CLASSIFICATION OF DRAWING

1.MACHINE DRAWING

 It is pertaining to machine parts or components. It is presented through a number of

orthographic views, so that the size and shape of the component is fully understood. Part

drawings and assembly drawings belong to this classification. An example of a machine drawing

is given in Fig.

2. PRODUCTION DRAWING

A production drawing, also referred to as working drawing, should furnish all the dimensions,

limits and special finishing processes such as heat treatment, honing, lapping, surface finish,

etc., to guide the craftsman on the shop floor in producing the component. The title should also

mention the material used for the product, number of parts required for the assembled unit,

etc.

Since a craftsman will ordinarily make one component at a time, it is advisable to prepare

the production drawing of each component on a separate sheet. However, in some cases the

drawings of related components may be given on the same sheet. Figure 1.2 represents an

example of a production drawing.

3.PART DRAWING

Component or part drawing is a detailed drawing of a component to facilitate its manufacture.

All the principles of orthographic projection and the technique of graphic representation must

be followed to communicate the details in a part drawing. A part drawing with production

details is rightly called as a production drawing or working drawing.

4.ASSEMBLY DRAWING

A drawing that shows the various parts of a machine in their correct working locations is an

assembly drawing . There are several types of such drawings.

4.1 DESIGN ASSEMBLY DRAWING

When a machine is designed, an assembly drawing or a design layout is first drawn to clearly

visualize the performance, shape and clearances of various parts comprising the machine.

4.2 DETAILE ASSEMBLY DRAWING

It is usually made for simple machines, comprising of a relatively smaller number of simple

parts. All the dimensions and information necessary for the construction of such parts and for

the assembly of the parts are given directly on the assembly drawing. Separate views of specific

parts in enlargements, showing the fitting of parts together, may also be drawn in addition to

the regular assembly drawing.

4.3 SUB ASSEMBLY DRAWING

Many assemblies such as an automobile, lathe, etc., are assembled with many pre-assembled

components as well as individual parts. These pre-assembled units are known as sub-assemblies.

A sub-assembly drawing is an assembly drawing of a group of related parts, that form a

part in a more complicated machine. Examples of such drawings are: lathe tail-stock, diesel

engine fuel pump, carburettor, etc.

4.4 INSTALLATION ASSEMBLY DRAWING

On this drawing, the location and dimensions of few important parts and overall dimensions of

the assembled unit are indicated. This drawing provides useful information for assembling the

machine, as this drawing reveals all parts of a machine in their correct working position.

4.5 ASSEMBLY DRAWING FOR CATALOGUES

Special assembly drawings are prepared for company catalogues. These drawings show only

the pertinent details and dimensions that would interest the potential buyer. Figure  shows

a typical catalogue drawing, showing the overall and principal dimensions.

Speed change lever (1)

Depth adjusting knob (2)

Mech. feed engagement lever (3)

Hand feed lever (4)

Feed change knob (5)

Switch for tapping (6)

Gear shifting lever (7)

Main switch (8)

Lamp switch (9)

Selector switch (10)

Forward/reverse switch (11)

Pilot lamp (12)

Feed disengagement push button (13)

Start push button (14)

Emergency stop (15)

Elevating handle (16)

Clamping handle (17)

Supply inlet (18)

4.6 ASSEMBLY DRAWING FOR INSTRUCTION MANUAL

These drawings in the form of assembly drawings, are to be used when a machine, shipped

away in assembled condition, is knocked down in order to check all the parts before reassembly

and installation elsewhere. These drawings have each component numbered on the job. Figure

 shows a typical example of such a drawing.

4.7 EXPLODED ASSEMBLY DRAWING

In some cases, exploded pictorial views are supplied to meet instruction manual requirements.

These drawings generally find a place in the parts list section of a company instruction manual.

Figure 1.6 shows drawings of this type which may be easily understood even by those with less

experience in the reading of drawings; because in these exploded views, the parts are positioned

in the sequence of assembly, but separated from each other.

 4.8 SCHEMETIC ASSEMBLY DRAWING

It is very difficult to understand the operating principles of complicated machinery, merely

from the assembly drawings. Schematic representation of the unit facilitates easy understanding

of its operating principle. It is a simplified illustration of the machine or of a system, replacing

all the elements, by their respective conventional representations. Figure shows the

schematic representation of a gearing diagram.

4.9 MACHINE SHOP DRAWING

Rough castings and forgings are sent to the machine shop for finishing operation (Fig).

Since the machinist is not interested in the dimensions and information of the previous stages,

a machine shop drawing frequently gives only the information necessary for machining. Based

on the same principle, one may have forge shop drawing, pattern shop drawing, sheet metal

drawing, etc.

4.10 PATENT DRAWING

When new machines or devices are invented, patent drawings come into existence, to illustrate

and explain the invention. These are pictorial drawings and must be self-explanatory. It is

essential that the patent drawings are mechanically correct and include complete illustrations

of every detail of the invention. However, they are not useful for production purposes. The

salient features on the drawing are numbered for identification and complete description.