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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.
This Standard specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. (In order to emphasize that unified screw threads are based on inch modules, they may be denoted unified inch screw threads.)
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.
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.
UNF threads are particularly important in hydraulic fittings and connections, where pressure and fluid dynamics play significant roles. The precision of UNF threads helps maintain seals under high pressure, preventing leaks and ensuring the safe operation of hydraulic systems.
Unified Thread Standard - Coarse, Fine, and Extra Fine.
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.
