SIST-TP CEN/TR 16391:2014

SLOVENSKI STANDARD
SIST-TP CEN/TR 16391:2014
01-marec-2014
0HKDQVNHYLEUDFLMHLQXGDUFL3UHQRVYLEUDFLMQDURNH9SOLYVNORSQLKVLOSUL
YPHVQLNXURþQHJDVWURMDQDRFHQMHYDQMHL]SRVWDYOMHQRVWL
Mechanical vibration and shock - Hand-transmitted vibration - Influence of coupling
forces at the hand-machine interface on exposure evaluation
Mechanische Schwingungen und Stöße - Hand-Arm-Schwingungen – Einfluss der
Ankopplungskräfte an der Schnittstelle zwischen Hand und Maschine auf die Bewertung
der Schwingungseinwirkung
Chocs et vibrations mécaniques - Vibrations transmises à la main - Evaluation de
l'exposition aux effets des forces de couplage à l'interface entre la main et la machine
Ta slovenski standard je istoveten z: CEN/TR 16391:2012
ICS:
13.160 Vpliv vibracij in udarcev na Vibration and shock with
ljudi respect to human beings
SIST-TP CEN/TR 16391:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 16391:2014


TECHNICAL REPORT
CEN/TR 16391

RAPPORT TECHNIQUE

TECHNISCHER BERICHT
October 2012
ICS 13.160
English Version
Mechanical vibration and shock - Hand-transmitted vibration -
Influence of coupling forces at the hand-machine interface on
exposure evaluation
Chocs et vibrations mécaniques - Vibrations transmises à Mechanische Schwingungen und Stöße - Hand-Arm-
la main - Evaluation de l'exposition aux effets des forces de Schwingungen - Einfluss der Ankopplungskräfte an der
couplage à l'interface entre la main et la machine Schnittstelle zwischen Hand und Maschine auf die
Bewertung der Schwingungseinwirkung


This Technical Report was approved by CEN on 24 June 2012. It has been drawn up by the Technical Committee CEN/TC 231.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16391:2012: E
worldwide for CEN national Members.

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Contents Page
Foreword .3
Introduction .4
1 Scope .5
2 Normative references .5
3 Symbols and abbreviations .5
4 Contact force and hand-transmitted vibration .5
5 Influence of coupling force on vibration exposure evaluation .6
6 Control of coupling forces in the workplace .6
7 Design of machinery .8
Annex A (informative) Evidence for dependence on contact forces . 10
Annex B (informative) Evaluation of vibration exposure as function of the coupling force . 11
Annex C (informative) Examples of coupling forces . 13
Bibliography . 16

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Foreword
This document (CEN/TR 16391:2012) has been prepared by Technical Committee CEN/TC 231 “Mechanical
vibration and shock”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
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Introduction
The coupling force between the hand-arm system and a hand-held, hand-guided or hand-fed machine during
its use is an important factor in the transfer of damaging vibration energy to the hand and arm. There is
evidence that reducing coupling forces is likely to decrease the damaging effects of exposure to hand-
transmitted vibration. However, the relationship between vibration exposure, coupling forces and damage to
the hand-arm system is still the subject of research studies. There is a need for practical advice for users on
how to minimise and control contact forces and guidance on how to account for those reduced contact forces
when assessing vibration exposures. Machine manufacturers of hand-held and hand-guided machines need
advice on how to achieve the best compromise between the requirements for both low coupling forces and
low vibration magnitudes.
The aims of this Technical Report are to:
 provide guidance on good-practice for both workplace control of exposure and machine design and
 encourage further research to improve the current state of knowledge.
This Technical Report provides an overview of the current state of knowledge on the relationship between
vibration exposures, coupling forces and damage to the hand-arm system. It provides general guidance on
how to build the reduction of coupling forces into workplace action plans to control vibration exposures and
how the reduction of coupling forces may be incorporated into machine design. An example of an empirical
relationship for accounting the coupling force in assessments of vibration magnitudes is also provided.
Technical Reports have no effect on the regulations specified by European Directives. That means that at
present coupling forces should not be used to modify workplace assessments of vibration exposure according
to the EU Physical Agents Directive (vibration) 2002/44/EC or the measurement of vibration emission declared
according to the EU Machinery Directive 2006/42/EC.

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1 Scope
This Technical Report provides an overview of the current state of knowledge on the relationship between
vibration exposures, coupling forces and damage to the hand-arm system. It provides general guidance on
how to build the reduction of coupling forces into workplace action plans to control vibration exposures and
how the reduction of coupling forces may be incorporated into machine design. An example of an empirical
relationship that accounts for the coupling force in assessments of vibration magnitudes is also provided.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 1005-2, Safety of machinery — Human physical performance — Part 2: Manual handling of machinery
and component parts of machinery
EN 1005-3, Safety of machinery — Human physical performance — Part 3: Recommended force limits for
machinery operation
EN ISO 5349-1, Mechanical vibration — Measurement and evaluation of human exposure to hand-transmitted
vibration — Part 1: General requirements (ISO 5349-1)
EN ISO 5349-2, Mechanical vibration — Measurement and evaluation of human exposure to hand-transmitted
vibration — Part 2: Practical guidance for measurement at the workplace (ISO 5349-2)
ISO 15230:2007, Mechanical vibration and shock — Coupling forces at the man-machine interface for hand-
transmitted vibration
3 Symbols and abbreviations
For the purposes of this document, the symbols and abbreviations given in ISO 15230:2007 apply.
4 Contact force and hand-transmitted vibration
EN ISO 5349-1 recognises that, although characterisation of the vibration exposure currently uses the
acceleration of the surface in contact with the hand as the primary quantity, it is reasonable to assume that the
biological effects depend largely on the coupling of the hand to the vibration source. It further notes that the
coupling of the hand to the vibrating surface can affect considerably the vibration magnitudes measured.
The importance of coupling force on measurement is also emphasised in EN ISO 5349-2, which advises that
different measurement ought to be made if there are changes in the feed forces applied to machines.
EN ISO 5349-1 states that coupling forces should be measured, and notes that a standard on measurement
of coupling forces was (in 2001) in preparation. ISO 15230 was published in 2007 and defines parameters
relating to the measurement of coupling forces (feed-force, grip force, contact pressures, etc.).
ISO 15230 defines the coupling force as the combination of compressive push/pull and grip forces. It provides
a basis for obtaining good-quality information on the forces between the vibrating surface and the hand.
However, workplace measurement of coupling force is a complex process that requires specialised equipment
and knowledge.
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NOTE Coupling force does not include forces acting tangentially to the vibrating surface, such as the force required
to twist a handle. It is the (compressive) coupling force that is assumed to influence the transmission of damaging vibration
energy into the hand.
5 Influence of coupling force on vibration exposure evaluation
The method for assessing workplace exposure to hand-arm vibration is standardised in EN ISO 5349-1. This
standard evaluates the risk of harm from vibration based on two factors:
 the vibration at the surface in contact with the hand and
 the exposure time over the working day.
However, EN ISO 5349-1 also recognises that the biological effects of vibration are likely to depend on the
coupling of the hand to the vibration source.
Annex A summarises the state of current knowledge on the relationship between vibration exposure, coupling
force and damage to the hand-arm system. The relationship between vibration exposure, coupling forces and
damage to the hand-arm system is still the subject of research studies. However, there is evidence that
reducing coupling forces is likely to decrease the damaging effects of exposure to hand-transmitted vibration.
Methods for compensating data on vibration magnitude according to the coupling force have been developed.
Annex B provides an example of one such system. The method shown in Annex B requires information on
coupling forces, based on measurements according to ISO 15230. Currently there is limited data available on
typical coupling forces for normal workplace tasks. Annex C shows some examples of the coupling forces
used for a range of hand-held and hand-guided machines.
This Technical Report provides a bibliography of papers that contribute to the evidence linking coupling forces
associated with the use of hand-held and hand-guided machinery and vibration injury.
6 Control of coupling forces in the workplace
6.1 General
In general, workplaces and work tasks should be designed as far as possible to provide workers with
ergonomically good postures for both the body and the hand and arm. Awkward and strained postures will
tend to result in higher than necessary coupling-forces between the hand and the handle of the machine.
The work tasks should be generally designed to promote minimum coupling forces. This should begin with
selection of the most appropriate machines for the task; it may also include adapting the workstations to
reduce contact forces and will include the provision of information for and instruction and training of the
machine operators.
Some actions to reduce coupling forces may increase the magnitude vibration, when evaluated according to
EN ISO 5349-1. Understanding how and why the vibration increases may help to identify solutions that will
lead to both reduced coupling force and reduced vibration exposure.
6.2 Machine selection
Hand-held machines (power tools) should be selected based on their capability to do the job. In general,
smaller, more compact, machines tend to require lower supporting and twisting forces to hold and manoeuvre
them and should be used where they are an option. However, smaller, low-weight, machines may not be
suitable if they need higher feed and gripping forces to compensate for the reduced mass. Sometimes, larger
and heavier machines are simply more capable of doing the job being asked of them. For this reason, good
ergonomic design of machines may be more important than simply reducing the mass and making the
machine smaller.
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Things to consider when selecting machines for the workplace:
a) Is it able to the job?
b) Does it perform the task efficiently?
c) Is it designed ergonomically such that it:
1) is easy to operate,
2) is comfortable to use and
3) requires low coupling forces?
d) Is it low-vibration?
6.3 Workstations and work-tasks
Guidance on ergonomic design criteria and assessment of manual-handling risks related to work activities is
given in EN 1005-2. While EN 1005-2 specifically excludes hand-guided (including hand-held) machines, the
general good ergonomic practices may be employed, such as:
 Bringing work pieces up to the natural working level of the worker;
 Orienting work pieces so that the worker is not required to lift and apply force away from the body;
 Providing overhead-support for hand-operated machines.
Additional guidance is given in EN 1005-3 on the applied forces that can be applied by typical working
populations under different work situations.
Overhead support for machines can provide an opportunity for introducing vibration controls that would not
normally be possible because of the additional weight. Effective vibration reductions have been achieved by
fitting the hand-held machine into a frame with vibration-isolated handles. With the weight of the machine
supported, the worker is only guiding the machine and the additional weight of the frame does not add to the
load that the worker has to support.
Adding mass can have an additional advantage; it will act to reduce the amount of motion in the body of the
machine, reducing the vibration magnitude.
6.4 Information and training
Users of machines need to understand how to get the best out of the machines they use. It is important that
workers understand how a machine needs to be operated, why certain operating methods are recommended
and why others are not desirable.
Instruction and training provided to users should be based on information provided by machine manufacturers
on the safe use of their machinery.
When excessively high push forces are applied the magnitude of hand-arm vibration on machines often
increases. This increase in vibration is not usually indicating more effective machine operation and may be an
indicator that the machine is no longer operating efficiently. Unfortunately, the machine operator can
misinterpret this increase in vibration (and noise) as an indication that the machine is working more effectively
and will apply forces much higher than those that are necessary for the task being performed.
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Many machines are designed with anti-vibration systems that isolate the worker from the vibration of the
machine. Poorly trained operators often relate low vibration with low work-rates of the machine, and push
harder until they can feel the vibration. This overloads the anti-vibration systems, giving the worker a high
vibration exposure but makes little difference to the real work rate.
It is generally important that the workers allow the machine to do the job and that they do not put in excessive
effort themselves. The feeling that there is a need to push hard can be a result of the machine accessories
being inappropriate for the job, or poorly maintained. Examples of conditions that lead to excessive force
being applied include:
a) Blunt drill bits, moil-points or chisels – Workers feel the need to push if the machine is not operating as
quickly as it normally does. This may be due to blunt accessories. In addition, excessive push forces will
cause drill bits and chisel to become blunt more quickly than they should.
b) The wrong accessory for the job – Using an abrasive that is too hard for the task can result in the
abrasive surface becoming smooth rather than wearing properly. Abrasives that are too soft will quickly
wear, without being able to adequately abrade the surface. In both situations, the worker will feel that it is
necessary to push harder to get the work done.
c) Poorly maintained machines – For most machines with a rotary action, any out-of-balance in the machine
can both increase vibration and increase the forces required to properly control the machine.
Reduced machine performance is one indicator that a machine is in need of maintenance or inspection.
Workers need to be trained to recognise the changes in machine characteristics that indicate the need for
inspection and maintenance. These signs may include:
 more time required to do the job,
 greater forces required (increased strain and coupling forces),
 increase vibration,
 increase noise,
 overheating.
7 Design of machinery
7.1 General
Machines designed using the guidance and recommendation provided in EN 1005-2 and EN 1005-3 will
improve general ergonomic handling of machines, and lead to optimised coupling forces between the hand
and machine handles.
EN 1005-2 provides ergonomic recommendations for the design of machinery involving manual handling.
While EN 1005-2 specifically excludes hand-guided (including hand-held) machines, the general good
ergonomic practices are applicable to all hand-machines. This standard gives guidance on factors such as
mass, mass-distribution, size, grips and handles and working postures.
EN 1005-3 provides guidance to the manufacturers of machinery on controlling health risks due to machine-
related muscular force exertion. It provides recommended force limits for machinery, based on the actions
being carried out and the capability of the working population to provide the necessary force. It considers
speed, frequency and duration of the operation that will be carried out with the machine.
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7.2 Applied forc
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