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Threaded Rods & Threading

Wednesday, 22 November 2023
Threaded rods come in many diameters, lengths, materials and finishes.  These headless fasteners have a wide variety of uses, and we offer a vast array from stock as well as custom products.
On Threaded Rod the thread can be the whole length or on one or both ends – Single or Double ends.
Threads can be produced by Cutting or Rolling.  The Cutting process dictates that material is removed from full diameter bar, where as Rolling is actually a Cold Forming process is that it does not remove any material, and commences with a bar diameter of approximately Pitch diameter.
If one looks carefully at a standard hexagon head bolt once can see taper into the thread where the shank has been extruded down to allow the thread to be rolled up to diameter. *  On a cup head bolt bare shank is smaller (thread roll diameter) than the thread.

The Thread Rolling process involves one, two or sometimes three dies with grooves to form threads, or in some cases Knurles.  As pressure is applied the feed stock is forced into the grooves on the dies and as the dies turn the thread is roll formed.   Bolt machines usually have one stationary die and one reciprocating, while threaded rod rollers will have two or three dies, all of which are in motion.

Advantages of thread rolling over cutting includes:
  • Material savings as no material is removed.
  • Cold working produces a thread which most agree is 10% to 20% stronger, due to the grain being uninterrupted.
  • The surface finish of a rolled thread is harder (and often smoother) than a cut thread offering greater wear resistance.
  • Threads can be rolled at high speeds – much faster than cutting.
  • The process is accurate and uniform.