Review of BARA Machine Safety Conference

This present review of the event is not intended as a slide-by-slide report of the presentations, rather it is highlights some of the points made, not all of which were on the presentation slides (attendees received a CD-Rom with PDF copies of all the presentations plus some other useful documents and information).

Philip Parry, from the Electrical and Control Systems Group at the HSE (Health and Safety Executive), started by discussing machinery safety standards for functional safety, with the context being the existing Machinery Directive and the amended Directive that will come into force on 29 December 2009. For example, he highlighted how the essential health and safety requirements (EHSRs) are being altered so that 1.2.7 of the Directive (Failure of the control circuit) is being removed, with its contents being moved to an expanded 1.2.1 (Safety and reliability of control systems). Parry also drew attention to the fact that ISO 13849-2 (Safety of machinery. Safety-related parts of control systems. Validation), which is seldom used in its current form, is being revised in line with the 2006 version of ISO 13849-1.

In response to a question from the floor, Parry reminded those purchasing machines for their own use that they should undertake a risk assessment, even if the machine is CE marked.

In a discussion after the presentation, Parry said that although all harmonised standards are being reviewed and updated to bring them into line with the new Machinery Directive (2006/42/EC), in most cases it is expected that the only amendment will be to Annex ZZ, so that ZZA will refer to the existing Directive and ZZB will refer to the new Directive. However, EN 953 (Safety of machinery. Guards. General requirements for the design and construction of fixed and movable guards) is being revised to take account of the new Directive's requirements relating to fixings for fixed guards.

Industrial robots

Steven Shaw, HM Principal Specialist Inspector from the HSE, spoke about standards for industrial robots. With the robot standards currently part-way through a major revision, Shaw was able to give an insight into the changes being made.

During his presentation Shaw said that although EN ISO 10218-1:2006 (Robots for industrial environments - Safety requirements - Part 1: Robot) had been published there was no BS version available from BSI. However, the BSI website now shows that BS EN ISO 10218-1:2006 is available, published on 31 October 2008. In most respects EN ISO 10218-1 is similar to the old standard (ISO 10218:1992, also known as EN 775:1992 and BS 7228-6:1992) but expanded in some areas, and with sections relating to applications removed to Part 2. Shaw said that prEN ISO 10218 - 2: Robots for industrial environments - Safety requirements - Part 2: Robot system and integration), which relates to the application of industrial robots rather than their design, anticipates technologies that are not yet being used. In particular, it addresses collaborative working, in which an operative and a robot function together, without being separated by physical guards. While Shaw was able to give a useful insight into the forthcoming Part 2, he said that some sections of the standards are likely to be so heavily revised that it was not worth discussing the current text during the Machinery Safety Conference.

Shaw's responsibilities include maintaining the HSE's publication HSG43, Industrial Robot Safety, and he took the opportunity to ask delegates whether they use this and, if so, how useful they find it. The document is now somewhat out of date and must either be updated or withdrawn - which could be the case, given that EN ISO 10218-1 is now available and EN ISO 10218:2 is in development. Any views on this can be emailed to [email protected] and they will be forwarded.

Steven Langley, of ISS Safety Ltd, a system integrator that often works closely with Rockwell Automation, presented two case studies. The first related to the upgrading of safety on an aluminium strip processing line, while the second referred to pin and ball handling machinery at a bowling alley.

Pros and cons of safety networks

Seb Strutt, of Sick UK, discussed EN ISO 13849-1 and EN IEC 62061 and noted that German companies appeared to prefer EN ISO 13849-1. However, he advised delegates to use the table in the front of EN ISO 13849-1 to decide which machinery safety standard to apply under what circumstances.

The main part of Strutt's presentation focussed on a real-life robot cell application and how AS-i Safety at Work (ASiSafe), DeviceNet Safety and Profisafe could be applied. He then outlined what he saw as the pros and cons of each for this type of application, in terms of factors such as cost, ease of programming/configuration, and the availability of IP67 remote I/O blocks.

A useful tip from Strutt was to download a copy of the SISTEMA ISO 13849-1 Safety Integrity Software Tool for the Evaluation of Machine Applications in accordance with EN ISO 13849-1. This is available free of charge from the BGIA website (and soon it will also be available from the Sick website). Users can choose to download the calculator in English or German from www.dguv.de/bgia/de/pra/softwa/sistema/index.jsp.

Paul Laidler (see photo), of Laidler Associates, discussed the new Machinery Directive 2006/42/EC and its implications for machine builders. He also highlighted some of the 'grey' areas, such as the definition of a 'natural and legal' person, and whether essential health and safety requirement 1.2.3 ('Starting') now permits the use of software-initiated restarts.

Because of the new Directive coming into force, coupled with the fact that machines scheduled for delivery before the new Directive may be unavoidably delayed until after the New Directive comes into force, and the way machine builders and system integrators can currently choose which standards to work to for certain types of machinery, Laidler recommended that suppliers and customers should agree a common user requirements specification for new projects in order to avoid any conflict at the time of delivery.

It is rare for an entirely new technology to be launched into the field of machinery safety, but that is exactly what the Pilz SafetyEYE is. Stewart Robinson, of Pilz Automation Technology, explained how the system operates, with a set of three cameras installed above the hazardous machinery, plus an analyser monitoring the images for incursions into predefined warning and detection zones. He then outlined how DaimlerChrysler, which jointly developed the system with Pilz, has installed a number of the systems within its plant where the new C class Mercedes-Benz is being built. Compared with conventional safety light curtains, laser area scanners and pressure-sensitive mats, SafetyEYE has the potential to reduce both the hardware and installation/commissioning costs. Robinson also stated that an upgraded version of the system is currently under development; this features quad-core processors in the analyser unit to enable multiple camera units to be used with a single analyser or to reduce the response time of a system equipped with a single camera unit.

AS-i Safety developments

Peter Cheetham, Chairman of the AS-Interface UK Expert Alliance, discussed the advantages offered by AS-i Safety at Work (ASiSafe), especially now that remote output modules are available and the configuration software provides a far more intuitive overview of the circuit logic. He also reported that the UK market is currently seeing an annual growth in sales for safety slaves in excess of 60 per cent. This is thought to be largely due to machine builders and system integrators using ASiSafe alongside fieldbus networks. Although ASiSafe was developed to provide safety functionality on the same cable as a conventional AS-i network, the ease with which AS-i can be interfaced with higher-level networks (such as DeviceNet, Profibus, CC-Link and Industrial Ethernet) enables machine builders to use their customers' choice of fieldbus for automation and control, plus ASiSafe for the safety-related control system. Alternatively, ASiSafe can be retrofitted easily on machines that are having just their safety systems upgraded.

David Collier, of Schneider Electric, spoke about SafeEthernet. With the current trend among machine builders and suppliers towards the use of Ethernet-based fieldbus protocols, SafeEthernet is likely to become popular for a variety of applications. In his presentation, Collier outlined two case studies. The first related to a chemical plant that used SafeEthernet on a fibre-optic hyperring, with redundant monitoring, within a batch safe shutdown system. His second case study showed how SafeEthernet was used over a fibre-optic network extending for 30km. A redundant network with ring management is used to monitor emergency stops on unmanned locks on a German waterway.

Collier also reported that wireless/satellite links are starting to be used for SafeEthernet communications in applications such as construction site cranes and offshore operations.

The conference concluded with a question-and-answer session.

BARA is now planning the next Machine Safety Conference. MachineBuilding.net will announce the date, venue and programme as soon as the information is available.