ISO/TR 17529:2014

TECHNICAL ISO/TR
REPORT 17529
First edition
2014-11-15
Machine tools — Practical guidance
and example of risk assessment on
electro-discharge machines
Machines-outils — Lignes directrices et appréciation du risque pour
les machines d’électro-érosion
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Information for the risk assessment . 1
2.1 General . 1
2.2 Hazard identification on EDM equipment and EDM systems during the life phases . 4
3 Hazard identification . 8
4 Risk estimation, evaluation, and reduction. 9
4.1 Safety requirements and/or protective measures . 9
4.2 Protective measures and their verification procedures . 9
4.3 Information for use . 9
5 Risk estimation methods .10
5.1 General .10
5.2 Risk estimation according to ISO/TR 14121-2 .10
5.3 Risk estimation according to ISO 13849-1 .10
5.4 Risk estimation according to ISO 28881 .11
5.5 Risk parameter .14
6 Example of risk assessment .16
Bibliography .23
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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 39, Machine tools, Subcommittee SC 10, Safety.
iv © ISO 2014 – All rights reserved

Introduction
This Technical Report gives additional guidance to the manufacturer to use ISO 28881 by showing a
process of the risk assessment based on type A and B standards.
Some documents (e.g. technical reports, guidelines) have already been published but they usually
describe about the risk assessment only for machines or for control systems. Manufacturers need
guidance that covers both aspects of machines and control systems.
This Technical Report deals with risk assessment for machine and control jointly, i.e. the result of the risk
assessment carried out for significant hazards listed in ISO 28881:2013, Table 1, including the results of
risk reduction by the protective measures described in ISO 28881:2013, Clauses 5 and 6 and the process
of the selection of PL as described in ISO 28881:2013, 5.2, are shown.
r
This Technical Report, based on the following International Standards, is worked out in cooperation
with JMTBA (Japanese Machine Tool Builder Association) and ISO/TC 39/SC 10.
— ISO 28881;
— ISO 12100;
— ISO 13849-1;
— ISO/TR 14121-2.
TECHNICAL REPORT ISO/TR 17529:2014(E)
Machine tools — Practical guidance and example of risk
assessment on electro-discharge machines
1 Scope
This Technical Report gives practical guidance on conducting risk assessment for machinery in
accordance with ISO 12100, ISO 13849-1, and ISO/TR 14121-2. It describes the method, tools, and
examples used to generate ISO 28881, to reduce the risk of potential harm on EDM equipment and EDM
systems by persons involved in the design, installation, or modification of machinery (e.g. designers,
technicians, safety specialists).
2 Information for the risk assessment
2.1 General
The following points should be considered:
— specifications of the EDM equipment and EDM systems (For example of limits of the machinery, see
Table 1.);
— type of machinery (For examples, see Figures 1 and 2.);
— hazards and associated hazardous situations;
— estimated risk for each identified hazard and hazardous situations including intended use and any
reasonably foreseeable misuse;
— evaluation of the risk and making decisions about the need for risk reduction.
Eliminate or reduce the risk by means of the three-step method in accordance with ISO 12100:2010, 6.1.
— step 1: inherently safe design measures;
— step 2: safeguarding and/or complementary protective measures;
— step 3: information for use.
Table 1 — Example of specifications of the EDM equipment and EDM systems
Items Wire EDM Sinker EDM
EDM machine figure See Figure 1 See Figure 2
Power supply
Input voltage 200 V a.c., three-phase 200 V a.c., three-phase
Electrical supply capacity 13,5 kVA 13,0 kVA
Compressed air 0,5 MPa to 0,7 MPa 0,6 MPa
Equal to or more than 75 l/min
Machine weight 2 000 kg 5 000 kg
Generator
Type of circuits Transistor pulse Transistor pulse
(energy retrieval type)
Output voltage 300 V 200 V
Output current 50 A 60 A
Linear axis (X, Y, Z)
Stroke (mm) X350 × Y250 × Z220 X300 × Y200 × Z200
Output power a.c. 0,6 kW a.c. 1,0 kW
Feeding speed 1 300 mm/min 5 000 mm/min
Z-axis With brake With brake
Without balancer Without balancer
Rotary axis Not applicable C-axis
Output power a.c. 0,5 kW
Electrode
Size Wire diameter: 0,1 to 0,3 [mm] Not specified
Max. weight 10 kg 50 kg
Automatic tool changer Not applicable Applicable
Number of electrodes 1 spool 30 electrodes
Max. weight per electrode 10 kg 10 kg
Workpiece 650 × 450 × 195 mm
Max. size 800 × 600 × 215 mm 650 × 450 mm
Max. weight 500 kg 800 kg
Dielectric fluid
Material Water Oil with flash point more than 60 °C
Container capacity 440 l 350 l
Installation environment
Temperature 10 °C to 35 °C 10 °C to 35 °C
Relative humidity 35 % to 75 % (no condensation) 35 % to 75 % (no condensation)
2 © ISO 2014 – All rights reserved

Key
1 shielded enclosure with door(s) 6 workpiece
2 wire supply spool 7 lower wire guide
3 wire electrode 8 upper wire guide
4 wire evacuation 9 interlocking guard
5 electrical cabinet (generator) 10 fix guards
Figure 1 — Example of wire cutting machine
Key
1 local fire alarm
2 fire detection device
3 electrical cabinet (generator)
4 interlocking shielded guard
5 linear electrode changer
Figure 2 — Example of die sinking machine with linear electrode changer
2.2 Hazard identification on EDM equipment and EDM systems during the life phases
2.2.1 Whole life cycle of the EDM equipment and EDM systems
The phases of the life cycle of the EDM equipment and EDM systems considered to be significant in this
example are the following:
— transportation (including in-house transport and movement);
— assembly, installation, and commissioning;
— setting and operation;
— cleaning and maintenance;
— fault finding and troubleshooting;
— removal, dismantling, and disposal.
4 © ISO 2014 – All rights reserved

2.2.2 Space limits
EDM equipment and EDM systems are assumed to be used in the industrial environment of the factory.
EDM equipment and EDM systems are assumed to be used in the environment without direct sunshine,
dust, and water splash.
EDM equipment and EDM systems are not assumed to be used in the atmosphere having fire or explosion
hazard.
Necessary area for all phases of the life cycle of the EDM equipment and EDM systems (i.e. installation,
operation, maintenance, etc.) is assumed to be secured. However, concrete size is not specified here
because it does not seem to be reasonable from the objective of this example.
2.2.3 Time limits
This example describes only the aspects of time limits which should be generally determined because it
is not reasonable to specify concrete values here from the objective of this example.
— life of the machine;
— interval of inspection;
— interval of parts replacement;
— interval of cleaning and maintenance.
2.2.4 Use limits (intended use and reasonably foreseeable misuse)
Intended use and reasonably foreseeable misuse of the EDM equipment and EDM systems should be
considered in each phase of the life cycle.
The EDM is assumed to be used by a person
— who is a trained operator,
— without visual or hearing impairment,
— without restrictions on physical ability of upper or lower limbs, or
— without usage of medical implants liable to be affected by electromagnetic radiation (e.g. pacemaker).
See Table 2 for example of lifecycle and task in automatic, setting, and discharge alignment operation on
EDM equipment and EDM systems.
Table 2 — The phases of lifecycle and tasks in automatic, setting, and discharge alignment
operation
Task, operator, and reasonably foreseeable misuse
Automatic Description Wire EDM Sinker EDM
operation
(1) Automatic workpiece preparation
(machining)
— measuring workpieces (vertical, parallel, edge, etc.) X X
— measuring workpieces (with high voltage) X X
— measuring workpieces (with low voltage) X X
(2) Automatic electrode preparation
— connection of wire electrode X
— vertical wire alignment (adjusting by U-axis and V-axis) X
— clamping electrode (with automatic tool changer) X
— measuring electrodes (edge, centre, etc.) X
(3) Making and verifying machining program
— programmed operation without electric discharge power X X
(4) Tasks during processing
— starting process X X
— intervention during processing X X
— adjusting flushing pressure X
— adjusting flushing pressure (injection, suction) X
— monitoring process condition X X
— a
...