MACHINERY & MACHINE SAFETY ENSURING MODERN MANUFACTURING SAFETY
By Lee Ray, operations manager for Industrial Products (UK) at TÜV SÜD, a global product testing and certification organisation
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raditionally, end-users have been protected from hazardous elements of machinery by physical guarding. Indeed, essential health and safety requirements (EHSRs) cover aspects such as guarding that must be built into a machine before it can carry CE marking, which shows it conforms with all applicable EU standards. Now that the United Kingdom has left the EU, machinery end-users will slowly start to see a UKCA mark replacing the CE marking on compliant products.
The interaction between person and machine has become more prevalent over the years with employees loading materials at various points of a robot cell and removing the finished product once complete. A physical barrier is not practical to use at these load and unload points as it would impact on efficiency. As long as the possibility of material ejection has been considered, there is an alternative.
Electro-sensitive protective equipment (ESPE), such as light guards, light curtains and light grids (AOPDs), and laser scanners (AOPDDRs), and two- dimensional vision systems, are now more widely used than ever before as they provide the safe, barrier-free access that more modern manufacturing methods require. This is because human operators can access a danger zone and rely on optical sensors to stop any potentially hazardous movement within it. However, despite its importance for the safety of machinery end- users, we often visit sites where ESPE inspection and testing is neglected. The IEC 61496 (Safety of machinery - Electro-sensitive protective equipment) series specifies requirements for the design, construction and testing of ESPE designed specifically to detect persons as part of a safety- related system, employing AOPDs for the sensing function. This is then
36 MARCH 2021 | FACTORY&HANDLINGSOLUTIONS
used in conjunction with ISO 13855 (Safety of machinery — Positioning of safeguards with respect to the approach speeds of parts of the human body) to determine the correct installation location for the ESPE, to prevent a person making contact with a hazardous moving part. ISO 13855 specifies parameters based on values for approach speeds of parts of the human body (walking speed and upper limb movement) and provides a methodology to determine the minimum distances to a hazard zone from the detection zone, or from actuating devices of safeguards.
However, there are no specific references to how often these systems should be inspected to ensure that they continue to provide the same level of protection. The Health and Safety Executive’s HSG180 guide helps machinery end-users to answer this question. It refers to Regulation 6 of the Provision and Use of Work Equipment Regulations 1998 (PUWER). This covers the extent and nature of inspections, to help ensure that the appropriate systematic checks are done.
Inspection and tests must first be done when the complete ESPE and machine package is installed, and thereafter when modification or repairs have been made. In addition, periodic inspections should be completed. HSG180 defines the recommended maximum period between each periodic inspection and test as being six months for type 4 ESPE and 12 months for type 2 ESPE. However, this is still quite subjective as the guidance then says that the frequency of inspections ultimately depends upon on the equipment that the ESPE is fitted to and the risk as a whole.
TÜV SÜD would always follow the recommendation provided by the HSE in the first instance until a testing plan can be provided. This would depend on
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