bs_iso128

STD-BSI BS IS0 LZB-ENGL L782 1111 Lb24bb9 O8b780L 257 m BRITISH STANDARD

Technical drawings - General principles of presentation

ICs 01.100.01

NO COPYING ?VITHOUT BSI PERMISSION EXCEPT AS PERMIlTED BY COPYRIGHT LAW

BS IS0 1281982

COPYRIGHT British Standards Institute on ERC Specs and StandardsLicensed by Information Handling ServicesCOPYRIGHT British Standards Institute on ERC Specs and StandardsLicensed by Information Handling Services

STD.BS1 BS IS0 LZ8-ENGL L982 m Lb24bb9 08b7802 L93 m BS IS0 1281982

National foreword This British Stan- reproduces verbatim IS0 128:2000 and implements it as the UK national standard. This standard, together with BS 8888 and other implemented European and Intmnalional standards listed in annexes A and B of BS 8888, supersedes all parts of BS 308 which are withdrawn The European and Intemaiional Standards that were implemented to form subsections of Part 3 of BS 308 and were dual numbered, are now listed by the implementation number o@, e.g. BS EN IS0 xxxx The pocket guide previously available is currentJy under review. The UK participation in its preparation was entrusted to Technid Committee "DW/4, Engineering drawing, metrology, precision measurement and all related documentation, which has the responsibility to:

- aid enquirers to understand the tee - present to the responsible intedonaUEuropean committee any enquiries

on the inteqptation, or proposals for change, and keep the TJK interests informed;

- monitor related intemaiional and European developments and promulgate them in the UK.

A list of organizations represented on this committee can be obtained on request to itssecretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the sedion entitled "International Standards Correspondence Index", or by using the "F'ind" facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract Users of British Stan- are responsible for their corred application Cornpllance with a British Standard does not of itself confer immunity from legal obligations.

Summary of pages This document comprises a fmnt cover, an inside front cover, the IS0 title page, pages ii and iii, a blank page, pages 1 to 15 and a back cover. The BSI copyright notice displayed in this document indicates when the document waslastissued.

This British standard, having Amendments issued since publication been prepared under the direction of the Consumer Amd No.

on 16 September 2000 Committee and comes into effect the authority of the Standards Committee, waa published under products and SeMces Sector

comments Date

Q M I 092000

ISBN O 580 36433 X


International Standard 128

Technical drawings - General principles of presentation Dessins techniques - principes g6nhux de mpdsentation

First edition - 1982-07-Ql

UDC 744.4

hcrlpton : technical drawings, graphic symbols, generalities.

Ref. No. IS0 12&1982(El


Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 member bodies). The work of developing Inter- national Standards is m i e d out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been set up 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.

Draft International Standards adopted by the technical committees are circulated to the member bodies fw approval before their acceptance 8s International Standards by the IS0 council.

IntemWioMl Standard IS0 128 was developed by Technical Committee ISO/TC 10, Technicd ¿mwngs, and was circulated to the member bodies in April 1980.

It has been approved by the member bodies of the following countries :

France Norway GreeCe Poland India Romania M Y South Africa, Rep. of Japan Spain Korea, Rep. of Sweden k X k 0 USSR Netherlsnds

Auarb Dsnmark Germany, F.R. SwiaerllUld United Kingdom USA

Th¡¡ International Standerd together with IS0 64161981 cancels and repiaces IS0 Recommandation R 128-1960 of which it constitutes B technical revision.


STD.BSI BS IS0 LZB-ENGL 1982 m Lb24bb9 08b7805 9T2

Contents

iii


~~. ~~ ~ ~

STD.BSI BS IS0 128-ENGL L7B2 m Lb24bb7 OBb7BOb 837

INTERNATIONAL STANDARD IS0 128-1962 (E)

Technical drawings - General principles of presentation

1 Scope and field of application

This International Standard specifies the general principles Of presentation to be applied to technical drawings following the orthographic projection methods.

Additional International Standards are under preparation for other methods of representation.

This International Standard is intended for all kinds of technical drawings (mechanical, electrical, architectural, civil engineering, etc.). However, it is recognized that in some specific technical areas the general rules and conventions cannot ad- equately cover all the needs of specialized practices, and that additional rules are required which may be specified in separate standards. For these areas the general principies should however, be respected in order to facilitate international ex- change of drawings and to ensure the coherence of drawings in a comprehensive system relating to several technical functions.

Attention has been given in this International Standard to the requirements of reproduction, including microcopying.

2 Views

2.1 Designation of views

View in direction a = View from the front

View in direction b = View from above

View in direction c = View from the left

View in direction d = View from the right

View in direction e = View from below

View in direction f = View from the rear

The front view (principal view) having been chosen (see 2.41, the other customaty views make with it and between themselves angles of 900 or multiples of 900 (sert figure II .

e t Figure 1

2.2 Relative position of views

Two alternative orthographic projection methods, of equal standing, can be used :

- the first angle projection method (formerly referred to as method E),

- the third angle projection method (formerly referred to as method A).

NOTES 1 For uniformity among the figures given throughout this Interna- tional Standard, as examples, the rdative positions of v i e m are those provided by the first angle projection method. It should be understood. however. that each of the two methods could equally have been used without prejudica to the principle established.

2 The fgures shown are not intended as desisign examples and are depicted in the simplest form to illustrate the text.

1


STD-BSI BS IS0 128-ENGL 1982 m l b 2 4 b b 9 0867807 775 m IS0 128-1982 (E)

2.2.1 First angle projection method

Weh reference to the front view (a), the other views are ar- ranged as follows ( s e e figure 2) :

The view from above (bl, is placed underneath

The view from below (e), is placed above

The view from the left (c), is placed on the right

The view from the right (dl, is placed on the left

The view from the rear (f) may be placed on the left, or on the right, as convenient.

Figure 2

Figure 4

The distinguishing symbol of this method is shown in figure 5.

Figure 5

2.2.3 Layout of views using reference arrows

The distinguishing symbol of th¡¡ method is shown in figure 3.

Figure 3

22.2 Thkd angle projection method

WW refetence to the front view (al, the other views are ar- ranged as fdbws (see figure 4) :

The view from above (b), is placed above

h view from below (e), is placed underneath

The view from the left (cl, is placed on the left

The view from the M t (dl, is placed on the right

The view from the rear (fl may be placed on the left, or on the right, as convenient.

ln those cases where it is an advantage to position the views not according to the strict pattern of the first or the third angle projection methods, the use of reference arrows permits the various views to be freely positioned.

Wnh the exception of the principal view, each view shalt be identified by a capital letter which is repeated near the arrow needed to indicate the direction of viewing for the relevant view. The designated views may be located irrespective of the principal view. The capital letters identifying the referenced views shall be placed either immediately below or above the relevant views. In any one drawing the references shall be placed in the same way. No other indication is necessary (see figure 6).

IA n

OØ7 C D E

2


STD.BSI BS IS0 128-ENGL 1982 m Lb24669 O867808 b o 1 m

2.3 Indication of method

Where one of the methods specified in 2.2.1 and 2.2.2 is being used, the said method must be indicated on the drawing by means of its distinguishing symbol as shown in figures 3 or 5.

The symbol shall be placed in a space provided for the purpose in the title block of the drawing.

For the layout of views using reference arrows specified in 2.2.3, no distinguishing symbol is required.

2.4 Choice of views

The most informative view of an object shall be used as the front or principal view. Generally, this view shows the part in the functioning position. Parts which can be used in any position should preferably be drawn in the main position of manufacturing (H mounting.

When other views (including sections) are needed, these shall be selected according to the following principles :

- to limit the number of views and sections to the minimum necessary and sufficient to fully delineate the object without ambiguity;

- to avoid the need for hidden outlines and edges;

- to avoid unnecessary repetition of detail.

A

2.5 Special views

If a direction of viewing different from those shown in 2.1 is necessary, or if a view cannot be placed in its correct position using the methods shown in 2.2.1 and 2.2.2, reference arrows as indicated in 2.2.3 shall be used for the relevant view (see figures 7 and 8).

whatever the direction of viewing, the capital letters referenc- ing the views shall always be positioned normal to the direction of reading.

2.6 Partial views

Partial views may be used where complete views would not improve the information to be given. The partial view shall be cut off by a continuous thin freehand line (type C) or straight lines with zigzags (type D) (see figures 7, 9, 10 and others).

2.7 Local views

Provided that the presentation is unambiguous, it is permitted to give a local view instead of a complete view for symmetrical items. The local view should be drawn in third angle projection, regardless of the arrangement used for the general execution of the drawing.

L o c a t views shall be drawn with continuous thick lines (type A), and shall be connected to the principal view by a centre line (type G). Examples of local views are shown in the figures 41, 42, 43 and 44.

A

Figure 7 Figure 8

3


3 Lines

3.1 Types of lines

Only the types and thicknesses of line shown in the following table shall be used.

In cases where other types or thicknesses of line are used for special fields (for example electrical or pipe-work diagrams), or if the lines specified in the table are used for applications other than those detailed in the last column of the table, the conventions adopted must be indicated in other International Standards or explained by notes on the drawing concerned.

Typical applications of different types of lines are shown in figures 9 and 10.

TaMe

1 Une A

Dewription

A l Visible outlines Continuous thick

General applications See figures S, 10 and other relevant figures

A2 visibleedges

c"-

H r---- ""

Continuous thin (straight or curved1

Continuous thin freehand21

Continuous thin (straight) with zigzags Dashed thick21

Dashed thin

Chain thin

Chain thin, thick at ends and changes of direction

1 BI lmagkry tines of intersection i B2 Dimension lines ~ B3 Projection lines ' 134 Leader tines B5 Hatching B6 Outlines of reVdved sections in place B7 Short centre lines

C1 Limits of partial or interrupted views and

Dl line (see faures 53 and 54)

El Hidden outlines E2 Hidden edges F1 Hidden outlines F2 Hidden edges

G1 Centre lines G2 Lines of symmetry G3 Trajectories

H l Cutting planes

-

sections, if the limit is not a chain thin

"".

-

J -----.-.- Chain thin double-dashed K - - - - - - - -

J1 Indication of lines or surfaces to which a special Chainthick

K1 Outlines of adjacent parts

requirement applies

K2 Alternative and extrem positions of movable parts K3 Centroidal lines K4 Initial outlines prior to forming (see figure 5 8 ) K5 Parts situated in front of the cutting plane

(see figure 4 8 1 L

11 This type of line is suited for production of drawings by machines. 2) Although two alternatives are available, it is recommended that on any one drawing, only one type of line be used.


Y

""""""""-"" A A

Figure 9

Figure 10


3.2 Thicknesses of lines 3.5 Termination of leader lines

Two thicknesses of line are used. The ratio of the thick to the A leader line is a line referring to a feature (dimension, object, thin line shall not be less than 2: l . outline, etc.).

The thickness of lines should be chosen according to the size Leader lines should terminate : end the tvpe of the drawing from the following range :

- with a dot, if they end within outlines of an object ( s e e 0,18, O,=, 0.35. 0,5, 0,7, 1, 1,4 and 2 m m 1 1 figure 12);

For all views of one piece to the same scale, the thickness of - with an arrow head, if they end on the outline of an ob- the lines should be the sam. ject (see figure 13);

3.3 Spacing of lines

The minimum spaœ benNeen parallel lines, including hatching, should never be l e s s than twice the thickness of the heaviest line. It is recommended that these spaces should never be less than 0.7 mm.

3.4 Order of priority of coinciding lines

when two or more l i n e s of different type coincide, the following order of priority should be observed (see figure 11 ).

1) visible outlines and edges (continuous thick line, W A);

2) hidden outlines and edges (dashed line, type E or F);

3) cutting planes (chain thin line, thick at ends and changas of cutting planes, type H);

4) centre lines and lines of symmetry (chain thin line, tvpe G);

5) centroidal lines (chain thin double-dashed line, type KI;

Adjacent outlines of assembled parts shall coincide, black thin sections excepted (see 4.3 and fyure 231.

- without dot or arrowhead, if they end on e dimension line (see figure 14).

Figure 12

Figure 13

A-A

Figure 11 figure 14

1) W ¡ to difficuHies in w i n methods of reproduction, the line thickness of 0,18 mm should be avoided.

6


4 Sectionsl)

4.1 Notes on hatching of sections

Hatching is generally used to show areas of Sections. Allowance must be made for the methods of reproduction that are to be used.

The simplest form of hatching is usually adequate for the purpose, and may be based upon continuous thin lines ( t y p e 6 ) at a convenient angle, preferably eo, to the principal outlines or lines of symmetry of the sections ( s e e figures 15, 16 and 17).

Figure 15 Figure 16 Figure 17

Separate areas of a section of the same component shall be hatched in an identical manner. The hatching of adjacent com- ponents shall be carried out with different directions or spac- ings (see figures 18 and 19).

I """- / / / / / / / I / / / f

Figure 18

Spacing between the hatching lines should be chosen in pro- portion to the size of the hatched areas, provided that the r e quirements for minimum spacing are maintained ( s e e 3.3).

In the case of large areas, the hatching may be limited to a zone following the contour of the hatched area ( s e e figure 19).

Where sections of the same part in parallel planes are shown side by side, the hatching shall be identical, but may be offset along the dividing line between the sections if greater clarity is considered necessary (see figure 20).

Figure 19

A-A

A T Figure 20

"I- T A

Hatching shall be interrupted when it is not possible to place in- scriptions outside the hatched area ( s e e figure 21). Figure 21

I I In the French language, two terms are employed for section :

"Section" : A section at the cutting plene showing no other outlines.

"coupe" : A section (or sectional v i e w 1 at the cutting plane including other visible outlines situated beyond the cutting plane when Seen in the direction of viewing.

7


4.2 Hatching to indicate type of materials

Hatching may be used to indicate type of materials in sections.

If different types of hatching are used to indicate different materials, the meaning of these hatchings shall be clearly defined on the drawing, or by reference to appropriate standards.

4.3 Thin sections

Thin sections may be shown entirely black ( s e e figure 22); a space of not less than 0,7 mm must be left between adjacent sections of this type (see figure 23).

U Figure P

Figure 23

4.4 Notes on sections

The general rules for the arrangement of views (see 2.2) apply equally when drawing sections.

Where the location of a single cutting plane is obvious, no indication of its position or identification is required ( s e e figures 24 and 35).

Where the location is not obvious, or where it is necessary to distinguish between several cutting planee (see figures 25 to 291, the position of the cutting plane(s1 shall be indicated by means of a thin chain line, thick at ends and changes of direction (type H). The cutting plane should be idSnWied by designations, for example capital letters, and the direction of viewing shouid be indicated by arrows. The section should be indicated by the relevant designations (see figures 25 to 2 9 1 .

The designations on the referenced sections shall be placed either immediately below or above the relevant sections, but in any one drawing the references shall be placed in the sam way. No other indication is necessary.

In certain caaes, the parts located beyond the cutting plane need not be drawn completely.

In principle, ribs. fasteners, shafts, spokes of wheels, and the like are not cut in longitudinal sections, and therefore should not be hatched (see figures 28 and 29).

4.5 Cutting planes (examples)

Section in one plane (see figures 24 and 25)

Figure 24

A-A

ate

Figure 25

Section in two parallel planes (see figure 26)

Y A - A

Figure as

I"

8


IS0 128-1982 (E)

Section in three contiguous planes (see figure 27)

A - A

n

Figure W

Section in two intersecting planes, one shown revolved into the plane of projection ( s e e figure 28)

A - A

Figure 28

In the case of parts of revolution containing regularly spaced details that require to be shown in section, but are not situated in the cutting plane, provided that no ambiguity can arise, such details may be depicted by rotating them into the cutting plane ( s e e figure 29); but some indication of having done so is recommended.

A - A +

4.6 Sections revolved in the relevant view or removed sections

4.6.1 When revolved in the relevant view, the outline of the section shall be drawn with continuous thin lines (type B) and further identification is not necessary (see figure 30).

Figure 30

- or in a different position and identified in the conventional manner as in 4.4 by designations [see figure 31b)l.

'.

Figure 3le)

A - A

P Figure 29 Figure 3lbl

9


4.7 Half sections

Symmevical parts may be drawn half in full view and half in section (see figure 32).

Figure 32

4.8 Local sections

tinuous thin freehand line (type Cl (see figure 33) or by continuous thin straight line 6th zigzags (@pe DI (see figure 9).

Figuro 33

4.9 Arrangement of successive sections

Succemive sections may be emrngsd in a manner similar to the examples shown in figures 34,s and 36 as convenient for the layout and understanding of the drawing.

B: B c-c D-D

Figuro 34

10


5

5.2 Intersections

5.2.1 True intersections

True geometric intersmion lines shall be drawn with continuous thick lines ltvpe A), when visible, or with dashed lines ( t y p e E or F) when hklden (see figure 38).

d"" ""m

J I 1

A

A - A B-B c - c Figure 36

Other conventions

5.1 Adjacent parts

Where their representation is neœssary, parts adjacent to an object shall be drawn with chain thin doubladashed lines (type KI. The adjacent part shall not hide the principal part, but may be hidden by the latter ( s e e figure 37).

Adjacent parts in sections shall not be hatched.

Figure 38

6.2.2 Imaginary intemections

Imaginary intersection lines su ch as fillets or rounded corners) may be indicated in a view by means of continuous thin lines (type B), not touching the outlines Ism figure 39).

Figure r)

Figure 37

11


5.2.3 Simplified representation of intersections

Simplifitxl representations of true gttonwtric W inlayinlrry in tersectiocl litws tnay tnt applied at intersections :

betwtwn t w o cylinders : tlw curved lines of intersectiorl alt! replaced by straight litws (see figures 40, 41 and 43);

between a cylinder and a rectangular prism : the displacement of the straight line of intersection is omitted (see figures 42 and 44).

As the difference in size h t w e t t n the intersecting parts in- crease~~, the simplified representatiotl (see figures 40 to 4 4 ) only gives a better approach to a real intersection, provided that the axes of the intersecting parts are both mutually perpendicular and intersect. or nearly so.

NOTE This simplified representlttiutr should be avoided if it affects the coniprehensibility of the drawing.

Figure 40

Figure 42

Figure 43

4

Figure 41 figure 44


IS0 128-1- (E)

5.3 Conventional representation of square ends 5.4 Parts located in front of a cutting plane and openings

5.3.1 Square ends on shafts

If, it is necessary to indicate parts located in front of the cutting plane, these parts are to be represented by chain thin double dashed lines (type K) ( s e e figure 48).

In order to avoid drawing a supplementary view or section. square ends ( s e e figure 4 5 ) or tapered square ends on shafts (see figure 46) may be indicated by diagonals drawn as continuous thin lines ( t y p e B). -II=* m

dp

I - m

B - 2 1 r

A - A Figure 45 r -

m

""""

1 1

2

Figure 46

5.3.2 Square and rectangular openings

In order to indicate an opening in a flat part in frontal view, without aid of additional sections, this opening may be shown by drawing its diagonals in continuous thin lines (typa B) (see figure 47).

A - A

Figure 48

5.5 Views of symmetrical parts

To save time and space, symmetrical objects may be drawn as a fraction of the whole ( s e e figures 49 to 5 2 ) .

The line of symmetry is identified at its ends by two thin short parallel lines drawn at right angles to it (see figures 49, 50 and 52).

Another method is to show the lines representing the object ex- tending a little beyond the line of symmetry (see figure 51 ). In this case, the short parallel lines may be omitted.

NOTE - In the epplkation of this practice, it ia essential that due care is taken to avoid loss of understanding of the drawing.

Figure 47

13


Figure 50

5.6 Interrupted views

In order to save space, it is permissible to show M l Y those Por- tions of a long object which are sufficient for its definition. The limits of the parts retained are shown as for partial views (see 2.6). and the portions are drawn close to each 0 t h ( s e e figures 53 and 54).

U

Flgure 53

Figure 54

5.7 Simplified representation of repetitive features

The presentation of repetitive features may be simplified as shown in figures 55 and 56.

NOTE - In all caws, the number and kind of repetitive features should be defined by dimensioning or by a note.

Figure 61

Figure 56

=I= Figure 52

Figure SB

14


STD-BSI BS IS0 128-ENGL 1982

5.8 Elements on a larger scale

In cases where the scale is 80 small that details of the feature cannot be shown or dimensioned, the feature of the part may be framed by a continuous thin line (type B) and identified by a capital letter [sea figure S a l l .

The relevant feature is then drawn to a stated larger scale ac- companied by its identification letter [see figure 57b)l.

W Lb24669 O8b7820 LO9 W ISO 128-1962 (E)

6.9 Initial outlines

m e n it is necessary to depict the initial wdim of a part prior to forming, the initial o u t l i n e shall be indicated by chain thin doubledashed lines (type KI (see figure 5 8 1 .

Flgure 8B

Figure Wal

Figura Wb)

The use of cdoum on technical drawings is not recommended. If it is essential for clarity to use colours, then their meanings shall be clearly shown on the drawing or in other relevant documents.

6.11 Tran8psrent objects

Ali objecta made of transpantnt material should be drawn as non-transparent.

15


BS IS0 1281982

BSI 389 Chiswick High bad London W4 4AL

BSI - British Standards Institution

BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international leveL It is incorporated by Royal Charter. Revisions British standards are updated by amendment or revision. Usem of British standards should make sure that they possess the latest amendments or editions. It is the constant ahn of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguil~ while using this British Standard would inform the Secretary of the technid committee responsible, the identity of which can be found on the inside front cover. Tek 020 8996 9OOO. Fax O20 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribem automatidly receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tek Ou) 8996 9001. F a O20 8996 7001. In response to orders for international standards, it is BSI policy to supply the BSI implementation of th- that have been published as British Standards, unless otherwise requested Information on standards BSI provides a wide range of i n f o d o n on national, European and international standards through its Library and its Technical Help to Exporters Service. Various BSI electronic i n f o d o n services are also available which give details on all its products and services. Contact the Information Centre. Tek 020 8996 7111. Fax: 020 8996 7048. Subscribii membem of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tek O20 8996 7002. Fax: O 2 0 8996 7001. copyright

Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the internaiional stan-on bodies. Except as permitted under the Copyright, D e s i i and patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means - electronic, photocopying, recording or otherwise - without prior written permission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other p-e than implementation then the prior ~ t t e n permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement Details and advice can be obtained from the copyright Manager. Tek 020 8996 7070.


Documents

bs_iso128