Muting in practice: The Leuze path to a safe solution

Muting allows the safety function on machines or systems to be temporarily bypassed so that material can be fed in or out through protective devices such as light curtains or laser scanners without interrupting the production process. Personal safety must be guaranteed at all times. Muting applications repeatedly reach their limits in practice, allowing incorrect operation and manipulation. In such cases, alternative security concepts are required.

Unconscious risks

Various types of muting are used in industrial automation: 2-sensor, 4-sensor, time-controlled or sequence-controlled processes. The international standard DIN EN IEC 62046^[1] regulates the requirements for entry and exit stations with muting and stipulates in particular:

• Muting must be activated via at least two independent bridging signals
• Muting must offer protection against foreseeable incorrect operation or manipulation

The standard thus defines clear requirements for the implementation of muting applications. In practice, however, it is not always fully complied with – either because the specific application requirements are not fully known and may therefore differ from real-life conditions, or because risky compromises are deliberately made to achieve high process stability. As a result, safety functions become less effective, and manipulation or incorrect operation are more likely. For operators, this means an unconsciously increased liability risk and potentially serious consequences for employee safety.

Limits of muting and alternatives

In summary, muting makes it possible to distinguish between transported objects and people, contributing to automation and efficiency. However, the process must always be protected against foreseeable incorrect operation and manipulation. Alternative safety solutions are particularly necessary if muting sensors cannot reliably detect transported objects or if large variations in object width create gaps that are too wide alongside the transported goods. Muting on forklift trucks is no longer considered state of the art in terms of safety technology. In all these cases, the hazard area remains potentially accessible and dangerous. Safe and standard-compliant solutions are available for these challenges. Leuze provides support through a clearly structured development and testing process – from planning and programming to comprehensive validation and verification.

The path to a safe solution

The path to a safe solution from Leuze begins with the customer’s individual requirements: automated operation must be reliable and safe. After conducting a thorough analysis with risk or hazard assessment, a safety designer develops a customized concept and works out specific safety functions for the respective application. The engineering team selects, integrates, programs and tests the appropriate hardware and sensors. A consistent dual control principle ensures functionally safe implementation. Comprehensive functional tests ensure that all safety and standard functions work reliably. Commissioning at the customer’s site will take place only after successful validation under real operating conditions. Finally, the customer receives complete documentation, including a validation plan and CE declaration of conformity.

This offers three key advantages:

• Simple – functional safety is complex, but Leuze’s expertise, engineering, and services make it simple for the customer.
• Safe – all solutions are strictly standards-based and fully documented, so that compliance can be verified at any time.
• Productive – functional safety and efficient processes are interlinked, ensuring reliable, cost-effective peration.