MIL-DTL-45916C
3.5 Thread locking feature. The locking element for Type I inserts shall be nylon. The
insert and internal thread locking devices for Type II inserts shall be an integral, all metal unit.
Threads in the area of the locking feature on Type II inserts may be displaced or deformed. The
installed insert shall provide a locking torque with the mating screw or bolt within the limits of
Table I.
TABLE I. Internal Thread Self-Locking Torque (Inch-Pounds).
Fine Threads
Coarse Threads
Nominal Size
Maximum
Minimum
Nominal Size
Maximum
Minimum
Internal
Locking
Breakaway
Internal
Locking
Breakaway
Thread
Torque
Torque
Thread
Torque
Torque
*.086-64
2.5
**
.086-56
2.5
**
*.112-48
5
**
.112-40
5
**
*.138-40
10
1.0
.138-32
10
1.0
*.164-36
15
1.5
.164-32
15
1.5
.190-32
18
2.0
.190-24
18
2.0
.250-28
30
3.5
.250-20
30
4.5
.3125-24
60
6.5
.3125-18
60
7.5
.375-24
80
9.5
.375-16
80
12.0
*.4375-20
100
14.0
*.4375-14
100
16.5
.500-20
150
18.0
.500-13
150
24.0
*.5625-18
200
24.0
*.5625-12
200
30.0
.625-18
300
32.0
.625-11
300
40.0
.750-16
400
50.0
.750-10
400
60.0
* Inactive for new design.
** Some indication of torque.
3.6 Threads. All threads shall be right hand.
3.6.1 Internal threads. Internal threads shall be in accordance with FED-STD-H28 and as
specified in MS35914 and MS51836. Thread gaging shall be performed after application of
protective coating and prior to application of the lubricant. When a locking feature is employed,
the GO plug gage shall enter a minimum of 3/4 turn before engaging the locking device. When
the application of a lubricant on Type II inserts prevents the use of standard gages, the inserts
shall permit a minimum free rotational bolt thread engagement of 3/4 turn before engaging the
locking device.
3.6.2 External threads. External threads shall be a special form to permit a self-threading
action when the insert is installed. External threads shall be as specified on MS35914 and
MS51836.
3.6.3 Lead threads. Internal lead threads shall not exceed two pitches, including chamfer.
3.6.4 Concentricity. For Types I and IA, the internal thread pitch diameter shall be
concentric with the external pitch diameter within 0.004 TIR for sizes up to and including 0.190,
and 0.006 TIR for sizes larger than 0.190 internal thread. For Type II inserts, the internal thread
pitch diameter shall be concentric with the external pitch diameter within 0.006 TIR.
3.7 Surface roughness. The surface roughness of the inserts prior to protective coating
shall not exceed 125 micro-inches in accordance with ASME B46.1.
3.8 Mechanical properties.
3.8.1 Pullout resistance. Type I and II inserts shall withstand the pullout strengths specified
in Table II with no failure of either the insert or parent material and shall have no elongation on
excess of 2%.
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