VIBRATION EMISSIONS
Employers are advised to refer to the HSE publication “Guide for Employers”.
All hand held power tools vibrate to some extent, and this vibration is transmitted to the
operator via the handle, or hand used to steady the tool. Vibration from about 2 to 1500
herz is potentially damaging and is most hazardous in the range from about 5 to 20 herz.
Operators who are regularly exposed to vibration may suffer from Hand Arm Vibration
Syndrome (HAVS), which includes ‘dead hand’, ‘dead finger’, and ‘white finger’. These
are painful conditions and are widespread in industries where vibrating tools are used.
The health risk depends upon the vibration level and the length of time of exposure to
it……in effect, a daily vibration dose.
Tools are tested using specialised equipment, to approximate the vibration level generated
under normal, acceptable operating conditions for the tool in question. For example, a
grinder used at 45° on mild steel plate, or a sander on soft wood in a horizontal plane
etc.
These tests produce a value ‘a’, expressed in metres per second per second, which
represents the average vibration level of all tests taken, in three axes where necessary,
and a second figure ‘K’, which represents the uncertainty factor, i.e. a value in excess of
‘a’, to which the tool could vibrate under normal conditions. These values appear in the
specification panel below.
HAND-ARM VIBRATION
16
MODEL No:
CR2
DESCRIPTION:
PLUNGE ROUTER
Declared vibration emission value in accordance
with EN12096
Measured vibration emission value -
a:
4.7 m/s
2
Value determined according to EN28622-1
You will note that a third value is given in the specification - the highest measured reading in
a single plane. This is the maximum level of vibration measured during testing in one of the
axes, and this should also be taken into account when making a risk assessment.
‘a’ values in excess of 2.5 m/s
2
are considered hazardous when used for prolonged periods.
A tool with a vibration value of 2.8 m/s
2
may be used for up to 8 hours (cumulative) per day,
whereas a tool with a value of 11.2 m/s
2
may be used for ½ hour per day only.
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