Product directives requiring CE marking demande that the manufacturer to carry out the necessary research, tests and trials on components, accessories or the entire product in order to determine whether it can be installed and used safely.
The results of these investigations must be reported in the Technical File, as they are used to:
- document their execution
- demonstrate compliance with the Essential Health and Safety Requirements (EHSRs) of the respective directives
The tests that can be carried out can be static or dynamic, include the use of instrumentation or not, and each changes depending on what needs to be investigated.
The safety tests we are able to provide you with are those most commonly required in industry, and are as follows:
- noise tests
- vibration tests
- electromagnetic compatibility (EMC) tests
- electrical safety tests (LVD)
- other specific tests
THE MACHINERY DIRECTIVE AND SAFETY TESTS
For products such as machines, partly completed machinery, installations and devices, the Machinery Directive 2006/42/EC refers to safety tests and cites them:
- in the content of the Instructions
- in the supplementary EHSRs to prevent hazards due to machine mobility
- in the supplementary EHSRs to prevent hazards due to lifting operations
- in Annex VII – a) Technical File for machinery – b) Relevant Technical Documentation for partly completed machinery
- in Annex IX – EC type–examination
- in Annex X – Full quality assurance
- in Annex XI – Minimum criteria to be observed by Member States for the notification of bodies
In particular in Annex VII – Technical File the Machinery Directive indicates:
The manufacturer must carry out necessary research and tests on components, fittings or the whole machinery to determine whether by its design or construction it is capable of being assembled and put into service safely. The relevant reports and results shall be included in the technical file.
NOISE TESTING
Noise is an important factor to consider and measure in order to protect a worker's health.
This refers in particular to checking the noise emissions emitted by a machine during its operating cycle both at the workstation and in other positions, so that the health of the operator is not endangered. If the operator is subjected to excessive noise for a long period of time, the risk of suffering damage to his or her hearing, and more, is greatly increased.
The Noise Risk Assessment is therefore fundamental and imposes obligations on the manufacturer with a view to prevention, with the aim of eliminating the noise risk or reducing it to a minimum where it cannot be eliminated.
Noise
Noise is an unwelcome and undesirable acoustic signal, which can be of artificial or natural origin.
A human being subjected to noise on a constant basis can easily suffer damage to their auditory system, of varying severity depending also on the acoustic power.
The effects caused by noise are subtle, as they are often not noticeable immediately but over time and, depending on their severity, can produce not only to physical trauma but also psychological effects.
The Machinery Directive 2006/42/EC and Noise
Annex I of the Machinery Directive 2006/42/EC establishes the noise emitted by a machine as one of the Essential Health and Safety Requirements to be monitored and complied with:
1.5.8. Noise
Machinery must be designed and constructed in such a way that risks resulting from the emission of airborne noise are reduced to the lowest level, taking account of technical progress and the availability of means of reducing noise, in particular at source.
The level of noise emission may be assessed with reference to comparative emission data for similar machinery.
The Machinery Directive goes further into specifics, stating what the Instruction Manual must contain in its content on the subject of noise:
[…]
j) instructions relating to installation and assembly for reducing noise or vibration;
[…]
u) the following information on airborne noise emissions:
— the A-weighted emission sound pressure level at workstations, where this exceeds 70 dB(A); where this level does not exceed 70 dB(A), this fact must be indicated,
— the peak C-weighted instantaneous sound pressure value at workstations, where this exceeds 63 Pa (130 dB in relation to 20 µPa),
— the A-weighted sound power level emitted by the machinery, where the A-weighted emission sound pressure level at workstations exceeds 80 dB(A).
These values must be either those actually measured for the machinery in question or those established on the basis of measurements taken for technically comparable machinery which is representative of the machinery to be produced.
In the case of very large machinery, instead of the A-weighted sound power level, the A-weighted emission sound pressure levels at specified positions around the machinery may be indicated.
Where the harmonised standards are not applied, sound levels must be measured using the most appropriate method for the machinery. Whenever sound emission values are indicated the uncertainties surrounding these values must be specified. The operating conditions of the machinery during measurement and the measuring methods used must be described.
Where the workstation(s) are undefined or cannot be defined, A-weighted sound pressure levels must be measured at a distance of 1 metre from the surface of the machinery and at a height of 1,6 metres from the floor or access platform. The position and value of the maximum sound pressure must be indicated.
Noise Reference Standards
The activity of noise detection and measurement is assigned to experts, since it must be carried out following the indications of acoustic standards that regulate the process and execution of the tests, so that their result can be considered certified and presumed to be compliant. These include standards:
- UNI EN ISO 3746:2011, determines sound power levels and sound energy levels of noise sources using sound pressure measurements
- UNI EN ISO 11204:2010, determines emission sound pressure levels of machinery or equipment, at a work station and at other specified positions
- UNI EN ISO 4871:2009, describes acoustical and product information to be presented in technical documents for the purposes of drawing up the noise emission declaration for machinery and equipment
- UNI EN ISO 11200:2020, provides guidelines for the use of basic standards for the determination of sound pressure levels of machinery and equipment.
I Noise Tests and Trials
Noise Tests are equipment tests carried out using special instrumentation, which certify the noise value emitted by a machine in different operating situations. The related technical documentation must be included in the machine's Technical File.
The Sound Level Meter is the instrument normally used, and is designed to measure the sound level emitted by a source. It is equipped with a microphone and allows an immediate measurement of the noise (in its simplest version) or to also analyse noise at various frequencies, measure transmission loss through architectural barriers, etc.
When it is not possible to use a sound level meter due to the inherent characteristics of the machine, Noise Dosimeters are used, i.e. sound exposure meters that are applied directly to the operator's shoulder on the side most exposed to noise.
Acoustic Calibratorsare also used for phonometric tests, i.e. devices used to calibrate the entire instrument chain directly in the field before and after each acoustic survey campaign.
Noise Risk Assessment
The machine manufacturer must design and construct their products in such a way that risks from airborne noise emissions are kept to a minimum. It is therefore their responsibility to reduce the risks caused by machine noise in terms of possible noise damage.
As early as the design phase, the source (or sources) of noise emission must be identified, and the necessary solutions to reduce the resulting risks must be introduced, such as the adoption ofacoustic guards, noise barriers, sound-absorbing walls.
The phonometric survey of the acoustic climate already present in the environment where the machine will be positioned (acoustic mapping) is also a noise risk assessment activity, since its results will be added to those of the machine.
The manufacturer's proof of compliance with noise obligations comes not only from the technical documentation of the Noise Risk Assessment, but also from the affixing of the nameplate on the machine showing the sound power level guaranteed by the results of the noise tests carried out.
IMPORTANT
As is clearly understood, every time the subject of machinery safety is mentioned, reference is made to factors that really need to be given special consideration, as they are directly and genuinely related to the safety of operators and the protection of their health.
Noise-induced hypoacusis is one of the most reported occupational health problems in Italy, which is certainly a cause for reflection.
VIBRATION TESTING
As well as Noise, Mechanical Vibration is a risk agent that must be measured, and subsequently evaluated, to ensure that a machine complies with the essential health and safety requirements of the law.
In fact, subjecting an operator to the prolonged use of machines or equipment that emit vibrations of a certain magnitude can not only lead to discomfort and difficulty in carrying out their work, but also greatly increases the risk of causing serious harm to health, such as Hand-arm vibration syndrome.
The vibration tests that a manufacturer is obliged to perform are an integral part of the CE marking certification process of a machine. Whether or not a machine complies with the essential safety reference requirements also depends on the presence of these tests.
The manufacturer's obligation is always the same: to assess the risk, in this case from vibrations, with the aim of eliminating it and, if this is not possible, to reduce it as much as possible through active or passive reductions where appropriate.
Vibrations
Vibrations with regard to the concept of machinery safety are understood as mechanical oscillations of an object about an equilibrium point, and Directive 2002/44/EC – Minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibration) classifies them into two categories
hand–arm vibration: mechanical vibrations that, when transmitted to the human hand–arm system, entails risks to the health and safety of workers, in particular vascular, bone or joint, neurological or muscular disorders;
whole–body vibration: the mechanical vibration that, when transmitted to the whole body, entails risks to the health and safety of workers, in particular lower–back morbidity and trauma of the spine.
Hand Arm Vibration (HAV) are vibrations transmitted to the hand–arm joint as a result of holding (with one or both hands) a machine or vibrating equipment that needs to be operated by hand. This may be, for example:
- demolition hammers
- chainsaws
- brushcutters
- grinders
Whole Body Vibration (WBV) are vibrations transmitted through contact with the seat of a means of transport or self–propelled machine when the operator is driving it, or from stationary industrial machinery. The former are usually track-mounted or road-mounted handling equipment, or transport equipment used in industry and agriculture such as
- cranes
- crane trucks
- tractors
- bulldozers
- forklifts
On the other hand, stationary industrial machines that emit vibrations may include
- crushers
- vibrating screens
Among the factors that are measured for vibrations are exposure time, vibration intensity, and the axes along which they propagate.
The Machinery Directive 2006/42/EC and Vibrations
In Annex I of the Machinery Directive 2006/42/EC in the section “Risks due to other hazards”, it includes vibrations emitted by a machine among the Essential Health and Safety Requirements to be met:
1.5.9. Vibrations
Machinery must be designed and constructed in such a way that risks resulting from vibrations produced by the machinery are reduced to the lowest level, taking account of technical progress and the availability of means of reducing vibration, in particular at source.
The level of vibration emission may be assessed with reference to comparative emission data for similar machinery.
Not only that, in order to address the hazards caused by the mobility of machines, the Instructions have additional essential health and safety requirements, including information on vibrations:
3.6.3. Instructions
3.6.3.1. Vibrations
The instructions must give the following information concerning vibrations transmitted by the machinery to the hand-arm system or to the whole body:
— the vibration total value to which the hand-arm system is subjected, if it exceeds 2.5 m/s2. Where this value does not exceed 2.5 m/s2, this must be mentioned,
— the highest root mean square value of weighted acceleration to which the whole body is subjected, if it exceeds 0.5 m/s2. Where this value does not exceed 0.5 m/s2, this must be mentioned,
— the uncertainty of measurement.
These values must be either those actually measured for the machinery in question or those established on the basis of measurements taken for technically comparable machinery which is representative of the machinery to be produced.
Where harmonised standards are not applied, the vibration must be measured using the most appropriate measurement code for the machinery concerned.
The operating conditions of the machinery during measurement and the measurement codes used must be described.
Finally, also in Annex VII – Technical File for Machinery the Machinery Directive refers indirectly to vibration tests, including them within the tests that the manufacturer is generally obliged to carry out before placing the machine on the market or putting it into service:
1️ Technical file for machinery:
Part A of this annex describes the procedure for compiling a technical file. The technical file must demonstrate that the machinery complies with the requirements of this Directive. It must cover the design, manufacture and operation of the machinery to the extent necessary for this assessment. […]
1️ The technical file shall comprise the following:
1️ a) a construction file including:
[…]
— full detailed drawings, accompanied by any calculation notes, test results, certificates, etc., required to check the conformity of the machinery with the essential health and safety requirements,
— the documentation on risk assessment demonstrating the followed procedure, including:
1️ i) a list of the essential health and safety requirements which apply to the machinery,
1️ ii) the description of the protective measures implemented to eliminate identified hazards or to reduce risks and, when appropriate, the indication of the residual risks associated with the machinery, […]
— any technical report giving the results of the tests carried out either by the manufacturer or by a body chosen by the manufacturer or his authorised representative […]
The manufacturer of the machine or vibrating equipment is therefore obliged to provide information on the vibrations emitted by its products, and does so by including it in the UMM (Use and Maintenance Manual) as indicated in the Machinery Directive.
The Reference Standards for Vibrations
As with noise testing, Vibration tests are assigned to experienced personnel who are able to carry out the instrumental tests according to the reference standards, so that they are carried out in a manner that pursues the presumption of conformity. Standards relating to Vibrations include:
- UNI EN ISO 20643:2012 Mechanical vibration – Hand–held and hand–guided machinery – Principles for evaluation of vibration emission
- UNI EN ISO 1032:2009 – Mechanical vibration – Testing of mobile machinery in order to determine the vibration emission value
- UNI EN ISO 7096:2009 – Earth–moving machinery – Laboratory evaluation of operator seat vibration
- UNI EN 13059:2008 – Safety of industrial trucks – Test methods for measuring vibration
- UNI EN 13490:2009 – Mechanical vibration – Industrial trucks – Laboratory evaluation and specification of operator seat vibration.
Vibration Tests and Trials
Vibration tests are equipment tests that measure the vibrations transmitted by a vibrating machine/equipment to the hand-arm system or the operator's whole body.
The vibrations emitted are measured according to test standards that take into account realistic operating conditions, i.e. measurement procedures carried out in the field under real working conditions, with operators standing or sitting depending on the type of machine/equipment, so that the results produced can be reproduced as accurately as possible. In this way, it is possible to take into account the effects of the mode of use in an appropriate manner.
The instruments that are used to carry out vibration tests include:
- the Accelerometer, is a device that is fixed to the vibrating surface and detects the oscillations coming from it, transforming them into electrical signals that are sent to a vibrometer for analysis
- the Vibrometer, is a portable device that receives the electrical signals transmitted by the accelerometer and processes them, also allowing a comparison between the measured values and the limit values in force.
All instrumentation used to carry out vibration tests must be calibrated before and after each series of measurements, calibrated every two years and comply with the relevant standards.
As is the case for noise, the technical documentation relating to vibrations must also be included in the machine/equipment's Technical File.
IMPORTANT
The reports of occupational illnesses attributable to physical agents made from 2012 to 2017 inclusive, clearly show that pathologies such as Carpal Tunnel Syndrome, Raynaud's Syndrome and Lumbar Disc Hernia can be traced back to mechanical vibrations transmitted to the hand-arm system or to the whole body, as a causal or concausal factor of the illness itself.
The better the manufacturer succeeds in eliminating/minimising the vibration risk at source, the less chance the operator will have of suffering from vibration-related health problems.
OTHER SPECIFIC TESTS
Depending on the type of machine or device, other tests, such as mechanical, welding, structural tests, etc., may also be necessary.
