“Methodology for the specification of safety requirements during the design and manufacture of machinery for wood processing”
1. Documents applicable to requirements concerning wood processing machines
A schematic reference to the applicable documents containing safety requirements for the design and manufacture of wood processing machinery are presented in a graph in Figure 1.
Fig.1 Legal documents and standards applicable to evaluations of compliance, for wood processing machinery, with essential safety and health requirements.
These documents include the European Union Directive (implemented in Poland as Regulations) and harmonised standards of type A, B and C. Recommendations (RfU) must also be mentioned, wherein certain practical problems are taken into consideration during the assessment of machinery conformity. The VG1 Group develops such recommendations specifically for wood processing machinery. The basis for conformity assessment of machinery is the risk assessment, especially when there are no specific risk requirements pertaining to an important aspect.
2. Priority for requirements of directives and standards
The safety requirements pertaining to the same topics are defined in various legal documents and standards. In determining which of these requirements are to be applied, the following principles must be followed:
1. The basic reference document for wood processing machinery is the 2006/42/EC Directive (implemented in the Polish legal system by regulations);
2. Additional directives pertaining to machines for wood processing are the 2004/108/EC Directive on electromagnetic compatibility and, as regards some machinery used outdoors, the 200/14/EC Directive on noise emissions by equipment operated outdoors;
3. The requirements of the directive are presented in detail in harmonised standards which, however, are not obligatory. Therefore their application depends on the decision of the manufacturer;
4. If harmonised standards are not used, the assessment of conformity of the machine with essential safety requirements is based on risk assessment;
5. If harmonised standards are applied, the requirements set out in type C standards shall have priority;
6. In the absence of type C standards, type A and type B standards shall be used. The requirements of type B standards shall have priority over the requirements of type A standards (in the extent of these standards).
3. Machine type (fixed, transportable, portable or hand-held)
Depending on the machine type, different harmonised standards shall be used. For machinery of:
§ stationary and transportable types – type C standards are used for those machines for which such standards have been developed (standards and series of standards):
- EN 848 for routing machines;
- EN 859; EN 860; EN 861 for planing machines;
- EN 940 for combined woodworking machines;
- EN 1218 for tenoning machines;
- EN 1807 for band sawing machines;
- EN 1870 for circular sawing machines;
- EN 12750 for four sided routing (planing) machines;
- EN 691 used for other stationary and transportable woodworking machinery.
The arrangement of content and the scope of requirements mentioned above in type C standards is usually identical or very similar and covers, among others, the list of significant risks and safety requirements pertaining to:
- Machine control system: reliability (PL safety assurance level), relative to all safety features implemented in the machine, which are listed in each of these standards, as well as the proper placement of controls. It also includes requirements pertaining to the failure of electrical and pneumatic power supplies. Note: As regards the labeling of controls, the PN-EN 60204-1 standard should be followed.
- Protection against mechanical hazards, including: ensuring the stability of the machine, proper design, mounting and replacement of the cutting tool, maximum stopping time and requirements for the braking system, requirements for the table and guides for the workpiece, the recommended design and strength parameters of covers for the drives and working area of the machine as well as reliable and safe mounting of the workpiece or the safety equipment used during manual feeding of the workpiece.
- Protection against non-mechanical hazards, including: fire, noise, emission of chips and dust, shock by the electrical system and static electricity, electromagnetic interference, laser radiation, hazards related to the pneumatic system of the machine. This section also discusses the effects of assembly errors and requirements pertaining to power supply disconnection and machine maintenance.
- Information on the use of the machine, including: machine labeling (the required content, symbols and language of labels, the recommended labeling methods and life of labeling), as well as formal and substantive requirements, including providing the detailed contents of the operating instructions. In accordance with these, the instructions prepared by the machine manufacturer should include among others:
- the repetition of labeling, pictograms and other instructions placed on the machine;
- information on the use of the machine, including reasonably foreseeable misuse and a list of additional machine equipment that can be used for specific applications;
- information and warnings about the need to reduce the hazards of inhaling harmful dusts (e.g. by wearing masks), wearing hearing protectors to protect against hearing loss, etc.;
- instructions for the installation and removal of damaged parts and accessories;
- instructions to ensure stability of the machine during processing;
- information about recommended cutting tools, their type and condition, and acceptable speeds;
- acceptable types and dimensions of the workpiece;
- instructions for proper training of operators in using, setting, and operating the machine;
- guidelines for general or local lighting, and the use of lasers;
- the required technical parameters for suitable equipment for the removal of chips and dust;
- instructions for maintenance and cleaning;
- a method for safely dissipating residual energy from the pneumatic system;
- methods and intervals for checking the machine’s safety devices;
- a declaration on the machine’s noise emissions in the air.
Annexes to standards include descriptions and illustrations presenting experimental methods for testing whether the machine satisfies safety requirements — for example, noise or stability, or for testing machine assemblies or parts of key importance to safety, such as: tool covers, guides, brakes, tool spindles, clamping devices. These tests (static or dynamic in nature) use measurements of physical quantities, such as time, force, geometric quantities or quality assessment (such as condition of the cover after an impact performed as part of an impact test).
§ portable – the EN 61029-1 and standards in the EN 61029-2 series shall be applied.
The EN 61029-1 standard covers portable machines driven by an electric motor or magnetically, intended for use indoors and outdoors, that can be easily carried by one person. These machines can, additionally, be provided with handles or wheels for easier transport, used under the supervision of the operator in a safe, stable position without fixing or after fixing. Such portable machines may not be used for continuous operation, nor used in a production line, and can be connected to the electricity grid with a flexible cable and a plug. The maximum power of portable machines is 4 kW with three phase alternating electric current up to 440 V, or 250 W with one phase alternating or direct current power supply with a maximum rated voltage of up to 250 V. The scope of shared requirements, covered in EN 61029-1 , includes: markings and information attached to the machine, protection against electrical shock, requirements pertaining to startup, power and current intake, heating, leakage current, environmental requirements (dust and noise), IP degree of protection against moisture and against access of foreign solid objects, insulation resistance and electric strength, resistance under conditions of continuous operation and abnormal conditions, stability, protection against mechanical hazards, mechanical strength, requirements pertaining to the design of important mechanical and electrical parts, resistance to high temperatures, heat, creeping currents and corrosion. It is also required that they do not emit harmful radiation. The standard also includes a description of tests and drawings of equipment used for verification of requirements by measurements or experimentally.
The EN 61029-1 standard with shared requirements shall also be applied to detailed standards in the EN 61029-2 series pertaining to specific portable machines, referred to as tools in the standard. Examples of these tools include saws, band saws, planers, thickness planers, wood routing machines, etc. The detailed requirements of the standards in the EN 61029-2 series pertain, in particular, to design solutions of handles and covers of cutting tools and supports of the workpiece (tables and guides).
§ hand tools with electric drives are subject to the EN 60745-1 standard and standards in the EN 60745-2 series.
The EN 60745-1 standard defines the requirements pertaining to safe use of hand tools driven by an electric motor or driven magnetically with a rated voltage of up to 250 V of single phase alternating current, or direct current and 440 V of three phase current. Typical risks related to the use of hand tools are discussed, which may be encountered by all users during normal use and some foreseeable misuse of these tools. As regards hand tools with electric drives, similarly to portable machines, the EN 60745-1 general standard is used jointly with one of the detailed standards in the EN 60745-2 series, applicable to the hand tool in question. The topics covered in the EN 60745-1 standard, as well as the test methods and test equipment, are similar to those mentioned in the EN 61029-1 standard, with the exception of the requirements of stability, which are not included in the EN 60745-1 standard. Standards in the EN 60745-2 series provide more details to the requirements of the EN 60745-1 standard, in particular as regards protection against mechanical hazards.
Inclusion of a particular machine in a specific type is decided according to how machine types are defined:
- stationary machine – machine designed to be set on the ground or fixed to the ground or other parts of the building structure and remaining stationary during use.
- transportable machine – machine set on the ground, stationary during use, and provided with devices, usually wheels, for moving it.
- portable machine – machine installed on a table intended for stationary work which can be carried by a single person. The table can also be an integral part of the machine, if it has foldable, hinged legs.
- manual tool with electric drive – a machine held and guided manually during use.
4. Place of use of the machine (indoors or outdoors)
For some machines intended for outdoor use, the 2000/14/EC directive is also applicable. It mentions two types of woodworking machinery which, in accordance with Article 13, are subject only to noise marking. These include:
§ band-sawing machines for construction purposes
§ table circular saw machines for construction purposes
For these machines the measurement should be performed using the method described in EN ISO 3744: 1995. The tests should be performed under load.
The measuring surface, the number of microphone positions and the measuring distance should conform with ISO 7960:1995:
§ appendix J (only item J2 letter b)) – band sawing machines
§ appendix A (only item A2 letter b)) – circular sawing machines
An example of machine labeling is shown in Figure 2.
Fig. 2 An example of machine labeling according to directive 2000/14/EC.
5. Machine mentioned (or not mentioned) in Annex IV to the 2006/42/EC Directive
Annex no. IV to the 2006/42/EC directive mentions the following woodworking machinery:
1. Circular saws (single and multiple ones) for processing of wood and similar materials or for processing of meat and similar materials, of the following types:
1.1. Sawing machinery with blade(s) remaining in a fixed position during cutting, having a fixed table or support with manual feed of the workpiece or with a demountable power feed;
1.2. Sawing machinery with blade(s) remaining in a fixed position during cutting, equipped with a manually operated table or a carriage performing reciprocating movements;
1.3. Sawing machinery with blade(s) remaining in a fixed position during cutting, with a built-in mechanical device for the work-pieces, and manual loading and/or unloading;
1.4. Sawing machines with blade(s) moving during cutting, with a mechanical drive for blade movement, and manual loading and/or unloading.
2. Hand-fed surface planing machines for woodworking.
3. Thicknessers for one side dressing of wood, with a built-in feeding mechanism and manual loading and/or unloading.
4. Band-saws with manual loading or unloading for working with wood and analogous materials or for working with meat and analogous materials, of the following types:
4.1. Sawing machines with blade(s) remaining in a fixed position during cutting, equipped with a fixed table, or a table or support for the workpiece performing reciprocating movements;
4.2. Sawing machines where the blade(s) is/are mounted on a carriage performing reciprocating movements.
5. Combined machines of the types referred to in 1 to 4 and 7 for working with wood and analogous materials.
6. Hand-fed tenoning machines with several tool holders for woodworking.
7. Hand-fed vertical spindle moulding machines for working with wood and analogous materials (vertical bottom moulding machines).
For machines that were manufactured in accordance with harmonised standards and when the standards include all the relevant essential requirements for health and safety, the following apply:
a) conformity assessment procedure connected with internal control of machine manufacture; or
b) EC type examination procedure with internal control of machine manufacture; or
c) full quality assurance procedure.
If the machine has not been manufactured in accordance with harmonised standards, or only partly in accordance with such standards, or if the harmonised standards do not cover all the relevant essential requirements for health and safety, or if no harmonised standards exist for a given machine, one of the following procedures is used:
a) EC type examination procedure with internal control of machine manufacture;
c) full quality assurance procedure.
For other woodworking machinery not mentioned in Annex no. IV, a conformity assessment procedure connected with internal control of machine manufacture.
The conformity assessment procedure connected with internal control of machine manufacture can be carried out by the manufacturer themselves, whereas a notified body must be involved in the EC-type examination procedure and the full quality assurance procedure.
6. A machine, for which a type C harmonised standard was developed
Compliance with all requirements of type C standards indicated presumes compliance of the requirements of the directive with which the standard is harmonized. However, it must be checked whether the standard includes annotations pertaining to issues which the standard does not cover, and, if required, a supplementary assessment of conformity must be performed.
Although the use of standards is not mandatory, in practice it is the easiest way to achieve compliance with the essential safety requirements.
If certain technical solutions in the machine were not resolved in accordance with the requirements of the type C standard, the manufacturer (or the notified body for machines included in Annex IV of directive 2006/42/EC) must verify that the solution adopted does not increase the level of occupational risk, in comparison to solutions provided in the standard. Risk assessment is preformed for this purpose.
7. The use of requirements of standards of type A and B in the absence of requirements of type C standards
If there is no type C standard for a particular woodworking machine, the assessment is performed according to the EN ISO 12100 standard, or depending on the type of machine, according to the EN 691; EN 61029-1 or EN 60745-1 standard. During the assessment, a risk assessment is performed, and, if required, assessment according to type B standards, for example pertaining to covers, safe distances, hydraulic systems, etc.
8. Application of recommendations (RfU)
Recommendations for woodworking machinery are developed by the VG1 group, which associates bodies notified for carrying out conformity assessments of woodworking machinery in the EU. The purpose of recommendations is to establish a joint position in the event of ambiguities or uncertainties pertaining, in particular, to interpretation of some safety requirements of harmonised standards or the machine directive.
The agreed and approved recommendations are also available at the EU web sites so they can also be used by manufacturers of woodworking machines.
9. Practical procedure for machine conformity assessment
During the machine assessment procedure, usually performed using checklists developed on the basis of the Machine Directive and the standards harmonised with it, the procedure is as follows:
1. if a type C harmonised standard exists – assessment according to the standard, and then assessment of compliance with essential safety requirements according to the Machine Directive
2. if a type C harmonized standard does not exist – assessment according to type A standard, taking into account the requirements of applicable type B standards, and the applicable recommendations (RfU), and then assessment of compliance with essential safety requirements according to the Machine Directive
In both cases the assessment basis should be the risk assessment; the initial stage of this assessment consisting in identifying the risks and, in particular, the significant risks.
In the first case, when the type C standard exists, the identification of hazards and protective measures is already provided in the standard.
10. The priority of actions taken by the manufacturer (the safety triad)
Following the risk assessment, the manufacturer of the machine should take action to ensure that the machine satisfies the essential safety requirements defined in the 2006/42/EC directive (and other directives pertaining to the machine).
The sequence of taking these actions should be as follows:
1. Reducing the risk at the source. Attempting to build an inherently safe machine. Eliminating risks, or risk reduction resulting directly from the machine design.
2. Using technical safeguards, i.e. covers, safety devices and complementary protective measures.
3. Preparing information for the machine user concerning the residual risk which was not eliminated. Such information can be presented in the operating instructions and directly as labeling on the machine or its packaging.
Selected nonconformity examples.
Case study no. 1. Inability to lock the power disconnector of the woodworking machine.
Description
The isolating disconnector installed in the machine (Fig. 1) cannot be locked in the disconnected position (0).
Fig.1 The isolating disconnector of the woodworking machine which cannot be locked in the disconnected position..
Nonconformity with:
§ 1.6.3. Isolation of energy sources
Machines must be equipped with devices disconnecting them from all power sources. Such devices must be clearly labeled. It must be possible to lock them if reconnection could endanger exposed persons. Also, the isolator must be capable of being locked in situations where an operator is unable, from any of the points to which he has access, to check that the energy is cut off.
The 2006/42/EC Directive
Preventive actions
Replacement of the disconnector with a different type, which can be locked in the (0) position.
Case study no. 2. Inability to lock the power disconnector of the woodworking machine.
Description
The suction connection in the cover of the wood routing machine (Fig. 2a), in the event it is not connected to the chips and dust extraction, allowed free access to the tool, e.g. during repairs or maintenance.
Fig. 2 Suction connection in the cover of the cover of the wood routing machine.
Nonconformity with:
§ 1.4.1. General requirements
Guards and protective devices:
- must be located at an adequate distance from the danger zone,
The 2006/42/EC Directive
§ 4.2.4.1 reaching through holes of regular shape – persons of more than 14 years of age
PN-EN ISO 13857: 2010 Safety of machinery – Safety distances to prevent hazard zones being reached by upper and lower limbs
Preventive actions
A barrier was added in the form of a rod welded inside the suction connection, preventing reaching with the hand or fingers into the hazard zone (of the cutting tool).
Case study no. 3. Inadequate locking device in the cover of the band sawing machine for wood
Description
In the cover of the band saw wheels of the band sawing machine, a limit switch was installed interlocked with the sawing machine drive (Figure 3a), which shuts down the drive if the cover is opened when the sawing machine is running, and prevents starting the machine when the cover is open. However, this safety device can be easily bypassed (without tools), intentionally or unintentionally. It is enough to press and hold the limit switch with the hand and the sawing machine can be started with the START button, even though the cover is open, therefore causing a hazardous situation when access to the hazardous zone is not protected.
Fig. 3 Inadequate locking device in the cover of the band sawing machine for wood
Nonconformity with:
§ 1.4.1. General requirements
Guards and protective devices:
- may not be easy to bypass or render non-operational,
The 2006/42/EC Directive
Preventive actions
The solution was changed (Fig. 3b) in such a way that bypassing the interlock is not possible without intentional action (such as dismantling the cam or the limit switch).
Case study no. 4. Absence of the necessary equipment of the circular saw for wood
Description
The circular saw for wood, with a table, was equipped with a circular saw of standard size and a riving knife adequate for this saw. The sawing machine can also be used with saws of other thicknesses and outside diameters, which was described in detail in the operating instructions. No standard equipment is provided for the sawing machine.
Fig.4 Replaceable riving knives for different circular saws.
Nonconformity with:
§ 5.3.5 Devices reducing the possibility of kickback or reducing its effects.
The woodworking machine should be provided with parts, for mounting the riving knife, and riving knives adapted to the range of circular saws which can be used with the sawing machine
§ 5.3.9 Protective equipment
All woodworking machinery should be provided with an angled pusher or pusher handle stipulated for all machines. The woodworking machine should also be provided with a place for their storage.
EN 1870-19:2013 Safety of woodworking machines –Circular sawing machines – Part 1: Circular saw benches (with or without a movable table), edging saws and building site saws
Preventive actions
The standard equipment of the circular saw was supplemented with replaceable riving knives, covering the dimensional range of saws as well as the handle and pusher for material.