “The integration can be implemented very easily without an additional evaluation device. The safety outputs have sufficient switching capacity". The jointly developed safety concept was also optimized with a view to shortening switching times. Stefan Albrecht: "The desired and calculated safety distance between the light curtain and the danger zone could be realized in this way."

Follow-up time measurement, pre-configuration and AS-i safety interface

Measurements by Schmersal have shown that the calculated value is reliably undercut in practice - even when the system is labeling heavy objects. Stopping time measurements of this kind are part of the range of services offered by the Schmersal Safety Services division. Rofin-Sinar is very satisfied with this: "The advice and service from Schmersal was really good," says the company.


 

Infrared emitters for efficient heat processes in industry


The SLC 440 are barely visible behind a panel in the loading area. With dimensions of 28 x 33 mm, they are extremely compact and can be easily installed on standard brackets because the integrated seven-segment display supports the fitter with the adjustment. In addition, the series can be parameterized directly on the object without additional tools such as a PC. This task is also unnecessary for the personnel at Rofin-Sinar, because the Schmersal Competence Center for Optoelectronics in Mühldorf/Inn provides the safety light curtains, which Connectors be integrated into the safety circuit, ready for installation and preconfigured with the intended parameterization.

The new safety concept has proven itself in the machines that are manufactured in the new design. The responsive and compact Optoelectronics also improves the ergonomics of the Combiline Advanced RT systems because the field of view of the loading area has been made larger.

For this reason, too, the improvements achieved with the redesign are very well received by customers, especially since Rofin-Sinar documents the safety in black and white. Josef Pfaffinger: “We take one for each individual system run-on time measurement before. In this way, we document that the user is definitely on the safe side and that all normative requirements are met.”

On FachPack 2015 the Schmersal Group presents a new version of the safety light curtains and light grids type SLC/SLG 440, which is equipped with an integrated interface for AS-Interface Safety at Work (AS-i Safety). It offers all the functions of the basic version, such as fixed light beam blanking with and without a movable edge area, movable blanking of one or two beams, and various muting variants.

The direct integration into AS-i safety networks allows, for example, easy integration into complete communication networks, which can be set up in the Safety separated and Safety integrated architectures. In addition, the optoelectronic protective devices of the SLC/SLG 440-AS series enable faster, easier installation via the yellow AS ribboncable and a significantly denser flow of information, for example when querying diagnostic-relevant information from the object.

General technical knowledge

What types of light barriers are there?

Photoelectric sensors are sensors that use a beam of light to determine the presence or absence of objects in their detection area. Here are some of the most common shapes:

  • One-way light-barriers consist of a transmitter and a receiver housed in separate housings. The transmitter generates a beam of light that is detected by the receiver. If an object interrupts the light beam, this is recognized by the receiver, which triggers an appropriate action. Single-beam safety light barriers are particularly suitable for applications in which small objects are to be detected because they have a very narrow detection area.
  • Light grids or multi-beam photoelectric sensors work with several light beams. They consist of several transmitters and receivers arranged in a line or in a matrix. If an object interrupts one or more of these beams, this is registered by the receivers. Multiple light beam safety devices are often used in safety applications because they can cover a wider detection area and breaking multiple beams at the same time triggers a stronger reaction than breaking a single beam.
  • Reflection light barriers are transmitters and receivers housed in one housing. The emitter creates a beam of light that hits an object and is reflected back to the receiver. If an object enters the detection area, the amount of reflected light changes, which is detected by the receiver.
  • Diffuse mode sensor work in a similar way to retro-reflective sensors. However, they use a reflector to direct the light beam back to the receiver. When an object breaks the beam of light, the amount of light that reaches the receiver changes, which in turn triggers an action.

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Author information
Angela Struck

Angela Struck is editor-in-chief of the development scout and freelance journalist as well as managing director of Presse Service Büro GbR in Ried.