Machine safety

Directives and standards

Directives and standards are of great importance for manufacturers of machines and safety components. We are participating in standardisation organisations for machine safety and we work daily with the practical application of safety requirements in combination with production requirements.

We are happy to share our knowledge with our customers. Read more about machine safety, directives and standards by using the links below.

The machinery directive

Retained fastenings

Safety in control systems

Safety distance

SISTEMA

Functional safety design tool - FSDT-01

The european Machinery Directive

The 29th of December 2009 the new Machinery Directive became applicable. It is an update of the common EU rules that has existed since 1995 for machine builders and suppliers. Machines which have been placed on the market since the 29th of December 2009 must comply with the new Machinery Directive 2006/42/EC. Before that, the old Machinery Directive 98/37/EC was valid.

The objectives of the Machinery Directive, 2006/42/EC, are to maintain, increase and equalise the safety level of machines within the members of the European Community. Based on this, the free movement of machines/products between the countries in this market can be achieved.

The different parts of the directive
The Machinery Directive can be said to consist of two different parts. One part describes how a machine needs to be certified in order to be allowed to be placed on the European market. It sets a number of requirements on how the certification shall be accomplished and what documentation has to be produced. The other part consists of the essential health and safety requirements that have to be met in order to be allowed to place a machine on the market. It states e.g. that the manufacturer shall perform a risk assessment of the machine and reduce the risks associated with transport, assembly, operation and maintenance of the machine. Other requirements include e.g. ergonomics, noise, emergency stops, control systems, moving parts and how the machine should behave at start and stop.

What has changed?
The new directive did not introduce any radical changes compared to the old, but large parts have been rewritten and clarified. Following is a list of some of the more important changes:

The scope has been extended and clarified
The borderline with other directives (e.g. low voltage and lifts) has been clarified. Which machines are included and excluded has also been clarified.
The requirements for partly completed machinery has been clarified
There were requirements in the old directive about partly completed machinery, but these were not clear. It has been clarified what has to be done in order to place a partly completed machinery on the European market and which documentation has to accompany the partly completed machinery.
New procedures for assessment of conformity
Some assessment procedures have been removed (e.g. forward documentation to a notified body for safe keeping) and a new has been introduced (full quality assurance).
The content of the instruction manual has been extended
In the new directive the requirements of the instruction manual has been rewritten and clarified. Among other things the following new items shall be included: EC declaration of conformity, warnings about misuse, information about remaining risks, protective measures to be taken, conditions in which the machinery meets the requirement of stability, operating method to be followed in the event of an accident or breakdown, specification of spare parts to be used.
Clarifications for the requirements of the technical documentation
The technical documentation shall be produced for all machinery, including partly completed machinery. The new directive clarifies that the documentation of the risk assessment shall be part of the technical documentation.

Furthermore worth mentioning is that safety components now shall be CE marked in conformity with the Machinery Directive, and not just EMC and low voltage.

Where can I get help?
You can download the Machinery Directive by using the link below. As a help to interpret the directive there are some different documents, and one especially worth mentioning is the extensive guide from the European Commission that explains many of the items in the Machinery Directive. Another interesting document is a detailed comparison of the old and new directive. You can find these documents below as well.

If you have any questions regarding the Machinery Directive you are welcome to contact us.

The new Machinery Directive (pdf)
Guide to application of the Machinery Directive (pdf)
Comparison of the old and new Machinery Directive (pdf)

Retained fastenings

The Machinery Directive requires the fastening for fixed guards to remain attached to the guards or to the machinery even when the guards are removed. In fact, this requirement only concerns the parts of the guard that needs to be removed for maintenance, and should not be applied to all parts of a fencing system. This text explains how to interpret the requirements.

The Machinery Directive 2006/42/EC contains a requirement regarding fixed guards which has raised questions. The requirement says:

1.4.2.1. Fixed guards
Fixed guards must be fixed by systems that can be opened or removed only with tools.
Their fixing systems must remain attached to the guards or to the machinery when the guards are removed.
Where possible, guards must be incapable of remaining in place without their fixings

The part of the directive that raises questions is the requirement which states that fixing systems must remain attached to the guard or the machinery when the guards are removed. At first sight, the requirement could be interpreted to refer to all guards. But the basic idea is that the fastenings will not be lost when the guard is removed e.g. for maintenance, so it is much less likely that the guard will only partially be replaced because one or more fastenings have been lost or not replaced at all.

A risk analysis must be performed by the machine builder to find out all working moments that needs to be done. If it is foreseen that a fixed guard will need to be removed and replaced then it could be a ground for using fastenings attached to the guard or to the machinery. The standard EN 953+A1, Safety of machinery. Guards. General requirements for the design and construction of fixed and movable guards (which is revised to the Machinery Directive) gives this requirement:

7.2 Retained fastenings
Where it is foreseen (e.g. maintenance) that the fixed guard will be removed then the fastenings shall remain attached to the guard or to the machinery.

It is emphasised that when it is envisaged that the guard will be removed, the fastenings shall remain attached to the guard or to the machinery.

In the guide to application of the Machinery Directive you can find further explanation for the requirement regarding retained fastenings:

...
Application of this requirement depends on the manufacturer's assessment of
the risk concerned. The requirement applies to any fixed guards that are liable to
be removed by the user with a risk of loss of the fixings, for example, to fixed
guards that are liable to be removed during routine cleaning, setting or
maintenance operations carried out at the place of use. The requirement does not
necessarily apply to fixed guards that are only liable to be removed, for
example, when the machinery is completely overhauled, is subject to major
repairs or is dismantled for transfer to another site.
...

This state, even clearer, that the requirement applies to guards that are liable to be removed during cleaning or maintenance. The requirement does not necessarily apply to guards that are being removed for a completely overhaul or major repairs.

But what if the guards needs to be removed regularly? Is it still enough to have a fixed guard which shall be assembled and disassembled? The Machinery Directive gives this requirement regarding moving transmission parts:

1.3.8.1 Moving transmission parts
...
Interlocking movable guards should be used where frequent access is envisaged.

If a guard should be removed regularly it increases the risk of leaving the guard off to the side which makes moving parts and other sources of risk constantly accessible. This risk is, of course, the same for all moving parts of the machine and does not only concern transmission parts.

Summary
If you in the risk analysis finds a working moment that requires fixed guards to be assembled and disassembled (e.g. for maintenance, cleaning etc), the fastenings shall remain attached to the guard or machine. If this working moment occurs frequently (the machine builder determines what is frequently) an interlocking movable guard should be used instead. The last-mentioned solution is definitely a safer and better solution even if the work doesn’t occur often. Even if the fastenings are attached to the guard there is a substantial risk that the guard will not be put back together for the sake of convenience. This is an extract from another part of the Machine Directive which supports this:

1.4 Required characteristics of guards and protective devices
1.4.1. General requirements
Guards and protective devices must:
...
– not be easy to by-pass or render non-operational,
...
– enable essential work to be carried out on the installation and/or replacement of tools and for maintenance purposes by restricting access exclusively to the area where the work has to be done, if possible without the guard having to be removed or the protective device having to be disabled.
...

The requirement of retrained fastenings therefore only applies to guards that during planned works needs to be assembled and disassembled. But you should consider using interlocking movable guard even in these cases. In the second part of the extract above, the Machinery Directive moreover states that you shouldn’t choose a guard that needs to be taken apart during maintenance.

Safety in control systems

Building a protection system that works in practice and provides sufficient safety requires expertise in several areas. The design of the safety functions in the protection system in order to ensure they provide sufficient reliability is a key ingredient. As help for this there is, for example, the EN ISO 13849-1 standard.

The outdated standard EN 954-1 (categories) has been replaced by the new standards EN ISO 13849-1 and EN 62061. EN ISO 13849-1 uses the term Performance Level, PL to describe the probability of dangerous faults in safety related control systems, while EN 62061 uses the term Safety Integrity Level, SIL.

The Standard you should use depends on the choice of technology, experience and customer requirements. We notice that most of our customers prefer PL as it is technology-neutral and that they can use their previous knowledge of the categories.

For more information about safety in control systems, risk assessment and examples of safety calculations, please see the first chapter in our Safety Products catalog.

ABB Safety Products catalog (PDF)

Safety distance

The safety distance is a minimum distance between a light curtain and a dangerous area. The safety distance shall guarantee that a person is not able to reach a dangerous machine part before the machine movement has stopped. This is calculated with the formula from EN ISO 13855 (previously EN 999). We explain how to calculate the safety distance for light curtains and light beams in the Safety Handbook.

A new standard in 2010
In 2010 the standard EN 999 was revised and got a new number (EN ISO 13855 Positioning of safeguards with respect to the approach speeds of parts of the human body). ABB Jokab Safety has extensive knowledge about the safety distance standard since we participated in the standardization committee that performed the revision.

What was changed?
No extensive changes were made with the new standard, but here are some of the most important changes:

Height of a light curtain
A formula that calculates how far it is possible to reach towards the machine when reaching above a light beam or light curtain was introduced. This means that you should not only calculate the distance from the light curtain to the hazard zone but also calculate the lowest height on the uppermost beam, to prevent reaching above the light curtain into the hazard zone.
New technical guards
Information for calculating safety distance for cameras, scanners and hatches was introduced in the standard.
Help with stopping time measurement
An informative attachment was created that specifies what you should think about when measuring the stop time and which methods you should avoid. It also specifies what a measuring protocol should contain.
New definition for stop
The standard says that the stopping time should be measured until the dangerous function comes to a complete halt (not just the movement). For some machines even heat could be a dangerous function. Moreover, for machines with a slow stopping process, it is possible to get a more practical and realistic safety distance by defining the stop as something other than 0 mm/s. For instance by considering the last 2 mm movement as harmless and exclude them from the stopping time, or by measuring the stop until the speed is below e.g. 10 mm/s. When using these types of redefinitions of the stop it need to be documented and you must be able to make a case for them or to validate them with help from standards that specify low-speed for certain types of machines.

If you have any questions regarding safety distance or machine safety in general, you are welcome to contact us.

SISTEMA

A tool for determining performance level (PL) and generating technical documentation.

The standard EN ISO 13849-1 requires calculations. To do this in a manageable way a software tool provides excellent help. One commonly used software tool for this is SISTEMA, developed by IFA (The Institute for Occupational Safety and Health) in Germany. With SISTEMA it is possible to “build” safety functions, verify them and generate the technical documentation required. The tool is freeware and can be downloaded from the IFA website.

One downside of SISTEMA is that it only supports EN ISO 13849-1. If you need to comply with IEC 62061 we recommend to use FSDT instead (see link above).

To work with SISTEMA in a rational way, we have developed a library of our products for download. The library is of a standardized format called VDMA 66413. The purpose is that all manufacturers of safety products should present their functional safety data in the same way.

Download SISTEMA (IFA website)
ABB Jokab Safety library.zip

Functional safety design tool - FSDT-01

FSDT is an ABB software for determining PL and SIL of safety functions and generating technical documentation.
The tool helps simplifying the process of safety function design, verification and documentation. It supports the compliance of the requirements of both EN ISO 13849-1 and IEC 62061 as well as the European Machinery Directive.

To simplify the use of FSDT with our products we have created a library containing all of our safety products. In the library all functional safety data (e.g. PL, SIL, PFHd, Category) is stored for our products, and you can easily select the required products and build safety functions that FSDT calculates for you. The library is in VDMA 66143 format, which means it is compatible with most softwares for functional safety calculation.

Please turn to your local ABB contact in order to purchase FSDT.
Our VDMA library and more information about FSDT can be found in the links below.

FSDT webpage
ABB Jokab Safety library.zip

Interlocking devices and guards - EN ISO 14119

Limiting devices for industrial robot cells

Using an HMI for reset and start?

EN ISO 14119, the only harmonized standard for interlocking devices associated with guards

Starting May 2015, EN ISO 14119 is the only harmonized standard for interlocking devices associated with guards. EN 1088 cannot be used anymore.

Read more...

Limiting devices for industrial robot cells

The standards EN ISO 10218-1 and -2 (Harmonized standards to the Machinery Directive) give requirements on how to safely limit the space of the industrial robot.

Read more...

Question: Is it allowed to use an HMI for reset and start of a machine?

Answer: We recommend to use a separate pushbutton for the reset of a machine, and avoid using an HMI for this. For the start function it is OK to use an HMI. The reasoning behind this is explained in the link below.

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Machine safety

Directives and standards

The machinery directive

Retained fastenings

Safety in control systems

Safety distance

SISTEMA

Functional safety design tool - FSDT-01

The european Machinery Directive

Retained fastenings

Safety in control systems

Safety distance

SISTEMA

Functional safety design tool - FSDT-01

Interlocking devices and guards - EN ISO 14119

Limiting devices for industrial robot cells

Using an HMI for reset and start?

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