Types Of Machine Drawing 5tb63

Debre Markos University Mechanical Engineering Department

Machine Drawing MEng 2301 Lecture 2 Types of Machine Drawing By: Addisu Dagne 2012/13 Academic Year 1

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Assembly Drawing  An assembly working-drawing indicates how the individual

parts of a machine or mechanism are assembled to make a complete unit.  An assembly working-drawing serves the following purposes: o It describes the shape of the assembled unit. o it indicates how the parts of the assembled unit are positioned in

relation to each other. o It identifies each component that forms part of the assembled unit. o It provides a parts list that describes and lists essential data concerning each part of the assembled unit.

 It is preferable that the dimension of the parts of the

machine are not shown as they would crowd the drawing. 2

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Assembly Drawing

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Assembly Drawing

 The parts list of an assembly working-

drawing itemizes important data about each part of an assembled unit such as part name, material, quantity required, and size specifications.

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Sectioned parts on Assembly Drawings  The section lines on sectioned adjacent parts of assembly

working-drawings should vary in order to make the shapes of the sectioned parts more apparent.  Different types of section lines as well as different spacing and different angles of inclination are recommended for this purpose.  As a general rule solid parts that do not have interior features, such as shafts, rivets, pins, keys, and threaded fasteners, remain un-sectioned on assembly workingdrawings.

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Sectioned parts on Assembly Drawings

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Assembly Drawing - Parts Identification  Every part on an assembly working-drawing must be

identified by means of a part number. Each part number is lettered within a parts identification balloon that has a leader that ends at or on the part identified.  Hints Regarding Parts Balloons and leaders Group balloons in straight lines, clockwise and in sequence, if possible, around the view or views. Place balloons at a reasonable distance from the views. A minimum distance of 25 mm is recommended. Use straight leaders when possible. Bend a leader when it is necessary to maintain clarity. 7

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Assembly Drawing - Parts Identification  Draw leaders at varying angles. Avoid vertical and

horizontal leaders.  Place parts balloons adjacent to parts being identified in order to avoid extra-long leaders and the need to over too many other parts.  Leaders that over sectioned parts should be drawn so they do not become confused with the section lines.  Avoid drawing leaders through the corners of parts.

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Assembly Drawing - Parts Identification

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Assembly Drawing - Parts Identification

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Assembly Drawing - Parts Identification

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Assembly Drawing - Parts Identification • An arrowhead is used

when a leader terminates at a line that represents the edge of a part.

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• A dot is used when a leader is

drawn onto a surface of a part across a line that represents the edge of the part.

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Assembly Drawing - Parts Identification Leaders can be bent to maintain clarity. Keep bends to a minimum

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POINTS TO As a general rule, assembly working-drawings are not

dimensioned. Hidden lines that do not add to the clarity of an assembly working-drawing should be omitted. Do not position parts identification balloons haphazardly. Try to group them in straight lines around the views, preferably clockwise and in sequence. Parts leaders should be drawn at an angle. Adjacent parts that are sectioned should have different types of section lines, should have section lines drawn at different angles, or should be spaced differently in order to make them readily apparent. 14

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POINTS TO On assembly working-drawings shafts, rivets, keys,

screw-thread fasteners, and other solid parts are not usually sectioned. When necessary, reference information is shown on assembly working drawings in the form of notes and dimensions.

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Sub-assembly Drawings 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, carburetor, etc.

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Part Drawing/Detail Drawing A detail drawing is a drawing of an individual part,

which includes an orthographic projection and dimensions. Component or part drawing is a detailed drawing of a component to facilitate its manufacture. A part drawing shows the number of views of each single part of a machine to facilitate its manufacturing. It should give all the dimensions, limits, tolerances and special finishing; if any.

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Catalogue Drawings Special assembly drawings are prepared for company

catalogues. These drawings show only the pertinent details and dimensions that would interest the potential buyer.

Schematic Drawings A schematic drawing is the simplified illustration of a

machine or system, replacing all the elements by their respective conventional representations, to understand the principle of operation. 18

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Shop Drawings Shop Drawing— A shop drawing includes the part

drawing, subassembly and the complete assembly of a product for manufacturing.

Patent Drawings A patent drawing gives the correct and complete

features of a new technology or innovation adopted for a machine or system. The drawings are pictorial in nature and self — explanatory but not useful for production purposes. 19

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