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Content. Screw Thread Design - Fastenal UNJ thread is a thread form having root radius limits of 0.150 to 0.180 times the thread pitch. With these enlarged radii, minor diameters of external thread increase and intrude beyond the basic profile of the UN and UNR thread forms.
UNJF - Unified Fine Threads. UNJF Thread Series, is suitable for the production of bolts, screws, and nuts for aerospace applications where the Root Radius is controlled. External threads of this series have greater tensile stress area than comparable sizes of the Coarse series.
The UNJ screw thread is intended for threaded parts and used in weight sensitive applications requiring high fatigue strength, resistance to vibration, and where parts are physical size, and strength sensitive.
The UNJF thread table shows selected thread sizes whose dimensions correspond to the UNF templates. The thread designation in the UNJF thread table is made up of the abbreviation UNJF and the outside diameter in inches.
unified-thread-standard-charts Created Date: 9/22/2023 10:07:53 PM ...
The thread dimensions of UNJF threads are standardized, allowing for precise engineering and manufacturing processes. This includes specifications for major and minor diameters, as well as pitch diameter, which must be adhered to for optimal performance in threaded connections.
In summary, while both UNF and UNJF threads are fine threads within the Unified Thread Standard, UNJF threads are specifically tailored for high-pressure fluid systems where leak-tight connections are critical.
