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Posted By Trevor Siddoway
Dear colleagues,
I am currently in discussion with our technical team and production department regarding an issue with machinery guarding and wonder if anyone with particular expertise in this field can offer any practical advice.
We have several component assembly machines, which operate behind Perspex guards to protect the operator from the hazards associated with moving turntables and ‘pick and place’ mechanisms. The machines are operated via a control panel and emergency stop buttons are within easy reach of the operator, the guards themselves are interlocked.
However… as things stand if a stoppage occurs and the component is lodged in the jaws of the ‘pick and place’ the operator runs the risk of a nip or worst still a broken finger. The reason for this is that simply lifting the guard stops movement within the machine but air is left in the system keeping pressure on the jaws. The current SOP is to hit the emergency stop (which dumps air), then open the guard.
Unfortunately operators (being operators) take shortcuts by not operating the emergency stop and only get found out when an injury occurs, therefore we are trying to find an engineering solution to reduce this risk.
Now to the main issue for which I seek advice. My understanding is that an interlocked guard ‘should prevent movement of the dangerous parts of the machine’ PUWER Reg 11 (1) (b). Unfortunately a retro fit solution to dump the air every time the guard is lifted means a major rework of the logic system and will have a major impact on production; as various machine components will have to be realigned after every stoppage requiring the intervention of a technician.
I need to balance the needs of production with the need to keep our operators safe and comply with the law. Can it be argued that we are complying with legislation as things stand and we just need to change culture or do we have to go that extra mile which borders on the impractical?
Incidentally we have engineered out the problem at the design stage for our new machines.
Apologies for the long post.
Trevor
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Posted By Eric Taylor
Trevor,
Training and education seem to be needed. Why on earth would you cut corners when there appear to be demonstrable dangers if you do! Safe systems of work and all that.
As for the cost of modifying the equipment, whilst you need to make any solution "reasonably practicable", what would the cost of the retro-fit be against a couple of claims for injuries? Might persuade the powers that be to invest a bit more?
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Posted By Trevor Siddoway
Eric,
Operators are fully trained, as for cutting corners, it happens because of production pressures (why do people jump traffic lights), We are putting considerable effort into changing our culture and Cost v risk is well known but it will have a big impact on production. I know it comes down to what's reasonably practicable and I suppose I'm looking for the views of people who have had similar experiences.
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Posted By MT
Maybe a different way of looking at it would be to remove the risk of injury from the equation by utilising tools instead of hands? If the operatives could use a grabber device of some sort to retrieve the component, then that would remove the risk of injury.
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Posted By Philip Beale
my way of thinking would be to connect the current guard into the emergency stop circuit. As you said pushing the emergency stop button dumps the air.
or adding second switch onto the guard they open which is wired into the emergency stop circuit. this should only be a simple re-wire (extending the circuit so effectively you have added another emergency stop)
Although this may cause problems if it dumps every time they open the guard for removal in normal operation and there is a problem re-starting the machine after ES
Phil
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Posted By R Joe
Trevor
A couple of thoughts. If operating the ES before unblocking is the required way of working presumably this isn't required too frequently, otherwise the technicians would be constantly resetting / re-aligning in any case. If this is the scenario, is the cost of an additional switch wired into the ES circuit as suggested, really a big issue (although you may find that an independent dump valve is the more acceptable longer term option – what solution do the newer machines have)?
Alternatively, do operators in reality need to open the guard to clear blockages fairly frequently? If this is the case, management will ultimately come unstuck because the issue will be one of ‘condoned practice' rather than operator 'non-compliance' post event (which is never likely to get HSE sympathy in any case, and certainly not in relation to machinery guarding issues). Not a good situation to be in if there is a risk of a significant injury, and one that management would be sensible to tackle before the event – especially if the solution already exists on similar machines.
Ask your managers the simple question – would they be happy justifying this to HSE post accident? If the answer is no, and the guarding would be upgraded, do it now, or put a planned upgrade programme in place at least.
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Posted By 9-Ship
I think need to remember that PUWER Reg 11 gives the 4 step approach to machine guarding and is covered by the term 'practicable' and NOT reasonable practicable.
i.e. if it is technically possible to guard/prevent access to the danger zone, then the solution is practicable and hence possible.
To argue 'reasonably practicable' is not the correct legal argument.
From other posts here, it seem others are making techincal suggestions that appear to be valid - so before dropping down the Reg 11 steps to the bottom one of relying on simply training/instructing operators not to put their hands in to the danger area, you need to show you have fully investigated and evaluated the technical options first.
Can't remember the case law, that defines practicable, its too many years since I did my diploma!! Practicable = technically possible.
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Posted By Trevor Siddoway
9-Ship,
Yes you are quite correct and we have discussed that Practicable means 'Technically Possible.' (Reasonably Practicable HSWA but Practicable under PUWER).
In theory it is technically possible to make changes but we would have to employ a 3rd party to assist us and the retro fit might throw up other unforseen problems. To my mind cost should not be a sticking point but this and the downtime associated with the retrofit would bring back arguments of risk v cost.
I am calling our local HSE inspector for advice but I appreciate all the responses to date.
Trevor
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Posted By Trevor Siddoway
I spoke to HSE this morning and received solid practical help and advice geared towards the needs of the business and the safety of our employees. Even had an offer to run our solution past a machinery expert which we will take up.
Always worth a call.
Trevor
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