Posted On :

Mechanical - Metrology and Measurements - Thread Measurement

**TECHNICAL
TERMS**

·** Pitch**

It is the distance measured parallel to
the screw threads axis between the corresponding points on two adjacent threads
in the same axial plane. The basic pitch is equal to the lead divided by the
number of thread starts.

·** Lead:**

The
axial distance advanced by the screw in one revolution is the lead.

·** Addendum**

Radial distance between the major and
pitch cylinders for external thread. Radial distance between the minor and
pitch cylinder for internal thread.

·** Dedendum**

It is the radial distance between the
pitch and minor cylinders for external thread. Also radial distance between the
major and pitch cylinders for internal thread.

·** Pressure angle (a**)

It is the angle making by the line of
action with the common tangent to the pitch circles of mating gears.

·** Module(m)**

It
is the ratio of pitch circle diameter to the total number of teeth

·** Lead angle**

It is the angle between the tangent to
the helix and plane perpendicular to the axis of cylinder.

·** Straightness**

A line is said to be straight over a
given length, if the variation of the distance of its from two planes
perpendicular to each other and parallel to the general direction of the line
remains within the specified tolerance limits

**Roundness **Roundness
is defined as a condition of a surface of revolution. Where all** **points
of the surface intersected by any plane perpendicular to a common axis in case
of cylinder and cone.

Tags : Mechanical - Metrology and Measurements - Thread Measurement

Last 30 days 48 views