Machine Drawing Solution Oct’2015

Machine Drawing Solution Oct’2015

Part A

1.

Removed section views do not follow standard view alignments as practiced in multiview drawings. Removed sections are made in a manner similar to revolved sections, by passing an imaginary cutting plane perpendicular to a part then revolving the cross section 90 degrees. However, the cross section is then drawn adjacent to the orthographic view, not on it. Removed sections are used when there is not enough room on the orthographic view for a revolved section. 

(Or)

A revolved section is made by revolving a cross section view 90° about an axis of revolution and superimposing the section view on the orthographic. A removed section is similar except the view is removed to another part of the drawing. 

2.

Tolerance is defined as the maximum permissible variation of size or form or position of a feature.  It is classified into Dimensional tolerance and Geometrical tolerance.

Dimensional tolerance

The permissible variation of a size is called dimensional tolerance. It is the difference between the maximum and minimum permissible limits of the given size.

   Bilateral tolerance  of equal variation                            Bilateral tolerance of unequal variation

Unilateral tolerance with zero variation in one direction    Maximum and minimum size directly indicated

If the variation is provided on one side of the basic size, it is termed as unilateral tolerance. Similarly, if the variation is provided on both sides of the basic size, it is known as bilateral tolerance

Geometrical tolerance

Geometrical tolerance is defined as the maximum permissible overall variation of form or position of a feature.

3.

It is not possible to achieve in practice, a geometrically ideal surface of a component and hence, production drawings of components must also contain information about the permissible surface conditions. Machine components which have undergone machining operation, when inspected under magnification, will have some minute irregularities. The actual surface condition will depend upon the finishing process adopted.

The properties and performance of machine components are affected by the degree of roughness of the various surfaces. The higher the smoothness of the surface, the better is the fatigue strength and corrosion resistance. Friction between mating parts is also reduced due to better surface finish.

4.

5.


Angle of chamfer = 30°

Part B

From Engg. Graphics I