kSIST FprEN ISO 28881:2021

Machine tools - Safety - Electrical discharge machines (ISO/FDIS 28881:2021)

This document specifies safety requirements and/or protective measures applicable to EDM equipment and EDM systems intended to be adopted by persons undertaking their design, construction, installation and/or supply, such as:
—    manually controlled EDM die sinking or EDM drilling machines;
—    numerically controlled EDM die sinking or EDM drilling machines; and
—    numerically controlled EDM wire cutting machines.
This document also includes information to be provided by the manufacturer to the user.
This document is not applicable to arc eroding and electro-chemical machining equipment.
This document takes account of the precondition of the intended use as well as the reasonably foreseeable misuse, in normal workshop environments and non-explosive atmospheres, including transportation, installation, setting, maintenance, repair and dismantling for removal or disposal of EDM equipment and EDM systems.
This document is also applicable to auxiliary devices essential for EDM processing.
This document deals with all significant hazards, hazardous situations or hazardous events relevant to EDM equipment and EDM systems, where they are used as intended and under conditions of misuse which are reasonably foreseeable by the manufacturer (see Clause 4).
This document is intended to apply to machines manufactured after the date of publication of this document.
When requirements of this type-C standard are different from those which are stated in type-A or -B standards, the requirements of this type-C standard take precedence over the requirements of other standards for machines that have been designed and built according to the requirements of this type-C standard.
This document defines required performance level and safety categories of the safety-related parts of the control system for EDM equipment and EDM systems as defined in ISO 13849-1:2015.

Werkzeugmaschinen - Sicherheit - Funkenerodiermaschinen (ISO/FDIS 28881:2021)

Dieses Dokument legt die Sicherheitsanforderungen und/oder Schutzmaßnahmen fest, die auf EDM-Geräte und EDM-Systeme anwendbar sind und die von Personen zu beachten sind, die mit der Planung, dem Bau, der Installation und/oder der Lieferung dieser Geräte und Systeme betraut sind, wie beispielsweise
—   manuell gesteuerte EDM-Senkerodiermaschinen oder EDM-Bohrmaschinen;
—   numerisch gesteuerte EDM-Senkerodiermaschinen oder EDM-Bohrmaschinen; und
—   numerisch gesteuerte EDM-Drahterodiermaschinen.
Dieses Dokument enthält auch Informationen, die dem Anwender durch den Hersteller zur Verfügung gestellt werden müssen.
Das vorliegende Dokument gilt nicht für Maschinen zur Lichtbogenerosion und elektrochemischen Bearbeitungsmaschinen.
Dieses Dokument berücksichtigt die Voraussetzungen für die bestimmungsgemäße Verwendung sowie die vernünftigerweise vorhersehbare Fehlanwendung unter üblichen Werkstattbedingungen und in nicht explosionsfähiger Atmosphäre, einschließlich Transport, Installation, Einrichtung, Wartung, Reparatur und Demontage zur Entfernung oder Entsorgung von EDM-Einrichtungen und EDM-Systemen.
Dieses Dokument gilt auch für Zusatzeinrichtungen, die für die EDM-Bearbeitung erforderlich sind.
Dieses Dokument behandelt alle signifikanten Gefährdungen, Gefährdungssituationen oder Gefährdungsereignisse, welche im Zusammenhang mit EDM-Einrichtungen und EDM-Systemen, bei bestimmungsgemäßer Verwendung und bei Fehlanwendung, welche für den Hersteller vernünftigerweise vorhersehbar sind, stehen (siehe Abschnitt 4).
Das vorliegende Dokument gilt für Maschinen, die nach dem Ausgabedatum dieses Dokuments hergestellt wurden.
Wenn Anforderungen an diese Typ-C-Norm von jenen abweichen, die in Typ-A- oder Typ-B-Normen festgelegt sind, haben die Anforderungen dieser Typ-C-Norm Vorrang vor den Anforderungen anderer Normen für Maschinen, die nach den Anforderungen dieser Typ-C-Norm konstruiert und gebaut wurden.
Dieses Dokument definiert den erforderlichen Performance Level und die Sicherheitskategorien der sicherheitsrelevanten Teile des Steuerungssystems für EDM-Ausrüstungen und EDM-Systeme, wie in ISO 13849-1:2015 definiert.

Machines-outils - Sécurité - Machines d'électro-érosion (ISO/FDIS 28881:2021)

Le présent document spécifie les exigences de sécurité et/ou mesures de protection applicables aux équipements et aux systèmes d'usinage par électro-érosion, que doivent respecter les personnes chargées de la conception, de la construction, de l'installation et/ou de la fourniture, notamment:
—    les machines de forage par étincelage ou de perçage par électro-érosion à commande manuelle;
—    les machines de forage par étincelage ou de perçage par électro-érosion à commande numérique; et
—    les machines de découpe par électro-érosion à fil à commande numérique.
Le présent document contient aussi les informations fournies à l'utilisateur par le fabricant.
Le présent document ne s'applique pas aux machines d'érosion par arc électrique ni aux machines d'usinage électrochimique.
Le présent document tient compte des conditions préalables d'utilisation normale ainsi que du mauvais usage raisonnablement prévisible, en environnement industriel normal et sans atmosphère explosive, ce qui inclut le transport, l'installation, le réglage, la maintenance, la réparation et le démontage pour évacuation ou mise au rebut des équipements et des systèmes d'usinage par électro-érosion.
Le présent document s'applique également aux dispositifs auxiliaires essentiels au procédé d'usinage par électro-érosion.
Le présent document traite de l'ensemble des phénomènes dangereux significatifs, situations dangereuses ou événements dangereux liés aux équipements ou aux systèmes d'usinage par électro-érosion, dans les conditions d'utilisation normale ainsi que dans des conditions de mauvais usage raisonnablement prévisibles par le fabricant (voir Article 4).
Le présent document est applicable aux machines construites après sa date de publication.
Lorsque les dispositions de la présente norme de type C diffèrent de celles qui sont données dans les normes de type A ou B, les dispositions de la présente norme de type C ont priorité sur celles des autres normes, pour les machines conçues et construites conformément aux dispositions de la présente norme de type C.
Le présent document définit le niveau de performance exigé et les catégories de sécurité des éléments du circuit de commande liés à la sécurité pour les équipements et les systèmes d'usinage par électro-érosion, tels que définis dans l'ISO 13849-1:2015.

Obdelovalni stroji - Varnost - Elektroerozijski stroji (EDM) (ISO/FDIS 28881:2021)

General Information

• Status: Not Published
• Public Enquiry End Date: 29-Nov-2019
• ICS: 25.120.40 - Electrochemical machines
• Technical Committee: VSN - Safety of machinery
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 22-Jul-2022
• Due Date: 26-Sep-2022
• Directive: 2006/42/EC - Directive 2006/42/EC of the European Parliament and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC (recast)
• Mandate: M/396 - Mandate to CEN and Cenelec for standardisation in the field of machinery
• Ref Project: EN ISO 28881:2022 - Machine tools - Safety - Electrical discharge machines (ISO 28881:2022)

RELATIONS

• Revised: SIST EN ISO 28881:2013 - Machine tools - Safety - Electro discharge machines (ISO 28881:2013)
• Effective Date: 30-May-2018
• Revised: SIST EN ISO 28881:2013/AC:2013 - Machine tools - Safety - Electro-discharge machines - Technical Corrigendum 1 (ISO 28881:2013/Cor 1:2013)
• Effective Date: 30-May-2018
• Replaces: SIST EN ISO 28881:2013 - Machine tools - Safety - Electro discharge machines (ISO 28881:2013)
• Effective Date: 20-Jul-2022
• Replaces: SIST EN ISO 28881:2013/AC:2013 - Machine tools - Safety - Electro-discharge machines - Technical Corrigendum 1 (ISO 28881:2013/Cor 1:2013)
• Effective Date: 20-Jul-2022

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 28881:2019
01-november-2019

Obdelovalni stroji - Varnost - Elektroerozijski stroji (EDM) (ISO/DIS 28881:2019)

Machine tools - Safety - Electrical discharge machines (ISO/DIS 28881:2019)
Werkzeugmaschinen - Sicherheit - Funkenerodiermaschinen (ISO/DIS 28881:2019)
Machines-outils - Sécurité - Machines d'électro-érosion (ISO/DIS 28881:2019)
Ta slovenski standard je istoveten z: prEN ISO 28881
ICS:
25.120.40 Elektrokemijski stroji Electrochemical machines
oSIST prEN ISO 28881:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 28881:2019
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oSIST prEN ISO 28881:2019
DRAFT INTERNATIONAL STANDARD
ISO/DIS 28881
ISO/TC 39/SC 10 Secretariat: SNV
Voting begins on: Voting terminates on:
2019-09-20 2019-12-13
Machine tools — Safety — Electrical discharge machines
Machines-outils — Sécurité — Machines d'électro-érosion
ICS: 25.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 28881:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2019
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oSIST prEN ISO 28881:2019
ISO/DIS 28881:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
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Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 List of significant hazards ........................................................................................................................................................................... 6

5 Safety requirements and/or protective measures ............................................................................................................ 8

5.1 General requirements ....................................................................................................................................................................... 8

5.2 Safety-related parts of control systems for EDM equipment and EDM systems ............................ 9

5.3 Operating modes ................................................................................................................................................................................10

5.3.1 Operating mode selection .....................................................................................................................................10

5.3.2 Protective measures relating to operating modes ...........................................................................10

5.4 Stop functions .......................................................................................................................................................................................12

5.4.1 Operational stop ............................................................................................................................................................12

5.4.2 Emergency stop .............................................................................................................................................................13

5.5 Specific requirements ....................................................................................................................................................................13

6 Information for use .........................................................................................................................................................................................21

6.1 General ........................................................................................................................................................................................................21

6.2 Marking, signs and written warnings ...............................................................................................................................21

6.3 Instruction handbook ....................................................................................................................................................................21

6.3.1 Instruction handbook — General ...................................................................................................................21

6.3.2 Special recommendations for EDM site preparation.....................................................................22

6.3.3 Special recommendations for EDM operation ....................................................................................24

6.3.4 Noise ........................................................................................................................................................................................26

Annex A (informative) Examples and schematic diagrams ........................................................................................................27

Annex B (normative) Noise-emission measurements .....................................................................................................................36

Annex C (informative) Fire protection codes for special regional cases ......................................................................37

Annex ZA (informative) Relationship between this European standard and the essential

requirements of EU Directive 2006/42/EC aimed to be covered ....................................................................50

Bibliography .............................................................................................................................................................................................................................51

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oSIST prEN ISO 28881:2019
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Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/iso/foreword .html.

This document was prepared by Technical Committee [or Project Committee] ISO/TC [or ISO/PC] ###,

[name of committee], Subcommittee SC ##, [name of subcommittee].

This second/third/… edition cancels and replaces the first/second/… edition (ISO #####:####), which

has been technically revised.
The main changes compared to the previous edition are as follows:
— xxx xxxxxxx xxx xxxx
A list of all parts in the ISO ##### series can be found on the ISO website.
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Introduction

This International Standard has been prepared to be a Harmonized Standard to provide one means of

conforming to the Essential Safety Requirements of the Machinery Directive of the European Union and

associated EFTA regulations.
This document is a type-C standard as defined in ISO 12100:2010.

The machinery concerned and the extent to which hazards, hazardous situations and events are

covered are indicated in the Scope of this International Standard. In addition, electrical discharge

machining (EDM) equipment and EDM systems are intended to be designed according to the principles

of ISO 12100 for hazards which are not dealt with in this International Standard.

When requirements of this type-C standard are different from those which are stated in type-A or -B

standards, the requirements of this type-C standard take precedence over the requirements of other

standards for machines that have been designed and built according to the requirements of this type-C

standard.

This International Standard defines required performance level and safety categories of the safety-

related parts of the control system for EDM equipment and EDM systems as defined in ISO 13849-1.

The requirements of this International Standard concern designers, manufacturers, suppliers and

importers of machines described in the Scope.

This International Standard also includes a list of informative items intended to be provided by the

manufacturer to the user.
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oSIST prEN ISO 28881:2019
DRAFT INTERNATIONAL STANDARD ISO/DIS 28881:2019(E)
Machine tools — Safety — Electrical discharge machines
1 Scope

This International Standard specifies safety requirements and/or protective measures, applicable to

EDM equipment and EDM systems, such as
— manually controlled EDM die sinking or EDM drilling machines;
— numerically controlled EDM die sinking or EDM drilling machines, and
— numerically controlled EDM wire cutting machines.

intended to be adopted by persons undertaking the design, construction, installation and/or supply

of such equipment. This International Standard also includes information to be provided by the

manufacturer to the user.

This International Standard is not applicable to arc eroding and electro-chemical machining equipment.

This International Standard takes account of the precondition of the intended use as well as the

reasonably foreseeable misuse, in normal workshop environments and non-explosive atmospheres,

including transportation, installation, setting, maintenance, repair and dismantling for removal or

disposal of EDM equipment and EDM systems.

This International Standard is also applicable to auxiliary devices essential for EDM processing.

This International Standard deals with all significant hazards, hazardous situations or hazardous

events relevant to EDM equipment and EDM systems, where they are used as intended and under

conditions of misuse which are reasonably foreseeable by the manufacturer (see Clause 4).

This International Standard is intended to apply to machines manufactured after the date of publication

of this International Standard.
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.

ISO 3746, Acoustics — Determination of sound power levels and sound energy levels of noise sources using

sound pressure — Survey method using an enveloping measurement surface over a reflecting plane

ISO 4871, Acoustics — Declaration and verification of noise emission values of machinery and equipment

ISO 11202, Acoustics — Noise emitted by machinery and equipment — Determination of emission sound

pressure levels at a work station and at other specified positions applying approximate environmental

corrections

ISO 13849-2:2003, Safety of machinery — Safety-related parts of control systems — Part 2: Validation

ISO 13850, Safety of machinery — Emergency stop function — Principles for design

ISO 13855, Safety of machinery — Positioning of safeguards with respect to the approach speeds of parts

of the human body

ISO 13857:2008, Safety of machinery — Safety distances to prevent hazard zones being reached by upper

and lower limbs
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ISO 14118, Safety of machinery — Prevention of unexpected start-up

ISO 7010, Graphical symbols — Safety colours and safety signs — Required safety signs

IEC 60204-1:2016, Safety of machinery — Electrical equipment of machines — Part 1: General requirements

IEC 60529, Degrees of protection provided by enclosures (IP Code)

IEC 61000-6-2, Electromagnetic compatibility (EMC) — Part 6-2: Generic standards — Immunity for

industrial environments

IEC 61000-6-4, Electromagnetic compatibility (EMC) — Part 6-4: Generic standards — Emission standard

for industrial environments

IEC 61310-1, Safety of machinery — Indication, marking and actuation — Part 1: Requirements for visual,

acoustic and tactile signals

IEC 61310-2, Safety of machinery — Indication, marking and actuation — Part 2: Requirements for marking

IEC 61558-1, Safety of power transformers, power supplies, reactors and similar products — Part 1: General

requirements and tests

IEC 61800-5-2:2007, Adjustable speed electrical power drive systems — Part 5-2: Safety requirements —

Functional

EN ISO 14119:2013, Safety of machinery - Interlocking devices associated with guards - Principles for

design and selection (ISO 14119:2013)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 12100 and ISO 13849-1 and

the following apply.
3.1
electrical discharge machining
EDM
any machining process based on spark erosion

Note 1 to entry: Electrical discharge machining is generally abbreviated as "EDM".

3.2
EDM process

removal of material in dielectric fluid by electrical discharges, which are separated in time and

randomly distributed in space, between two electrically conductive electrodes, and where the energy

in the discharge is controlled

Note 1 to entry: The two electrically conductive electrodes are the tool electrode and the workpiece electrode.

3.3
EDM equipment

machine tool that includes all the necessary units for the process of EDM machining

EXAMPLE Generator, control circuits and dielectric fluid container.
3.4
EDM system

assembly of EDM equipment and other machines or devices, which are arranged, linked and controlled

to function as an integrated whole

1) The graphical symbol collections of ISO 7000, ISO 7001 and ISO 7010 are also available online in the ISO web

store. For more information, consult http: //www .iso .org/iso/fr/publications _and _e -products/databases .htm

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3.5
EDM die sinking

removal of material by spark erosion with a formed or bar-shape electrode to produce various shapes

in the workpiece

Note 1 to entry: Shapes in the workpiece may be concave, convex and prismatic holes.

3.6
EDM drilling

removal of material by spark erosion with a tubular electrode to produce straight holes in the workpiece

3.7
EDM wire cutting

removal of material by spark erosion with a wire electrode to produce prismatic shapes in the workpiece

3.8
control circuit
circuit used for the control, including monitoring, of the machine
Note 1 to entry: For electrical equipment, see IEC 60204-1:2016, 3.1.10.
3.9
machine control system

system that responds to input signals from parts of machine elements, operators, external control

equipment or any combination of these, and generates output signals causing a machine to behave in

the intended manner, as specified in ISO 13849-1:2006, 3.1.32
3.10
numerical control
computerized numerical control
CNC

automatic control of a process performed by a device, which makes use of numerical data introduced

while the operation is in progress
[SOURCE: ISO/IEC 2806:1994, definition 2.1.1 — modified.]
3.11
electronic handwheel

manually operated control device that initiates and maintains an axis movement by pulse generation

input to the numerical control during its rotation
3.12
enabling device

additional manually operated device used in conjunction with a start control and which, where

continuously actuated, allows a machine to function
[SOURCE: ISO 12100:2010, 3.28.2 — modified.]
3.13
hold-to-run control device

control device that initiates and maintains hazardous machine functions only as long as the manual

control (actuator) is actuated
[SOURCE: ISO 12100:2010, 3.28.3 — modified.]
3.14
dielectric fluid

non-conductive medium to improve the discharge effect, evacuate debris and cool the

workpiece/electrode
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3.15
flammable dielectric fluid

dielectric fluid used in EDM, characterized by its relative ease of ignition and relative ability to sustain

combustion
3.16
flash point

minimum temperature at which the dielectric fluid used in the sinking EDM gives off sufficient

combustible gas or vapour to ignite and sustain combustion
3.17
dielectric fluid container
tank system to keep the dielectric fluid in a condition suitable for EDM
EXAMPLE Filtering and cooling.
3.18
work tank

unit surrounding the work area to contain the dielectric fluid for EDM processes

3.19
work area

space within the envelope of the machine where the EDM process can take place

(inside and around the work tank)
3.20
generator

unit to convert the electrical power supplied to the EDM equipment and EDM system for the purpose of

being used for spark erosion processing
3.21
electrical machining power

electrical power supplied to the EDM equipment and EDM system transformed by the generator in

specific electric energy, supplied as a tool to the sinker/wire electrode and the workpiece, to perform

machining by electro-thermal material removal
3.22
electrode changer

mechanism integrated with the machine to supply an electrode to the machine, in

exchange for another electrode

Note 1 to entry: The changing device is expected to enable an operator to load/unload electrodes from outside of

the work area.
3.23
workpiece changer

mechanism forming part of the machine to supply a workpiece or pallet to the

machine, in exchange for another workpiece or pallet

Note 1 to entry: The workpiece changer/pallet changer is designed to enable an operator to load/unload the

workpiece or pallet to the magazine from outside of the work area.
3.24
operating mode
possible mode for use of the machine
3.24.1
automatic mode (MO 1: Automatic)

mode for use under numerical control to achieve programmed sequential operation with the guards

closed, until stopped by a program or an operator
Note 1 to entry: This term is equivalent to machining mode.
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Note 2 to entry: For machinery having automatic setting programs, such operations are considered automatic mode.

3.24.2
setting mode (MO 2: Setting)

mode for use without electrical machining power, for operations in which adjustments for the

subsequent machining are performed by the operator

Note 1 to entry: Measuring cycles (e.g. touching of the workpiece with a probe or electrode), checking the

movement of the workpiece and/or electrode using the electrode and/or workpiece changer, checking/optimizing

the injection or suction flushing, a dry run for checking the NC program, etc. are procedures forming part of the

setting mode (see 5.3.2.2).
3.24.3
discharge alignment mode (MO 3: Manual intervention)

mode for use for specific alignment with the electrical discharge on and with the guards of EDM

equipment temporarily open and alternative safety measures activated

EXAMPLE Exhaust air extraction adjustment, vertical wire alignment, dielectric fluid flushing adjustment

and visual machining inspection.
3.24.4
service mode (MO service)
mode for service and maintenance tasks
Note 1 to entry: In MO service, the machining of a workpiece is not allowed.

EXAMPLE Axis calibration by e.g. laser, generator calibration, repeatability test

3.25
performance level

discrete level to specify the ability of safety-related parts of control systems to perform a safety

function under reasonably foreseeable conditions
[SOURCE: ISO 13849-1:2006, 3.1.23 — modified.]
3.26
mean time to dangerous failure
MTTF
expectation of the mean time to dangerous failure
[SOURCE: ISO 13849-1, 3.1.25]
3.27
electro-magnetic compatibility

ability of EDM equipment and EDM systems to function satisfactorily in their electro-magnetic

environment without introducing intolerable electro-magnetic disturbances to anything in that

environment

Note 1 to entry: Electro-magnetic compatibility is generally abbreviated as "EMC".

3.28
shielding

mechanical barrier or enclosure of conductive material intended to attenuate the emission/penetration

of a varying electro-magnetic field into an assigned region
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4 List of significant hazards

This clause lists all the significant hazards, hazardous situations and events, as far as they are dealt with

in this International Standard, identified by risk assessment as significant for this type of machinery,

and which require action to eliminate or reduce the risk.

NOTE 1 The purpose of risk assessment is to identify hazards, and to estimate and evaluate risk to be reduced

and to transfer the remaining risk to the user (see Clause 6). There are many methods and tools available for this

purpose and several are described in this International Standard. The method or tool chosen is largely a matter

of industry, company or personal preference. The choice of a specific method or tool is less important than the

process itself. The benefits of risk assessment come from the discipline of the process rather than the precision

of the results: as long as a systematic approach is taken to get from hazard identification to risk reduction, all the

elements of risk are considered (see ISO/TR 14121-2).

The list of hazards given in Table 1 is the result of a risk assessment carried out for all EDM equipment

covered by this International Standard. The technical measures and information for use in Clauses 5

and 6 are based on the risk assessment and deal with the identified hazards by either eliminating them

or reducing the effects of the risks they generate.

NOTE 2 The designer’s attention is focused on hazards which can occur during the life of the machine. The risk

assessment assumes risks to both the operator(s) and other person(s) who can have access to the hazard zone(s)

for conditions of intended use, including reasonably foreseeable misuse of the machine (see ISO 12100:2010,

3.23 and 3.24) for both spark erosion with automatic mode and operations requiring intervention (e.g. setting,

maintenance and repair).

The significant hazards covered by this International Standard are listed in Table 1.

Particular attention is paid to hazards dealing with:
— electrical hazards (electrode voltage);
— flammable dielectric fluid (level, temperature, fire detection);

— hazardous substances (included in waste disposal, used filters, used dielectric fluid, electrodes and

sludges);

— electro-magnetic emissions (radiated and conducted); see IEC 61000-6-2 EMC for immunity and

IEC 61000-6-4 EMC for emission.
Table 1 — List of significant hazards and major sources of these hazards
associated with electrical discharge machines
Hazardous
Reference
No. Hazard type situation Activity Danger zone
to Table 3
action
1 Mechanical hazards:
Acceleration, de-
celeration (kinetic
energy of elements Movements of machine
Setting, machining At and near the ma-
1.1 in controlled or un- elements, failure of the A1, A2, A3, A8
and maintenance chine
controlled motion): control circuit
being run over,
impact
Loading/unloading, Between clamps and
1.2.1 Workpiece clamping A1, A2, A3
reorienting workpiece
Power-operated,
Cutting parts, sharp 1.2.2 Automatic workpiece/ Envelope of work-
workpiece/ elec- A1, A2, A3
1.2 edges: crushing and electrode changing piece/electrode motion
trode change
shearing
1.2.3 Moving parts (e.g. Manual operation, Between workpiece/
axes, rolling elements), fail- workpiece/elec- electrode and ma- A1, A2, A3, B4
ure of the control circuit trode change chine parts
This list is derived from ISO 12100:2010, Table B.1.
6 © ISO 2019 – All rights reserved
---------------------- Page: 14 ----------------------
oSIST prEN ISO 28881:2019
ISO/DIS 28881:2019(E)
Table 1 (continued)
Hazardous
Reference
No. Hazard type situation Activity Danger zone
to Table 3
action
Manual or automatic work-
Manual or power-op-
Moving and/or piece/electrode changing, Between workpiece/
erated workpiece/

1.3 rotating elements: spindle rotation and wire electrode and ma- A1, A2, A3, B4

electrode changing
entanglement rollers rotation, failure of chine parts
and spindle rotation
the control circuit
Hydraulic/pneumatic

High pressure: fluid systems ejection, leak- Setting, machining At and near the ma-

1.4 A4
injection or ejection age, flushing and residual and maintenance chine
pressure
Work tanks where
Rough, slippery
Ejection or spillage of fluids whole-body access is
surface: slipping, During and after
and lubricants, trailing possible, slippery floor
1.5 tripping and falling machining and A6
floor-mounted or loose and high working po-
of persons (related maintenance
connection cables sitions, area surround-
to machinery)
ing the machine
Loss of stability:
— unbalanced
machine or
parts
— inappropriately
Machine assembly,
Impact, trapping and/or
fixed part of
transportation, At and near the ma-
1.6 crushing by inclination A9
machine
installation and chine
and/or falling of machine
commissioning
— lifted machine
or parts by
crane
— transportation
with overload
2 Electrical hazards:
Live parts (direct
Contact with workpiece/
contact): electrical Process control,
electrode, wire/wire-path Workpiece, electrode,
2.1 shocks to persons, setting and mainte- B1, B2
and contact with unprotect- tooling fixture
effect on medical nance
ed circuits
implants, shock
Parts that become
live under fault
At and near the ma-
conditions (indirect Contact with parts of the Maintenance and ser-
chine, insulation of
2.2 contact): elect
...