Page 10 - THREADING CATALOG

INTRODUCTION
INTRODUCTION Threads can be classified by the following criteria: Pitch
Thread Classifications

Thread pitch can be classified by “coarse pitch”
Gender
and “fine pitch.” The terms refer to the size of the
Depending on the location of the surface, the thread may
threads relative to the screw diameter and do not
be external (cut on a rod) or internal (cut into a hole).
imply differences in thread quality, tolerances,
or cost. They can be compared as follows:
External Thread
Internal Thread
Coarse Pitch
• Fewer threads per axial distance.
• Larger thread form relative to screw diameter.
• More resistant to stripping and cross threading
due to greater flank engagement.
• Install much faster as they require
fewer turns per unit length.

Designation Fine Pitch
The threads are divided into fasteners or connection • More threads per axial distance.
parts, running or kinematic (in a movable • Smaller thread form relative to screw diameter.
connection) by main application. Often the fastening • Stronger due to a larger stress area
threads carry a second function - sealing the for the same diameter thread.
threaded connection, ensuring its tightness. • Less likely to vibrate loose as they have a smaller
helix angle and allow finer adjustment.
• Develop greater preload with less tightening torque.

coarse thread fine
thread length thread
Handedness
This represents the direction of the thread helix,
which can twist in two possible directions: clockwise
(CW) and counter-clockwise (CCW). When the thread
is designed to be turned in a clockwise direction,
it is known as a “right-handed (RH) thread.” When
the thread is designed to be turned in the opposite
direction, it is known as a “left-handed (LH) thread.”
view direction
left hand right hand

when turns CW, when turns CW,
screw-out plate screw-in plate

ISCAR
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