ISO 841:2001

INTERNATIONAL ISO
STANDARD 841
Second edition
2001-10-15
Industrial automation systems and
integration — Numerical control of
machines — Coordinate system and motion
nomenclature
Systèmes d'automatisation industrielle et intégration — Commande
numérique des machines — Systèmes de coordonnées et nomenclature
du mouvement
Reference number
©
ISO 2001
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ii © ISO 2001 – All rights reserved

Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Machine coordinate system.1
4.1 Designation .1
4.2 Origin .2
4.3 Z axis.2
4.4 X axis.2
4.5 Y axis.3
4.6 Rotary axes A, B and C .3
5 Principal machine motions.3
5.1 Designation .3
5.2 Direction .3
6 Additional motions .4
6.1 Linear motions .4
6.2 Rotary motion.4
6.3 Letter restrictions .4
6.4 Direction .4
7 Schematic drawings of machines.4
7.1 Examples of machine drawings .4
7.2 Designation .5
Annex A (normative) Examples of machine motions.6
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
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Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 841 was prepared by Technical Committee ISO/TC 184, Industrial automation systems
and integration, Subcommittee SC 1, Physical device control.
This second edition cancels and replaces the first edition (ISO 841:1984), which has been technically revised. The
following changes have been made:
� the content has been restructured in a more logical order;
� axes and motions have been clearly distinguished;
� new machine types have been added;
� motion designation for more complex machines has been added.
Annex A forms a normative part of this International Standard.
iv © ISO 2001 – All rights reserved

Introduction
This International Standard defines a standard machine coordinate system and the machine motions so that a
programmer can describe the machining operations without having to know whether the tool approaches the
workpiece or the workpiece approaches the tool.
The standard machine coordinate system is used to provide the coordinates of a moving tool (or point in the
working space or on a drawing) with respect to a stationary workpiece.
INTERNATIONAL STANDARD ISO 841:2001(E)
Industrial automation systems and integration — Numerical
control of machines — Coordinate system and motion
nomenclature
1 Scope
This International Standard describes a machine coordinate system related to the primary motions of individual
numerically controlled machines and the associated machine motions.
The machine coordinate system is used to provide the coordinates of a moving tool (or a point in the working space
or on the drawing) with respect to a stationary workpiece. Thus a programmer can describe the machine operations
without having to know whether the tool approaches the workpiece or the workpiece approaches the tool.
NOTE 1 Individual numerically controlled machines means that all axes are mounted on one base or frame and all motions
are related to one standard coordinate system.
NOTE 2 For the sake of simplicity the majority of the text of this International Standard is written in terms accorded to
machine tools but nevertheless accorded to numerically controlled machines in general. Coordinate systems and axis motion
nomenclature for industrial robots is defined in ISO 9787, Manipulating industrial robots — Coordinate systems and motion
nomenclatures.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 2806:1994, Industrial automation systems — Numerical control of machines — Vocabulary
ISO 6983-1:1982, Numerical control of machines — Program format and definition of address words — Part 1:
Data format for positioning, line motion and contouring control systems
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 2806 apply.
4 Machine coordinate system
4.1 Des
...