Drafting Technology

 Creation and the Creator:

The scientists explore what is, and the engineers create what has never been. A Product

Manufactured for the first time may have complicated construction and also may be discarded on the grounds that its production cost is prohibitive. This needs improvement with respect to the cost structure as well as functional simplicity of the structure too. Therefore the creator or the design engineer with his knowledge of the art of production and understanding of the sciences must be constantly engaged in implementing the scientific principles to create new products and also to improve the existing ones.

How designs are engineered into reality?

To create a new product or to improve the existing one the design engineer must have in

His mind a complete picture of its working principles, functional requirements and the production processes involved in its manufacture. His thinking of the product must be conveyed to the workman so as to enable him to fabricate it. The workman can be made to understand easily the shape, size and the production processes required to fabricate the product only through the sketches, since the sketches alone can explain him better than any amount of verbal or written explanations. The sketches, when drawn accurately according to the standard accepted practice, to convey all the necessary information to enable the workman to fabricate and make an assembly of the product, are called engineering drawings. This universal graphical expression is the language of engineer. The art and technique of producing the drawings is called drafting. The design engineer instructs and guides the draftsman either directly or indirectly to prepare the drawings. According to these drawings, the workman will fabricate the product to its actual size and shape. Thus the drawings play an important role as a means of communication through which the ideas of the design engineer are transformed into reality in the form of new or improved products useful to the mankind.  

                                     

Should an engineer be a draftsman?

     Draftsman takes drafting alone as his profession. But a professional engineer needs only to convey the creative ideas he has in his mind to the draftsman in the graphical language they both know. Void of the skill, art and technique of drafting, even the idea can be conveyed to the `draftsman. An engineer is required to know how to read and interpret the drawings, but the draftsman should know how to prepare it making use of his skill, art and technique. Thus it is easily perceived that an engineer need have not be a draftsman to the extent the professional draftsman should be. But he must have the elements of draftsmanship in him.

Computer aided drafting

      

 Although the manual drafting is the most common prevailing practice, some industries are now using computerized drafting machines for their drafting work in order to minimize the drafting time. In one of the computerized drafting machines, the data flows from a key board through floppydiscs, cards and tapes to a control unit. The control unit which is a small computer translates the input data into commands which in turn flows to a drawing head which produces the drawing. In a machine, an electron beam is used to produce lines, dimensions, symbols from the data supplied by the computer. Because of their tremendous cost, presently their use is limited. Of coures in the years ahead to come, the computerized drafting may replace the manual drafting considerably, yet the technical personnel should know how to read and interpret the drawing.

Standards in drafting practice

      

 In order to make the drafting practice as uniform as possible throughout the country and also to make it similar to the accepted practice in other countries so that the drawings made anywhere will have a clear and unmistakable meaning, Indian standards institution (ISI) introduced a code of practice for general engineering drawing IS:  696, in 1955.subsequent revisions were undertaken and the latest code has been published in 1972. Although the drafting practice in India is based on the British practice, in preparing this code assistance has bees derived from the standards issued by a number of countries and also from the recommendations of International organization for standardization (ISO).

                               The recommendations are made in this code for sheet sizes and their layout scales to be adopted for drawing, lettering types and sizes, standard line thickness, methods of projection, sections, conventional representation, dimensioning, tolerance, machining symbols, abbreviations etc.

                               The standards and conventions adopted in this text are based mainly on IS: 696-1972 and the various other related codes issued by Indian standards institution. 

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