SIST EN 792-7:2002+A1:2008
(Main)Hand-held non-electric power tools - Safety requirements - Part 7: Grinders
Hand-held non-electric power tools - Safety requirements - Part 7: Grinders
This European Standard applies to hand-held non-electric power tools driven by rotary or linear motors, powered by compressed air or hydraulic fluid and intended to be used by one operator and supported by:
- the operator's hand or hands;
- a harness;
- a suspension, e.g. a balancer.
This European Standard applies to hand-held non-electric power tools intended for grinding and cutting-off, with bonded, coated and super abrasive products for use on all kinds of materials.
This European Standard lists the significant hazards caused by such power tools and specifies safety requirements valid for different aspects of safety during their foreseeable lifetime.
This part of the standard covers power tools used with:
- abrasive products with a peripheral operating speed less than or equal to 80 m/s;
- cutting-off wheels with a peripheral operating speed less than or equal to100 m/s;
- abrasive products with outside nominal diameter less than or equal to 230 mm;
- cutting-off wheels with outside nominal diameter less than or equal to 300 mm;
- wire brushes.
This Part of the standard does not apply to:
- die grinders with collets which are treated in EN 792-9;
- polishers and sanders which are treated in EN 792-8;
- cutting-off machines used for construction, rescue purposes which are driven by an internal combustion engine which are treated in EN 1454.
There are no grinders covered by this Part of this European Standard driven by internal combustion engines.
Typical abrasive products used together with hand-held grinders are listed in annex C.
Special requirements and modifications on a hand-held power tool for the purpose of mounting it in a fixture are not covered by this part.
NOTE At the date of publication no grinders driven by internal combustion engines are known.
Handgehaltene nicht-elektrisch betriebene Maschinen - Sicherheitsanforderungen - Teil 7: Schleifmaschinen für Schleifkörper
Diese Europäische Norm gilt für handgehaltene nicht-elektrisch betriebene Maschinen, die durch Motore mit drehender oder linearer Bewegung angetrieben werden, wobei die Energie aus Druckluft oder über Hydaulik-flüssigkeit bezogen werden kann. Die Maschinen sind dazu bestimmt, durch eine Person verwendet und
- mit einer oder beiden Händen gehalten,
- in einer Einspannvorrichtung aufgenommen,
- in einer Halterung, z. B. Aufhängevorrichtung, aufgenommen
zu werden.
Diese Europäische Norm gilt für handgehaltene nicht-elektrisch betriebene Maschinen zum Schleifen und Trennen, mit gebundenen, beschichteten und Hochleistungs-Schleifkörpern für alle Materialarten.
Diese Europäische Norm listet die wesentlichen, von diesen Maschinen ausgehenden Gefährdungen auf und beschreibt die besonderen Sicherheitsanforderungen für die verschiedenen Sicherheitsaspekte während ihrer vorhersehbaren Lebensdauer.
Handgehaltene Maschinen, die in diesem Teil der Norm behandelt werden:
- Schleifmaschinen für Schleifkörper mit Umfangsgeschwindigkeit von 80 m/s oder weniger;
- Trennscheiben mit Umfangsgeschwindigkeit von 100 m/s oder weniger;
- Schleifkörper mit äußeren Maßen von 230 mm Durchmesser oder weniger;
- Trennscheiben mit äußeren Maßen von 300 mm Durchmesser oder weniger;
- Maschinen mit Drahtbürsten.
Diese Europäische Norm gilt nicht für:
- Schleifmaschinen für Schleifstifte, siehe EN 792-9;
- Schleifmaschinen für Schleifblätter und Polierer, siehe EN 792-8;
- Trennschleifmaschinen für das Bau- oder Rettungswesen, die durch einen Verbrennungsmotor angetrie-ben werden, siehe EN 1454.
Diese Europäische Norm gilt nicht für Schleifmaschinen für Schleifkörper, die durch einen Verbrennungsmotor angetrieben werden.
Typische Schleifprodukte, die zusammen mit handgehaltenen Schleifmaschinen verwendet werden, sind in Anhang C aufgelistet.
(....)
Machines portatives à moteur non électrique - Prescriptions de sécurité - Partie 7: Meuleuses
Neelektrična ročna orodja - Varnostne zahteve - 7. del: Brusilniki
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 792-7:2002+A1:2008
01-november-2008
1HHOHNWULþQDURþQDRURGMD9DUQRVWQH]DKWHYHGHO %UXVLOQLNL
Hand-held non-electric power tools - Safety requirements - Part 7: Grinders
Handgehaltene nicht-elektrisch betriebene Maschinen - Sicherheitsanforderungen - Teil
7: Schleifmaschinen für Schleifkörper
Machines portatives à moteur non électrique - Prescriptions de sécurité - Partie 7:
Meuleuses
Ta slovenski standard je istoveten z: EN 792-7:2001+A1:2008
ICS:
25.140.10 3QHYPDWLþQDRURGMD Pneumatic tools
SIST EN 792-7:2002+A1:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 792-7:2002+A1:2008
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SIST EN 792-7:2002+A1:2008
EUROPEAN STANDARD
EN 792-7:2001+A1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2008
ICS 25.140.99; 25.140.10 Supersedes EN 792-7:2001
English Version
Hand-held non-electric power tools - Safety requirements - Part
7: Grinders
Machines portatives à moteur non électrique - Prescriptions Handgehaltene nicht-elektrisch betriebene Maschinen -
de sécurité - Partie 7: Meuleuses Sicherheitsanforderungen - Teil 7: Schleifmaschinen für
Schleifkörper
This European Standard was approved by CEN on 3 November 2001 and includes Amendment 1 approved by CEN on 23 July 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 792-7:2001+A1:2008: E
worldwide for CEN national Members.
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .6
3 Terms and definitions .7
3.1 General terms and definitions.7
3.2 Terms and definitions related to grinders.7
4 List of significant hazards .9
5 Safety requirements and measures.10
Mechanical safety .10
5.1
5.2 Thermal safety.12
5.3 Noise .13
5.4 Vibration .13
5.5 Materials and substances processed, used or exhausted.14
5.6 Ergonomics .14
5.7 Safety related measures and means.15
6 Information for use .15
6.1 Marking, signs and written warnings.15
6.2 Instruction for use .16
7 Verification .20
7.1 Noise .20
7.2 Vibration .20
7.3 Test of deformation of flanges .20
7.4 Test of guards .21
7.5 Unintentional start .22
7.6 Structure of verification of safety requirements .23
Annex A (informative) Examples of grinders covered by this standard.24
Annex B (informative) Symbols for labels and signs .25
Annex C (informative) List of abrasive products for hand-held grinders.26
Annex D (normative) Design, material and thickness of guards .31
Annex E (informative) Example of calculating procedure of clamping force .36
Annex F (informative) Example of flanges.40
Annex ZA (informative) !Relationship between this European Standard and the Essential
Requirements of EU Directive 98/37/EC".45
Annex ZB (informative) !Relationship between this European Standard and the Essential
Requirements of EU Directive 2006/42/EC".46
Bibliography .47
2
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
Foreword
This document (EN 792-7:2001+A1:2008) has been prepared by Technical Committee CEN/TC 255 "Hand-
held non-electric power tools - Safety", the secretariat of which is held by SIS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by March 2009, and conflicting national standards shall be withdrawn at
the latest by December 2009.
This document includes Amendment 1, approved by CEN on 2008-07-23.
This document supersedes !EN 792-7:2001".
The start and finish of text introduced or altered by amendment is indicated in the text by tags ! ".
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s).
!For relationship with EU Directive(s), see informative Annexes ZA and ZB, which are integral parts of this
document."
The "European Committee of Manufacturers of Compressors, Vacuum Pumps and Pneumatic Tools",
PNEUROP, has given substantial contributions to this standard.
The standard has been created in close co-operation with CENELEC/TC 61F with the aim of achieving
requirements for mechanical safety in the EN 50144 series, which are similar for hand-held electric and non-
electric power tools.
NOTE Other technical committees in CEN dealing with hand-held power tools have been asked to follow the safety
requirements as in EN 792.
The annexes to this part of the standard are:
Annex A (informative) Examples of grinders covered by this standard
Annex B (informative) Symbols for labels and signs
Annex C (informative) List of abrasive products for hand-held grinders
Annex D (normative) Design, material and thickness of guards
Annex E (informative) Example of calculating procedure of clamping force
Annex F (informative) Example of flanges
!Annexes ZA and ZB" (informative) Relationship of this European Standard with EC Directives.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.
3
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
Introduction
This European standard is a type C standard as stated in EN 1070.
The machinery concerned and the extent to which hazards, hazardous situations and events are covered are
indicated in the scope of this standard.
When provisions of this type C standard are different from those which are stated in type A or B standards, the
provisions of this type C standard take precedence over the provisions of other standards, for machines that
have been designed and built according to the provisions of this type C standard.
EN 792 consists of a number of independent parts for individual types of hand-held non-electric power tools.
Other European Standards deal with safety rules for hand-held power tools used in e.g. the following fields:
agriculture and forestry such as chain saws, hedge-trimmers, brush cutters, grass trimmers;
construction and building such as cutting-off power tools, concrete vibrators;
food industry, such as fowl secateurs, sheep shears.
Endeavours have been made to achieve co-ordination with the relevant Technical Committees so that the
safety requirements are compatible.
This standard is divided in the following Parts:
Part 1: Assembly power tools for non-threaded mechanical fasteners (former Part 14)
Part 2: Cutting-off and crimping power tools (former Part 15)
Part 3: Drills and tappers
Part 4: Non rotary percussive power tools
Part 5: Rotary, percussive power drills
Part 6: Assembly power tools for threaded fasteners
Part 7: Grinders
Part 8: Sanders and polishers
Part 9: Die grinders
Part 10: Compression power tools
Part 11: Nibblers and shears
Part 12: Small circular, small oscillating and reciprocating saws
Part 13: Fastener driving tools
Certain Parts of EN 792 cover hand-held non-electric power tools, driven by internal combustion engines
powered by gaseous or liquid fuel. In these parts, the safety aspects relating to internal combustion engines
are found in a normative annex.
The Parts are type C standards and refer to pertinent European Standards of type A and B where such
standards are applicable.
4
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
1 Scope
This European Standard applies to hand-held non-electric power tools driven by rotary or linear motors,
powered by compressed air or hydraulic fluid and intended to be used by one operator and supported by:
the operator's hand or hands;
a harness;
a suspension, e.g. a balancer.
This European Standard applies to hand-held non-electric power tools intended for grinding and cutting-off,
with bonded, coated and super abrasive products for use on all kinds of materials.
This European Standard lists the significant hazards caused by such power tools and specifies safety
requirements valid for different aspects of safety during their foreseeable lifetime.
This part of the standard covers power tools used with:
abrasive products with a peripheral operating speed less than or equal to 80 m/s;
cutting-off wheels with a peripheral operating speed less than or equal to100 m/s;
abrasive products with outside nominal diameter less than or equal to 230 mm;
cutting-off wheels with outside nominal diameter less than or equal to 300 mm;
wire brushes.
This Part of the standard does not apply to:
die grinders with collets which are treated in EN 792-9;
polishers and sanders which are treated in EN 792-8;
cutting-off machines used for construction, rescue purposes which are driven by an internal combustion
engine which are treated in EN 1454.
There are no grinders covered by this Part of this European Standard driven by internal combustion engines.
Typical abrasive products used together with hand-held grinders are listed in annex C.
Special requirements and modifications on a hand-held power tool for the purpose of mounting it in a fixture
are not covered by this part.
NOTE At the date of publication no grinders driven by internal combustion engines are known.
5
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text, and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of the publications referred to
in this European Standard are valid only when they are incorporated in this standard by amendment or
revision. For undated references the latest edition of the publication referred to, applies (including
amendments).
EN 292-1:1991, Safety of machinery - Basic concepts, general principles for design – Part 1: Basic
terminology, methodology.
EN 292-2:1991, Safety of machinery - Basic concepts, general principles for design – Part 2: Technical
principles and specifications.
EN 563, Safety of machinery - Temperatures of touchable surfaces - Ergonomics data to establish
temperature limit values for hot surfaces.
CR 1030-1, Hand-arm vibrations - Guidelines for vibration hazards reduction – Part 1: Engineering methods
by design of machinery.
EN 1127-1, Explosive atmospheres – Explosion prevention and protection – Part 1: Basic concepts and
methodology.
EN 10111, Continuously hot-rolled low carbon sheet and strip for cold bending - Technical delivery conditions.
EN 10130, Cold rolled low carbon steel flat products for cold forming - Technical delivery conditions.
EN 12096, Mechanical vibration - Declaration and verification of vibration emission values.
EN 28662-1, Hand-held portable power tools - Measurement of vibration at the handle – Part 1: General
(ISO 8662–1:1998).
EN ISO 4871, Acoustics - Declaration and verification of noise emission values of machinery and equipment.
EN ISO 8662-4, Hand-held portable power tools - Measurement of vibration at the handle – Part 4: Grinders.
EN ISO 11688-1, Acoustics - Recommended practice for the design of low-noise machinery and equipment –
Part 1: Planning (ISO/TR 11688-1:1995).
EN ISO 11688-2, Acoustics - Recommended practice for the design of low-noise machinery and equipment –
Part 2: Introduction to the physics of low-noise design (ISO/TR 11688-2:1998).
EN ISO 14163, Acoustics - Guidelines for noise control by silencers (ISO 14163:1998).
!EN ISO 15744:2008, Hand-held non-electric power tools – Noise measurement code – Engineering
method (grade 2) (ISO 15744:2002)."
ISO 525, Bonded abrasive products - General requirements.
6
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1 General terms and definitions
3.1.1
hand-held power tool
machine driven by rotary or linear motors powered by compressed air, hydraulic fluid, gaseous or liquid fuel,
electricity or stored energy (e.g. by a spring) to do mechanical work and so designed that the motor and the
mechanism form an assembly that can easily be brought to its place of operation. The hand-held power tool is
operated by one or two hands
NOTE Hand-held power tools driven by compressed air or gas are called pneumatic tools. Hand-held power tools
driven by hydraulic liquid are called hydraulic tools.
3.1.2
rotary power tool
hand-held power tool the machine spindle of which rotates
3.1.3
inserted tool
tool inserted in the hand-held power tool to perform the intended work
3.1.4
service tool
tool intended for performing maintenance or service on the hand-held power tool
3.1.5
control device
device to start and stop the hand-held power tool or to change the direction of the rotation or to control the
functional characteristics such as speed and power
3.1.6
maximum operating pressure
maximum pressure that a hand-held power tool may be operated at, as specified by the manufacturer
3.2 Terms and definitions related to grinders
3.2.1
grinder
power tool driving a rotating spindle on which an abrasive product is mounted
NOTE A grinder equipped with a cutting off wheel is often called a cutting off machine.
3.2.2
machine spindle
shaft of the grinder which supports, locates and drives the abrasive product
3.2.3
rated speed, r/min
maximum rotational speed of the machine spindle, in revolutions per minute under operating conditions with
the abrasive product mounted and at the upper limit of the energy supply, e.g. pressure or flow, as specified
by the manufacturer
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
3.2.4
maximum operating speed
maximum peripheral speed of an abrasive product, given in m/s, as specified by the manufacturer of the
abrasive product
3.2.5
flange
disc, normally of metal, mounted on the machine spindle to support and clamp the abrasive product
3.2.6
flange set
means provided to clamp an unthreaded abrasive product, on the rotating machine spindle
3.2.7
backing flange
flange fixed to the machine spindle and having an unrecessed flat surface against which an abrasive product
is screwed, e.g. a cup wheel, a cone or a plug.
NOTE The terms backing, back flange or fixed flange are terms also used
3.2.8
flange contact diameter, d
f
outside diameter of the contact surface of a flange
3.2.9
guard
device which partly encloses the abrasive product
3.2.10
blotter
thin piece of a compressible material placed between the abrasive product and the flange of the grinder
3.2.11
tightening torque
torque for tightening the clamping device to fasten the abrasive product to the machine spindle
For other terms, see EN 1070 and also ISO 3857-3 and ISO 5391. For examples of grinders see annex A
8
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
4 List of significant hazards
The following significant hazards can occur in the use of grinders.
Table 1 — List of significant hazards
Significant hazard type Reference to safety requirement
By design or Information for
guarding use
4.1 Mechanical hazards
- cutting 5.1.1, 5.1.3
- drawing in or trapping (caused by hair, clothing etc. 5.1.6 6.2.2
getting entangled in a rotating power tool)
- friction or abrasion hazard 5.1.1
- loss of stability 5.1.2
- whipping hose 6.2.2
- ejection from high pressure hydraulic systems 5.1.4
- ejection of parts due to:
. cracked abrasive product 5.1.6 6.2.2
. incorrect mounting of the abrasive product 5.1.7, 5.1.8
. misuse of grinder 6.2.2
. overspeed of grinder 5.1.5
. use of incorrect flanges 5.1.9
. use of wrong abrasive product 6.2.2
- hose and hose coupling specifications 6.2.2
4.2 Electrical hazards 6.2.2
4.3 Thermal hazards 5.2
- explosions 6.2.2
- health damage due to hot or cold surfaces 5.2
4.4 Hazards caused by noise 5.3 6.2.2
4.5 Hazards generated by vibration 5.4 6.2.2
4.6 Hazards generated by materials and substances
processed, used or exhausted
- inhalation of harmful dust 5.5.2
- formation of explosive dust 6.2.2
- sparks 6.2.2
- exhaust air 5.5.1 6.2.2
- lubricants 5.5.3
- hydraulic fluid 6.2.2
4.7 Hazards caused by neglecting ergonomic principles
- repetitive strain injuries 5.6.1 6.2.2
- unsuitable postures 5.6.1, 5.6.2, 5.6.3,
- inadequate grip design and tool balance 5.6.1 6.2.2
- neglected use of personal protection equipment 5.6.1 6.2.2
4.8 Hazards caused by failure of energy supply
- unexpected return of energy supply after a breakdown 6.2.2
- incorrect hydraulic fluid flow and outlet pressure 6.2.2
4.9 Hazards caused by missing and/or incorrectly
positioned safety related means
- start and stop device 5.7.1
- unintentional start 5.7.2 6.2.2
9
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
5 Safety requirements and measures
5.1 Mechanical safety
5.1.1 Surfaces, edges and corners
Accessible parts of the power tool, except the insert tool, shall not have sharp edges or angles or rough or
abrasive surfaces, see 3.1 of EN 292-2:1991.
5.1.2 Supporting surface and stability
The power tool shall be so designed that it can be laid aside and remain in stable position on a plane surface.
5.1.3 Run-down time
The run-down time, after the stop command has been given, shall be as short as possible.
5.1.4 High pressure ejection
Hydraulic systems of the power tool shall be enclosed so as to give protection against high pressure fluid
ejection.
5.1.5 Speed control
The rated speed of the grinder shall not be exceeded under the conditions marked on the power tool. It shall
be possible to measure rotational speed by a tachometer.
At no load, the speed may exceed the rated speed by no more than 10 % at rated input values and with an
unworn wheel mounted.
The speed control device of a grinder shall be designed to prevent incorrect assembly. The speed control
device shall be manufactured of non-corrodable material.
5.1.6 Guards
Grinders shall be equipped with guards to protect against:
accidental contact with the abrasive product;
ejection of fragments of the abrasive product;
sparks and debris.
Guards are not mandatory, but recommended, for cones and plugs with the diameter less than 50 mm and for
wire brushes
For internal grinding guards are not needed.
The guards shall fulfil the following requirements:
be designed so that in case of an abrasive product burst the guard shall reduce the risk of injury to the
operator and remain attached to the grinder;
be located so that the risk of accidental contact between the operator and the abrasive product during
intended use is minimized;
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
the clearance between the inside of the guard and the periphery of a new abrasive product shall be:
max. 8 mm and min. 3 mm for nominal diameter ≤ 125 mm
max. 10 mm and min. 6 mm for nominal diameter > 125 mm
The design, material and thickness of guards is specified in annex D.
If the specification of design, material and thickness in annex D is not followed, the guard shall withstand the
test as specified in 7.4.
If other material than steel plate is used, it shall be equally suitable for all working conditions.
5.1.7 Attachment of abrasive product
The grinder shall be designed to prevent the abrasive product coming loose, for instance unscrewed by inertia
and spun off, after the stop comment has been given.
5.1.8 Spindles
Spindles shall be designed so that they locate the abrasive product. Machine spindles shall be made resistant
to impact.
The direction of the spindle threads shall be such that any clamping device, collet or wheel with threaded hole
shall tend to tighten during grinding.
Key
1 Machine spindle
2 Machine spindle with threads
Figure 1 — Maximum spindle run-out
For spindles, that locates a plain bore wheel, the diameter shall have the tolerance of concentricity of 0,05 mm
maximum total indicator reading to the true running centre of the spindle. See Figure 1.
For spindles with a threaded portion intended for locating abrasive products with threaded bores, the pitch
diameter of the thread shall have the tolerance of concentricity of effective diameter of 0,1 mm maximum total
indicator reading to the true axis of the spindle.
The diameter of the part, which locates the abrasive product shall have a tolerance of e8 or better.
For grinders intended to be used with threaded hole wheels, the manufacturer shall give information of the
spindle thread size on the grinder, preferably on the spindle.
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
5.1.9 Flanges
Flanges shall be designed that they clamp and locate each type of abrasive product securely to the grinder
and provide true running under operation.
Flanges shall be tested for deformation under load according to 7.3.
Annex E can serve as a base for the calculation of flanges and the tightening torque.
Annex F gives the principle design of flanges and will at the revision be completed with calculated dimensional
values.
Flanges in a set shall have the same contact diameter and shall have equal contact surface, except for
abrasive products of types 27, 28 and 42 which are allowed to use a backing flange with a diameter larger
than that of the clamping nut, see Figures F.7 a) and F.7 b).
For grinding wheel type 41 the flanges shall have the same external diameter and the backing flange may
have a larger contact surface than the outer flange. See Figure F.7 c).
Backing flanges (normally fixed) may have a larger contact surface than the outer flange if this arrangement
fulfils the requirement of absorbing the grinding forces (type S 6 and 11) See Figure F.3.
All flanges shall have a chamfer or recess around the centre hole to prevent pieces of the abrasive product
from splintering due to high edge pressure arising when clamping it. See Figure 2. Backing flanges to be used
with threaded bore abrasive products shall not be recessed, unless the abrasive product has a riveted anchor
plate. See Figures F.4 and F.5.
Key
1 chamfer or recess
Figure 2 — Example of chamfer or recess on a flange
At least one of the flanges shall be keyed, screwed, shrunk or otherwise secured to prevent rotation relative to
the machine spindle.
The contact surface of the flanges (both set of flanges and backing flanges) shall run true with a tolerance
giving a total indicator reading of max. 0,1 % of the diameter at the position of the indicator. The indicator shall
be positioned near the outside diameter.
2
The steel in the flanges shall have a minimum tensile strength of 430 N/mm . Other materials may be used, in
which case the flange shall be tested and fulfil the requirement of clause 7.3.
The part of the flanges which locates and guides the abrasive products with unthreaded holes shall have the
same tolerances as specified in 5.1.8.
5.2 Thermal safety
Parts of the grinder which are held during use or can be inadvertently touched shall follow the provisions of
EN 563.
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SIST EN 792-7:2002+A1:2008
EN 792-7:2001+A1:2008 (E)
Low temperatures shall be avoided by design.
NOTE The limit values for low temperatures are studied by CEN/TC 122.
Power tools for use in potentially explosive atmospheres should comply with EN 1127-1. However because
the suitability of a power tool for use in potentially explosive atmospheres will depend not only on the power
tool but the inserted tool and the workpiece, it is not possible to give any detailed advice in this st
...
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