Technical Product Specification (TPS) – Specification

BS 8888:2006

Incorporating Corrigendum No. 1

BRITISH STANDARD

Technical product specification (TPS) – Specification

ICS 01.100.01; 01.110

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Publishing and copyright information The BSI copyright notice displayed in this document indicates when the document was last issued.

ISBN 0 580 49398 9

The following BSI references relate to the work on this standard: Committee reference TDW/4 Draft for comment 06/30130606 DC

Publication history First published August 2000 Second edition October 2002 Third edition October 2004 Fourth edition October 2006

Amendments issued since publication

Amd. no. Date Text affected 16851 29 December 2006 Clarification of figures in Annex A and Annex E. Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006

Contents Foreword iii 1 Scope 1 2 References 1 3 Terms and definitions 2 4 Global standards underpinning BS 8888 3 5 Expression of the concept 5 6 Types of documentation 6 7 Scales 8 8 Lines, arrows and terminators 9 9 Lettering 9 10 Projections 10 11 Views 10 12 Sections 11 13 Symbols and abbreviations 11 14 Representation of features 13 15 Representation of components 14 16 Dimensioning and tolerancing 16 17 Geometrical tolerancing 23 18 Surface texture indication 23 19 Graphical representation and annotation of 3-D data (3-D modelling output) 24 20 Security 25 21 Storage and retrieval 25 22 Marking 26 23 Protection notices 27 Annexes Annex A (normative) Normative references 28 Annex B (informative) Informative references 51 Annex C (normative) Document security – Enhanced 52 Annex D (informative) Key differences between BS 8888 geometrical tolerancing and ASME Y14.5 geometric dimensioning and tolerancing (GD&T) 53 Annex E (informative) BS ISO 1101:1984 to BS ISO 1101:2004 – The evolution 57 Annex F (informative) Technical product specification – Geometrical product specification (GPS) 69 Annex G (informative) Technical product realization – UK development 79 Annex H (informative) Index of choices and defaults for BS 8888:2006 84 List of figures Figure 1 – Metric reference graduations 8 Figure 2 – Auxiliary view showing true shape of inclined surface 11 Figure 3 – Interpretations using the principle of independency for a cylindrical component for which a tolerance of size only is given on the drawing 17

Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 88, an inside back cover and a back cover.

Figure 4 – Interpretation of limits of size with dependency of size and form 19 Figure 5 – Dimensioning of keyways 21 Figure 6 – Examples of general tolerance notes 22 Figure 7 – Method of indicating that the independency system of tolerancing has been used 26 Figure 8 – Method of indicating that the dependency system of tolerancing has been used 26 Figure E.1 – Indication of orientation of the tolerance zone 58 Figure E.2 – Use of the median feature 59 Figure E.3 – Restricted parts of a feature 60 Figure E.4 – Example of a common tolerance zone 60 Figure E.5 – Example of a common tolerance zone 61 Figure E.6 – Examples of the use of the “all around” symbol 61 Figure E.7 – Unequally disposed tolerance zone indicator 62 Figure E.8 – Example of the use of the compound toleranced feature 63 Figure E.9 – Indicating the start and end of the compound toleranced feature 63 Figure E.10 – Indicating a common set of toleranced features 64 Figure E.11 – Indicating a common compound tolerance zone 64 Figure E.12 – Two different ways of indicating a GPS with projected tolerance modifier 66 Figure E.13 – Explanation of the direction of the extended feature 66 Figure E.14 – Example of direct indication of a projected tolerance with an offset 66 Figure E.15 – Example of indirect indication of a projected tolerance with an offset 67 Figure E.16 – Example of the use of projected tolerance zone together with the median modifier 68 Figure E.17 – Example of the use of projected tolerance zone together with a common zone modifier 68 Figure F.1 – Model of the relationship between specification, verification and the actual workpiece 70 Figure F.2 – The link between design intent and metrology 71 Figure F.3 – The duality principle 73 Figure F.4 – The GPS matrix model 78 Figure G.1 – The relationship between the elements of a technical drawing 81 Figure G.2 – Schematic of the TPR triumvirate 83 Figure G.3 – Technical product realization 83 List of tables Table A.1 – Normative references 28 Table B.1 – Informative references 51

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Foreword Publishing information This British Standard was published by BSI and came into effect on 31 October 2006. It was prepared by Technical Committee TDW/4, Technical product specification (TPS) – Methodology, presentation and verification. A list of organizations represented on this committee can be obtained on request to its secretary. Supersession This British Standard supersedes BS 8888:2004, which is withdrawn. This fourth revision updates and extends the third edition, bringing in relevant standards published during 2005 and the first few months of 2006. This revision has been made with particular reference to online provision. Relationship with other publications The function of BS 8888 is to draw together, in an easily accessible manner, the full complement of International Standards relevant to the preparation of technical product specifications, in accordance with geometrical product specification (GPS) principles. However, it is not the intention that BS 8888 should be a “stand-alone” standard since it is part of a triumvirate of TPR (Technical Product Realization) standards comprising BS 8887 and BS 8889. The relationship of these three standards to each other is explained in Annex G. It should be noted that BS 8888 has recently been taken up by the Ministry of Defence as part of its DEF-STAN for defence project specification and that BSI does make educational/training aids available in this field and is currently planning a major education/training initiative which, it is expected, will lead to a programme of competency assessment and certification. “GPS Relevance” symbol Because the principal objective of BS 8888 is to provide for accurate, unambiguous technical product specification (TPS), the particular standards provision that constitutes the GPS system of dimensioning and tolerancing will be found throughout the document. Recognizing that on occasion it may be useful to be able to identify and pull together certain GPS elements into a continuous sequence, this edition of BS 8888 introduces the “GPS Relevance” symbol (see table below) as a means of doing this, for the first time. This segmented symbol is shaded to correlate with the layers of the GPS system itself and is placed in the margin adjacent to the clause or subclause to which it refers. The formation of the symbol is based on the following. An unambiguous GPS is built upon a solid base of foundation standards relating to fundamental principles and presentation media, for example. While the specification of a feature or component defines size, geometry and surface.

Where no specific relevance to the GPS system can be identified the symbol is left unshaded.

GPS Relevance symbol

Symbol Foundation Size Geometry Surface

No No No No

Yes No No No

No Yes No No

No No Yes No

No No No Yes

No Yes Yes No

Yes Yes Yes No

Presentational conventions The provisions of this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary verb is “shall”. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element. All dimensions shown in the figures in this standard are in millimetres. Contractual and legal considerations This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations.

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1 Scope This British Standard specifies requirements for the preparation of all forms of technical product specification. The requirements cross-refer substantially to International and European Standards which have been implemented as British Standards either in the BS ISO, BS EN, BS EN ISO series or as International Standards re-numbered as British Standards. The requirements are supplemented by commentary and recommendations on technical matters that are considered to be of assistance to users of this standard in the UK and which do not conflict with published International Standards in this field. Annex A and Annex B list cross-referenced standards and other documents, normative and informative respectively, by primary reference. Annex C (normative) sets out requirements for enhanced document security. Annex D (informative) identifies the main differences in approach between the provisions of this standard and those of the American Society of Mechanical Engineers (ASME) Y14.5:1994. Annex E (informative) provides a brief history of the development of BS ISO 1101. Annex F (informative) provides a summary report on the concepts that have underwritten the development of technical product specification (TPS) and its primary constituent, geometrical product specification (GPS), to date and discusses some of the drivers for future change. Annex G (informative) gives the rationale behind the development of BS 8888. Annex H (informative) gives a list of recommended default choices in response to options that are available in the body of BS 8888. NOTE 1 This is the paper-based version of BS 8888, which will henceforth be kept live and updated online. TPS Online, including BS 8888, can be found at http://www.bsi-global.com/bs8888, accompanied by the full range of cross-referenced standards, all hyperlinked to the relevant reference(s) within the text of the primary standard. When used in paper form, it is necessary that this standard be used in conjunction with the relevant cross-referenced standards NOTE 2 This British Standard is also available in CD-ROM format.

2 References

2.1 Normative references The normative documents listed in Annex A are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

2.2 Informative references This British Standard refers to other publications that provide information or guidance. These informative documents are listed in Annex B. Care should be taken to ensure that reference is made to the most recent edition.

3 Terms and definitions For the purposes of this British Standard, the following terms and definitions apply, together with those given in: BS ISO 10209-1 Technical product documentation – Vocabulary – Part 1: Terms relating to technical drawings: general and types of drawing BS EN ISO 10209-2 Technical product documentation – Vocabulary – Part 2: Terms relating to projection methods BS EN ISO 14660-1 Geometrical product specification (GPS) – Geometrical features – Part 1: General terms and definitions

3.1 date of acceptance point in time at which all interested parties agree that the technical product specification is to be considered finalized to the extent that manufacturing can commence. NOTE 1 This may be identified by other terms, e.g. “date of issue”. NOTE 2 For the implications of the date of acceptance see 4.2.4. 3.2 geometrical product specification GPS system for defining the shape (geometry), dimensions and surface characteristics of a workpiece 3.3 technical product document TPD means of conveying all or part of a design definition or specification of a product for manufacturing and verification purposes 3.4 technical product specification TPS collection of technical product documents comprising the complete design definition and specification of a product, for manufacturing and verification purposes NOTE 1 A TPS was previously called a technical product document set. NOTE 2 A TPS can consist of one or more TPDs. NOTE 3 A TPS will contain GPS application (see 16.1 for first reference).

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4 Global standards underpinning BS 8888

4.1 Introduction The ISO Geometrical Product Specification (GPS) Standards Matrix (see F.4) embodies the concept of “global” standards that underpin the whole GPS process. This principle is adopted in BS 8888 and the following standards shall be applied as “global” standards in support of BS 8888. BS EN ISO 1 Geometrical Product Specifications (GPS) – Standard reference temperature for geometrical product specification and verification BS ISO 10579 Technical drawings – Dimensioning and tolerancing – Non-rigid parts BS EN ISO 14253-1 Geometrical product specifications (GPS) – Inspection by measurement of workpieces and measuring equipment – Part 1: Decision rules for proving conformance or non-conformance with specifications BS EN ISO 14253-2 Geometrical product specifications (GPS) – Inspection by measurement of workpieces and measuring equipment – Part 2: Guide to the estimation of uncertainty in GPS measurement, in calibration of measuring equipment and in product verification DD ISO/TS 17450-1 Geometrical product specification (GPS) – Part 1: Model for geometrical specification and verification DD ISO/TS 17450-2 Geometrical product specification (GPS) – Part 2: Operators and uncertainties PD 6461-1 General metrology – Part 1: Basic and general terms (VIM) PD 6461-3 General metrology – Part 3: Guide to the expression of uncertainty in measurement (GUM)

4.2 The fundamental TPS principles

4.2.1 Introduction The following principles shall always be applied where compliance with BS 8888 is claimed.

4.2.2 The operator principle A geometrical characteristic is defined by an operator, which is based upon one or more operations and controlled unambiguously by indication in a TPD. COMMENTARY AND RECOMMENDATIONS ON 4.2.2 Two types of operators exist: specification operators, which are formulated as virtual measuring procedures, and verification operators, which define the sequence of operations used during the measuring process. (See DD ISO/TS 17450-1 and DD ISO/TS 17450-2.)

4.2.3 The duality principle The duality principle states that the verification operator is the physical implementation of the specification operator. COMMENTARY AND RECOMMENDATIONS ON 4.2.3 Were the verification operator (measuring procedure) to be a theoretically perfect implementation, the measurement result would be without measurement uncertainty. The principle that the specification operator defines the requirement in the TPS is the core of the “duality principle”, which requires that the specification operator be defined independently of any measuring procedure or item of measuring equipment. However, likely deviation of the verification operator from the specification operator indicated in the TPS will contribute to the overall measurement uncertainty (see DD ISO/TS 17450-1 and DD ISO/TS 17450-2).

4.2.4 The TPS at its acceptance date is definitive, principle. What is not specified in a TPS at the date of acceptance cannot be required. COMMENTARY AND RECOMMENDATIONS ON 4.2.4 Requirements only exist where explicitly indicated in the TPS at the date of acceptance or if defined in BS 8888, at that date. The implication of this is that the acceptance date of the TPS implicitly restricts the interpretation of the specification contained within the TPS to those standards in force at the date of acceptance.

4.2.5 The default principle A complete specification operator can be indicated by the most concise indication for the relevant geometrical characteristic (i.e. the basic GPS). COMMENTARY AND RECOMMENDATIONS ON 4.2.5 The basic GPS constitutes the default definition of the specification operator, which might not be visible in the TPS (see DD ISO/TS 17450-2).

4.2.6 The reference condition principle If not otherwise indicated in the TPS, the reference temperature for the tolerances given in that TPS is 20 °C (see BS EN ISO 1) and the workpiece is assumed not to be influenced by any other external physical condition.

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4.2.7 The uncertainty in conformance principle Where no prior agreement as to the application of uncertainty exists, between two (or more) parties and: • where conformance with a specification is to be proven, measurement uncertainty, U reduces the specification to the conformance zone at both tolerance limits and shall always be applied in the interest of the customer purchasing the part; or • where non-conformance with a specification is to be proven, measurement uncertainty, U expands the tolerance at both tolerance limits, uncertainty of measurement shall always be applied in the interest of the manufacturer/seller of the part. NOTE It is recognized that a specification will itself contain uncertainty. COMMENTARY AND RECOMMENDATIONS ON 4.2.7 Within this TPS system, three categories of uncertainty are defined (DD ISO/TS 17450-2): a) specification uncertainty (attributed to the designer); b) correlation uncertainty (attributed to the designer); and c) measurement uncertainty (attributed to the metrologist).

5 Expression of the concept COMMENTARY AND RECOMMENDATIONS Before specifying a technical product, the broad requirement should be established, with particular attention being paid to the functions that the product will be expected to fulfil. The conceptual, design intent can then be depicted in the form of a design layout, scheme or simplified computer-generated model, although this will not normally be used in the detailed TPD for manufacturing purposes. The importance of this stage cannot be over-emphasized. Clear understanding of the purpose and function intended for the eventual product, knowledge of the requirements of the available manufacturing methods and awareness of relevant verification procedures, will help to ensure that the degree of complexity of the specification is appropriate and adequate. It is not the aim of this standard to attempt to instruct or constrain the design process. It is, however, of the greatest importance that the designer presents the product of his design process, i.e. the TPS containing the technical, product specification, in a manner that avoids ambiguity and any risk of misunderstanding or misinterpretation. For this reason, it is imperative that the designer be familiar with the requirements of this standard and aware of the increased precision that its use can bring. For these and many other reasons, management of the overall design process can be complex and the following standards might be found to be of assistance in this field. BS EN 61160 Design review BS EN 60300-3-3 Dependability management – Part 3-3: Application guide – Life cycle costing BS 7000-1 Design management systems – Part 1: Guide to managing innovation

BS 7000-2 Design management systems – Part 2: Guide to managing the design of manufactured products BS 7000-10 Design management systems – Part 10: Glossary of terms used in design management BS 8444-3 Risk management – Part 3: Guide to risk analysis of technological systems

6 Types of documentation

6.1 General The careful targeting of TPDs to known or intended users will greatly assist the accuracy with which the specification is converted into the final product. While precision and avoidance of ambiguity should always be paramount, the means employed to convey this information should always be seen to match the capability, or potential capability, of the available or achievable manufacturing facility. Specification beyond this level is unlikely to produce satisfactory results and will often prove expensive, both in terms of the cost of the over-specification itself and in terms of inadequate or unacceptable product.

6.2 Presentation media

6.2.1 General The presentation of the drawings shall conform to the following standards. BS EN ISO 5457 Technical product documentation – Sizes and layout of drawing sheets BS EN ISO 7200:2004 Technical product documentation – Data fields in title blocks and document headers

NOTE BS EN ISO 7200:2004 implements ISO 7200:2004 without change. This revision was developed to extend the scope of the standard to include TPS presented wholly or in part in the form of meta-data. Throughout its development, the United Kingdom expressed strong reservation as to the completeness of its content, particularly with regard to the omission of certain elements of the 1984 version still considered to be valid, but was unable to achieve consensus in support of their restoration. For this reason, BS 8888 includes (see 6.2.2) the requirement to apply certain additional standards as part of the application of BS ISO 7200:2004, all of which are already cross-referenced from BS 8888. These requirements are not in conflict with the provisions of the revised BS EN ISO 7200:2004 and do no more than restore these missing elements. Particular attention is drawn to Figure 1 and Figure 2 of BS EN ISO 7200:2004, which are provided by way of example but are not wholly correct in that the text is in lower case. These examples should be viewed in conjunction with the relevant clauses of BS EN ISO 3098 (all parts) and BS EN ISO 6428.

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6.2.2 Application of BS ISO 7200:2004 The application of BS ISO 7200:2004 shall be extended to include relevant provisions of the following standards. BS EN ISO 3098-0 Technical product documentation – Lettering – Part 0: General requirements BS EN ISO 3098-2 Technical product documentation – Lettering – Part 2: Latin alphabet, numerals and marks BS EN ISO 3098-3 Technical product documentation – Lettering – Part 3: Greek alphabet BS EN ISO 3098-4 Technical product documentation – Lettering – Part 4: Diacritical and particular marks for the Latin alphabet BS EN ISO 3098-5 Technical product documentation – Lettering – Part 5: CAD lettering of the Latin alphabet, numerals and marks BS EN ISO 3098-6 Technical product documentation – Lettering – Part 6: Cyrillic alphabet BS EN ISO 6428 Technical drawing – requirements for microcopying BS EN ISO 6433 Technical drawings – item references BS ISO 7573 Technical drawings – Item lists BS ISO 10209-1 Technical Product Documentation – Vocabulary – Terms relating to technical drawings general and types of drawings

6.2.3 Format Drawing sheets and other documents shall be presented in one of the following formats: a) landscape: intended to be viewed with the longest side of the sheet horizontal; b) portrait: intended to be viewed with the longest side of the sheet vertical. NOTE Contrary to BS EN ISO 5457, A4 sheets may be used in landscape or portrait mode.

6.2.4 Metric reference graduation COMMENTARY AND RECOMMENDATIONS Any metric reference graduation (scale bar) should be figure-less, have a minimum length of 100 mm and be graduated at 10 mm intervals. It should be located symmetrically about a centring mark, near the frame and within the border. It should have a maximum width of 5 mm and the continuous strokes should be of 0.5 mm maximum thickness (see Figure 1).

Figure 1 Metric reference graduations

6.3 Combined drawing COMMENTARY AND RECOMMENDATIONS A combined drawing should display an assembly, item list and constituent details, drawn separately but all on the same drawing.

6.4 Diagram COMMENTARY AND RECOMMENDATIONS The function of a system, or the relationship between component parts, may be depicted in a diagram employing simplified representations, as recommended in the following standards. BS EN ISO 3952-1 Kinematic diagrams – Graphical symbols – Part 1

BS EN ISO 3952-2 Kinematic diagrams – Graphical symbols – Part 2

BS EN ISO 3952-3 Kinematic diagrams – Graphical symbols – Part 3

BS EN ISO 3952-4 Technical drawings – Simplified representation for kinematics – Part 4: Miscellaneous mechanisms and their components BS 5070-1 Engineering diagram drawing practice – Part 1: Recommendations for general principles BS 5070-3 Engineering diagram drawing practice – Part 3: Recommendations for mechanical/fluid flow diagrams BS 5070-4 Engineering diagram drawing practice – Part 4: Recommendations for logic diagrams BS EN 61082-2 Preparation of documents used in electrotechnology – Part 2: Function-oriented diagrams

6.5 Document list – Drawing list COMMENTARY AND RECOMMENDATIONS A document list should consist of a list of all graphical representations and selected specifications required to build the assembly from which it derives its title and primary identifier.

7Scales Scales shall conform to the following standard. BS EN ISO 5455 Technical drawings – Scales

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8 Lines, arrows and terminators

8.1 Lines and terminators Lines shall conform to the following standards, as appropriate. BS EN ISO 128-20 Technical drawings – General principles of presentation – Part 20: Basic conventions for lines BS EN ISO 128-21 Technical drawings – General principles of presentation – Part 21: Preparation of lines by CAD systems BS ISO 128-22 Technical drawings – General principles of presentation – Part 22: Basic conventions and applications for leader lines and reference lines BS ISO 128-23 Technical drawings – General principles of presentation – Part 23: Lines on construction drawings BS ISO 128-24 Technical drawings – General principles of presentation – Part 24: Lines on mechanical engineering drawings BS ISO 128-25 Technical drawings – General principles of presentation – Part 25: Lines on shipbuilding drawings

8.2 Lines, terminators and origin indicators Arrows and terminators composed of lines shall conform to the following standard. BS ISO 129-1 Technical drawings – Indications of dimensions and tolerances – Part 1: General principles

9 Lettering

9.1 General Lettering shall conform to the following standard. BS EN ISO 3098-0 Technical product documentation – Lettering – Part 0: General requirements Lettering shall also conform to the following standards, as appropriate. BS EN ISO 3098-2 Technical product documentation – Lettering – Part 2: Latin alphabet, numerals and marks BS EN ISO 3098-3 Technical product documentation – Lettering – Part 3: Greek alphabet BS EN ISO 3098-4 Technical product documentation – Lettering – Part 4: Diacritical and particular marks for the Latin alphabet

BS EN ISO 3098-5 Technical product documentation – Lettering – Part 5: CAD lettering of the Latin alphabet, numerals and marks BS EN ISO 3098-6 Technical product documentation – Lettering – Part 6: Cyrillic alphabet

9.2 Notes When a landscape-format drawing sheet is used in its normal orientation, with the title block at the bottom right-hand corner, notes shall be lettered parallel to the long side of the sheet. When a landscape-format drawing sheet is used in portrait orientation, the title block shall be located at the left-hand side and notes shall be lettered parallel to the short side of the sheet. COMMENTARY AND RECOMMENDATIONS ON 9.2 Placement Notes of a general nature should, wherever practicable, be grouped together and not distributed over the drawing. Notes relating to specific details should appear near the relevant feature, but not so near as to crowd the view. Underlining Underlining of notes is not recommended. Where emphasis is required, larger characters should be used.

10 Projections Projections shall conform to one of the following standards: BS EN ISO 5456-2 Technical drawings – Projection methods – Part 2: Orthographic representations BS EN ISO 5456-3 Technical drawings – Projection methods – Part 3: Axonometric representations BS ISO 5456-4 Technical drawings – Projection methods – Part 4: Central projection BS EN ISO 10209-2 Technical product documentation – Vocabulary – Part 2: Terms relating to projection methods

NOTE BS EN ISO 5456-1, Technical drawing – Projection methods – Part 1: Synopsis, contains a survey of the various projection methods.

11 Views

11.1 General Views shall conform to the following standards. BS ISO 128-30 Technical drawings – General principles of presentation – Part 30: Basic conventions for views BS ISO 128-34 Technical drawings – General principles of presentation – Part 34: Views on mechanical engineering drawings

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11.2 Auxiliary views Where true representation of features is necessary, but cannot be achieved on the orthographic views, the features shall be shown in projected auxiliary views. An example is shown in Figure 2.

Figure 2 Auxiliary view showing true shape of inclined surface

12 Sections Sections shall conform to the following standards. BS ISO 128-40 Technical drawings – General principles of presentation – Part 40: Basic conventions for cuts and sections BS ISO 128-44 Technical drawings – General principles of presentation – Part 44: Sections on mechanical engineering drawings BS ISO 128-50 Technical drawings – General principles of presentation – Part 50: Basic conventions for representing areas on cuts and sections

NOTE ISO 128-44 and ISO 128-50 contained presentational defects in some figures (e.g. line types, line thickness, terminators and letter heights), which have, unavoidably, been carried forward to the BS implementations. It is stressed that the text of these standards is technically correct and users should, therefore, regard the figures as illustrations only. 13 Symbols and abbreviations

13.1 General 13.1.1 Abbreviations (text equivalents) shall be the same in the singular and plural. Full stops shall not be used except where the abbreviation forms a word (e.g. NO. as an abbreviation for “number”). 13.1.2 Symbols used for physical quantities and units of measurement shall conform to the following standards, as appropriate. BS ISO 31-0 Specification for quantities, units and symbols – Part 0: General principles BS ISO 31-1 Specification for quantities, units and symbols – Part 1: Space and time

BS ISO 31-2 Specification for quantities, units and symbols – Part 2: Periodic and related phenomena BS ISO 31-3 Specification for quantities, units and symbols – Part 3: Mechanics BS ISO 31-4 Specification for quantities, units and symbols – Part 4: Heat BS ISO 31-5 Specification for quantities, units and symbols – Part 5: Electricity and magnetism BS ISO 31-6 Specification for quantities, units and symbols – Part 6: Light and related electromagnetic radiations BS ISO 31-7 Specification for quantities, units and symbols – Part 7: Acoustics BS ISO 31-8 Specification for quantities, units and symbols – Part 8: Physical chemistry and molecular physics BS ISO 31-9 Specification for quantities, units and symbols – Part 9: Atomic and nuclear physics BS ISO 31-10 Specification for quantities, units and symbols – Part 10: Nuclear reactions and ionizing radiations BS ISO 31-11 Specification for quantities, units and symbols – Part 11: Mathematical signs and symbols for use in physical sciences and technology BS ISO 31-12 Specification for quantities, units and symbols – Part 12: Characteristic numbers BS ISO 31-13 Specification for quantities, units and symbols – Part 13: Solid state physics BS ISO 1000 Specification for SI Units and recommendation for the use of their multiples and of certain other units

13.2 Standard symbols and abbreviations Symbols appropriate to technical product specification are provided and detailed throughout the suite of documents cross referenced from this standard and these shall be used where appropriate. NOTE 1 It is strongly recommended that abbreviations not be used. Where, in particular technical fields, certain abbreviations are in common use and generally understood, it is accepted that these may continue to be used but new abbreviations shall not be introduced. NOTE 2 Former practice has resulted in certain abbreviations becoming accepted as symbols and these should not be considered to provide precedence for the proliferation of abbreviations COMMENTARY AND RECOMMENDATIONS ON CLAUSE 13 In the existing environment of outsourcing across national borders, every effort is being made to make the use of GPS, independent of language through the adoption of standard symbology. It is for this reason that the continued use of abbreviations is deprecated. Where particular specification requirements cannot be expressed using the available GPS system, full text description should be employed. It is suggested that where such a requirement occurs frequently, this be drawn to the attention of the relevant ISO committee through the appropriate BSI Technical committee.

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For diagrams used in technical applications, a library of harmonized graphical symbols has been developed with close cooperation between ISO and IEC. This is published in the following series of standards and it is recommended that they be applied wherever practicable to improve the universal applicability of the TPS. BS ISO 14617-1 Graphical symbols for diagrams – Part 1: General information and indexes BS ISO 14617-2 Graphical symbols for diagrams – Part 2: Symbols having general application BS ISO 14617-3 Graphical symbols for diagrams – Part 3: Connections and related devices BS ISO 14617-4 Graphical symbols for diagrams – Part 4: Actuators and related devices BS ISO 14617-5 Graphical symbols for diagrams – Part 5: Measurement and control devices BS ISO 14617-6 Graphical symbols for diagrams – Part 6: Measurement and control functions BS ISO 14617-7 Graphical symbols for diagrams – Part 7: Basic mechanical components BS ISO 14617-8 Graphical symbols for diagrams – Part 8: Valves and dampers BS ISO 14617-9 Graphical symbols for diagrams – Part 9: Pumps, compressors and fans BS ISO 14617-10 Graphical symbols for diagrams – Part 10: Fluid power converters BS ISO 14617-11 Graphical symbols for diagrams – Part 11: Devices for heat transfer and heat engines BS ISO 14617-12 Graphical symbols for diagrams – Part 12: Devices for separating, purification and mixing

14 Representation of features Conventions used for the representation of features shall conform to the following standards, as appropriate. BS EN ISO 4063 Welding and allied processes – Nomenclature of processes and reference numbers BS EN ISO 5261 Technical drawings – Simplified representation of bars and profile sections BS EN ISO 5845-1 Technical drawings – Simplified representation of the assembly of parts with fasteners – Part 1: General principles BS EN ISO 6410-1 Technical drawings – Screw threads and threaded parts – Part 1: General conventions BS EN ISO 6410-2 Technical drawings – Screw threads and threaded parts – Part 2: Screw thread inserts BS EN ISO 6410-3 Technical drawings – Screw threads and threaded parts – Part 3: Simplified representation BS EN ISO 6411 Technical drawings – Simplified representation of centre holes

BS EN ISO 6413 Technical drawings – Representation of splines and serrations BS ISO 13715 Technical drawings – Edges of unidentified shape – Vocabulary and indications BS EN ISO 14660-2 Geometrical Product Specifications (GPS) – Geometrical features – Part 2: Extracted median line of a cylinder and a cone, extracted median surface, local size of an extracted feature BS EN ISO 15785 Technical drawings – Symbolic presentation and indication of adhesive, fold and pressed joints BS EN 22553 Welded, brazed and soldered joints – Symbolic representation on drawings NOTE The BS ISO 128 series of standards covers the general subject of feature representation.

15 Representation of components

15.1 General Conventions used for the representation of components shall conform to the following standards, as appropriate. BS EN ISO 2162-1 Technical product documentation – Springs – Part 1: Simplified representation BS EN ISO 2162-2 Technical product documentation – Springs – Part 2: Presentation of data for cylindrical helical compression springs BS EN ISO 2162-3 Technical product documentation – Springs – Part 3: Vocabulary BS EN ISO 2203 Technical drawings – Conventional representation of gears BS 2917-1 Graphic symbols and circuit diagrams for fluid power systems and components – Part 1: Specification for graphic symbols BS 3238-1 Graphical symbols for components of servo- mechanisms – Part 1: Transductors and magnetic amplifiers BS 3238-2 Graphical symbols for components of servo-mechanisms – Part 2: General servo-mechanisms BS EN ISO 5845-1 Technical drawings – Simplified representation of the assembly of parts with fasteners – Part 1: General principles BS EN ISO 6410-1 Technical drawings – Screw threads and threaded parts – Part 1: General conventions BS EN ISO 6410-2 Technical drawings – Screw threads and threaded parts – Part 2: Screw thread inserts BS EN ISO 6410-3 Technical drawings – Screw threads and threaded parts – Part 3: Simplified representation

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BS EN ISO 6412-1 Technical drawings – Simplified representation of pipelines – General rules and orthogonal representation BS EN ISO 6412-2 Technical drawings – Simplified representation of pipelines – Isometric projection BS EN ISO 6412-3 Technical drawings – Simplified representation of pipelines – Terminal features of ventilation and drainage systems BS EN ISO 8826-1 Technical drawings – Roller bearings – Part 1: General simplified representation BS EN ISO 8826-2 Technical drawings – Roller bearings – Part 2: Detailed simplified representation BS EN ISO 9222-1 Technical drawings – Seals for dynamic application – Part 1: General simplified representation BS EN ISO 9222-2 Technical drawings – Seals for dynamic application – Part 2: Detailed simplified representation NOTE The BS ISO 128 series of standards covers the general subject of component representation.

15.2 Representation of moulded, cast and forged components Dimensional tolerancing for metal and metal alloy castings shall conform to BS 6615:1996. COMMENTARY AND RECOMMENDATIONS ON 15.2 It is recommended that tolerances for the dimensions of plastics mouldings be applied in accordance with the system provided in BS 7010. ISO 8062:1994 which is implemented in full by BS 6615 is currently undergoing extensive revision under the generic title Geometrical product specifications (GPS) — Dimensional and geometrical tolerances for moulded parts. This will be published in three parts: • Part 1: Vocabulary; • Part 2: Rules; and • Part 3: General dimensional and geometrical tolerances and machining allowances for castings. Parts 1 and 3 of ISO 8062 will be published as BS ISO 8062 Part 1 and Part 3, early in 2007 and it is expected that Part 2 will become available by the end of that year. Together, the three parts of BS ISO 8062:2007 will cancel and replace ISO 8062:1994 of which they will constitute a technical revision. Future action with regard to BS 7010 will be decided at that time.

16 Dimensioning and tolerancing

16.1 Interpretations of limits of size for the control of form

16.1.1 General COMMENTARY AND RECOMMENDATIONS The limits of size of an individual feature-of-size may be defined using one of the following principles: a) the principle of independency of size and form, where the limits of size are intended to exercise control only over the size of the feature-of-size, and not to exercise any control over its form; or b) the principle of dependency of size and form, where the limits of size are intended to exercise control over the form of the feature-of-size as well as its size. In both cases, an individual feature-of-size is defined as one cylindrical or spherical surface or as a pair of parallel surfaces, each feature-of-size being defined by a linear dimension. In neither case do the limits of size control the orientation of, or the spatial relationship between, individual features-of-size. If such relationships are functionally important, they need to be controlled separately by specifying geometrical tolerances. For example, a cube consists of three individual features-of-size, each composed of a pair of plane parallel surfaces. The perpendicularity of those individual features-of-size is not controlled by their size tolerances, and therefore if the function requires a perpendicularity tolerance, it should be specified. If the principle of dependency is applied then BS ISO 8015 becomes an informative document only.

16.1.2 Limits of size with independency of size and form COMMENTARY AND RECOMMENDATIONS With independency of size and form, limits of size control only the actual local sizes (two-point measurements) of a feature-of-size, and not its deviations of form (e.g. the circularity and straightness deviations of a cylindrical feature, or the flatness deviations of two parallel plane surfaces). Therefore, at the maximum material limit of size, the maximum limiting value of the form tolerance still applies (i.e. at maximum material limit of size it is permissible to have imperfect form). When applying the principle of independency it is necessary to specify each and every form tolerance (see Figure 3). According to the principle of independency, each specified dimensional and geometrical requirement on a drawing is met independently, unless a particular relationship is specified. Consequently, if a particular relationship of size and form is required, it needs to be specified on the drawing. This can be achieved by the use of the envelope requirement (see BS ISO 8015) or material modifiers. In effect this introduces the boundary or envelope of perfect form in the same manner as the principle of dependency (i.e. the maximum material limit of size defines the boundary or envelope of perfect form for the relevant surfaces).

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According to the principle of independency, each specified dimensional and geometrical requirement on a drawing is met independently, unless a particular relationship is specified. Therefore, where no relationship is specified, the geometrical tolerance applies regardless of feature size, and the two requirements are treated as unrelated (see Figure 3). Consequently, if a particular relationship of: •size and form; or •size and location; or • size and orientation; is required, it needs to be specified on the drawing.

Figure 3 Interpretations using the principle of independency for a cylindrical component for which a tolerance of size only is given on the drawing 25,0 24,9

a) Drawing presentation

a b c

NOTE There is no straightness control. Measurements a, b and c will lie between 25.0 mm and 24.9 mm, meeting the drawing requirement using two-point measurement only. The form is not controlled. b) Permissible interpretation: straightness

Maximum size

25,0 Maximum roundness deviation (resulting from a lobed form)

NOTE For any cross-section of the cylinder, there is no roundness control. c) Permissible interpretation: roundness

16.1.3 Limits of size with mutual dependency of size and form COMMENTARY AND RECOMMENDATIONS Where the feature-of-size is defined by limits of size only, the maximum material limit of size (i.e. the high limit of size of an external feature or the low limit of size of an internal feature) defines the boundary or envelope of perfect form for the relevant surfaces. If an individual feature-of-size is everywhere on its maximum material limit of size, the feature will have perfect form. If the individual feature-of-size is not on its maximum material size, errors in form will be acceptable provided that no part of the finished surfaces extends beyond the maximum material boundary or envelope of the perfect form, and that the feature-of-size is everywhere in accordance with its specified limits of size (see Figure 4). NOTE An external feature is also known as a “shaft type feature” and an internal feature is also known as a “hole type feature”. If the limits of size for the feature-of-size is at the least material limit of size (i.e. the low limit of size of an external feature or the high limit of size of an internal feature) then the form deviation can be at its maximum within the confines of the boundary or envelope of perfect form. If the limits of size specified permit form deviations large enough to be functionally unacceptable as the feature-of-size approaches its least material limit size, then these deviations can be controlled by specifying appropriate form tolerances. Such form tolerances will be maximum limiting values. The effect of these values will decrease as the feature-of-size approaches its maximum material limit of size, as no part of the finished surfaces of the feature-of-size is permitted to extend beyond the maximum material limit of perfect form. Where the principle of dependency is applied, verification of the feature-of-size and permissible form deviation is possible using “go/no-go” gauging techniques. The Taylor principle states that effective verification can only take place with a gauge touching the whole feature, ensuring that a mating part will “go” at the maximum material limit, while rejection checking is accomplished as a single examination with the two-point method (verification of least material limits). The application of the dependency principle however, implies that all features of size will have perfect form at maximum material limits and could impose higher production costs.

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Figure 4 Interpretation of limits of size with dependency of size and form

0 + 0,1 20 - 0,1 20 0

a) Drawing specification

20 20

19,9

20,1

20 20

19,9 20,1

19,9

b) Possible extreme errors of form

16.2 General Dimensioning and tolerancing shall conform to the following standards, as appropriate: BS ISO 129-1 Technical drawings – Indications of dimensions and tolerances – Part 1: General principles BS ISO 406 Technical drawings – Tolerancing of linear and angular dimensions BS EN ISO 1119 Geometrical product specifications (GPS) – Series of conical tapers and taper angles

BS EN ISO 1660 Technical drawings – Dimensioning and tolerancing of profiles BS 1916-1 Limits and fits for engineering – Part 1: Limits and tolerances BS 1916-2 Limits and fits for engineering – Part 2: Guide to the selection of fits in BS 1916:Part 1 BS 1916-3 Limits and fits for engineering – Part 3: Recommendations for tolerances, limits and fits for large diameters BS ISO 3040 Technical drawings – Dimensioning and tolerancing – Cones BS 4500-4 ISO limits and fits – Specification for system of cone (taper) fits for cones from C = 1:3 to 1:500, lengths from 6 mm to 630 mm and diameters up to 500 mm BS 4500-5 ISO limits and fits – Specification for system of cone tolerances for conical workpieces from C = 1:3 to 1:500 and lengths from 6 mm to 630 mm BS EN ISO 5458 Geometrical Product Specifications (GPS) – Geometrical tolerancing – Positional tolerancing BS EN ISO 6410-1 Technical drawings – Screw threads and threaded parts – Part 1: General conventions BS 6615 Specification for dimensional tolerances for metal and metal alloy castings BS 7010 Code of practice for a system of tolerances for the dimensions of plastic mouldings BS EN ISO 7083 Technical drawings – Symbols for geometrical tolerancing – Proportions and dimensions BS ISO 8015 Technical drawings – Fundamental tolerancing principle BS ISO 10579 Technical drawings – Dimensioning and tolerancing – Non-rigid parts BS ISO 13920 Welding – General tolerances for welded constructions – Dimensions for lengths and angles – Shape and position BS EN 20286-1 ISO system of limits and fits – Part 1: Bases of tolerances, deviations and fits BS EN 20286-2 ISO system of limits and fits – Part 2: Tables of standard tolerance grades and limit deviations for holes and shafts COMMENTARY AND RECOMMENDATIONS ON 16.2 Gaps between extension lines and features. It is the practice in the UK to leave a small gap between the extension line and the feature. In BS ISO 129-1 the illustrated examples do not show a gap but 5.3, includes the text, “in certain technical fields, a gap between the feature and the beginning of the extension line is acceptable”. The UK has always held to the view that for reasons of clarity a gap is preferable and given that in the revised standard the gap is permissible, it is intended that the current UK practice should be maintained.

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16.3 Presentation of decimals

16.3.1 Decimal marker The decimal marker shall be a comma.

16.3.2 Non-indicated decimals in tolerances Non-indicated decimals in a tolerance indication shall be taken as zeros e.g. 0,2 is the same as 0,20000000000…. COMMENTARY AND RECOMMENDATIONS ON 16.3 It is recommended that each group of three digits, counting from the decimal marker to the left and to the right, be separated from other digits by a small space (e.g. 12 345,067 8). In view of the requirement of 16.3.1, the use of a comma or a point for this purpose is deprecated, i.e. it is further recommended that separation of items in lists be effected by the use of a semi-colon. (See BS ISO 31-0, Specification for quantities, units and symbols – Part 0: General principles.)

16.4 Keyways Keyways in hubs or shafts shall be dimensioned by one of the methods shown in Figure 5. NOTE Further information on keys and keyways is given in BS 4235-1, Specification for metric keys and keyways – Part 1: Parallel and taper keys, and BS 4235-2, Specification for metric keys and keyways – Part 2: Woodruff keys and keyways.

Figure 5 Dimensioning of keyways

a) Parallel hub b) Tapered keyway in parallel hub c) Parallel keyway in tapered hub

d) Parallel shaft e) Parallel keyway in tapered shaft

f) Parallel shaft g) Tapered shaft

16.5 Screw threads Screw threads shall be specified according to functional requirement. COMMENTARY AND RECOMMENDATIONS ON 16.5 The following standards provide the definition for metric ISO screw threads. BS ISO 261 ISO general purpose metric screw threads – General plan. BS ISO 262 ISO general purpose metric screw threads – Selected sizes for screws, bolts and nuts. BS ISO 965-1 ISO general purpose metric screw threads – Tolerances – Part 1: Principles and basic data

16.6 Methods of specifying tolerances COMMENTARY AND RECOMMENDATIONS The necessary tolerances can be specified in one or more of the following ways: a) separate indication on the drawing; b) reference to general tolerances noted on the drawing; c) reference to a standard containing general tolerances; d) reference to other documents.

16.7 General tolerancing COMMENTARY AND RECOMMENDATIONS If reference to BS EN 22768-1 or BS EN 22768-2 for general tolerances is inappropriate, general tolerance notes may be used to apply a common tolerance to many of the features on a drawing. The example shown in Figure 6 illustrates the wide field of application of this system. Due to the inherent risk of unintentionally over-specifying form and orientation controls that can result from the use of general geometrical tolerances, reference to BS EN 22768-2 is inadvisable.

Figure 6 Examples of general tolerance notes

TOLERANCE EXCEPT WHERE OTHERWISE STATED +- X TOLERANCES EXCEPT WHERE OTHERWISE STATED

SIZE TOLERANCE - UP TO X +- A OVER X UP TO XX +- B TOLERANCE ON CAST THICKNESS OVER XX UP TO XXX +- C +- X % OVER XXX - +- D ON ANGLES +- E

FOR TOLERANCES ON FORGING DIMENSIONS SEE BS EN 10243-1

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17 Geometrical tolerancing

17.1 General Geometrical tolerancing shall conform to the following standards, as appropriate. BS ISO 1101 Technical drawings – Geometrical tolerancing – Tolerancing of form, orientation, location and run-out – Generalities, definitions, symbols, indications on drawings BS ISO 2692 Technical drawings – Geometrical tolerancing – Maximum material principle BS EN ISO 5458 Geometrical Product Specifications (GPS) – Geometrical tolerancing – Positional tolerancing BS ISO 5459 Technical drawings – Geometrical tolerancing – Datums and datum-systems for geometrical tolerances BS EN ISO 7083 Technical drawings – Symbols for geometrical tolerancing – Proportions and dimensions BS ISO 10578 Technical drawings – Tolerancing of orientation and location – Projected tolerance zone

18 Surface texture indication Indication of surface texture shall conform to the following standards. BS EN ISO 1302 Geometrical Product Specifications (GPS) – Indication of surface texture in technical product documentation BS EN ISO 8785 Geometrical product specification (GPS) – Surface imperfections – Terms definitions and parameters

The correct application of BS EN ISO 1302 requires the use of the following standards. Other normative references of BS EN ISO 1302 are also referenced in this standard. BS EN ISO 3274 Geometrical Product Specifications (GPS) – Surface texture: profile method – Nominal characteristics of contact (stylus) instruments BS EN ISO 4287 Geometrical Product Specifications (GPS) – Surface texture: Profile method – Terms, definitions and surface texture parameters BS EN ISO 4288 Geometrical Product Specification (GPS) – Surface texture – Profile method: Rules and procedures for the assessment of surface texture BS ISO 10135 Technical drawings – Simplified representation of moulded, cast and forged parts

BS EN ISO 11562 Geometrical Product Specifications (GPS) – Surface texture: Profile method – Metrological characteristics of phase correct filters BS EN ISO 12085 Geometrical Product Specifications (GPS) – Surface texture: Profile method – Motif parameters BS EN ISO 13565-1 Geometric Product Specifications (GPS) – Surface texture: Profile method – Surfaces having stratified functional properties – Part 1: Filtering and general measurement conditions BS EN ISO 13565-2 Geometrical Product Specifications (GPS) – Surface texture: Profile method – Surfaces having stratified functional properties – Part 2: Height characterization using the linear material ration curve BS EN ISO 13565-3 Geometrical Product Specifications (GPS) – Surface texture: Profile method – Surfaces having stratified functional properties – Part 3: Height characterization using the material probability curve BS EN ISO 14253-1 Geometrical Product Specifications (GPS) – Inspection by measurement of workpieces and measuring equipment – Part 1: Decision rules for proving conformance or non-conformance with specifications BS EN ISO 14660-1 Geometrical Product Specifications (GPS) – Geometrical features – Part 1: General terms and definitions BS EN ISO 81714-1 Design of graphical symbols for use in the technical documentation of products – Part 1: Basic rules NOTE Although it is not usual practice to make secondary references such as these, BS EN ISO 1302 itself is of such significance that it is considered appropriate to ensure their inclusion in the BS 8888 kits in this way.

19 Graphical representation and annotation of 3D data (3D modelling output) Graphical representation and annotation of 3D models shall conform to the following standards. DD 16792 Technical product documentation – Digital product definition – Data practices

COMMENTARY AND RECOMMENDATIONS ON CLAUSE 19 At time of publication of this standard, BS ISO 16792 is undergoing the final stages of approval. DD 16792 contains the draft of ISO 16792 circulated for comment, which is not expected to change substantially at final publication.

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20 Security

20.1 Introduction Many TPSs have minimal requirements for security, other than that provided by general handling and storage procedures (see Clause 21). However, where specific need for a general level of security is identified, the following requirements shall be met.

20.2 General security Procedures for ensuring the security of TPDs and TPSs shall conform to the following standard. BS EN ISO 11442-1 Technical product documentation – Handling of computer-based technical information – Part 1: Security requirements

20.3 Enhanced security Where enhanced security is claimed, the requirements of Annex C to this standard shall be met, in addition to those in 22.2.

20.4 Security level identification The level of security attributed to any given TPS shall be clearly identified by the relevant marking placed adjacent to the title or title block, of every TPD making up that TPS.

21 Storage and retrieval Methods for storage and retrieval of the document shall conform to the following standards, as appropriate. BS EN ISO 6428 Technical drawings – Requirements for microcopying BS EN ISO 11442-2 Technical product documentation – Handling of computer-based technical information – Part 2: Original documentation BS EN ISO 11442-3 Technical product documentation – Handling of computer-based technical information – Part 3: Phases in the product design process BS EN ISO 11442-4 Technical product documentation – Handling of computer-based technical information – Part 4: Document management and retrieval systems BS ISO 11442-5 Technical product documentation – Handling of computer-based technical information – Part 5: Documentation in the conceptual design stage of the development phase

22 Marking NOTE The marking of a TPD or TPS with the number of this standard constitutes a claim that the appropriate requirements of all relevant cross-referenced standards, in addition to the requirements directly stated in BS 8888, have been met. Attention is drawn to the “TPS at its acceptance date is definitive”, principle (4.2.4).

22.1 BS 8888 Technical product documents prepared in accordance with the requirements of this standard shall be marked with the number of this standard, i.e. BS 8888, in a prominent location.

22.2 BS 8888 (enhanced security) Technical product documents prepared in accordance with the requirements of this standard and meeting the requirements for enhanced security specified in Annex C, shall be marked with the number of this standard followed by a suffix “/D”, i.e. BS 8888/D, in a prominent location.

22.3 Tolerancing system Where the TPD or TPS has been prepared using the independency system of tolerancing (see commentary and recommendations on Clause 16), the mark identifying the number of this standard shall be supplemented by the letter “I” contained within an equilateral triangle, as shown in Figure 7.

Figure 7 Method of indicating that the independency system of tolerancing has been used

BS 8888 I

Where the TPD or TPS has been prepared using the dependency system of tolerancing (see commentary and recommendations on Clause 16), the mark identifying the number of this standard shall be supplemented by the letter “D” contained within an equilateral triangle, as shown in Figure 8.

Figure 8 Method of indicating that the dependency system of tolerancing has been used

BS 8888 D

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23 Protection notices COMMENTARY AND RECOMMENDATIONS It is suggested that where it is considered appropriate to place restrictions on the use of technical product documentation, the recommendations contained in the following standard be applied. BS ISO 16016 Technical product documentation – Protection notices for restricting the use of documents and products

© BSI 2006 • 27 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 le, the table also gives a have been lost details and clarity Not available es. In some figures, some es. In m compliance with BS 8888. Where availab ly illustrative purpos ly illustrative geometrical product specification geometrical product STTP: Screw threads and threaded parts threaded and threads Screw STTP: and magnetism available Not ts Not available e standard illustration Typical which need to be met in order clai information TPD: Technical product documentation SQUS – Part 6: Light and related electromagnetic radiations electromagnetic related and 6: Light SQUSPart – available Not SQUS – Part 1: Space and timeSQUS–Part phenomena related and 2: Periodic SQUSPart – SQUS 3: Mechanics – Part SQUS 4: Heat – Part 5: Electricity SQUS – Part available Not Not available Not available Not available Quantities and uni Quantities and Standard reference temperature for and verification oduced from other standards and are for pure standards and from other oduced ration from each standard. ration Normative references s containing requirements s containing BS ISO 31-6 ISO BS BS31-1 ISO BS31-2 ISO BS31-3 ISO BS31-4 ISO BS31-5 ISO BS31-0 ISO Standard referencedth Title of BS EN ISO 1 1 ISO EN BS references Normative 16.3.2

, 4.2 , 13.1.2 13.1.2 13.1.2 13.1.2 13.1.2 13.1.2 in the reproduction and reduction process. and reduction the reproduction in 4.1 13.1.2 Annex A (normative) NOTE The figures inthis annex are repr lists standard A.1 Table BS 8888 (sub)clause Table A.1 typical example of an illust table in the used Abbreviations GPP: General principles of presentationGPS: Geometrical product specifications tolerancingGT: Geometrical HCTI: Handling of computer-based technical Specificationfor quantities, units and symbols SQUS: drawings TD: Technical

28 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 existing contours on existing drawings landscape of plant subdivision beds/grass hidden outlines continuous line line dashed line dashed spaced Not available Not Not available Not Not available Not Dashed narrowDashed line lines by CAD systems Not available nventions and applications nventions and nuclear physicsnuclear available Not chemistry and molecular chemistry and e standard illustration Typical ) SQUS – Part 7: AcousticsSQUS– Part available Not SQUS – Part 8: Physical 8: Part – SQUS physics SQUS – Part 9: Atomic and 9: Atomic SQUS– Part SQUS – Part 10: Nuclear reactions and ionizing ionizing and reactions Nuclear 10: SQUS– Part radiations SQUS 11: Mathematical signs and – Part symbols for use sciences and technology physical in TD – GPP – Part 22: Basic co TD – GPP – Part leaderfor lines and reference TD – GPP – Part 23: Lines on construction drawings drawings on construction 23: Lines Part TD – GPP SQUS – Part 12: Characteristic numbersCharacteristic 12: SQUS– Part available Not TD – GPP – Part 21: Preparation of TD – GPP – Part SQUS – Part 13: Solid state physics state Solid 13: SQUS – Part for lines conventions 20: Basic Part TD – GPP available Not continued ( Standard referencedth Title of BS 128-21 ISO EN BS 128-20 ISO EN references Normative BS ISO 31-7 ISO BS BS ISO 31-8 ISO BS BS ISO 31-9 ISO BS BS ISO 31-10 31-10 ISO BS BS ISO 31-11 31-11 ISO BS BS ISO 31-12 ISO BS BS ISO 31-13 ISO BS BS ISO 128-22 128-22 ISO BS BS ISO 128-23 128-23 ISO BS 13.1.2 Table A.1 BS 8888 (sub)clause 13.1.2 13.1.2 13.1.2 13.1.2 13.1.2 8.1 8.1 13.1.2 8.1 8.1

© BSI 2006 • 29 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 indication of (limited) requiredareas of surface treatment, e.g. heat treatment planes of cutting position hidden edges hidden profiles Long-dashed dotted dotted Long-dashed line wide narrowDashed line c conventions for views c conventions for ) TD – GPP – Part 25: Lines on shipbuilding drawings drawings shipbuilding Lines on 25: GPP – Part – TD 30: Basi –GPP Part TD TD – GPP – Part 24: Lines on mechanical engineering TD – GPP Part drawings continued ( BS128-30 ISO Standard referencedthe standardof Title Typical illustration references Normative BS ISO 128-25 128-25 ISO BS BS ISO 128-24 128-24 ISO BS 8.1 11.1 Table A.1 BS 8888 (sub)clause 8.1

30 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 on mechanicalengineering conventions for cuts and conventions for ) drawings TD – GPP – Part 34: Views 34: Views TD – GPP – Part 40: Basic GPP – Part – TD sections 44: Sections on mechanical GPP – Part – TD drawings engineering continued ( BS128-40 ISO Standard referenced Title of the standardBS128-34 ISO Typical illustration BS128-44 ISO references Normative 12 Table A.1 BS 8888 (sub)clause 11.1 12

© BSI 2006 • 31 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Arrowhead, open Arrowhead,30° open rred options rred options for dimensioning, tolerancing and lettering. tolerancing Arrowhead,30°closed and filled NOTE AnnexH gives prefe and tolerances – Part 1: and tolerances – Part e standard illustration Typical ) TD – GPP – Part 50: Basic conventions for conventions 50: Basic Part TD – GPP cuts and sections on areas representing of dimensions TD – Indications General principles. continued ( BS ISO 128-50 BS ISO 129-1 Standard referenced Title of th references Normative 16.2 , 12 8.2 Table A.1 BS 8888 (sub)clause

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BS 8888:2006 29,980 29,959 D 30 f7 L

-0,020 -0,041 d

Not available Not

30 f7

ucegkd fbakd jrikd ht C Z LD MD PD LE NC AC S α

/2 α 30 f7 Form Orientation Location Run-out Modifier symbols s and recommendations for recommendations and s ) GPS – Indication of surface texture in technical texture surface of – Indication GPS documentation product GPS – Series of conical tapers and taper angles conical – Series of GPS TD – GT – Tolerancing of form, orientation, location location orientation, form, of – Tolerancing GT – TD symbols, definitions, – Generalities, and run-out drawings on indications Specification for SI Unit Specification the use of their multiples and of certain other units other certain multiples and of the use of their TD – Tolerancing of linear and angular dimensions continued ( BS EN ISO 1302 ISO EN BS BS EN ISO 1119 ISO EN BS BS ISO 1101 ISO BS BS ISO 1000 ISO BS Standard referenced Title of the standard Typical illustration references Normative BS ISO 406 ISO BS 18 16.2 17.1 13.1 Table A.1 BS 8888 (sub)clause 16.2

© BSI 2006 • 33 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available View Section Simplified ing – Part 2: Guide to the Part ing – mplified representation ) TD – Dimensioning and tolerancing of profiles of and tolerancing Dimensioning – TD Limits and fitsfor 1: engineering Limitsand – Part tolerances Limits and fits for engineer Limits and fits 1 selectionBS of fits in 1916:Part 3: for engineering – Part Limits and fits for and fits limits tolerances, for Recommendations large diameters TPD – Springs – Part 1: Si TPD – Springs – Part continued ( BS 1916-1 Standard referenced Title of the standard Typical illustration BS 1916-2 BS 1916-3 BS EN ISO 2162-1 references Normative BS EN ISO 1660 16.2 16.2 Table A.1 BS 8888 (sub)clause 16.2 16.2 15.1

34 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 maximum material requirement maximum material least material requirement material least m l esentation of data for esentation esentation of gears ) TPD – Springs – Part 3: Vocabulary 3: Vocabulary TPD – Springs – Part repr – Conventional TD Not available TD – GT Maximum material principle TPD – Springs – Part 2: Pr – Part TPD – Springs cylindrical, helical, compression springs continued ( BS EN ISO 2203 Standard referenced Title of the standardBS EN ISO 2162-2 Typical illustration references Normative BS EN ISO 2162-3 BS ISO 2692 15.1 Table A.1 BS 8888 (sub)clause 15.1 15.1 17.1

© BSI 2006 • 35 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 d. Annex H gives preferred Annex H d. Not available Not options for dimensioning, tolerancing and lettering. for dimensioning, options NOTE BS non-preferre NOTE 8888 ral requirements Not available rt 1: Specification for diagrams for fluid power diagrams e standard illustration Typical ) TPD – Lettering – Part 4: Diacritical and particular TPD – Lettering– Part marks for the Latin alphabet TPD – Lettering – Part 3: Greek alphabet 3: Greek TPD – Lettering– Part TPD – Lettering – Part 0: Gene TPD – Lettering– Part 2: Latin alphabet, numerals TPD – Lettering– Part and marks TD – Dimensioning and tolerancing – Cones tolerancing and TD – Dimensioning Graphic symbols and circuit symbols Graphic systems and components – Pa graphic symbols continued ( BS EN ISO 3098-4 BS EN ISO 3098-3 ISO EN BS BS EN ISO 3098-2 BS EN ISO 3098-0 BS 2917-1 BS Standard referencedth Title of , , , , references Normative 6.2.2 6.2.2 6.2.2 6.2.2 , , , , BS ISO 3040 ISO BS 9.1 6.2.1 9.1 6.2.1 9.1 6.2.1 9.1 6.2.1 16.2 15.1 Table A.1 BS 8888 (sub)clause

36 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available Not available General servo-mechanisms ofile method – Terms, ofile method – Terms, e standard Typical illustration ) Graphical symbolscomponents for of Transductors 1: and servo-mechanisms – Part magnetic amplifiers Graphical symbolscomponents for of 2: Part servo-mechanisms – GPS – Surface texture: Profile method – Nominal characteristics of contact (stylus)instruments and allied processes – Nomenclatureof Welding numbers reference processes and – Surface texture:Pr GPS parameters surface texture and definitions TPD – Lettering – Part 5: CAD lettering the CAD lettering of 5: LatinTPD – Lettering – Part alphabet,and numerals marks alphabet Cyrillic 6: Lettering– – Part TPD continued ( BS 3238-2 BS BS 3238-1 BS 3274 ISO EN BS 4063 ISO EN BS BS EN ISO 4287 Standard referenced Title of th BS EN ISO 3098-5 BS EN ISO 3098-6 , , references Normative 6.2.2 6.2.2 , , 15.1 6.2.1 6.2.1 15.1 18 14 18 Table A.1 BS 8888 (sub)clause 9.1 9.1

© BSI 2006 • 37 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 nate symbol: L nate symbol: Not available Not available Not available Not available Not available Not available Not available Angle sectionAngle Alter tion of bars and profile profile bars and of tion ication forsystem of cone ication forsystem of cone ofile method – Rules and e standardillustration Typical ) GPS – Surface texture: pr– Surface texture: GPS of surface texture assessment procedures for the (taper) fits for cones from C = 1:3 to 1:500, lengths lengths 1:500, to 1:3 C = from cones for fits (taper) mm 500 diameters up to and mm 630 to mm 6 from lengths 1:500, to = 1:3 C from cones for tolerances mm 630 to mm 6 from ISO limitsfits andSpecif – ISO limitsfits andSpecif – 1: Part practice – diagram drawing Engineering principles general for Recommendations 3: Part practice – diagram drawing Engineering flow fluid mechanical/ for Recommendations diagrams 4: Part practice – diagram drawing Engineering diagrams logic for Recommendations TD – Simplified representa sections – Scales TD 2: Orthographic – Part methods Projection – TD representations continued ( Standard referenced Title of th BS EN ISO 4288 ISO EN BS BS 4500-4 BS 4500-5 BS 5070-1 BS 5070-3 BS 5070-4 BS 5261 ISO EN BS BS EN ISO 5455 references Normative 5456-2 ISO EN BS Table A.1 BS 8888 (sub)clause 18 16.2 16.2 6.4 6.4 6.4 14 7 10

38 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 e standard illustration Typical ) TD – Projection methods – Part 3: Axonometric Part TD – Projection methods representations projection4: Central Part TD – Projection methods continued ( Standard referenced Title of th references Normative BS EN ISO 5456-3 BS ISO 5456-4 Table A.1 BS 8888 (sub)clause 10 10

© BSI 2006 • 39 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 A rred options rred options for dimensioning, A Typical illustration Typical tolerancing and lettering. tolerancing NOTE AnnexH gives prefe

m-systems for geometrical geometrical for m-systems ) GPS – GT Positional tolerancing tolerances TD – GT – Datums and datu TD – GT Datums and Title of the standard TPD – Sizes and layout of drawing sheets TPD – Sizes and layout of drawing continued ( BS EN ISO 5458 BS5459 ISO Standard referenced BS EN ISO 5457 references Normative 6.2.3 17.1 17.1 , , 17.1 Table A.1 BS 8888 (sub)clause 6.2.1 16.2

40 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Detailed Conventional Simplified

Insert head screw Hexagon ) TD – Simplified representation of the assembly of representation of the TD – Simplified 1: General principles parts with fasteners – Part TD – STTP – Part 1: General conventions General 1: TD – STTP Part TD – STTP – Part 2: Screw thread inserts inserts 2: Screw thread TD – STTP Part representation 3: Simplified TD – STTP Part TD – Simplified representation of centre holes TD – Simplified continued ( Standard referencedstandardthe Title of Typical illustration BS EN ISO 5845-1 ISO EN BS BS EN ISO 6410-1 ISO EN BS BS EN ISO 6410-2 ISO EN BS 6410-3 ISO EN BS BS EN ISO 6411 ISO EN BS references Normative 16.2 16.2 , 15 15 15 15 15 15 , , , , Table A.1 BS 8888 (sub)clause 14 14 14 14 14

© BSI 2006 • 41 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 e standard illustration Typical ) TD – Simplified representation of pipelines – Part 1: Part – representation of pipelines TD – Simplified representation orthogonal and rules General 2: Part – representation of pipelines TD – Simplified projection Isometric continued ( Standard referenced Title of th BS EN ISO 6412-1 BS EN ISO 6412-2 references Normative Table A.1 BS 8888 (sub)clause 15 15

42 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available Scupper on of pipelines – Part 3: 3: – Part pipelines of on Guide to the expression of Guide to the ation and drainage systems ation and ) General metrology – Part 3: 3: – Part metrology General uncertainty in measurement (GUM) General metrology – Part 1: Basic and general 1: – Part metrology General terms (VIM) TD – Item references TD–Representations of splinesserrations and for microcopying TD – Requirements Not available TD – Simplified representati featuresventil of Terminal continued ( PD 6461-3 PD 6461-1 BS EN ISO 6433 BS EN ISO 6413 BS EN ISO 6428 Standard referencedthe standardof Title 6412-3 ISO EN BS Typical illustration

, references Normative 6.2.2 , 4.1 4.1 6.2.1 15 14 21 Table A.1 BS 8888 (sub)clause 15

© BSI 2006 • 43 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 E Not available Not and document headers Not available – Terms, definitions and – Terms, 2: Detailed simplified e standard illustration Typical ) representation TD – Rolling bearings – Part bearings TD – Rolling TD – Rolling bearings – Part 1: General simplified TD – Rolling bearings Part representation Specification for dimensional tolerances for metal for dimensional tolerances for Specification castings alloy metal and TPD – Data fields in title blocks TD – Item lists principle tolerancing TD – Fundamental imperfections GPS – Surface parameters Not available TD – Symbols for geometrical tolerancing – TD – Symbols for geometrical tolerancing Proportions and dimensions continued ( BS 6615 BS BS EN ISO 7200:2004 7573 ISO BS BS8015 ISO 8785 ISO EN BS BS EN ISO 7083 Standard referencedth Title of references Normative 16.2 , , 6.2.2 17.1 , 16.2 8826-2 ISO EN BS BS EN ISO 8826-1 , , 15.1 6.2.2 16.1.1 16.1.2 18 15.1 6.2.1 Table A.1 BS 8888 (sub)clause 15.2 16.2

44 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available on of moulded, cast and cast of moulded, on Terms relating to technical relating Terms e standard Typical illustration ) TD – Seals for dynamic application – Part 2: Detailed – Part application dynamic TD – Seals for simplified representation TD –Simplified representati parts forged 1: – Part TPD – Vocabulary of drawing types and general drawings: TD – Seals for dynamic application – Part 1: General – Part application dynamic TD – Seals for simplified representation TPD – Vocabulary – Part 2: Terms relating to relating 2: Terms Part – TPD – Vocabulary methods projection continued ( BS ISO 10135 BS ISO 10209-1 BS EN ISO 9222-2 Standard referenced Title of th BS EN ISO 10209-2 references Normative BS EN ISO 9222-1 6.2.2 10 , , 18 3 15.1 3 Table A.1 BS 8888 (sub)clause 15.1

© BSI 2006 • 45 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available – requirements e standard Typical illustration ) TPD – HCTI – Part 1: Security 1: TPD – HCTI – Part TPD – HCTI – Part 2: Original documentation documentation Original 2: – Part TPD – HCTI available Not TD – Dimensioning and tolerancing – Non-rigid parts – Non-rigid tolerancing and TD – Dimensioning Projected tolerancezone TD – Tolerancing of orientation and location and of orientation TD – Tolerancing continued ( BS ISO 10579 Standard referenced Title of th references Normative BS EN ISO 11442-1 BS ISO 10578 16.2 , BS EN ISO 11442-2 21 20.2 4.1 Table A.1 BS 8888 (sub)clause 17.1

46 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available Not available Not Not available Not available Not available Not available Not available Not available Not available Not for welded constructions – constructions for welded e method – Part 2: Height 2: e method – Part Height 3: e method – Part e method – Surfaces having ile method – Metrological es in the product design es in e development phase e standard illustration Typical ) process TPD – HCTI – Part 3: Phas 3: TPD – HCTI – Part and management Document 4: – Part TPD – HCTI systems retrieval conceptual in the Documentation 5: – Part TPD – HCTI of th design stage texture: Prof GPS – Surface characteristics of phase correct filters characteristics of GPS – Surface texture: Profile method – Motif GPS – Surface parameters Profil Surface texture: GPS – and Filtering 1: stratified functional properties – Part general measurementconditions texture: Profil GPS – Surface curve ration material the linear using characterization texture: Profil GPS – Surface material probability curve the using characterization and Vocabulary – shape TD – Edges of undefined indications tolerances – General Welding Dimensions for length and angles – Shape and position and – Shape length and angles for Dimensions continued ( BS EN ISO 11442-3 BS EN ISO 11442-4 BS ISO 11442-5 BS EN ISO 11562 Standard referenced Title of th BS EN ISO 12085 BS EN ISO 13565-1 BS EN ISO 13565-2 BS EN ISO 13565-3 BS ISO 13715 BS EN ISO 13920 references Normative 21 21 21 18 Table A.1 BS 8888 (sub)clause 18 18 18 18 14 16.2

© BSI 2006 • 47 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not Not available Not Drawing Workpiece Extraction Association Guide toestimation the Part 2: Extracted median 2: Extracted median Part ) of uncertainty in GPS measurement, in calibration of calibration in in GPS measurement, of uncertainty verification in product and equipment measuring GPS – Inspection by measurement of workpieces and by measurement of – Inspection GPS for rules 1: Decision equipmentmeasuring – Part with non-conformance or proving conformance specifications workpieces and by measurement of – Inspection GPS 2: equipmentmeasuring – Part GPS – Geometrical features – Part 1: General terms and 1: General terms and – features Part GPS – Geometrical definitions GPS – Geometrical features – – Geometrical features GPS line of a cylinder and a cone, extracted median surface,line extracted feature an of size local continued ( BS EN ISO 14253-1 DD ENV ISO 14253-2 BS EN ISO 14660-1 Standard referenced Title of the standard Typical illustration BS EN ISO 14660-2 references Normative 18 , 18 , 4.1 3 Table A.1 BS 8888 (sub)clause 4.1 14

48 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 t x w Not available Fold – Data practices– Data available Not – Part 2: Tables of standard Tables 2: – Part deviations for holes and d uncertainties Not available e standard illustration Typical ) GPS – Part 2: Operators an 2: GPS – Part Bases of 1: ISOof limits and fits – Part system fits and deviations tolerances, fits and limits of ISOsystem tolerance grades and limit TPD – Digital product definition and Model for geometrical specification 1: GPS – Part verification shafts TD – Symbolic presentation and indication of adhesive, adhesive, of and indication presentation – Symbolic TD fold and pressed joints continued ( DD17450-2 ISO/TS BS EN 20286-1 BS EN 20286-2 DD17450-1 ISO/TS DD 16792 BS EN ISO 15785 Standard referencedth Title of references Normative D.5 , 4.2 4.2 , , 4.1 16.2 16.2 19 4.1 14 Table A.1 BS 8888 (sub)clause

© BSI 2006 • 49 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006 Not available Not available Not available NOTE Annex H gives preferred options for dimensioning, dimensioning, for options gives preferred Annex H NOTE tolerancing andlettering e standard illustration Typical ) Welded, brazed and soldered joints – Symbolic joints soldered brazed and Welded, drawings on representation for linear 1: Tolerances – Part tolerances General dimensions and angular without individual tolerance indications for features 2: Tolerances – Part tolerances General indications tolerance individual without graphicalDesign of symbols for use in the technical 1: Basic rules Part – of products documentation continued ( Standard referencedth Title of BS EN 22553 EN BS BS EN 22768-1 BS EN 22768-2 BS 81714-1 ISO EN references Normative Table A.1 BS 8888 (sub)clause 14 16.7 16.7 18

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Annex B (informative) Informative references Table B.1 lists standards and other documents which provide information or guidance relevant to the application of BS 8888. NOTE Standards which are referred to both normatively and informatively are listed in Annex A only. Abbreviations used in the table GSD: Graphical symbols for diagrams SMKK: Specification for metric keys and keyways TD: Technical drawings DMS: Design management systems

Table B.1 Informative references

BS 8888 Referenced Title of document (sub)clause document 6.4 BS EN ISO 3952-1 Kinematic diagrams – Graphical symbols – Part 1 6.4 BS EN ISO 3952-2 Kinematic diagrams – Graphical symbols – Part 2 6.4 BS EN ISO 3952-3 Kinematic diagrams – Graphical symbols – Part 3 6.4 BS EN ISO 3952-4 TD –Simplified representation for kinematics – Part 4: Miscellaneous mechanisms and their components 16.4 BS 4235-1 SMKK – Part 1: Parallel and taper keys 16.4 BS 4235-2 SMKK – Part 2: Woodruff keys and keyways 10 BS EN ISO 5456-1 TD – Projection methods – Part 1: Synopsis 5 BS EN 61160 Design review 5 BS EN 60300-3-3 Dependability management – Part 3-3: Application guide – Life cycle costing 5 BS 7000-1 DMS – Part 1: Guide to managing innovation 5 BS 7000-2 DMS – Part 2: Guide to managing the design of manufactured products 5 BS 7000-10 DMS – Part 10: Glossary of terms used in design management 5 BS 8444-3 Risk management – Part 3: Guide to Risk analysis of technological systems 16.7 BS EN 10243-1 Steel die forgings – Tolerances on dimensions – Part 1: Drop and vertical press forgings 13 BS ISO 14617-1 GSD – Part 1: General information and indexes 13 BS ISO 14617-2 GSD – Part 2: Symbols having general application

Table B.1 Informative references (continued)

BS 8888 Referenced Title of document (sub)clause document 13 BS ISO 14617-3 GSD – Part 3: Connections and related devices 13 BS ISO 14617-4 GSD – Part 4: Actuators and related devices 13 BS ISO 14617-5 GSD – Part 5: Measurement and control devices 13 BS ISO 14617-6 GSD – Part 6: Measurement and control functions 13 BS ISO 14617-7 GSD – Part 7: Basic mechanical components 13 BS ISO 14617-8 GSD – Part 8: Valves and dampers 13 BS ISO 14617-9 GSD – Part 9: Pumps, compressors and fans 13 BS ISO 14617-10 GSD – Part 10: Fluid power converters 13 BS ISO 14617-11 GSD – Part 11: Devices for heat transfer and heat engines 13 BS ISO 14617-12 GSD – Part 12: Devices for separating, purification and mixing 23 BS ISO 16016 TPD – Protection notices for restricting the use of documents and products 6.4 BS EN 61082-2 Preparation of documents used in electrotechnology – Part 2: Function-oriented diagrams

Annex C (normative) Document security – Enhanced

C.1 Introduction Where requirements for enhanced security are known to exist, the procedures identified in this annex shall be applied in addition to those specified in Clause 20.

C.2 Identification of security classification C.2.1 Any required security classification and/or caveat, shall be inserted in the TPS, immediately after classified information is incorporated. C.2.2 Each sheet shall be classified according to its content. C.2.3 The security classification shall always appear at the top and bottom of A4 sheets and at the top left and bottom right hand corners of sheets larger than A4. C.2.4 The security classification shall either be: a) larger than the largest text used in the TPS; or b) bolder and the same size as the largest text used in the TPS.

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C.3 Marking for enhanced security Technical product document sets, prepared in accordance with the requirements of this clause in addition to those of BS 8888, shall be identified by the addition of the suffix “/D” to the number of this standard, i.e. “BS 8888/D”, in a prominent location. NOTE The marking of a technical product document with the number of this standard and the suffix “/D”, constitutes a claim that the appropriate requirements of all relevant cross-referenced standards, in addition to the requirements directly stated in BS 8888 and in Annex C, have been met.

Annex D (informative) Key differences between BS 8888 geometrical tolerancing and ASME Y14.5 geometric dimensioning and tolerancing (GD&T)

D.1 Introduction The standards currently cross referenced from BS 8888 have been the subject of extensive review and revision during recent years and this work still continues. Whilst working on these revisions attempt is made to bring about harmonization between ISO standards and existing ASME standards in the Y14.5 series but differences still remain. Some of these differences are of a minor nature or are self evident but others involve indications that are the same or very nearly so but which are interpreted differently between the two systems, giving rise to significant difference in outcome in some cases. This annex sets out to identify and analyse the differences between the systems, whilst making no claim as to which might be the more accurate in any particular application. However, it should be noted that where conformance to BS 8888 is claimed, it is implicit that the interpretations contained in the ISO system will apply. The differences addressed in this annex are not considered to be exhaustive and where the precise meaning of a particular requirement is critical to the performance of the workpiece to be specified, the applicable ISO standards should be consulted directly.

D.2 Applicability of standards If provisions from Y14.5 are to be invoked in a TPS prepared in accordance with BS 8888, the relevant Y14.5 cross reference shall be specifically identified at the point of application. By default the rules contained in the relevant ISO standards apply.

D.3 Exclusion of surface texture The ISO Standards comprising BS 8888 do not, currently, specify whether surface texture should be included or excluded when geometrical requirements are evaluated. However, the application of BS 8888 requires that surface texture be excluded by the use of appropriate filtering techniques. COMMENTARY ON D.3 – COMPARISON WITH Y14.5 ASME Y14.5.1M, which can be taken as an integral part of Y14.5 containing mathematical definitions of the Y14.5 principles, states that “all requirements apply after application of the smoothing functions defined in B46.1:1985,” i.e. surface texture has to be disregarded when evaluating workpieces using Y14.5 and thus is similar to the position taken in BS 8888.

D.4 Definition of datums Where a specified datum is of a form that allows the workpiece to “rock” when brought into contact with it (e.g. if the datum feature is a convex surface) the requirement applied through the application of BS 8888 is to “equalize the rock” such that an average position and orientation are used as the datum. Each requirement relating to the specified datum shall be evaluated individually to the same “average” datum. NOTE This rule is currently under revision to introduce more mathematical rigour but the intention of the rule will remain the same. COMMENTARY ON D.4 – COMPARISON WITH Y14.5 Y14.5 introduces the concept of “candidate datums” instead. This concept allows that every position that an unstable datum can rock to (with some limitations) is a valid “candidate datum”. A set of candidate datum reference frames can be derived for each set of requirements that are referenced to the same datum system, using the same precedence and the same material conditions. These sets of requirements are, by default, evaluated simultaneously to each candidate datum reference frame. If there exists a candidate datum reference frame where all the requirements are fulfilled, the workpiece is acceptable with regard to the requirements. These two sets of rules can result in substantially different conclusions especially if the form error of the datum feature is substantial. In general, the Y14.5 system accepts more workpieces as the form error of the datum feature increases. There are, however, examples where workpieces accepted under the applied BS 8888 (ISO) rules were subsequently ejected upon application of the Y14.5 rules, so assumptions should not be made. Attention is drawn to the fact that no measuring instrument currently available will evaluate workpieces strictly in accordance with either set of rules.

D.5 Size requirements The ISO System of limits and fits, defined in BS EN 20286-1, can be invoked by using the defined tolerance codes (e.g. h7 for a shaft and K8 for a hole). BS EN 20286-1, in turn, relies upon ISO/R 1938-1, which defines the inspection of workpieces for size requirements when the ISO tolerance codes are used.

54 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006

ISO/R 1938-1 defines a system of “hard gauges” that are to be used when verifying size tolerances. In this system, an allowance is made for gauge wear to the extent that in an extreme case a gauge may wear beyond the tolerance limit by up to 30% of the tolerance and still be useable. This means that workpieces can be up to 30% out of tolerance on the maximum material size (small hole or large shaft) and still be acceptable under the ISO limits and fits system. Additionally, the tolerance zones for hard gauges are located symmetrically around either the tolerance limit that the gauge is intended to test (minimum material side) or the wear limit (maximum material side), allowing the gauge to be outside its limit by half its tolerance. The tolerances given in BS EN 20286-1 are, therefore, not the real tolerances. These are derived adding the tolerances given in ISO/R 1938-1 to those of BS EN 20286-1. The need for this can be avoided by specifying the tolerance explicitly instead of applying the tolerance codes but this requires an indication of the size definition (e.g. envelope requirement), to ensure that the requirement is defined on the actual workpiece.

D.6 Tolerancing principle The ASME Y14.5 standard uses the Principle of Dependency (aka the Envelope Principle), invoked through Rule #1, for all features-of-size where only a tolerance of size is specified. The envelope of perfect form also applies to features-of-size which have additional geometrical form tolerances (such as flatness or circularity) applied. There are some exceptions to Rule #1: 1) It does not apply to stock materials (bar stock, sheet, tubing, etc.). 2) It does not apply to flexible parts subject to free state variation in the unrestrained condition. 3) It does not apply to features-of-size which have a straightness tolerance applied to their axes or median planes (by implication, this would also be the case where features-of-size have a flatness tolerance applied to the median plane, although the standard does not state this). 4) It may be overruled where a feature-of-size has a specified relationship between size and geometrical tolerances (by use of the m or l modifier in the geometrical tolerance). 5) It may be overruled with a statement such as “PERFECT FORM AT MMC NOT REQD” placed by a feature-of-size.

D.7 Features-of-size BS 8888 and ISOs ASME Y14.5:1994 Cylindrical surfaces Cylindrical surfaces Spherical surfaces Spherical surfaces Two parallel, opposed surfaces Two parallel, opposed surfaces A cone Two opposed elements (such as the ends of a slot) A wedge

Although not stated in either set of standards, the 180° rule, whereby a cylindrical or spherical surface is only considered to be a feature-of-size if its included angle is greater than 180°, is universally considered to be good practice.

D.8 Tolerance characteristics

Tolerance BS 8888 and ISOs ASME Y14.5:1994 Positional j The positional tolerance can be used to The positional tolerance is only used with control the location of features-of-size and features of size. also points, lines and flat planes. ASME Y14.5 recommends the use of the (d) to control a flat planar surface. Concentricity/ This tolerance is known both as a This tolerance is known only as a Coaxiality r “concentricity” tolerance and a “coaxiality” “concentricity” tolerance. tolerance. The definition for concentricity was changed The ISO definition uses the term in the 1994 version of Y14.5. Concentricity is “concentricity” to describe the situation defined as the condition where the median where the centre point of a feature is located points of all diametrically opposed elements of on a datum point or axis, and “coaxiality” to a figure of revolution are congruent with the describe the situation where an axis of a axis or centre point of a datum feature. feature is aligned with a datum axis. Although frequently confused with coaxiality, The concentricity/coaxiality tolerance is a this is different to coaxiality (which should be special case of the positional tolerance, controlled with a position tolerance, j). which can be used to control the location of Concentricity cannot be used with material the axes or centres of circular, cylindrical, condition modifiers (m or l ). spherical or conical features-of-size in relation to a datum axis or point. The concentricity/coaxiality tolerance can be replaced with a positional tolerance to provide an identical control. The concentricity/coaxiality tolerance, like the position tolerance, can be used with material condition modifiers (m or l ). Symmetry i The symmetry tolerance is a special case The symmetry tolerance was reintroduced of the positional tolerance, which can be to the 1994 version of Y14.5, having been used to control the location of the axis or removed from the previous version. median plane of a feature-of-size in Symmetry is defined as the condition where relation to a datum axis. the median points of all opposed or The concentricity/coaxiality tolerance can be correspondingly-located elements of two or replaced with a positional tolerance to more feature surfaces are congruent with the provide an identical control. axis or centre plane of a datum feature. The concentricity/coaxiality tolerance, like Symmetry cannot be used with material the position tolerance, can be used with condition modifiers (m or l). material condition modifiers (m or l ). Profile k and d The tolerance zones for profile tolerances The tolerance zones for profile tolerances are generated by placing a theoretical are generated by a vector offset from the circle (or sphere), with a diameter theoretically exact profile (or surface) to corresponding to the size of the tolerance, generate the boundary limits. on every point of the theoretically exact Where the theoretically exact profile (or profile (or surface) to generate the surface) contains sharp corners (or edges), boundary limits. the tolerance zone boundary is extended to Where the theoretically exact profile (or give a sharp corner (or edge). surface) contains sharp corners (or edges), Annotation is defined for unilateral and the tolerance zone boundary external to the unequal bilateral tolerance zones as well as corners (or edges) is radiused. symmetrical bilateral tolerance zones. Annotation is currently only defined for symmetrical bilateral tolerance zones. „ This form tolerance is to be known as This form tolerance is known as “circularity”. “roundness”.

56 • © BSI 2006 Licensed copy:PONTYPRIDD COLLEGE, 23/05/2007, Uncontrolled Copy, © BSI BS 8888:2006

Annex E (informative) BS ISO 1101:1984 to BS ISO 1101:2004 – The evolution

E.1 Revision of BS ISO 1101:1984 The 2004 revision of BS ISO 1101 was eagerly awaited, having not seen any published development for 21 years. The following is a summary of the significant changes. The 2004 edition saw a change in the title, introducing geometric product specifications (GPS) but continues to major on geometrical tolerancing of form, orientation, location and run-out. It is now a general GPS standard and acts as a signpost to other significant standards. A revised introduction sets out the new format of the standard and introduces revised terms such as “roundness” for “circularity”, in an effort to align with other GPS standards and also outlines the process of identifying old terms in parentheses throughout the document. A table has been added which identifies the line types used to illustrate the definition of the rules in Clause 18. An informative Annex A has been included to identify former practices. Annex B has expanded some of the information in the former Clause 3 giving normative information on geometrical deviations and Annex C gives normative references to the GPS Matrix Model.

E.2 BS ISO 1101:2004, Amendment 1 An amendment of BS ISO 1101:2004 is presently undergoing ISO TC/213 committee approval. This amendment titled “Representation of specifications in the form of a 3D model” is being introduced due to the extensive use by industry of 3D models within the technical product specification (TPS) field and the immanent publication of ISO 16792, Technical product documentation – Digital product definition data practices, which includes the presentation of annotation applied to 3D models. Existing technical product documentation (TPD) and GPS standards supporting TPS only refer to 2D applications and it has been recognized that there is an urgent requirement to review the existing 2D standards with a view to applicability within the 3D field. It has also been recognized that for some considerable time TPS will exist in 2D or 3D format and most likely as a mixture of both so, in order to promote uniformity, any new specification introduced as a result of a specific 3D application will also be suitable for 2D application. This amendment includes: • additional indication of the orientation of a tolerance zone where the interpretation could differ between in a 2D and 3D environment i.e. directional dependent tolerances such as straightness when applied to a view on a 2D drawing; • additional supplemental indications; • revised application of common zone (CZ); and • additional figures showing 3D applications.

The following is a summary of the significant proposed changes. NOTE The figures in this annex are under development and are included for purely illustrative purposes. Their usability cannot be guaranteed. Clause 3, Terms and definitions: the following will be added with explanatory notes: 3.2 annotation plane Conceptual plane containing annotation [ISO 16792:2006]. 3.3 intersection plane plane, established from an extracted feature of the workpiece, identifying a line on an extracted surface (integral or median) or a point on an extracted line. 3.4 orientation plane plane, established from an extracted feature of the workpiece, identifying the orientation of the width of the tolerance zone. Clause 5, Symbols: reference to BS ISO 10578 will be removed from Table 2, Projected tolerance zone. New symbols for “median feature” C and “unequally disposed tolerance” W will be added. B New symbols for “intersection plane” and “orientation B plane” covering parallelism, perpendicularity and symmetry have been added. Clause 6, Tolerance frame will be amended to identify more clearly the compartments of the tolerance frame and also introduce the following subclause:

6.5 If required, indications qualifying the direction of the tolerance zone and/or the extracted (actual) line shall be written after the tolerance frame. See example of indication of orientation of the tolerance zone in [Figure E.1].

Figure E.1 Indication of orientation of the tolerance zone

Clause 7, Toleranced features will be amended to include an opening paragraph that states: If not indicated using an appropriate modifier, a geometric specification is applied to a toleranced feature, which is a single complete feature. When the toleranced feature is not a single complete feature, see Clause 10.

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Additional text and figures illustrating 3D application of tolerances will be added to compliment the existing 2D examples. A new modifier symbol C (median feature) will be added with the following text and figure replacing the existing second indent. When the tolerance refers to the median line or median surface or a median point (defined by the feature so dimensioned), then the tolerance frame shall be either: • connected as an extension of the dimension line. • connected to the feature by a leader line terminating with an arrow head pointing directly at the surface, but with the addition of the modifier symbol placed to the right hand end of the second compartment of the tolerance frame (see [Figure E.2]).

Figure E.2 Use of the median feature

Clause 8, Tolerance zones: 8.1 will be replaced with the following text and figures (existing figures remain unchanged). The tolerance zone is positioned symmetrically from the exact geometrical form, orientation, or location, unless otherwise indicated (see 10.3). The tolerance value defines the width of the tolerance zone, and this width applies normal to the specified geometry (see examples of Figures 16 and 17) unless otherwise indicated (see examples of Figures 18 and 19). The tolerance value is not variable along the considered feature length, unless otherwise indicated either by: • a graphical indication, defining a proportional variation, between two specified values, along two specific locations on the considered feature. The start and end locations where the tolerance value varies are identified by two letters separated by an arrow (see [Figure E.3] and 12.2 for restricted parts of a feature). The values are related respectively with the letters indicated over the tolerance frame and their corresponding specified location on the considered feature (e.g. in Figure 19X, the value of the tolerance is 0,1 for the location J and 0,2 for the location K). By default, rule of proportionality is relevant to the curvilinear coordinates; • a specific company indication, when the variation is not proportional.

Figure E.3 Restricted parts of a feature

J K 0.1-0.2

8 J

Subclause 8.5 will be replaced by the following text and figures. Where a common tolerance zone is applied to several separate features, this common requirement shall be indicated by the symbol “CZ” for common zone following the tolerance in the tolerance frame (see examples of [Figure E.4 and Figure E.5]). A common tolerance zone is defined by all related individual tolerance zones, with a common geometrical characteristic and the same tolerance value, located and orientated between each other.

Figure E.4 Example of a common tolerance zone

Where CZ is indicated in the tolerance frame, all the related individual tolerance zones shall be located and orientated between each other using either implicit (0 mm, 0°, 90°, etc.) or explicit theoretically exact dimensions (TED).

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Figure E.5 Example of a common tolerance zone

Clause 9, Datums: complementary figures and text will be added to 9.2, 9.3 and 9.4 to illustrate 3D application of datums. Clause 10, Supplementary indications: the following text and illustrations will be added to 10.1 covering 3D application of the “all round” symbol. In 3D annotation, if a profile characteristic is applied to the entire outline of the cross-sections (intersection between the annotation plane required and the surface) or if it is applied to the entire surface represented by the outline, it shall be indicated by using the symbol “all around” (see [Figure E.6]). This indication does not involve the entire workpiece, but only the surfaces represented by the defined outline and identified by the tolerance indication (see [Figure E.6]).

Figure E.6 Examples of the use of the “all around” symbol

A new subclause 10.2, Indication of unequally disposed tolerance zone will be added. The following text and figures will be added to explain the new rules. If the tolerance zone is not centered on the theoretically exact geometrical form, then this unequally disposed tolerance zone shall be indicated using the U modifier as shown in [Figure E.7].

Figure E.7 Unequally disposed tolerance zone indicator

The extracted (actual) surface shall be contained between two equidistant surfaces enveloping spheres of defined diameter equal to the tolerance value, the centres of which are situated on a surface corresponding to the envelope of a sphere in contact with the theoretically exact geometrical form and whose diameter equal to the absolute value given after U with the direction of the shift indicated by the sign, plus indicating out of the material and minus into the material. The existing 10.2 will become 10.3, Indications for screw threads. Clause 12, Restrictive specifications: complementary figures and text will be added to 12.2 to illustrate 3D application. The following text and figures will be added to introduce the “between” concept. If a tolerance is applied to one identified restricted part of a feature or to contiguous restricted parts of contiguous feature(s), but does not apply to the entire outline of the cross-sections (or entire surface represented by the outline), this restriction shall be indicated using the symbol (called “between”) and by identifying the start and the end of the considered toleranced zone. The between symbol is used between two letters that identify the start and the end of the considered toleranced zone. This zone (compound toleranced feature) is elaborated from all segment or area between the start and the end of the identified features or parts of features. In order to clearly identify the tolerance zone, the tolerance frame shall be connected to the compound toleranced feature by a leader line starting from either side of the frame and terminating with an arrowhead on the outline of the compound toleranced feature (see example of [Figure E.8]). The arrowhead may also be placed on a reference line using a leader line to point to the surface.

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Figure E.8 Example of the use of the compound toleranced feature

Interpretation: The long dashed-dotted line (in the 3D Figure) represents the considered toleranced features. Surfaces a, b and c are not considered in this specification.

In order to identify the start and end of the compound tolerance feature, they shall be indicated in one of the following ways:

Figure E.9 Indicating the start and end of the compound toleranced feature

R J

Edge Radius edge

Location using a TED Use of ISP 13715 basic symbol

NOTE If not indicated (using, e.g., a TED) the edge of the feature is included. If the tolerance value is variable along the considered compound toleranced feature, the symbol called “from”) shall be used instead of “between”. See Clause 8. If a same specification is applicable to a set of compound toleranced features, this set can be indicated above the tolerance frame, one above the other (see example in [Figure E.10]).

Figure E.10 Indicating a common set of toleranced features

L M J K

J KL M

If all the compound toleranced features that are in this set are defined identically, it is possible to simplify the indication of this set, using the “n x” indication (see 6.2). In this case the indication of the letters identifying the start and end shall be placed into a square bracket. The rule defined in Clause 8 regarding the common zone indication is applicable to define a common compound tolerance zone (see example in [Figure E.11]).

Figure E.11 Indicating a common compound tolerance zone

Clause 13, Projected tolerance zone: the whole of this clause has been rewritten to include additional symbology and 3D applications and will be replaced by the following: The use of projected tolerance provides for the modification of the default toleranced feature used for the orientation or location of a GPS, by enabling the toleranced feature to become a portion of an extended feature, which is outside of the workpiece.

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The extended feature shall be constructed from an associated feature relative to the real integral surface and is the associated feature or its derived feature. The toleranced feature is thus a portion of the extended feature (see Table 3). NOTE The association criterion is by default, minimizing the distance between the integral feature and the associated feature, which is constraint tangent outside of the material.

Table 3 Toleranced feature with the projected tolerance modifier

Nominal feature to which the Toleranced feature leader line from the tolerance frame points A cylinder Portion of the associated cylinder An axis of a cylinder Portion of the axis of the associated cylinder A plane Portion of the associated plane A median plane Portion of the median plane of two associated planes constraint parallel

The use of the projected tolerance concept shall be indicated by the use of the symbol p after the tolerance value in the second compartment of the tolerance frame, see Figure 47A a) and b). The limits of the relevant portion of this extended feature shall be clearly defined and shall be indicated either directly or indirectly, as follows: When indicating the projected tolerance directly on a “virtual” integral feature representing the extended feature to be considered, it shall be represented by a chain thin double-dashed line in the corresponding drawing view, and the length of the extension shall be dimensioned with a theoretically exact dimension (TED) with the symbol p prior to the value. See [Figure E.12a)]. When indicating indirectly the length of the projected toleranced feature, the value shall be specified within square brackets “[“ “]” after the symbol p in the tolerance frame. See [Figure E.12 b)]. In this case the representation of the extended feature with a chain thin double-dashed line shall be omitted. However, the side of the part to which the projected tolerance applies shall be clearly specified by an arrow above the tolerance frame, see [Figure E.13].

Figure E.12 Two different ways of indicating a GPS with projected tolerance modifier

a) Direct indication of the length of b) Indirect indication of the length the extension by a TED of the projected toleranced feature in the tolerance frame

Figure E.13 Explanation of the direction of the extended feature

a) Reference surface defining the b) Direction of extension of starting of the toleranced feature toleranced feature

The reference surface, defined by the intersection of a plane and the considered feature, is, by default, the origin for the extended feature. If the portion of the extended feature is displaced from the reference surface by an offset, the offset shall be indicated. When directly indicated, the offset shall be specified by a theoretical exact dimension (TED), see [Figure E.14]. When indirectly indicated, the first value after the modifier corresponds to farthest extent of the extended feature and the second value (offset value), which is preceded by a minus sign, corresponds to the nearest extent of the extended feature (the length of the extended feature corresponds to the difference between these two values), see [Figure E.15].

Figure E.14 Example of direct indication of a projected tolerance with an offset

Figure E.15 Example of indirect indication of a projected tolerance with an offset

j i

c ) 0,2 P [32-7] k

d a g h

Key a) Extension of the outline b) “Reference” surface c) Leader line connected to the tolerance frame d) Associated “reference” surface e) Integral surface f) Associated feature g) Length of the projected toleranced feature, in this case L = 25 h) Offset of the projected toleranced feature from the reference surface, in this case 7 mm i) projected toleranced feature j) modifier defining that the tolerance applies to a portion of an extended feature and is limited by the information g) and h) k) Indication defining that the type of the toleranced feature is a median feature NOTE The associated “reference” surface, indicated with d) in the key, will require additional definition by the indication of a datum system to make the requirement unambiguous.

If the value of the offset is zero, the indication is omitted, see [Figure E.13]. The modifier p may be used with other types of modifier as appropriate, see [Figure E.16 and Figure E.17].

Figure E.16 Example of the use of projected tolerance zone together with the median modifier

Key a) Extension of the outline b) “Reference” surface c) Leader line connected to the tolerance frame d) Modifier defining that the tolerance apply to a portion of an extended feature and is limited by the subsequent information e) e) Length of projected toleranced feature, in this case 25 f) Modifier defining that the type of the toleranced feature is a median feature

Figure E.17 Example of the use of projected tolerance zone together with a common zone modifier

Clause 18, Definitions of geometrical tolerances: an extra column will be added to the “Indication and explanation” section of the table to illustrate 2D and 3D application of the symbols separately.

Annex F (informative) Technical product specification – Geometrical product specification (GPS)

F.1 Introduction Over the course of the 20th Century, with the advent of mass production, the need to be able to manufacture parts to a specification with a high degree of repeatability became more important than ever before. This led to a formalization of the methods used to specify workpieces through the use of engineering drawings with dimensions and tolerances, and the development of new methods to specify geometrical characteristics (geometrical tolerancing) and surface texture (i.e. roughness values). Most industrialized countries developed national standards to govern the methods used for engineering specifications, giving rise to the much loved BS 308 in the UK, and the ANSI Y14.5 (now ASME Y14.5) standard in America, as well as similar standards in many other countries. The evolution and development of these methodologies has continued throughout this period and into the 21st Century, with standards being added, extended and revised accordingly. Under the ISO banner, the standards organizations from many different nations have worked together to develop and harmonize the different standards used for engineering specifications, and to encourage a common approach, with a view to improving communications and addressing the needs of a more global economy. As a consequence of the way in which methodology has evolved and developed over the last 80 or so years, there are many areas in which the standards for engineering specifications are (or at least have been) ambiguous, inadequate, incomplete and even contradictory. These issues have been highlighted by several developments, including: • improvements to the accuracy with which a workpiece can be manufactured; • improvements to the accuracy with which a workpiece can be measured or inspected; • the trend in the developed world to focus on design and assembly, subcontracting component manufacture to suppliers who are often overseas, and might not speak the same language (this trend in particular has removed the option of the informal communication or “understanding” that would often exist between design and manufacturing when they were neighbouring departments in the same company); and • the requirements of CAD, CAM and CAQ system architects for formal mathematical definitions of all specification and verification operations that can be coded into software. In response to this situation, ISO initiated a project in the early 1990s with the aim of developing a coherent, comprehensive and complete system for the specification of workpiece geometry. This system is called geometrical product specification (GPS).

As its name suggests, GPS is concerned with the geometry of parts; it is not concerned with material properties or operating conditions. Specifically, GPS is concerned with the specification and verification of sizes, shapes and surface characteristics of a workpiece to ensure functional requirements are met. GPS is a new approach to product specification; but it builds on existing tools, and particularly the use of datums, geometrical tolerancing and surface texture tolerancing. GPS systematizes and extends these existing tools into a new methodology.

F.2 Key concepts

F.2.1 Different worlds or models The GPS approach is based on the concept that any given workpiece exists in several different “worlds”, or as several different versions, at the same time (see Figure F.1). There is the “specification model”, produced by the designer to represent the design intent or functional requirement; there is the actual manufactured workpiece; and there is the “verification model”, representing the metrological data extracted from the model by various measurement processes. The verification model is compared with the specification model in order to establish whether the workpiece complies with its specification.

Figure F.1 Model of the relationship between specification, verification and the actual workpiece

Function

Comparison

Designer

Specification Measured Graphical Real values representation workpiece

Production engineer Metrologist

Workpiece generation Extracted data/signal

F.2.2 Specification and verification One of the objectives of GPS has been to strengthen and clarify the relationship between the specification process, where the workpiece geometry is defined, and the verification process, where the workpiece is checked against its specification. It clearly makes sense for the inspection or verification process to inspect, as directly as possible, whatever quantity has been specified. Where the inspection process cannot directly check what has been specified, then there is greater scope for errors, or greater “uncertainty” in the process. When a workpiece is inspected or verified, a number of processes take place (see Figure F.2). These processes have been classified as partition, extraction, filtration, association, collection and construction. Much of the time, these processes are not consciously classified, it is just the way we do things.

Figure F.2 The link between design intent and metrology

Drawing Workpiece Extraction Association

Partition: a workpiece is “partitioned”, or broken down, into a number of real, integral features (actual surfaces). In other words, we tend to think of, and deal with, workpieces as a collection of individual surfaces – flat surfaces, cylindrical surfaces, curved surfaces, etc. Extraction: having partitioned a workpiece into a number of real, integral features, we need to extract some data from them, so that they can be quantified, measured or located. The real, integral feature can be defined as a set of an infinite number of points, defining the surface that separates the workpiece from its surroundings within the extents of that particular feature. When measuring or sampling a real integral feature, we cannot measure or sample an infinite number of points, we have to compromise and sample a finite number. The extracted, integral feature thus consists of a finite number of points

Filtration: in practice, it is found that extraction on its own is not sufficient to give a useful set of data representing the integral feature under consideration. In addition to extraction, some filtering or smoothing of the data is usually necessary, to remove noise, and unwanted detail. Association: having obtained an extracted model of the real, integral feature, consisting of a filtered and finite number of points, it may be that the verification process is required to check the form (i.e. straightness), orientation (i.e. perpendicularity) or location of a derived feature (axis, median plane or centre point) based on that integral feature. In order to do this, a theoretically perfect geometrical form, corresponding to the nominal form in the specification model (i.e. a perfect cylinder, perfect set of parallel opposed planes, perfect sphere, cone or wedge) has to be fitted to, or associated with, the extracted data. This is known as the associated integral feature. Collection: in additional to the above operations, features sometimes need to be treated as a group or pattern of features. Groups or patterns of holes are a common example of this. Collection is the process of grouping these features together. Construction: sometimes tolerances may be applied to features which are dependent on, or resultants of, other features. A construction operation is used to determine the toleranced feature. For instance, straightness may be applied to an edge, the edge being defined as the intersection of two planes. The edge is constructed from the two extracted planar features.

F.2.3 The operator principle and the duality principle The fact that these processes of partition, extraction, filtration, association, collection and construction take place during verification is of some consequence to the specifier. For instance, the designer or specifier can apply a flatness tolerance to a surface. In theory, that flatness requirement is applied to the entire set of an infinite number of points which comprise the real, integral surface. However, the verifier is going to check an extracted, integral surface, consisting of a finite number of points, which has been filtered to remove noise and unnecessary detail. The density of the extracted data, and the wavelength of the filters which have been used, will clearly influence the results. For this reason, the GPS approach requires these processes to be taken into account when specifying a workpiece requirement to the same extent that they will be required for its verification. This concept, that the verification process and the specification process should mirror each other, or be duals of each other, is known is the duality principle (see Figure F.3).

Figure F.3 The duality principle

SPECIFICATION VERIFICATION OPERATOR OPERATOR

"SKIN MODEL" "REAL SURFACE" Geometrical representation Set of physically existing features

Operation Operation partition physical partition extraction Difference physical extraction filtration contributes filtration association to association collection uncertainty collection construction construction

MEASURAND MEASURED VALUE Characteristics specification Characteristics

COMPARISON FOR CONFORMANCE

To some extent this already happens. Partition takes place automatically, as workpieces are modelled, or drawn, as a collection of discrete features. Collection also takes place routinely, as dimensions, tolerances or notes are used to indicate when several features are to be treated as a group or pattern of features. Construction again takes place quite automatically, as edges and vertices appear where defined surfaces meet and intersect. The processes of extraction and filtration, however, are normally left to the discretion of the verifier. The designer specifies the requirement for a real surface, the verifier checks it on the extracted surface, and the verifier will choose a sampling density and filtering function based on factors such as experience, informal understanding of the design requirements, in-house procedures, time available, equipment capabilities and limitations, mood, whim, etc. Under the GPS approach, this will change. The specifier will be required to define the sampling density and filtering function.

The process of association is also not normally considered by the designer or specifier. Association will have to take place if the verifier is required, say, to use the axis of a shaft as a datum, or to evaluate a positional tolerance on a hole. How the theoretically perfect associated feature is fitted to the extracted feature is again left to the verifiers discretion. Mathematically, there are several ways in which this association can take place, including, for instance, the least squares method, the maximum inscribing method, and the minimum circumscribing method. Again, under the GPS approach, the appropriate method of association will need to be defined by the specifier. Thus each element of the specification will contain its own definitions for the processes of extraction, filtration and, where appropriate, association. Each specification element, which is known as a specification operator, is, in effect, a virtual measurement procedure, containing all the information that may be required for its verification (including datums, sampling densities, filtering values, and association methods). The verification operator is the physical implementation of that virtual measurement procedure defined in the specification. This is known as the operator principle. The specification operator is not intended to dictate the verification method, merely to provide all the information that will be required in order that it may be verified. So far, this approach has only been fully implemented in the annotation system used for defining surface texture. The annotations, definitions and values required to implement the GPS approach with geometrical tolerancing are still under development, and standards dealing with the different types of tolerance characteristic are gradually starting to appear.

F.2.4 The default principle This new approach will, at first glance, greatly increase the work load on the specifier, and greatly increase the volume of annotation required to properly define a workpiece. In order to avoid both of these burdens, default values and methods are under preparation for the processes of extraction, filtration and association. Where the default values or methods are to be used, they need not be marked on the annotation. This is known as the default principle. For example, if the designer specifies a location tolerance for a hole, the GPS approach requires the specification to include data on which association method, sampling density, and filtering techniques or values should be used. However, the GPS approach will also provide default values for each of these items. The specifier will only produce annotation for these items where a value or method other than the default is required. This means that in many, and probably almost all, cases, the full and complete annotation will appear no different to the current annotation. The only difference will be that the values and methods to be used when verifying the requirement will be fully and unambiguously defined (by the default values and methods), and not left to the discretion of the verifier.

F.3 Uncertainty

F.3.1 Introduction A fundamental concept in the GPS system is that of “uncertainty”. The concept of “uncertainty” is not new; it is an established fact of metrology. The uncertainty associated with a measurement can be thought of as representing how “good” the measurement is. If several measurements are taken of a length with a ruler, each measurement will be slightly different. Consistency is achieved by recognizing the limitations of accuracy that can be achieved with a particular technique or piece of equipment, so no one would attempt to measure to accuracies of 0.01 mm with a ruler. The uncertainty associated with the ruler is a parameter that represents the range of possible values that could reasonably be obtained when measuring any given length with the ruler – this could be given as a simple value (perhaps 0.2 mm in this case), or a percentage, or a statistical quantity. Metrology equipment normally includes uncertainty values with the other data in its specification. The GPS system extends this concept of uncertainty to the specification model as well as the verification model, and considers three different types of uncertainty.

F.3.2 Correlation uncertainty Correlation uncertainty quantifies how well the workpiece specification correlates to the functional requirements of the workpiece. This uncertainty is the responsibility of the designer. Some of this uncertainty can be reduced or eliminated simply through professional competence, but some of it is inevitable. For instance, FEA techniques may be used to calculate the geometrical form of a structural component, but these calculations are approximations, and the operating conditions and material characteristics which the calculations are based on are themselves approximations and simplifications of the real-life situation.

F.3.3 Specification uncertainty Specification uncertainty arises from the range of possible interpretations of a specification. This uncertainty is again the responsibility of the designer. As with correlation uncertainty, some of this uncertainty can be eliminated through professional competence (ensuring specifications are complete, effective use of datum systems, etc.). Specification uncertainty can arise not only from poor design or specification, but also from inherent ambiguities or incompleteness in standards. For instance, ISO standards do not state whether surface texture should be included or excluded when checking for geometrical variation. This incompleteness in the standard may result in a range of possible interpretations of a single tolerance specification. The manufacturer is entitled to choose any legitimate interpretation to work to.

F.3.4 Measurement uncertainty (attributed to the metrologist) Measurement uncertainty has two aspects. The first is termed “method uncertainty”, and this is to do with differences between the specification operator and the verification operator, in other words, this is to do with what measurements are taken. If the verification operator is a perfect implementation of the specification operator, there is no method uncertainty. The second classification is termed “implementation uncertainty”, which arises from deviations in the implementation of the verification operator, so this would include operator error, faulty equipment, etc.

F.3.5 Making use of uncertainty Identifying sources of uncertainty has practical benefits, and quantifying uncertainty is a necessary aspect of specifying and verifying complete and unambiguous definitions of workpiece geometry. Identification of the sources of uncertainty can help with the allocation of resources. For instance, if correlation uncertainty is large, because component geometry is based on assumptions and highly approximate calculations, there would be little benefit in investing in highly accurate (and expensive) inspection equipment. Resources would be better targeted towards more accurate computer modelling and simulation, or acquiring more test data. When values can be assigned to measurement uncertainty, this can then be taken into account when verifying the workpiece. If checking to see whether tolerance limits have been complied with, then the each tolerance limit should be reduced by the amount of measurement uncertainty associated with the procedure. Where checking to see whether tolerance limits have been violated, each tolerance limit should be extended by the amount of measurement uncertainty associated with the procedure. Measurement uncertainty always “counts against” the verifier.

F.4 The GPS standards matrix GPS is a procedure for defining the shape (geometry), dimensions and surface characteristics of a workpiece in a manner that ensures optimum functioning of that workpiece. The procedure includes definition of the dispersion around the optimum within which the intended function will still be satisfactory. The manufacturing process will, nevertheless, produce workpieces that are not perfect, in that they show some deviation from the defined optimum and from each other. When comparing a workpiece with its specification, it is necessary to relate the following: • the workpiece conceived by the designer; • the workpiece as manufactured; and • the workpiece as measured. Standards developed in this field provide the fundamental rules for GPS, such as basic definition, symbolic representation and principles of measurement.

Several categories of standard relate to the concept. Some of these deal with the fundamental rules of specification, whilst others provide global principles and definitions. A third group addresses directly the various geometric characteristics such as size, distance, angle, form, location, orientation and roughness. The concept includes workpiece characteristics relating to different types of manufacturing process, together with the characteristics of specific machine elements (see Figure F.4). The application of GPS principles will only deliver benefit to their full potential if applied throughout the development of a product, i.e. in design, manufacturing, metrology and quality assurance.

Figure F.4 The GPS matrix model The global standards GPS standards or related standards that deal with or influence several or all 'general GPS chain' standards

General GPS matrix

General GPS chains of standards

1 The size chain 2 The distance chain 3 The radius chain 4 The angle chain 5 The form of line (independent of a datum) chain 6 The form of line (dependent on a datum) chain 7 The form of a surface (independent of a datum) chain 8 The form of a surface (dependent on a datum) chain 9 The orientation chain 10 The location chain 11 The circular run-out chain The 12 The total run-out chain 13 The datums chain fundamental 14 The roughness profile chain 15 The waviness profile chain GPS 16 The primary profile chain standards 17 The surface defects chain 18 The edges chain

Complementary GPS matrix Complementary GPS chains of standards

A. Process specific, tolerance standards

A1 The machining chain A2 The casting chain A3 The welding chain A4 The thermal cutting chain A5 The plastics moulding chain A6 The metallic and inorganic coating chain A7 The painting chain

B. Machine element, geometry standards

B1 The screw thread chain B2 The gears chain B3 The splines chain

Annex G (informative) Technical product realization – UK development

G.1 BS 8888 – Rationale BS 8888 is drafted with the sole objective of enabling this improvement in technical product specification on the basis of the application of established and developing International Standards. The prime objective of BSI Technical Committee TDW/4, Technical, product specification – Methodology, presentation and verification, is to ensure that the necessary tools to enable the preparation of detailed, accurate specifications, are available. Its activity covers seven complimentary generic subject areas: a) methodology for design implementation; b) geometrical product specification; c) graphical representation (engineering drawings/diagrams and 3D modelling); d) verification (metrology and precision measurement); e) technical documentation; f) electronic formats and controls; g) related tools and equipment. The committee is responsible for identifying and evaluating requirements for British Standards relating to the preparation, presentation and validation of technical specifications and for the drafting of any such standards for which a genuine need has been established. The programme of work addresses the requirements for standardization in technical specification, at all stages from the preparation of design concepts for physical realization to the validation of finished products. All such projects are based on existing or developing ISO Standards (particularly those of ISO/TC 10 and ISO/TC 213), where such standards exist. The committee is responsible for channelling UK expertise into relevant ISO projects to ensure that their outcome meets UK requirements to the best possible extent. This principal applies irrespective of the programme of ISO implementation within the European Standards Organization (CEN). Where appropriate International Standards/Projects do not exist, TDW/4 undertakes the responsibility for the drafting of any necessary British Standards or Technical Reports. This is done with a view to their subsequent introduction to the ISO programme, where appropriate. Given the importance of this subject area in both secondary and further education, The UK Technical Committee (TDW/4) takes an active interest in the preparation and promotion of educational support materials for schools, colleges and industrial training.

G.2 Technical product documentation The presentation aspects of TPS are primarily the province of ISO/TC 10, Technical product documentation, which has the brief “to develop, co-ordinate and maintain International Standards for technical product documentation (TPD), including technical drawings manually produced or computer based, for technical purposes throughout the product life cycle in order to facilitate preparation, management, storage, retrieval, reproduction, exchange and use.” Although this committee is founded on the more traditional discipline of “engineering drawing”, its remit has been extended to include the presentation of all forms of specification for technical products, whatever the media selected to carry that specification. In particular, this includes the graphical representation and annotation of the output of 3D modelling programmes. ISO/TC 213 is the international, standards technical committee responsible for the development of GPS in order to provide an integrated system for specification and verification of workpiece geometry (see Annex F). The work of ISO/TC 10 is closely linked to that of ISO/TC 213 by virtue of their joint application in TPS. However, it is important to have a clear understanding of the functional relationship between the various elements of the TPS and of their relative significance to the effectiveness of the specification. Figure G.1 provides a useful graphical representation of the relationships between the elements of the TPS.

Figure G.1 The relationship between the elements of a technical drawing

G.3 Technical product realization – The TPR concept. Having gained practical experience in the application of BS 8888 during the six years since its introduction in 2000, the BSI Technical Committee has also had the opportunity to address some of the misconceptions occasionally expressed by practising designers, engineers and metrologists. One of these, concerns the stage of manufacture at which BS 8888 should be implemented. There are, not infrequently, suggestions that since this standard sets out requirements for a specification, it is the actual manufacturing stage that will be most affected by its provisions. This is far from being a true picture.

The process of converting a concept to a correctly functioning product, relies on the cooperation of a sequence of disciplines (design, manufacture and verification) that need to be coordinated if a viable outcome is to be achieved. The instrument best suited to achieving that coordination is a correctly formatted, unambiguously expressed technical product specification (TPS) and BS 8888 is the British Standard that specifies how that TPS can most effectively be prepared. BS 8888 does not set out to provide instruction on “how to design” but it does seek to provide for the orderly presentation of the output of the design process, in a manner capable of conveying the requirements of the product through the manufacturing and verification processes. A TPS prepared to BS 8888 will therefore also carry briefing for the verification process most appropriate to the functional requirements of the product and can therefore be considered to govern the interface between both design and manufacture and manufacture and verification. Whilst it is true that manufacturing activity will be strongly influenced by the specification produced to BS 8888, it should be noted that the only one of the three disciplines not actually referenced in the titles is that of “manufacture”. Application of the standard actually impacts upon all three disciplines of specification, manufacture and verification, and the point of primary application is rather more at the interface between the disciplines. It is in an effort to convey this concept that TDW/4 has developed the term “Technical product realization (TPR)”: defined as “system facilitating cooperation between mechanical engineering disciplines to effect conversion of a concept into correctly functioning workpieces or product, to time and with minimal rework/reject requirement”. Accordingly, none of BS 8887, BS 8888 or BS 8889 can be a stand-alone document since none tells the whole “story”. Indeed, during the preparation of the first edition of BS 8888 in 2000, it was always the intention that it should be supported by the related TPR aspects of manufacture and verification. Thus, there are three standards concerned with design for manufacture (BS 8887), technical product specification (BS 8888) and technical product verification (BS 8889). These three together can be termed the “TPR Triumvirate” since it is by their interaction that they derive their power to improve manufacturing performance. The BS 8887 will be published at the same time as this edition of BS 8888 whilst BS 8889 is still in preparation but is expected to be published by the second quarter of 2007. There is obviously overlap in content between the three standards, and this is shown schematically in Figure G.2.

Figure G.2 Schematic of the TPR triumvirate

Specification Manufacture BS 8888 BS 8887

Verification BS 8889

In Figure G.2, the three areas of design, manufacture and verification are represented by three circles. However, it should be noted that this is an over-simplification since the three are not of equal size and the overlaps are not the same. For example, it is estimated that there is some 60% overlap between specification and manufacture yet only 30% overlap between specification and verification. However, this diagram merely shows the coverage between the triumvirate whereas their relationships and particularly the influence BS 8888 has on the whole is better shown by Figure G.3.

Figure G.3 Technical product realization

Technical product specification BS 8888 BS 8888

DESIGN VERIFICATION Concept MANUFACTURE Product BS 8887 BS 8889 BS 8888 BS 8888

Technical product specification

Technical product realization

Annex H (informative) Index of choices and defaults for BS 8888:2006 This annex provides a summary of the key choices available within BS 8888 and the cross-referred standards and identifies a BS 8888 default set of those options. In addition, it also provides the opportunity for a company or organization to reject the BS 8888 default set, and identify their preference for a default set. It is expected that this list, amended or otherwise, could be incorporated into the Quality Management System of a company or organization as a foundation of their draughting standard.

Standard Standard title Illustration BS 8888 Company number choice choice BS ISO 129-1 TD – Closed and filled arrowhead, 30º BS 8888 Dimensioning – Default General principles, definitions, methods of execution and Closed arrowhead, 30º BS 8888 special non- indications preferred

Open arrowhead, 30º BS 8888 non- preferred

Open arrowhead, 90º BS 8888 non- preferred

Oblique stroke BS 8888 option

Dimension line origin BS 8888 option

Point (where space is limited) BS 8888 option

BS ISO 406 TD – Tolerancing Angular dimensions shown in degrees and BS 8888 of linear and decimal parts of a degree – Default angular dimensions

Angular dimensions shown in degrees minutes BS 8888 and seconds – non- preferred

BS EN TPD – Lettering – Sloping lettering – A BS 8888 ISO 3098-2 Part 2: Latin non- alphabet, preferred numerals and marks

Vertical lettering – A BS 8888 non- preferred

Sloping lettering – B BS 8888 non- preferred

Vertical lettering – B BS 8888 Default

BS EN ISO TD – Projection First angle projection BS 8888 5456-2 methods – Part 2: option Orthographic representations

Symbol

Third angle projection BS 8888 Default

Symbol

BS ISO 5459 TD – GT – BS 8888 Datums and Default datum-systems A for geometrical tolerances

BS 8888 non- A preferred

BS EN 22553 Welded, brazed BS 8888 and soldered Default joints – Symbolic representation on drawings

BS 8888 non- preferred

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