machineinterlocks

Machine interlocks are devices or assemblies that prevent a machine from operating while a guard or access point to hazardous parts is open or not in the correct state, and that enforce safe sequencing of machine actions. They are a core element of machine safeguarding, reducing the risk of injury or equipment damage by controlling access and start-up.

Interlocks can be mechanical, electrical, or electronic. Mechanical interlocks use a physical latch or bolt paired with a sensing element to detect whether a guard is closed. Electrical interlocks monitor guard status with switches, relays, or safety controllers, and in many designs force a stop or prevent starting when the guard is open. Some systems employ guard locking interlocks that physically lock the guard and require a controlled release to proceed, ensuring the guard remains closed while the hazardous process is active.

Operation generally aims to return the machine to a safe state when a guard is opened, and to prevent actuation while the guard is open. In many hard interlock designs, opening a guard interrupts power and may latch the guard in place until a deliberate reset or release action occurs. Soft interlocks may only inhibit starting without locking the guard.

Standards and risk management guide the design and verification of interlocks. Relevant frameworks include ISO 14119 for interlocking devices, ISO 13849-1 for safety-related control systems, and IEC 62061 for prescriptive safety requirements. Interlocks are typically complemented by lockout/tagout procedures and regular inspection and testing to verify correct operation and identify wear or degradation.

Common applications span presses, CNC machines, conveyors, robotics cells, and packaging lines, wherever safe access control and proper sequencing are required.