Contactless safety sensors are the ideal solution for preventing unauthorized access to automated systems and machines.

Reliably Securing Access Doors and Hoods

Contactless Shut-off with Magnetic or RFID Encoding

In many applications, automated systems and machines require safety devices to prevent unauthorized access during operation. If noise, heat, or dust need to be kept out as well, light curtains are not enough. Doors, hoods, and flaps are a start, but they must be adapted to the requirements of automated systems. Modern, non-contact safety sensors offer a reliable solution for these application scenarios.

By Damien Wittwer, International Product Manager Safety, Contrinex

Oliver Schleicher
Oliver Schleicher
Managing Director
Leinfelden-Echterdingen, Germany
Gabriele Ulmer
Marketing Manager
Leinfelden-Echterdingen, Germany

Contactless industry safety sensors

System and equipment security solutions have to guarantee three features at the same time: First, for work safety and quality assurance reasons, no persons or objects are allowed in the security area. Second, emissions have to be kept inside. Third, no part can “escape” during operations or due to malfunctions. The simplest solutions are mechanical devices, such as doors and hoods. They shield production equipment, yet permit access when necessary.

Traditionally, these devices were mechanically fastened and secured with a lock. In the era of just-in-time manufacturing and high machine availability, this approach is no longer economically viable. This is why Contrinex' product portfolio includes two security sensors working with magnetic and RFID encoding. The sensors recognize the position of the protective device. The contactless technology means no wear and long maintenance intervals. For maintenance or repairs, they allow access without searching for any keys and guarantee that dangerous machine components are safely shut off the moment the device is opened.

Magnetically encoded protection devices

Traditional door position sensors are expensive and complicated to install due to the alignment needed. As mechanical components, they are also comparably susceptible to wear and tear. In addition, mechanical switches are relatively easy to trick. The magnetically encoded YSM sensor series system (Type 4 according to ISO 14119) is highly resistant to on-site manipulation due to its function. It is quick to install and immune to interference from neighbouring sensors.

The new security sensors are better protected than traditional mechanical solutions due to their closed housing (36 x 26 x 13 millimetres or 88 x 25 x 13 millimetres), especially in rough industrial environments with dirt, liquids, dust, wood shavings, or smoke. The sensors offer switching gaps between 4 and 18 millimetres and, due to magnetic transmission, also work behind a non-magnetic cover material such as plastic or stainless steel. When closed, the magnetic field penetrates the opposite sensor and generates the result “closed”.

This allows for a secure construction of the safety device due to a complete cover and also allows easy cleaning of all open surfaces. The sensor complies with IP6K9K, meaning it is dust and water resistant, even with high pressure cleaning or steam cleaning. This makes the safety sensors ideally suited to food and pharmaceutical applications as well.

Application range from pharmaceuticals to metalworking

The magnetically encoded sensors can monitor plant safety in a wide range of applications. Traditionally demanding environments, like the pharmaceutical industry or metalworking, are no exception. The robust safety sensors are suitable for ECOLAB®-approved washdown areas and, depending on the product version, can tolerate high-temperature operation of up to 80 degrees Celsius. They also work through the non-magnetic stainless steel common in the pharmaceutical industry.

Classic use in harsh environments is also possible due to protection classes IP67 (EN 60529) and IP6K9K. The wide operating distance allows flexible positioning. Installation is facilitated by the compact housing and easy wiring with optional pre-wired M12 plugs or 8-core 0.25 mm² cable. Thus, users can quickly set up a heavy-duty safety device according to EN/ISO 13849-1 category 4. This allows the optimal protection of hazardous equipment such as robot cells, industrial presses, welding equipment, processing equipment, injection molding machines, automated packaging lines, and more.

Another application area: modern laser cutting machines. Today, they allow high-speed, high-quality precision cuts of thin and thick metal parts. They typically use class 3B or class 4 lasers with a power of up to 30 kilowatts. The risks to human health are known. Safe laser encapsulation is therefore essential, and the laser beam must be reliably shut down whenever an access door or cover is opened.

The YSM sensors can be installed inconspicuously on doors, hoods, or covers in order to monitor access to the working area of a laser cutting machine. Combined with a suitable safety relay, they provide an economical and robust solution that reliably protects both operators and maintenance personnel.

Protect systems with numerous access points via RFID

If many individual access points to a system need to be monitored, YSR series RFID sensors are the perfect solution. At each access point, an RFID chip is placed exactly opposite the sensor module. In the closed position, the sensor detects the RFID chip, otherwise the sensor switches off the entire system via a relay. Up to 30 sensors can be connected in series to just one relay or controller, thus monitoring several doors.

The RFID code of the YSR version can either be randomized or defined by a teach function. External device monitoring and a feedback signal are also available. The sensor is designed for washdown areas with temperatures of up to 70 degrees Celsius and withstands harsh environmental conditions. This makes this sensor series versatile. Use cases that require monitoring of numerous access points can be found in the packaging industry, for example.

Even in food packaging, systems are highly automated, usually with several discrete process stages. Products are often transported on conveyor belts in a hygienic environment in compliance with strict cleaning regulations. Closed belt conveyors are an inexpensive way to maintain the required level of hygiene, maintain the integrity of the product and ensure reliable transportation. Detachable inspection flaps provide access to the belts for setup, routine maintenance, and troubleshooting.

Each packaging line has several inspection points that allow quick access to any point along the conveyor belt. YSR series RFID safety sensors attached to each inspection plate ensure that the conveyor stops immediately as soon as one of the access points is opened. With dimensions of 36 x 26 x 13 millimetres, the compact sensors in the system can be mounted both frontally and at a 90 degree angle. The connection variants available are M12 plugs or 8-core 0.25 mm² PVC cables. Due to their robust design with protection class IP67 (EN 60529), IP6K9K (ISO 20653), and ECOLAB® approval, they ideally cover the range of requirements from hygienic environments to rough applications.


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