Guidance for Packaging Machine Safety

New guidance is now available on how to make packaging machines safe. This will provide much-needed assistance for machines used widely in the food and beverage industry, general manufacturing industry and warehousing/distribution industry. Australian Standards have published 8 new standards to provide guidance for different types of packaging machines:

1. AS 4024.3401:2018 – Safety of Packaging Machines – Terminology and classification of machines
2. AS 4024.3403:2018 – Safety of Packaging Machines – Form, fill and seal machines
3. AS 4024.3404:2018 – Safety of Packaging Machines – Palletisers and depalletisers
4. AS 4024.3405:2018 – Safety of Packaging Machines – Wrapping machines
5. AS 4024.3406:2018 – Safety of Packaging Machines – Pallet wrapping machines
6. AS 4024.3407:2018 – Safety of Packaging Machines – Group and secondary packaging machines
7. AS 4024.3408:2018 – Safety of Packaging Machines – Strapping machines
8. AS 4024.3410:2018 – Safety of Packaging Machines – General Requirements

These standards provide consistency with international practice because they are adoptions of the EN 415 series from Europe but be aware some of these standards are quite old. For example AS 4204.3403 is an adoption of a 1999 version standard and AS 4024.3404 is an adoption of a 1997 version standard. This means that many of the document references in these standards are out of date and some of the control measures are lacking when compared to today’s levels of safety, so be aware!

It is always a good idea to formulate the Category / Performance Level (PL) / Safety Integrity Level (SIL) requirement of safety functions based on the risk of the application using methods from current standards, thus using AS/NZS 4024.1501 for Category Selection, AS/NZS 4204.1503 for PL selection and AS 62061 for SIL selection.

It is also a good idea to always investigate what current industry practices are when selecting risk reduction measures. This can be done by referencing any guidance material published on your state WorkSafe website, observing new models of that machine type, exploring how other sites with similar machines provide safety, etc.

That being said, the new Packaging Machine Standards, do provide great assistance for risk assessment of packaging machines because many of the common hazards found on these machines are illustrated. The standards also provide good information on what types of safety measures can be utilised to reduce risk to an appropriate level.

Written by
Craig Imrie
Functional Safety Engineer (TUV Rheinland #3814/11, Machinery)
Safety Consultant

Rockwell Automation

LISTEN. THINK. SOLVE.

Guidance for Light Curtains & Laser Scanners

The most misapplied safety devices in the industry are light curtains and laser scanners, common issues with installations include:

1. Application not suitable for light curtain/scanner, eg; the machine ejects parts, the machine has a long stopping time, environmental influences
2. Light curtain placed too close to the hazard – Insufficient safety distance 
3. Scanner safety field size is too small – Insufficient safety distance 
4. Stopping performance monitoring not provided when it should be
5. Muting sensors not mounted correctly

In the past, it hasn’t been easy for installers/designers to find guidance on all these topics in the one reference. We have had AS 4024.2801 in Australia since 2008, but this standard only provided sufficient guidance for safety distance calculation which addressed issues 2 and 3 from the above list.
Guidance is now at hand with the new standard AS 4024.2802:2017 being introduced. This standard provides information on all aspects of designing/installing presence sensing system such as light curtains and laser scanners.

AS 4024.2802:2017 covers safety distance calculation to address issues 2 and 3 in the above list, but it does a lot more as well.

It also provides an explanation of how to ensure the application is suitable for presence sensing devices, this guidance can help address issue 1 from the above list.

Issue 5 a major problem in the industry, it is common to see muting sensors mounted incorrectly and this increases the risk of operators inadvertently muting the light curtain and being exposed to hazards. AS 4024.2802:2017 has information on all common muting configurations and provides clear instructions on how the sensors are mounted and the timing sequence of the muting operation.
Issue 4 reflects the fact that many designers/installers aren’t aware of the requirement of stopping performance monitoring. If the light curtain/scanner is used as a trip device then the safety distance is integral to ensure the risk is controlled. If the machine’s stopping time is subject to deterioration (eg: brake wear) then the stopping time of the machine should be monitored. This information can be used to schedule preventative maintenance to ensure the safety risk is controlled and reduce unexpected downtime.

If you design/install or maintain presence sensing systems, such as light curtains or laser scanners, I recommend referencing the new AS 4024.2802:2017 standard.

Safety for Collaborative Robots

In recent times there has been a strong growth in the use of robots in Australian manufacturing, thus why collaborative robots is currently a hot topic. These robots are designed to operate in cooperation with humans, which presents some new safety considerations compared to traditional robots that operate behind a safety fence. There is a new Australian Standard, AS 4024.3303:2017, which provides guidance on the process involved to ensure your collaborative robot doesn't pose a threat to its human work colleagues.

A risk assessment must be carried out to determine if a collaborative robot is suitable for the application. This should also include determining the collaborative workspace of the robot and estimating the risk of the hazards so the appropriate risk reduction measures can be applied.

The collaborative workspace is the area where the robot and human co-inhabit during normal operation, see Figure 1 below.

Fig. 1 - The Collaborative Workspace

To reduce the risk associated with robots and humans working in this collaborative workspace one or more of the following methods can be utilised.

Safety-rated Monitored Stop

This method may be used to provide access for the operator to perform tasks, such as loading a part into the end effector. In this method, the robot will move to the collaborative workspace and perform a safety stop. This allows the operator to enter the collaborative workspace and perform their task. Once the operator is out of the collaborative area, the robot can resume normal operation. If the operator enters the collaborative workspace, when the robot is moving in the collaborative workspace, the robot will perform a safety stop and need to be manually reset.

The robot system must be able to detect the presence of an operator inside the collaborative workspace. The size of the collaborative workspace must be determined to take into consideration the speed of the robot, the reaction time of the robot, stopping time of the robot, speed of human movement and resolution of the system used to detect the presence of the operator.

Hand Guiding

This method works similar to the "Safety-rated monitored stop" however, once the operator is inside the collaborative workspace, they can operate the robot with a hand guiding device. This allows the operator to manually control the robot in close proximity for detailed tasks. When the robot is manually controlled, it will perform its movements at a controlled speed deemed acceptable from a risk assessment. If the operator releases the hand guiding device, the robot will stop and when the operator has left the collaborative workspace, the robot can resume normal operation.

Speed and Separation

In this method, the robot and operator can work at the same time in the collaborative workspace. The robot maintains a protective separation distance from the operator. If the distance between the operator and robot becomes less than the protective separation distance the robot will stop.

The speed of the robot must be monitored because the protective separation distance is reliant on the speed of the robot. The protective separation distance is also reliant on the on the robot’s reaction time and the accuracy/resolution of the system used to detect the distance of the operator.

The robot may change its speed depending on the position of the operator to reduce the protective separation distance or the robot may use alternative paths that ensure the protective separation distance is maintained.

Power and Force Limiting

In this method, the robot and operator can work at the same time in the collaborative workspace and contact between the operator and robot can occur. The energy and force of these collisions are limited below an established threshold limit. A risk assessment process is used in conjunction with data from Annex A of the standard, to determine the suitable energy and force thresholds for the tasks to be performed.

The robot keeps energy and force of contact below the threshold by:

• Increasing contact surface areas; rounded edges, smoothed edges, etc.
• Absorbing energy; using padding/cushioning, deformable components, etc.
• Limiting forces, speed
• Using sensors to anticipate collisions 

When considering a collaborative robot, it is essential that a risk assessment process is conducted to understand the risks associated with the application. With the use of the new standard, AS 4024.3303:2017, the appropriate collaborative methods can be selected. The standard also provides guidance, on what safety features the robot requires for each collaborative method.