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Interview: Dipl.-Ing. Wieland Link

CE markings for safety fences?

 

One question that constantly arises is whether a safety fence as such needs to carry a CE marking when it is delivered and what documents may need to be supplied with such products. In order to clear up this question, Safety System Products spoke to Dipl.-Ing. Wieland Link.

Mr. Link, does the Machinery Directive say anything about whether a safety fence should generally be considered a safety component?

The Machinery Directive 2006/42/EC, in contrast to the older version 98/37/EC, includes many additional annexes. One of these is Annex V and is titled "indicative list of safety components”. Safety fences are included in this list under the category guards.

Does this mean that a safety fence needs to be regarded in the same way as other safety components? Such as a light curtain for example?

That is a good question but it is important to understand here that components listed in Annex V of the Machinery Directive do not need to be certified. It is only when the safety components are also listed in Annex IV that manufacturers are obligated to have them tested by a so-called "notified body” or to have this type of inspection body install a full quality assurance system within the production process.

Mr. Link, there are, however, already safety fence systems available that have been supplied on the market with a CE marking. Do such products hold a special status as a result?

Let’s look at the example of the light curtain once again. It is also generally the case here that the product already has a CE marking when you remove it from the packaging. However, a differentiation needs to be made here. Light curtains are certified according to EN 61496-1. This standard only describes the technical design of the device and not its practical application on a machine or plant. This aspect is covered by the standard EN ISO 13857. It is only when a product fulfils the requirements of both standards that it provides the required safety function in accordance with the Machinery Directive or the current state of technology.

Does a standard also exist for the correct design of a safety fence?

Yes of course, the standard DIN EN ISO 13857. This standard describes the required dimensions for a safety enclosure and when it should or must protect against access to mechanical hazards on a machine. However, this standard does not describe e.g. which containment capabilities a safety fence needs to offer for a robot cell. A number of different factors can come into play here in combination, which the manufacturer of the safety fence could not know in advance.

Yet the question that still arises is why there are manufacturers on the market who have already certified individual elements and talk of a configurable system?

I am not saying that it is not possible to receive a CE marking for a safety fence in general. It is just that in my opinion this should be restricted to safety fences that only guarantee protection against access to a machine, not those that need to provide another safety function such as e.g. protecting against flying workpieces when a vacuum gripper fails on enclosed robot systems or when protection against laser radiation, noise or welding fumes is required. Such safety fences must take account of machine-specific hazards and risks and thus need to be designed in accordance with the requirements of the respective machine on a case-by-case basis.

Mr. Link, does this mean that a CE marking on system fences could restrict their universal application?

If they are only protecting against access to a machine then NO. But if they are designed to provide another safety function then the answer must be YES. A CE marking on a safety fence should not be considered a carte blanche and offers no guarantee that the requirements of the Machinery Directive have automatically been fulfilled as a result. The plant constructor/manufacturer is still obligated to conduct a comprehensive technical assessment of the safety of the machine or plant to be offered on the market and from this it will become apparent whether they can work with a system fence or not.

How should an appropriate safety fence be planned and selected in your opinion?

There are without doubt many possibilities for achieving the right results. If I was a manufacturer of safety fences, I would create a type of checklist or requirement list that catalogued all known hazards and indicated which types of safety fence from my product range covered which hazards and, where necessary, any combination of hazards. On the basis of this type of list, plant constructors/manufacturers could then quickly find out whether a suitable type of safety fence was already available on the market for their machine or whether the fence or guard needed to be individually manufactured specifically for the relevant plant.

Would this safety fence then need to be certified?

Generally speaking NO, because it is not subject to the requirements in Annex IV of the Machinery Directive. Certification is only obligatory for safety screens on presses, which are fitted to those presses with manual loading. A safety fence should generally be considered as part of the machine!

One last question: Does a manufacturer of a safety fence need to regard his product as partly completed machinery in the sense of the Machinery Directive and supply a declaration of incorporation?

No! According to the Machinery Directive, partly completed machinery must display characteristics of complete machinery to count as partly completed machinery, i.e. it must have at least a moving part or its own drive that represents a hazard; this is not the case for a safety fence element. However, a safety fence system must be supplied with detailed information about which safety functions the relevant type of fence provides and what dimensions and installations need to be provided and how this should be realised – meaning a product data sheet and detailed installation instructions.

Thank you very much for your time!

robotic cell

 


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