Jon Severn, the editor of MachineBuilding.net, reports on the seminar organised by the Machinery Safety Alliance at the National Space Centre, Leicester, on 23 May 2012.
First of all, the Machinery Safety Alliance deserves to be congratulated on the significant achievement of getting six companies (Festo, Fortress Interlocks, Pilz Automation Technology, Troax, UK Engineering and Werma) to collaborate in this way. The member companies have created an excellent website that has a growing collection of useful articles about machinery safety, and also provides a means of booking places on the seminars and for delegates to download the presentations afterwards.
Three seminars are being organised in 2012. The first was held at the National Space Centre, Leicester, on 23 May, and the other two are as follows:
- 27 June - Manchester Concorde Conference Centre
- 5 September - @Bristol Science Exhibition Centre
At the first seminar it was clear that the speakers had endeavoured to prepare presentations that focused on machinery safety issues and were not thinly disguised sales pitches. Furthermore, while the HSL (Health and Safety Laboratory, which is an agency of the Health and Safety Executive) is not formally a member of the Alliance, it is actively participating in all three seminars in 2012.
The first presentation on 23 May was by Richard Brooks of the HSL. As well as giving an introduction to the HSL, this presentation also discussed some of the broad conclusions that have been drawn from the HSL's investigations over many years. For example, incidents typically have several contributory causes, and equipment-related safety issues originate in all phases of the life-cycle, including the specification, design, manufacture, operation, servicing/maintenance and modification. It was also noted that prosecutions under The Supply of Machinery (Safety) Regulations 1992 are rare; the vast majority are under the Health and safety at Work etc Act 1974 and, to a lesser extent, The Provision and Use of Work Equipment Regulations 1998. While fear of prosecution might therefore be a relatively small incentive for machine builders and system integrators, machinery safety should be viewed as a means of engineering-in quality.
In the next session, David Collier (Pilz) discussed legislation and compliance, going back to basics and defining terms such as machinery, harm and hazard, and explaining the underlying structure for safety law in Europe. This session also covered responsibilities, standards, a strategy for risk assessment and risk reduction, and introduced the concepts of Performance Level (PL) determination (for EN ISO 13849-1) and Safety Integrity Level (SIL) determination (EN 62061).
Geoff McBride (Troax) spoke about fixed guards, movable guards and interlocks, as well as the requirements in relation to fixings and reach distances. He also demonstrated how colour can be used to highlight hazardous parts of machines, and discussed the question of when guards need to be CE marked as safety components, and when guards simply form part of a machine or integrated manufacturing system that has to be CE marked as a whole.
Interlocks were discussed in greater detail by Phill Caroll (Fortress Interlocks). His presentation covered interlocking principles, the different classes of interlocks, and the Harmonised standard EN 1088 - which is written partly for designers of interlocks and partly for those selecting interlocks. He also mentioned that a new draft amendment to EN 1088 has been proposed and, moreover, a new international standard, ISO 14119, has been proposed.
For the next session, David Collier returned to speak about the two functional safety standards likely to be of relevance to machine builders, namely EN ISO 13849-1 and EN 62061 (IEC 62061). His presentation showed when and where the two standards should be applied, and the differences and common ground between them, covering Performance Levels and Safety Integrity Levels, failure rates and diagnostic coverage.
Following a break for lunch (and an opportunity to see some of the exhibits at the National Space Centre), David Collier spoke once again, this time to talk through a worked example of a machinery safety system designed to comply with EN ISO 13849-1.
Machinery safety considerations often focus on the inputs and control elements of a system, but safe outputs are equally important. Klaus Gabriel (Festo) gave a presentation that looked at the types of pneumatic outputs that are commonly found on machinery, such as actuators that must be reduced in speed or force, or have their direction of movement monitored or changed, and movements that must be stopped, blocked or locked. He also discussed reliability of pneumatic components (in terms of B10d and MTTFd values), as well as diagnostic coverage and common-cause failures.
Pete Osborn (Werma Signaltechnik) talked about the need for warning signals, and how they must be intuitive, unambiguous, proportionate and appropriate. EN 60204-1 defines the colours to be used for signalling various machine conditions, and Peter Osborn explained that warning lamps, because they provide a safety function, must be reliable - which relates directly to the MTTFd defined in EN ISO 13849-1.
When he returned to the lectern for the last formal session, Richard Brooks referred to the 'state of the art' as mentioned in the Machinery Directive, and the way in which is continually evolving. One element of the state of the art is standards, and he mentioned the problems that can be encountered when searching for Type-C (machine-specific) standards, as standard titles do not include the terms that might be expected. Although there is a very broad variety of Type-C standards, machine builders need to know what steps to take when there is no Type-C standard for the machine being designed - and the presentation explained this very well. The presentation also outlined what to do when integrating several machines together.
Given the breadth and depth of experience of the presenters, the high standard of the presentations and excellent venue (comfortable and practical, as well as interesting), the £60 seminar fee was really very good value. Approximately 50 delegates attended the seminar in Leicester, and the events in Manchester and Bristol are likely to prove at least as popular. Follow the link to register for one of the Machinery Safety Alliance seminars.