Well Burman, not all CNC machines are the same, depends how old they are, the software, the interlock controls etc. So the RA needs to be specific and conducted on the job with the operataor. You really should do a PUWER assessment first to familiarise yourself with the interlocks, guards, and the work procedures that the operators follow, can they pause the programme (is that safe?) and also the size/weight of various tools/pieces that the machine works on how are thay handled, how clean is the work area, is the suds control adequate, are there safe procedures for cleaning and for repair/maintenance work.

If you can get hold of a copy of BS4163 there is a whole section there dedicated to CNC machines (including milling machies) which highlights the potential hazards and suggests appropriate control measures. The document is geared towards the education sector but you could easily adapt the information to reflect your line of work.

For use only by competent operators (or those under such direct supervision) Installed by competent persons Maintained by competent persons Adequate and compliant power supply and methods of isolation Adequately lit, appropriate segregation, signage, beacons etc. fault/defect reporting procedure.

What do you want to know about 4163?

A better standard to consider would be BS EN13128:2001+A2:2009 Safety of machine tools — Milling machines (including boring machines) This is the relevant Machinery Directive harmonised standard. The CEN comittee has done the risk assessment for you! Compliance with this standard would give you a presumption of conformity with the Machinery Directive and therefore with PUWER as well. It is not mandatory for your machine to comply with the standard but if you find non compliances you should attempt to justify them. You may find that your local Public library gives you on line, free read only access to all BS standards which includes BS EN, BS EN ISOs. etc. It should only be possible to operate the machine in low speed, hold to run setting mode with the guard open and it should not be possible to open the guard until the machine is in this mode. Guard safety interlocks should absolutely not be disabled unless alternative protection measures are taken. Another thing to watch out for on this type of machine is polycarbonate windoes which have become brittle with age. They should be replaced every year or so. Brittle windows can shatter in the event of tool or workpiece breakage. Operators have been killed and injured in this way before.