FEATURE MACHINE BUILDING, FRAMEWORKS & SAFETY


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DESIGNING FOR SAFETY: KEY PRINCIPLES AND BEST PRACTICES (PART 1)


This is the third article in a six-part series on


machinery safety. This article explores fundamental principles for designing inherently safe machines, focusing on control systems, hardware design, and effective risk minimisation techniques


M


achine safety is not just about adding protective measures after construction – it is about designing out risks from the


start. The international standard BS EN ISO 12100:2010 provides a structured methodology for achieving this goal, advocating for a layered approach that prioritises inherently safe design measures, engineering controls, and administrative safeguards. A machine built with safety at its core reduces reliance on external measures such as Personal Protective Equipment (PPE) and procedural controls, ensuring a more effective and long-lasting approach to safety.


ELIMINATING HAZARDS BEFORE THEY ARISE The most effective way to reduce risk is to eliminate hazards altogether. Thoughtful component placement can remove sharp edges, pinch points, and exposed moving parts. Lower voltage electrical systems or the limitation of high-pressure pneumatic and hydraulic circuits can reduce energy-related hazards. By automating processes and improving material handling, designers can also minimise human interaction with hazardous zones. These early-stage interventions prevent risks from materialising, making machines safer by design.


THE ROLE OF CONTROL SYSTEMS Control systems are the backbone of machinery safety, ensuring that machines operate within safe parameters and respond appropriately to failures. Safety-related control functions must meet strict reliability levels as defined by BS EN ISO 13849-1 (Performance Levels) and IEC 62061 (Safety Integrity Levels). A well-designed system will include


redundant and fail-safe mechanisms to prevent hazardous situations from occurring in the event of a fault. While emergency stop functions, in compliance with EN ISO 13850, can provide immediate machine shutdown when necessary, their inclusion depends on whether they effectively reduce risk. Programmable safety controllers, such


as Safety PLCs, require careful consideration in both software design and functionality. As safety systems grow increasingly complex, Safety PLCs are becoming more popular due to their ability to manage multiple safety functions efficiently. Additionally, the integration of safety-rated fieldbus networks, such as PROFIsafe, allows for streamlined communication between safety devices, improving both flexibility and system reliability.


22 DESIGN SOLUTIONS MARCH 2025


DESIGNING HARDWARE FOR SAFETY AND EFFICIENCY Beyond control systems, physical components also play a vital role in machine safety. Fixed and interlocked guards prevent unintended access to hazardous areas, ensuring that moving parts remain securely enclosed. Safety-rated actuators, sensors and switches contribute to controlled motion and detection of unsafe conditions, helping to maintain functional safety compliance. Careful selection of interlocking devices is crucial to ensuring that safety mechanisms function effectively. Different applications require different levels of security, reliability, and resistance to tampering. For example, traditional mechanical interlocks may be suitable for low- risk environments, but in complex or hazardous applications, RFID-based interlocks offer superior protection against manipulation and defeat attempts. These advanced systems ensure that access is only granted to authorised personnel and can integrate seamlessly with safety-rated fieldbus networks such as PROFIsafe. Mark Staples, sales manager EUCHNER (UK),


said: “As safety systems become more complex, the need for reliable structured control systems is greater than ever. Safety PLCs and integrated fieldbus networks allow for smarter, more adaptable, safety solutions that improve both compliance and machine performance.” Additionally, environmental factors must be


considered. Interlocks used in high-contamination environments, such as food processing or heavy manufacturing, need to be resistant to dust, moisture, and aggressive cleaning agents. Tamperproof fixings play an essential role in ensuring that interlocking devices remain secure, preventing unauthorised removal or bypassing of critical safety mechanisms. Selecting the right interlock for the right application is fundamental to maintaining safety integrity and compliance with functional safety standards.


PROTECTIVE MEASURES WITHOUT COMPROMISING EFFICIENCY Even when hazards cannot be fully eliminated, additional protective measures can reduce risks without disrupting machine performance. Physical guarding, barriers and safety enclosures protect workers from dangerous moving parts. Light curtains and presence-sensing devices detect unauthorised access, triggering safety functions while ensuring seamless product processing without interfering with workflow. The new generation of RFID key access systems, such as the CKS2 from EUCHNER,


Feature


ensures that issues like unexpected start-up and access control become an integral part of the safety-related control system rather than relying on procedural measures alone. These systems offer a higher level of security by linking operator permissions directly to the machine’s safety system, reducing the potential for human error and unauthorised access.


SAFETY AS A DRIVER OF COMPLIANCE AND PRODUCTIVITY A machine designed with safety in mind is not only safer but also more reliable and efficient. Proactively implementing best practices reduces costly downtime caused by accidents, simplifies regulatory compliance, and enhances user confidence. By addressing safety at the design stage, manufacturers create machines that are easier to maintain, more productive, and better suited to long-term operational success.


LOOKING AHEAD TO PART 2 This article has explored the fundamental principles of designing for safety, from eliminating hazards at the source to implementing advanced control systems and protective measures. In Part 2 (next month), we will discuss the process steps for creating a safe control system, starting with defining the Performance Level (PLr). We will also cover the different architectures and categories for safety-related controls, ensuring a comprehensive understanding of how to implement effective safety measures in machine design. By prioritising safety from the outset,


manufacturers and engineers can create machinery that not only meets compliance requirements but also enhances overall efficiency and reliability. Stay tuned for the next instalment, where we continue to unravel best practices in machine safety design.


EUCHNER (UK) T: 0114 2560123 www.euchner.co.uk


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