Machine Drawing

Screwed Fasteners 89

dharm
d:\N-Design\Des5-1.pm5 Seventh Print

5.9.4 Washers

A washer is a cylindrical piece of metal with a hole to

receive the bolt. It is used to give a perfect seating for

the nut and to distribute the tightening force uniformly

to the parts under the joint. It also prevents the nut

from damaging the metal surface under the joint.

Figure 5.16 shows a washer, with the proportions

marked.

Figure 5.17 illustrates the views of a hexagonal

headed bolt with a nut and a washer in position.

2D

2D+4

0.15 D

2D

DD

D

0.75 D L

Fig. 5.17 A hexagonal headed bolt with a nut and a washer in position

5.9.5 Other Forms of Bolts

5.9.5.1 Square Headed Bolt with Square Neck

It is provided with a square neck, which fits into a corresponding square hole in the adjacent part,

preventing the rotation of the bolt (Fig. 5.18).

DD

2D

1.5D + 3

0.8 D 0.8 D

Fig. 5.18 Square headed bolt with square neck

Fig. 5.16 Washer

0.15 D

2D+4

D+1