types of threads , thread gauges, classes and positions

1. APPLY THREAD MEASUREMENTS
AND THREAD MEASURING
TECHNIQUES

2. THREAD GAUGE
Thread
plug gauge
Thread
ring gauge
Used to check
external threads
Used to check
internal threads

3. TYPES OF THREAD
Metric
thread
unified
thread
NPT
thread
BSP
thread
BSW
thread
The "M" designation
for metric screws
indicates the nominal
outer diameter of the
screw thread, in
millimeters.
• commonly used in
the united
states and Canada.
• It has the same 60°
profile as the ISO metric
screw thread, but the
outer diameter and
pitch were chosen as
an inch fraction rather
than a millimeter value.
•American National
Standard Pipe
Thread standards
• used on threaded
pipes and pipe fittings
It has been adopted
as standard
in plumbing and pipe
fitting, except in
North America,
where NPT and
related threads are
used.
British Standard
Whitworth (BS
W) is
an imperial-
unit-
based screw
thread standard
.

4. 1-5/16-18 UN-2A
Example # 1:
Major diameter
Thread per
inch
Unified series
classes
Unified
thread
classes
External
threads
1A
2A
3A
Where easy and quick assembly is necessary
Where easy of manufacturing cost,
performance is the key consideration in
design. (nuts bolts or similar fasteners)
Where the accuracy of lead , thread
angle and closeness of fit is necessary.
(in aerospace and aircraft industry, medical and auto
racing industry)

5. 6-32 UNC-2B
Example # 2:
Major diameter
Thread per
inch
Unified series
classes
Unified
thread
classes
internal
threads
1B
2B
3B
Where easy and quick assembly is necessary
Where easy of manufacturing cost,
performance is the key consideration in
design.(nuts bolts or similar fasteners)
Where the accuracy of lead , thread
angle and closeness of fit is necessary.
(in aerospace and aircraft industry, medical and auto
racing industry)

6. M42X2-6g
Example # 3:
Metric series
Major
diameter
pitch
classes
Metric
thread
classes
Internal and
external
threads
4
6
8
Short length engagement.
Fine quality and short length
engagement .
Coarse quality and long length
engagement.
position
CLASSES

7. M42X2-6g
Example # 3:
Metric series
Major
diameter
pitch
classes
Metric
thread
positions
external
threads
4
6
8
position
positions
e
g
h
small allowance
No allowance
Large allowance

8. M12X1-6H
Example # 3:
Metric series
Major
diameter
pitch
classes
Metric
thread
positions
internal
threads
4
6
8
position
positions
G
H No allowance
small allowance

9. THANK YOU