Machine Safety and Functional Safety for Robot Cells and Automated Machinery

Oct 5

3 min read

Every robot cell and automated machine has to answer one question before it runs in production: can someone get hurt? Machine safety is the discipline that answers it properly, with evidence, before anyone is near a moving axis.

In Australia, the duty sits with everyone in the chain. Designers, manufacturers, suppliers, installers and the business that runs the machine all have obligations under WHS law to eliminate or minimise risk so far as is reasonably practicable. A safe machine is not a fence and an e-stop; it is a designed, documented and verified system.

The standards that matter

AS/NZS 4024 series is the Australian umbrella standard for safety of machinery, covering risk assessment, guarding, interlocks and safety distances.
ISO 13849-1 and -2 set out how safety-related control systems are designed and validated, using Performance Levels from PLa to PLe.
IEC 62061 is the alternative route for electrical and programmable safety systems, using Safety Integrity Levels.
ISO 10218-1 and -2 cover industrial robots and robot cells. The 2025 revision is the first major update since 2011. It makes functional safety requirements explicit, introduces robot classes, folds the collaborative robot requirements of ISO/TS 15066 into the main standard and adds cybersecurity requirements.

If your robot cell was designed to the 2011 edition, it is not automatically unsafe. Any new cell, or any significant modification to an existing one, should now be designed against the 2025 edition.

How a safe machine is designed

1. Risk assessment

We start by listing every task people do around the machine: operating, loading, cleaning, setting, maintenance and fault-finding. Each hazard is rated for severity, frequency of exposure and the chance of avoiding it. This tells us which risks must be engineered out and how strong each safety function needs to be.

2. Inherently safe design first

The best guard is not needing one. Lowering forces and speeds, moving pinch points out of reach and designing for loading from outside the cell remove hazards instead of managing them.

3. Safeguarding

What can't be designed out is guarded: fixed fencing, interlocked doors with guard locking, light curtains, safety laser scanners, safety mats and two-hand controls. Each device is placed using the correct safety distance for its response time.

4. Safety functions and the safety controller

Each protective measure becomes a defined safety function, such as "opening the cell door stops the robot and removes power from the welding source". Each function gets a required Performance Level from the risk assessment. It is then built with a safety PLC or safety relays, safe torque off on the drives and robot safe-zone monitoring where appropriate.

5. Verification and validation

We calculate the achieved Performance Level for each function, then physically test every one: open every door, break every light curtain, trip every scanner zone and confirm the machine stops the way the design says it will. The results go into a validation report that stays with the machine.

Common gaps we find on existing machines

Interlocks wired through a standard PLC with no safety rating.
Light curtains mounted too close to the hazard for the machine's stopping time.
Bypass keys or maintenance modes with no reduced-speed or hold-to-run control.
No documented risk assessment, so nobody can show the safeguards are adequate.
Second-hand machines modified on site with no review of the original safety design.

These are fixable, often without replacing the machine. A safety upgrade is usually far cheaper than the cost of a serious incident or a regulator's improvement notice.

Functional safety at DPAC

DPAC Robotics & Automation has a TÜV-certified Functional Safety Engineer in house. Every robotic welding cell, palletising cell and automated machine we build is designed, calculated and validated to the current standards, and handed over with a risk assessment and validation report.

We also provide machine safety services for equipment we didn't build:

Risk assessments on new or existing machinery.
Safety system design, including safety PLC programming.
Safety upgrades and retrofits for older machines and robot cells.
Validation and documentation for modified or relocated equipment.

Not sure your machine would stand up to scrutiny? Book a machine safety review and we'll tell you where you stand and what it takes to fix it.