UNF fastener in tension
Thread geometry, SAE proof strength and initial preload for a UNF fastener under tension.
Initial preload, F_i12236 lb
Proof strength, S_p85 kpsi
Major diameter, d0.5 in
Threads per inch, N20
Pitch, P = 1/N0.05 in
Pitch diameter, d_p0.468 in
Minor diameter, d_r0.435 in
Tensile stress area, A_t159.95 1e-3 in²
Method & references
- UNF fastener in tension — SAE proof-strength system.
The computation is a literal port of the original client-side JavaScript from /calculators/unf_1.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.