Bolt, commonly used with nuts, are the most widely used
non-permanent fastening. The bolt head is usually hexagonal but may be square
or round. The shank is screwed with a vee thread for all or parts of its
length.
Materials
Most bolts are
made of low or medium carbon steel
by forging or machining and the threads are formed by cutting or rolling.
Forged bolts are called black and
machined bolts are called bright.
They are also made in high tensile (HT bolts 8.8), alloy steel, stainless
steel, brass and other metals.
TYPES OF BOLTS
1. Machine
Bolt 4.
Stove Bolt
2. Eye Bolt 5. U bolt
3. Stud Bolt 6. Carriage Bolt
TYPES OF SCREWS
1. Cap Screw
2. Machine Screw
3. Set Screw
4. Power Screw
THE AMERICAN NATIONAL SCREW THREAD
TYPES OF THREADS-
1. UNC
(Unified National Coarse Series) – is recommended for general use, where
jar and vibration are not important factors, where dis-assembly of parts is
frequent, and where tapped holes are in metals other than steel.
2. UNF (Unified National Fine Series) – is
frequently used in automotive and aircraft work especially where jar and
vibration (tending to loosen the nut) are present, where a fine adjustment is
required with the use of a castle nut, and where a fine adjustment is required with
the use of castle nut, and where tapped holes are in steel (avoid UNF in
brittle materials)
3. UNEF (Unified
National Extra Fine)
– is particularly useful in aeronautical equipment, suitable where thin-walled
materials is to be threaded, where fine adjustment are required, and where jar
and vibration are excessive. Screws with these threads are likely to be made of
heat treated alloy steel.
4. 8UN (Unified
8 – thread series)
– is used on bolt for high-pressure pipe flanges, cylinder-head studs, etc. These
are several constant pitch series, the 12 UN, 16 UN, and 20 UN. These threads
are useful because in the regular coarse thread, the pitches continue to
increase with size and it becomes increasingly difficult to induce the desire
initial tension in the bolt, so necessary for tight joint. Even for the 8 UN
thread, impact wrenches or very large leverages are needed for tightening to
stresses of the order of the yield strengths.
EXTRA FINE 8-THREAD SERIES TABLE
EXTRA FINE 8-THREAD SERIES TABLE
EXTRA
FINE SERIES (NEF AND UNEF)
|
8-THREAD
SERIES (8 N and 8 UN)
(Primary
Sizes)
|
||||||
Size
|
Basic Major
Diameter, in.
|
Th./In. (tpi)
|
Minor Dia. Ext
Th.
|
Stress Area AS
sq. in.
|
Size
|
Minor Dia.
Ext. Th.
|
Stress Area As
sq. in
|
12
|
0.2160
|
32
|
0.1777
|
0.0270
|
1
|
0.8466
|
0.606
|
1/4
|
0.2500
|
32
|
0.2117
|
0.0379
|
1 1/8
|
0.9716
|
0.790
|
5/16
|
0.3125
|
32
|
0.2742
|
0.0625
|
1 ¼
|
1.0966
|
1.000
|
3/8
|
0.3750
|
32
|
0.3367
|
0.0932
|
1 3/8
|
1.2216
|
1.233
|
7/16
|
0.4375
|
28
|
0.3937
|
0.1274
|
1 1/2
|
1.3466
|
1.492
|
1/2
|
0.5000
|
28
|
0.4562
|
0.170
|
1 5/8
|
1.4716
|
1.78
|
9/16
|
0.5625
|
24
|
0.5114
|
0.214
|
1 3/4
|
1.5966
|
2.08
|
5/8
|
0.6250
|
24
|
0.5739
|
0.268
|
1 7/8
|
1.7216
|
2.41
|
11/16
|
0.6875
|
24
|
0.6364
|
0.329
|
2
|
1.8466
|
2.77
|
3/4
|
0.7500
|
20
|
0.6887
|
0.386
|
2 1/4
|
2.0966
|
3.56
|
13/16
|
0.8125
|
20
|
0.7512
|
0.458
|
2 1/2
|
2.3466
|
4.44
|
7/8
|
0.8750
|
20
|
0.8137
|
0.536
|
2 3/4
|
2.5966
|
5.43
|
15/16
|
0.9375
|
20
|
0.8762
|
0.620
|
3
|
2.8466
|
6.51
|
1
|
1.0000
|
20
|
0.9387
|
0.711
|
3 1/4
|
3.0966
|
7.6738
|
1 1/16
|
1.0625
|
18
|
0.9943
|
0.799
|
3 1/2
|
3.3466
|
8.96
|
1 1/8
|
1.1250
|
18
|
1.0568
|
0.901
|
3 3/4
|
3.5966
|
10.34
|
1 3/16
|
1.1875
|
18
|
1.1193
|
1.009
|
4
|
3.8466
|
11.81
|
1 1/4
|
1.2500
|
18
|
1.1818
|
1.123
|
4 1/4
|
4.0966
|
11.38
|
1 5/16
|
1.3125
|
18
|
1.2443
|
1.244
|
4 1/2
|
4.3466
|
15.1
|
1 3/8
|
1.3750
|
18
|
1.3068
|
1.370
|
4 3/4
|
4.5966
|
16.8
|
1 7/16
|
1.4375
|
18
|
1.3693
|
1.503
|
5
|
4.8466
|
18.7
|
1 1/2
|
1.5000
|
18
|
1.4318
|
1.64
|
5 1/4
|
5.0966
|
20.7
|
1 9/16
|
1.5625
|
18
|
1.4943
|
1.79
|
5 1/2
|
5.3466
|
22.7
|
1 5/8
|
1.6250
|
18
|
1.5568
|
1.94
|
5 3/4
|
5.5966
|
24.9
|
1 11/16
|
1.6875
|
18
|
1.6193
|
2.10
|
6
|
5.8466
|
27.1
|
HEX
HEAD BOLT STANDARD DIMENSION (by
American Society Of Mechanical Engineering)
Bolt
Diameter
|
Body
Diameter
Max Min
|
Across
Flat
|
Across
Corner
Max Min
|
Height
of Bolt
|
Length
Tread 6 in. below
|
Length
Tread 6 in. Above
|
||
¼
|
0.26
|
.237
|
7/16
|
.505
|
.484
|
11/64
|
.75
|
1.0
|
5/16
|
.324
|
.298
|
½
|
.577
|
.522
|
7/32
|
.88
|
1.13
|
3/8
|
.388
|
.360
|
9/16
|
.650
|
.62
|
¼
|
1.0
|
1.25
|
7/16
|
.452
|
.421
|
5/8
|
.722
|
.687
|
19/64
|
1.13
|
1.38
|
½
|
.515
|
.482
|
¾
|
.866
|
.826
|
11/32
|
1.25
|
1.50
|
5/8
|
.642
|
.605
|
15/16
|
1.083
|
1.033
|
27/64
|
1.50
|
1.75
|
¾
|
.768
|
.729
|
1
1/8
|
1.299
|
1.24
|
½
|
1.75
|
2.00
|
7/8
|
.895
|
.852
|
1
5/16
|
1.516
|
1.447
|
37.64
|
2.0
|
2.25
|
1
|
1.022
|
.976
|
1
½
|
1.732
|
1.653
|
43/64
|
2.25
|
2.50
|
1
1/8
|
1.149
|
1.098
|
1
11/16
|
1.949
|
1.859
|
¾
|
2.50
|
2.75
|
1
¼
|
1.277
|
1.223
|
1
7/8
|
2.165
|
2.066
|
27/32
|
2.75
|
3.00
|
1
3/8
|
1.404
|
1.345
|
2
1/16
|
1.949
|
1.859
|
29/32
|
3.00
|
3.25
|
1
½
|
1.531
|
1.47
|
2
¼
|
2.598
|
2.48
|
1
|
3.25
|
3.50
|
1
¾
|
1.785
|
1.716
|
2
5/8
|
3.031
|
2.893
|
1
5/32
|
3.75
|
4.00
|
2
|
2.039
|
1.964
|
3
|
3.164
|
3.306
|
1
11/32
|
4.25
|
4.50
|
2
¼
|
2.305
|
2.212
|
3
3/8
|
3.897
|
3.719
|
1
½
|
4.75
|
5.00
|
2
½
|
2.559
|
2.461
|
3
¾
|
4.33
|
4.133
|
1
21/32
|
5.25
|
5.50
|
2
¾
|
2.827
|
2.711
|
4
1/8
|
4.763
|
4.546
|
1
13/16
|
5.75
|
6.00
|
3
|
3.081
|
2.961
|
4
½
|
5.196
|
4.959
|
2
|
6.25
|
6.50
|
3
¼
|
3.335
|
3.21
|
4
7/8
|
5.629
|
5.372
|
2
3/16
|
6.75
|
7.0
|
3
½
|
3.589
|
3.461
|
5
¼
|
6.062
|
5.786
|
2
5/16
|
7.25
|
7.50
|
3
¾
|
3.858
|
3.726
|
5
5/8
|
6.495
|
6.198
|
2
½
|
7.75
|
8.00
|
4
|
4.111
|
3.975
|
6
|
6.928
|
6.612
|
2
11/16
|
8.25
|
8.50
|
