Please can someone help me with some HAV (Hand Arm Vibration) advice?

One of our workplaces has some routers which are used for grinding/sanding carbon fibre. To conduct a vibration risk assessment we have obtained some vibration magnitude figures in mm/sec from the equipment manufacturer, but my understanding is that these figures have been obtained from various points on the machine. They don't take into account "real world" use, i.e. the vibrations transferred along the material being worked upon (i.e. being held) to the operator's hand.

There are several different types of personal HAV monitor (which can be positioned on the operator's hand, for example), but all of these require a figure inputting into them in mm/sec² prior to any monitoring.

One company who sells such HAV monitors have quoted us about £900 to come in and take some readings from the material being held/worked upon using an accelerometer, which would give us the figures (in mm/sec²) we need to inpout into the HAV monitor - Is this reasonable, or are they trying to sell us a service to be able to use their HAV monitors?

Personally, I'd prefer to get hold of a suitable accelerometer and conduct our own measurements, which we can then input into a HAV monitor and work out the true figures for the vibration risk assessment from there, but I'm under the impression that this is a specialist bit of kit which can't be purchased(?)

Edited by user 08 February 2017 16:35:45(UTC)  | Reason: Added info to clarify that the vibration is being transferred from the machine along the material be

gerry,

I agree with original poster Rob, the vibrations that potentially cause harm are the vibrations transferred along the material being worked upon to the operator's hand (if he is holding the part) - not the vibration of some part of the tool that is not in contact with the operator.

JohnW

Unlike drills or grinders a router operative is normally holding/supporting the work piece or jig and in consequence they are not receiving direct accelaration from the equipment but the transmitted force.

Whilst the figure will probably lower than the information upon a manufacturers data sheet the duration of exposure (trigger time) will likely be longer than using a drill.

Personally I would start with a simple device, input the manufacturer provided figure and see what result derives - if it is at the top end of medium or high risk then go down the route of a more in depth professional assessment

If these are rising heads (come up from under the table) a bit more caution is advised as the drive bearings wear more frequently than a lowering head which will affect the order of magnitude over time (manufacturers have a tendency to state new equipment figures).

The acceleration unit is metres/s²

​​​​​​​JohnW

Aren't values normally expressed as m/s2 (should be a superscript 2)

The acceleration unit used in HAV monitors is in mm/s² (or m/s²), which makes translating manufacturer's stated units of mm/s somewhat difficult - Unless I'm missing something? Forgive me if this is a dumb question, but I need help with this.

I think that "chatter" is the best way of describing the vibrations as they are transferred from the cutting/grinding part of the router and along the workpiece. The objects being worked upon are bespoke and uneven in shape, and require a skilled technician to shape/sand/grind them.

From the replies, it sounds like the key element in all of this is the operative's hand which is receiving the vibrations, rather than the router's quoted vibration magnitude(?) - Does this mean that it's the workpiece which needs to be assessed, in which case it would make sense to get an external company in to perform tests on various workpieces as they are being held, rather than the router? I'd guess (correct me if I'm wrong) that this is a necessary course of action in order to undertake a proper analysis of vibration exposure..?

I'll just add that there have been no reported problems from operatives, and that the time spent working with the routers is <30 minutes per day.

At less than 30 minutes per day you can afford to relax a wee bit I think?

Make sure the operatives hands don't get cold and focus on best technique, avoid excessive pressure or forcing the workpiece.