Safety gates, covers and flaps safeguard access to plant and machinery. In particular they provide protection against hazardous movements of plant and machinery or from flying parts. The challenge for design engineers is to choose the right solution from the wide range of safety switches, guard locking devices and safety gate systems available.
Increasing automation in mechanical engineering means that the demands on machine safety are also rising. The issues of availability, cost-effectiveness and process safety must all be accommodated. Design engineers have access to a wide range of sensors for safety gate monitoring. These operate to different principles and offer a variety of design options for safe, but user-friendly solutions. After all, if the machine is not user-friendly, manipulation of safety equipment is inevitable.
When selecting the right components for safe monitoring of movable guards in accordance with EN 60947-5-3, there are various questions that need to be answered, such as: Does it involve a gate, cover or flap which is regularly opened and closed? Does the process need protecting as well as the operator? Are components exposed to heavy soiling, strong vibration and extreme temperatures?
Mechanical safety switches for simple applications
Mechanical safety gate switches are suitable for safety gate monitoring or guard locking functions on simple safety gate applications, where there are no increased requirements for protection against manipulation and defeat. They prevent a safety gate, cover or flap being opened unintentionally, thanks to increased actuator extraction force. Many applications require two switches to provide the necessary safety. That can quickly increase the engineering work involved.
In extreme environmental conditions, where contamination is present for example, or mechanical overload, when safety gates drop over the course of time, the lifetime of a switch is reduced considerably. In such cases, Pilz safety bolts PSENbolt represent a safe, complete solution. The combination of safety switch, handle and bolt is particularly suitable for safety gates that are difficult to adjust or in areas where safety gates are opened and closed frequently, as the actuator is mechanically guided into the switch actuator head. Alternatively Pilz also offers the safe hinge switches PSENhinge for rotatable and hinged gates and flaps. They are better protected against manipulation because they are built into the hinge of the safeguard and are thus concealed, while also saving space.
Non-contact safety switches – Maximum safety
Non-contact safety switches are becoming increasingly important, particularly on machines that are operated frequently and are exposed to heavy vibration. As the response tolerance is generally high, these switches are flexible and easy to install on the machine. Non-contact safety switches are also suitable for applications with increased protection type requirements of IP67 and IP69K.
Non-contact safety switches distinguish between two operating principles: magnetic safety switches with normal manipulation protection and coded safety switches with high manipulation protection. A compact design is characteristic of both switches and enables the installation to be concealed; that’s an important factor when developing safe machinery. What’s more, with the Pilz safety switches PSENmag and PSENcode it is possible to achieve PL e of EN ISO 13849-1, SIL 3 of EN/IEC 62061 and Cat. 4 of EN 954-1.
Magnetic safety switches PSENmag are particularly cost-effective as their installation saves both time and space.
Connector and cable for all mounting and approach directions, plus an assured operating distance of 3 or 10 mm, enable flexible assembly and rapid, simple installation. Due to their magnetic action principle, magnetic safety switches are also suitable for use on machinery with a high stainless steel content, such as packaging machines for example.
Coded safety switches with RFID technology are the right choice for applications in which metal swarf is discharged. With magnetic switches there would be a risk of metal dust being deposited, invalidating the safety mechanism.Generally speaking, coded safety switches such as Pilz PSENcode are used when the demand is for safety and a high level of protection against manipulation. They combine integrated evaluation and excellent diagnostics with built-in protection against manipulation and defeat, all in a compact design.
Various coding types provide different levels of manipulation security. For example, the unique fully coded actuator, where a PSENcode switch accepts only one PSENcode actuator, excludes any manipulation.
Integrated evaluation also enables the PSENcode to be connected in series without compromising the safety classification; as a result, there is no need for additional inputs on the evaluation device.
Additional process protection for increased requirements
Many doors, covers or flaps must be opened more frequently for operational or assembly purposes. The disadvantage of mechanical guard locking devices is that the adjustment has to be as precise as possible. For this type of requirement Pilz offers the PSENslock, a non-contact, coded safety switch with a magnetic interlock of 500 N or 1000 N, all in one system. With this combination of safe position monitoring and process guard locking, PSENslock provides a safe alternative to existing mechanical technology. A high level of protection against manipulation and defeat, combined with low wear and tear, ensure a long service life. When space is at a premium, there are some circumstances in which safeguards must be located close to a hazardous movement. In this case the hazard may still remain once the machine is switched off. This is known as a hazardous overrun, and in such a case it is absolutely essential to use a safe guard locking device. The guard lock is only lifted once standstill is safely detected or after a safe delay time. These tasks can be performed by mechanical guard locking devices with spring interlock, such as the PSENmech or integrated safety gate systems PSENsgate from Pilz.
Integrated systems save time and money
The safety gate system PSENsgate from Pilz relies on a combination of electronics and mechanics. It meets the requirements of the very highest category in just one system. The compact safety gate system combines safety gate monitoring, safe guard locking and control elements, including additional functions such as E-STOP and escape/auxiliary release. As the system also detects broken pins and broken bolts, it offers additional safety for machinery with a particularly high hazard potential. Complete systems such as these are mostly used on larger safety gates. Coding guarantees protection against manipulation and defeat. A closing lock or reset interlock can also be implemented by using up to five padlocks on the bolt.
The benefits of complete solutions
With safety-related equipment on machinery it’s not just the individual components that matter but the way in which they interact. In this respect, complete solutions with totally compatible components comprising safe sensor and control technology offer high potential savings.Corresponding sensors and evaluation devices from a single manufacturer operate with compatible interfaces between the components. So the user has no need to check the data sheets or run complex tests in order to ensure that the selected components will interact smoothly in practice. Individual Pilz components can be packaged together to suit any automation requirement. The comprehensive product range covers the whole spectrum of safety requirements for safety gate monitoring.
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