Drawing office management and organization by zmb20253

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									Chapter 1
Drawing office management and
organization

Every article used in our day-to-day lives will probably     7    Dimension figures
have been produced as a result of solutions to a sequence    8    Relative importance of dimensions
of operations and considerations, namely:                    9    Indication of materials on drawings
                                                            10    Various degrees of finish
1    Conception                                             11    Screw threads
2    Design and analysis                                    12    Flats and squares
3    Manufacture                                            13    Tapers
4    Verification                                           14    Abbreviations for drawings.
5    Disposal.
                                                            There were also five figures illustrating:
The initial stage will commence when an original
marketable idea is seen to have a possible course of        1    Method of projection
development. The concept will probably be viewed            2    Types of line
from an artistic and a technological perspective.           3    Views and sections
   The appearance and visual aspects of a product are       4    Screw threads
very important in creating an acceptable good first         5    Tapers.
impression.
   The technologist faces the problem of producing          First angle projection was used for the illustrations
a sound, practical, safe design, which complies with        and the publication was printed on A5 sheets of paper.
the initial specification and can be produced at an            During the early days of the industrial revolution
economical cost.                                            manufacturers simply compared and copied component
   During every stage of development there are many         dimensions to match those used on the prototype.
progress records to be maintained and kept up to date       However, with the introduction of quantity production
so that reference to the complete history is available to   where components were required to be made at different
responsible employees.                                      factory sites, measurement by more precise means was
   For many years various types of drawings, sketches       essential. Individual manufacturers developed their own
and paintings have been used to convey ideas and            standard methods. Clearly, for the benefit of industry
information. A good recognizable picture will often         in general a National Standard was vital. Later the
remove ambiguity when discussing a project and assist       more comprehensive British Standard of Limits and
in overcoming a possible language barrier.                  Fits was introduced. There are two clear aspects, which
   British Standards are listed in the British Standards    are necessary to be considered in the specification of
Catalogue and the earliest relevant Engineering             component drawings:
Standards date back to 1903. Standards were developed
to establish suitable dimensions for a range of sizes of    1 The drawing shows the dimensions for the
metal bars, sheets, nuts, bolts, flanges, etc. following      component in three planes. Dimensions of the
the Industrial Revolution and used by the Engineering         manufactured component need to be verified because
Industry. The first British Standard for Engineering          some variation of size in each of the three planes
Drawing Office Practice published in September 1927           (length, breadth and thickness) will be unavoidable.
only contained 14 clauses as follows:                         The Designers contribution is to provide a
                                                              Characteristics Specification, which in current jargon
    1 Sizes of drawings and tracings, and widths of           is defined as the ‘Design Intent Measurand’.
      tracing cloth and paper                               2 The metrologist produces a ‘Characteristics
    2 Position of drawing number, date and name               Evaluation’ which is simply the Measured Value.
    3 Indication of scale
    4 Method of projection                                  The drawing office is generally regarded as the heart
    5 Types of line and writing                             of any manufacturing organization. Products,
    6 Colour of lines                                       components, ideas, layouts, or schemes which may be
2     Manual of Engineering Drawing

presented by a designer in the form of rough freehand            (e) quality control and inspection,
sketches, may be developed stage by stage into working           (f) updating, modification, and reissuing of
drawings by the draughtsman. There is generally very                  drawings.
little constructive work which can be done by other          2   Company standards Many drawing offices use
departments within the firm without an approved                  their own standard methods which arise from
drawing of some form being available. The drawing is             satisfactory past experience of a particular product
the universal means of communication.                            or process. Also, particular styles may be retained
    Drawings are made to an accepted standard, and in            for easy identification, e.g. certain prestige cars
this country, is BS 8888, containing normative and               can be recognized easily since some individual
informative references to international standards. These         details, in principle, are common to all models.
standards are acknowledged and accepted throughout           3   Standards for dimensioning Interchangeability and
the world.                                                       quality are controlled by the application of practical
    The contents of the drawing are themselves, where            limits, fits and geometrical tolerances.
applicable, in agreement with separate standards relating    4   Material standards          Physical and chemical
to materials, dimensions, processes, etc. Larger                 properties and non-destructive testing methods must
organizations employ standards engineers who ensure              be borne in mind. Note must also be taken of
that products conform to British and also international          preferred sizes, stock sizes, and availability of rod,
standards where necessary. Good design is often the              bar, tube, plate, sheet, nuts, bolts, rivets, etc. and
product of teamwork where detailed consideration is              other bought-out items.
given to the aesthetic, economic, ergonomic and              5   Draughting standards and codes of practice
technical aspects of a given problem. It is therefore            Drawings must conform to accepted standards, but
necessary to impose the appropriate standards at the             components are sometimes required which in
design stage, since all manufacturing instructions               addition must conform to certain local requirements
originate from this point.                                       or specific regulations, for example relating to safety
    A perfect drawing communicates an exact                      when operating in certain environments or
requirement, or specification, which cannot be                   conditions. Assemblies may be required to be
misinterpreted and which may form part of a legal                flameproof, gastight, waterproof, or resistant to
contract between supplier and user.                              corrosive attack, and detailed specifications from
    Engineering drawings can be produced to a good               the user may be applicable.
professional standard if the following points are            6   Standard parts are sometimes manufactured in
observed:                                                        quantity by a company, and are used in several
                                                                 different assemblies. The use of standard parts
(a) the types of lines used must be of uniform                   reduces an unnecessary variety of materials and
    thickness and density;                                       basically similar components.
(b) eliminate fancy printing, shading and associated         7   Standards for costs The draughtsman is often
    artistry;                                                    required to compare costs where different methods
(c) include on the drawing only the information which            of manufacture are available. A component could
    is required to ensure accurate clear com-                    possible be made by forging, by casting, or by
    munication;                                                  fabricating and welding, and a decision as to which
(d) use only standard symbols and abbreviations;                 method to use must be made. The draughtsman
(e) ensure that the drawing is correctly dimensioned             must obviously be well aware of the manufacturing
    (adequately but not over-dimensioned) with no                facilities and capacity offered by his own company,
    unnecessary details.                                         the costs involved when different techniques of
Remember that care and consideration given to small              production are employed, and also an idea of the
details make a big contribution towards perfection,              likely costs when work is sub-contracted to specialist
but that perfection itself is no small thing. An accurate,       manufacturers, since this alternative often proves
well delineated engineering drawing can give the                 an economic proposition.
draughtsman responsible considerable pride and job           8   Data sheets Tables of sizes, performance graphs,
satisfaction.                                                    and conversion charts are of considerable assistance
   The field of activity of the draughtsman may involve          to the design draughtsman.
the use, or an appreciation, of the following topics.
                                                             Figure 1.1 shows the main sources of work flowing
1 Company communications Most companies have                 into a typical industrial drawing office. The drawing
  their own systems which have been developed over           office provides a service to each of these sources of
  a period of time for the following:                        supply, and the work involved can be classified as
  (a) internal paperwork,                                    follows.
  (b) numbering of drawings and contracts,
  (c) coding of parts and assemblies,                        1 Engineering The engineering departments are
  (d) production planning for component manufac-               engaged on
       ture,                                                   (a) current production;
                                                                    Drawing office management and organization                            3

                                                               (f) drawings resulting from value analysis and
                      Engineering                                  works’ suggestions.
                                                         Figure 1.2 shows the organization in a typical drawing
                                                         office. The function of the chief draughtsman is to
                                                         take overall control of the services provided by the
                                                         office. The chief draughtsman receives all work coming
                       Drawing                           into the drawing office, which he examines and
           Sales                           Service
                        office                           distributes to the appropriate section leader. The section
                                                         leader is responsible for a team of draughtsmen of
                                                         various grades. When work is completed, the section
                                                         leader then passes the drawings to the checking section.
                                                         The standards section scrutinizes the drawings to ensure
                                                         that the appropriate standards have been incorporated.
                     Manufacturing                       All schedules, equipment lists and routine clerical work
                        units                            is normally performed by technical clerks. Completed
                                                         work for approval by the chief draughtsman is returned
Fig. 1.1                                                 via the section leader.
                                                            Since drawings may be produced manually, or by
                                                         electronic methods, suitable storage, retrieval and
  (b) development;                                       duplication arrangements are necessary. Systems in
  (c) research;                                          common use include:
  (d) manufacturing techniques, which may include
       a study of metallurgy, heat-treatment, strength   (a) filing by hand into cabinets the original master
       of materials and manufacturing processes:             drawings, in numerical order, for individual
  (e) advanced project planning;                             components or contracts;
   (f) field testing of products.                        (b) microfilming and the production of microfiche;
2 Sales This department covers all aspects of            (c) computer storage.
  marketing existing products and market research
  for future products. The drawing office may receive    The preservation and security of original documents is
  work in connection with                                of paramount importance in industry. It is not normal
  (a) general arrangement and outline drawings for
       prospective customers;                                                            Chief
  (b) illustrations, charts and graphs for technical                                 draughtsman
       publications;
  (c) modifications to production units to suit
       customers’ particular requirements;
  (d) application and installation diagrams;
  (e) feasibility investigations.                                Section
                                                                 leaders
3 Service The service department provides a reliable,
  prompt and efficient after-sales service to the
                                                                                                       Technical
  customer. The drawing office receives work                    Designers
                                                                                                        clerks                   Finished drawings
  associated with
  (a) maintenance tools and equipment;                            Senior                               Standards
  (b) service kits for overhauls;                              draughtsmen                              section
  (c) modifications to production parts resulting from
       field experience;                                       Draughtsmen                             Checkers
  (d) service manuals.
4 Manufacturing units Briefly, these cover all
  departments involved in producing the finished end-           Trainees
  product. The drawing office must supply charts,
  drawings, schedules, etc. as follows:
  (a) working drawings of all the company’s                                   Drawing office library
       products;
  (b) drawings of jigs and fixtures associated with                           Reprographic section
       manufacture;
  (c) plant-layout and maintenance drawings;
  (d) modification drawings required to aid               Manufacturing
                                                             units
                                                                             Sales             Service             Development
       production;
  (e) reissued drawings for updated equipment;           Fig. 1.2
4   Manual of Engineering Drawing

practice to permit originals to leave the drawing office.    perform a much more effective role in the design process
A drawing may take a draughtsman several weeks to            and many examples of its ability follow—but it will
develop and complete and therefore has considerable          not do the work on its own. The input by the
value. The reprographic staff will distribute copies which   draughtsman needs to follow the same standards applied
are relatively inexpensive for further planning,             in the manual method and this fact is often not
production and other uses. A library section will            understood by managers hoping to purchase CAD and
maintain and operate whatever archive arrangements           obtain immediate answers to design enquiries. The
are in operation. A large amount of drawing office           draughtsman needs the same technical appreciation as
work comes from continuous product development and           before plus additional computing skills to use the varied
modification so easy access to past designs and rapid        software programs which can be purchased.
information retrieval is essential.                             To introduce CAD an organization must set out clear
                                                             objectives which are appropriate to their present and
                                                             future requirements and Fig. 1.3 includes aspects of
Engineering drawing                                          policy which could appear in such plans. The following
                                                             need consideration:
practices
                                                             (a) CAD management roles;
The comments so far refer to drawing offices in general      (b) creation, training and maintenance of capable
and typical organizational arrangements which are likely         CAD operators;
to be found within the engineering industry. Good            (c) CAD awareness of design project team members
communication by the use of drawings of quality relies           in addition to their leaders;
on ensuring that they conform to established standards.      (d) the flow of work through the system and the
   BS 5070, Parts 1, 3 and 4 dealing with engineering            selecting of suitable types of project;
diagram drawing practice, is a companion standard to         (e) associated documentation;
BS 8888 and caters for the same industries; it provides      (f) possible changes to production methods;
recommendations on a wide variety of engineering             (g) needs involving the customer;
diagrams. Commonly, as a diagram can be called a             (h) system needs relating to planning, security and
‘drawing’ and a drawing can be called a ‘diagram’, it            upgrading;
is useful to summarize the difference in the scopes of       (i) CAD library and database (Storage of drawings,
these standards. BS 8888 covers what are commonly                symbols, etc.) and archive procedures.
accepted to be drawings that define shape, size and
form. BS 5070 Parts 1, 3 and 4 covers diagrams that             Many similar aspects will be appropriate in particular
are normally associated with flow of some sort, and          applications but good intentions are not sufficient. It is
which relate components (usually indicated by symbols)       necessary to quantify objectives and provide dates,
functionally one to another by the use of lines, but do      deadlines, numbers, individual responsibilities and
not depict their shape, size or form; neither may they       budgets which are achievable if people are to be
in general indicate actual connections or locations.         stretched and given incentive after full consultation.
   Therefore, any drawing or diagram, whether                Present lines of communication will probably need to
produced manually or on computer aided draughting            be modified to accommodate CAD, and planning
equipment, must conform to established standards and         integration is vital. A possible approach here is the
will then be of a satisfactory quality for commercial        appointment of a CAD Director with the ultimate
understanding, use and transmission by electronic and        responsibility for CAD technology assisted by a Systems
microfilming techniques. All of the examples which           Manager and an Applications Manager.
follow conform to the appropriate standards.
                                                                                                 Feedback

Drawing practice and the                                                              Company application.
computer (CAD: Computer                                                                Design, manufactu-
                                                                                     ring, sales and service
aided draughting and                                             Company                 Organization
                                                                                                                Implementation and
                                                                                                                  communication
design)                                                       computer strategy
                                                               and policy for 5
                                                                 year term
                                                                                         and methods              systems for all
                                                                                                                      users
                                                                                           Hardware
The computer has made a far bigger impact on drawing
office practices than just being able to mimic the
                                                                                           Software
traditional manual drawing board and tee square                                                                    Performance
technique. However, it depends on drawing office                                                                    monitoring
                                                                                           Resources
requirements and if only single, small, two dimensional                                                             and control
drawings and sketches are occasionally required, then
there may be no need for change. CAD can however             Fig. 1.3   General computer policy relationships
                                                                             Drawing office management and organization      5

   A CAD Director has the task of setting and                        however, demanded more specific and precise
implementing objectives and needs to be in a position                specifications.
to define binding policy and direct financial resources.                A national form of draughting presentation was
He will monitor progress. A Systems Manager has the                  needed to promote a common understanding of the
role of managing the computer hardware, the software                 objectives and in September 1927, BS 308 came to
and the associated data. Company records and designs                 fruition, as the recognized National Code of Practice
are its most valuable asset. All aspects of security are             for Engineering Drawing.
the responsibility of the Systems Manager. Security                     The initial issue was A5-size and contained only 14
details are dealt with in the next chapter. The                      clauses. Dimensioning was covered in four paragraphs
Applications Manager is responsible for day to day                   and tolerancing in only one. The recommendations
operations on the CAD system and the steady flow of                  were based on just two example drawings. The recom-
work through the equipment. He will probably organize                mended projection was first angle.
training for operators in the necessary computer skills.
Both of these managers need to liaise with the design                Revisions
project leaders to provide and maintain a draughting
facility which is capable of increasing productivity to              The life span of BS 308 was 73 years and five revisions
a considerable degree.                                               were made. The first in December 1943, followed by
   Figure 1.4 shows the probable position of the CAD                 others in 1953, 1964, 1972 and 1985. The 1972 revision
Director in the management structure. His department                 was a major one, with the introduction of three separate
will be providers of computer services to all other                  parts replacing the single document:
computer users within the company.
                                                                       The fifth (1985) revision replaced the Imperial
                      Managing Director                                standard with a Metric edition.
                                                                       BS 308 was finally withdrawn and replaced by BS
                                                                       8888 in 2000. The revisions were necessary to keep
  Manufacturing     Chief        Finance             CAD               abreast of technological innovations.
    Manager        Engineer      Manager            Director
                                                                     As manufactured products became more sophisticated
                     Chief                                           and complex, the progress and development of
                  Draughtsman
                                           Applications    Systems
                                                                     manufacturing and verification techniques accelerated.
                                            Manager        Manager   Advances in the electronics industry ensured more
                                                                     applications in manufacturing with a very high degree
Fig. 1.4                                                             of sophistication. Much progress was also made since
                                                                     that single paragraph in the original 1927 version
                                                                     relating to tolerancing, together with the four paragraphs
Why introduce BS 8888                                                and the two examples covering dimensioning. Geo-
and withdraw BS 308?                                                 metrical tolerancing was not referred to at all in early
                                                                     versions. The subject gained prominence during the
                                                                     1960s, especially when it was realized that a symbolic
For 73 years, BS 308 was a highly regarded drawing                   characterization would assist in the understanding of
office practice document. Why the change and what                    the subject by users and replace the use of lengthy
was behind the decision to withdraw BS 308 and replace               notes relating to geometric controls.
it with BS 8888?                                                        This activity was addressed by the major revision
                                                                     in 1972 with the publication of Part 3, devoted entirely
A drawing standard                                                   to the dimensioning of geometric tolerancing.
From time immemorial, drawings have been the medium
used to convey ideas and intentions. Hence the adage                 The replacement of BS 308
that ‘a picture is worth a thousand words’. No need for
language, the picture tells it all. In recent years there            Formerly, the Chief Designer and the drawing office
has, unfortunately, developed another opinion since                  set, and were responsible for, company manufacturing
CAD appeared on the scene, that there is no need for                 standards and procedures, for other disciples to follow.
a draughtsman now as the computer does it all. The                   This practice gradually eroded away because of the
truth of the matter is that the computer is able to extend           advancement of progressive and sophisticated
the range of work undertaken by the draughtsman and                  techniques in the manufacturing and verification fields.
is really a very willing slave. The evolution of the                    Increasing commercial pressure for Design for
Industrial Revolution required the ‘pictures’ to be more             Manufacture and Design for Inspection, created the
detailed. In the pre-mass-production era, manufacture                demand for equal status. During the period separate
was based on ‘matched fits’, with the assistance of                  standards were gradually developed for design,
verbal communication. The advent of mass production                  manufacture and measurement. Each discipline utilized
6   Manual of Engineering Drawing

similar terms but often with slightly different            Basic differences
interpretations despite their apparent commonality.        The fundamental differences between BS 308 and BS
   An urgent need to harmonize the meaning of these        8888 are:
terms was recognized by ISO. An international meeting
in 1989 formed a Joint Harmonization Group.                • The title: Technical product documentation (TPD)
   The Danish Standards Association funded a project         Specification for defining, specifying and graphically
to bring all design, measurement, and metrology              representing products.
standards together using definitions common to all,        • Confirmation of the conventional use of the comma
but with appendices for each discipline.                     as the decimal marker.
   A full ISO committee (ISO/TC 213) was formed,           • BS 308 was a Code of Practice, a guidance document.
with the Danish being responsible for the secretariat.       BS 8888 is essentially an applications specification,
The task allocated to this very vibrant committee            providing a route map to 106 ISO standards. The
progressed considerably, with many new international         operative word is ‘specification’. BS 8888 carried
standards being published.                                   forward and contains a significant number of valuable
   A major happening that would affect the future of         clauses contained in BS 308, which, at present, is
BS 308 was the UK’s agreement in 1993 with the               not in any ISO documentation.
European Standards Authority (CEN), whereby BSI            • BS 8888 is capable of accommodating significant
would withdraw standards relating to technical drawing       technical changes, known to be in development, plus
in favour of the implemented ISO standards covering          the facility to accommodate future additions and
the same subject. Initially, BSI systematically withdrew     changes.
various clauses of BS 308 as the relevant ISO Standards    • With 106 related ISO standards, BS 8888 has a
were introduced.                                             much broader field of application than its predecessor
   PD 308 was introduced in June 1996 as a guidance          and its 30 related ISO standards.
document to assist the transition from BS 308 to the       • BS 8888 provides common understanding, and
implementation of ISO drawing standards. In 1999, as         acceptance between the designer and the metrologist
was the case in 1927, major decisions were deemed            of ‘uncertainty’. These are caused by differences
necessary, and the following were made:                      between the Design Intent Measurand (Char-
                                                             acteristics Specification) and the Measured Value
• To transfer the United Kingdom totally to the ISO          (Characteristics Evaluation) of the actual
  Standards base.                                            manufactured part.
• To prepare an applications standard to serve as both     • BS 8888 is a uniform source of reference and will
  a specification for specifying and graphically             be regularly updated to keep abreast of developments
  representing products, and as a route map to the           as new international standards are finalized and
  ISO Standards.                                             implemented.
• To withdraw BS 308.                                      • It will capture any fundamental changes and will
From this positive commitment, BS 8888 was created           reflect moves towards an integrated system for
and published on 15 August 2000.                             definition, manufacture and verification.
  The complete comprehensive title of BS 8888 is:          • BS 8888 links each standard to the appropriate stage
                                                             of the design process and lays the foundations for
BS 8888. Technical product documentation (TPD).              future development.
Specification for defining, specifying and graphically
representing products.                                     BS 8888 will be revised every two years.

								
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