The Guide for Safe Machinery from SICK is a practically orientated reference book for manufacturers, designers, system engineers and operating organizations responsible for machine safety. The new edition contains, among other topics, useful informations and support in the implementation of the new standard EN ISO 14119. This new standard contains specific requirements for selecting and using interlocking devices. Otto Görnemann, Manager Machine Safety & Regulations explains in SICKinsight what effect do the changes in this standard have for machine manufacturers.
The Guide for Safe Machinery is available in several languages. It describes various ways to safeguard machinery and protect persons against accidents taking into account the applicable European directives, regulations, and standards. The legal requirements relating to machinery in other regions (as for example North America or Asia) are described in separate versions of this guide.
EN ISO 14119: Changes and effects on machine manufacturers
SICK is represented on numerous national and international standards committees. Otto Görnemann, Manager Machine Safety & Regulations at SICK, talks about current trends:
SICKinsight: Mr Görnemann, what are you currently working on?
Otto Görnemann: Our main priority at the moment is to support our customers as they adapt to the new EN ISO 14119. The most common protective devices in machine building are interlocking devices used in connection with physical guards. The new standard doesn’t represent a technological revolution, but it does require careful consideration due to the number of changes and additions.
SICKinsight: What is new in this standard and what has changed?
Otto Görnemann: First, it is important to note that as an ISO document the new standard will be more widely recognized than the purely European standard
EN 1088. The new standard contains specific requirements for selecting and using
interlocking devices. It takes into account improved, modern technologies such as
non-contact position detection, RFID and electromagnetic guard locking. The bypassing of interlocking devices is systematically evaluated and the standard stipulates requirements to prevent this. It also defines requirements for correct incorporation into the controller and the evaluation of fault masking.
SICKinsight: What exactly is fault masking?
Otto Görnemann: When electro-mechanical safety switches or reed position switches are connected in series to a single safety module, it is possible for a fault detected by a safety module to be overwritten by the foreseeable actuation of another switch. This phenomenon reduces fault detection for the position switch in question and the reliability of the entire safety function.
SICKinsight: What effect do the changes in this standard have on machine
Otto Görnemann: As mentioned, the changes are not revolutionary. The new standard enables machine manufacturers to use existing technologies in a flexible manner, however it demands careful selection and design and a bit more effort in preventing foreseeable manipulation and integration in the controller (functional safety).
SICKinsight: What is the best way to deal with these changes?
Otto Görnemann: Not all existing solutions will need to be revised, however I would advise machine manufacturers to have these carefully inspected and adjusted accordingly. Hardly any of the new requirements are absolutely new in terms of technology; they are simply laid down for the first time in a standard. Product manufacturers such as SICK have been taking these requirements into account for years, for example, through the use of RFID technology in T4000 transponder safety switches. To address the well-known problem of fault masking in series connections, SICK has developed the Flexi Loop safe sensor cascade, which completely prevents fault masking, among other things. Flexi Loop can also be retrofitted in existing control concepts and systems.
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