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Two years ago, the HSE issued guidance, which warned about the hazard of parts being ejected from machines and the need to ensure that vision panels are properly constructed and maintained.

01 August, 2003

HSE warns that CNC machines pose a threat

Engineering workers run the risk of serious or fatal injuries because guards on CNC turning machines are not being maintained properly, warns the Health and Safety Executive (HSE).

A survey of CNC machines carried out by HSE inspectors has revealed evidence of cracked and damaged vision panels. These critical safety parts can also deteriorate and lose much of their impact resistance over time due to the effects of metalworking fluid.

On about two thirds of their visits, the inspectors also found that users had not assessed the arrangements needed to maintain the machine so that it was safe to use.

"Vision panels constructed of plain, unprotected polycarbonate need to be assessed periodically to ensure that they will continue to provide adequate protection against ejected parts," explains Nick Hitchcott of the HSE Manufacturing Sector. "This needs to be done even on machines where there is no obvious evidence of damage to the panel."

The risk of entanglement has largely been eliminated in modern computer-controlled lathes, which are normally fully enclosed and interlocked. But the enclosure panels need to be maintained in good condition to prevent injuries from ejected parts.

There is a history of incidents at this type of machine where parts have been ejected and operators seriously injured, sometimes fatally, because vision panels have failed to contain the projectile.

In more than half of the premises visited by the HSE inspectors, employers admitted that ejections had occurred or the inspectors saw, for themselves, evidence of cracked or damaged panels. The HSE says that machines older than two years need to be assessed unless they are fitted with a special, fullyprotected, laminated vision panel where the layers are bonded together.

Two years ago, the HSE issued guidance, which warned about the hazard of parts being ejected from machines and the need to ensure that vision panels are properly constructed and maintained.

The risks vary according to the type of work being done and the work-holding methods that are used but, by following the HSE`s guidance, employers can ensure that if any improvements are needed they are cost-effective and proportional to the risk. Machine manufacturers and suppliers should be aware of the potential problems and can offer advice on the kind of remedial action that needs to be taken or supply upgraded parts.