2 Budynas-Nisbett:Shigley's lll.Design of Mechanical 8.Screws,Fasteners,and ©The McGraw-Hill Mechanical Engineering Elements the Design of Companies,2008 Design,Eighth Edition Nonpermanent Joints Screws,Fasteners,and the Design of Nonpermanent Joints 399 Table 8-2 Diameters and Area of Unified Screw Threads UNC and UNF* Coarse Series-UNC Fine Series-UNF Nominal Tensile- Minor- Tensile- Minor- Major Threads Stress Diameter Threads Stress Diameter Size Diameter per Inch Area A Area A. per Inch Area A Area A. Designation in 2 in2 in2 N in2 in2 0 0.0600 80 0.00180 0.00151 0.0730 64 0.00263 0.00218 72 0.00278 0.00237 2 0.0860 56 0.00370 0.00310 64 0.00394 0.00339 3 0.0990 48 0.00487 0.00406 56 0.00523 0.00451 0.1120 40 0.00604 0.00496 48 0.00661 0.00566 U 0.1250 40 0.00796 0.00672 0.00880 0.00716 0.1380 32 0.00909 0.00745 40 0.01015 0.00874 8 0.1640 32 0.0140 0.01196 36 0.01474 0.01285 10 0.1900 24 0.0175 0.01450 32 0.0200 0.0175 12 0.2160 24 0.0242 0.0206 28 0.0258 0.0226 1456 0.2500 20 0.0318 0.0269 28 0.0364 0.0326 0.3125 18 0.0524 0.0454 24 0.0580 0.0524 3876 0.3750 16 0.0775 0.0678 24 0.0878 0.0809 0.4375 14 0.1063 0.0933 20 0.1187 0.1090 12 0.5000 13 0.1419 0.1257 20 0.1599 0.1486 0.5625 12 0.182 0.162 18 0.203 0.189 583478 0.6250 11 0.226 0.202 18 0.256 0.240 0.7500 0 0.334 0.302 16 0.373 0.351 0.8750 9 0.462 0.419 0.509 0.480 1.0000 8 0.606 0.551 12 0.663 0.625 1 1.2500 7 0.969 0.890 12 1.073 1.024 1 1.5000 6 1.405 1.294 12 1.581 1.521 *This table was compiled from ANSI B1.1-1974.The minor diometer was found from theiod-1.299038p the pitch diameter fromd-0.649519p.The mean of the pitch diameter and the minor diameter was used to compute the tensilestress area. Figure 8-3 (a)Square thread;(b)Acme thread bBudynas−Nisbett: Shigley’s Mechanical Engineering Design, Eighth Edition III. Design of Mechanical Elements 8. Screws, Fasteners, and the Design of Nonpermanent Joints 402 © The McGraw−Hill Companies, 2008 Screws, Fasteners, and the Design of Nonpermanent Joints 399 p p 2 p p 2 p 2 d dr d dr p 2 29° (a) (b) Figure 8–3 (a) Square thread; (b) Acme thread. Coarse Series—UNC Fine Series—UNF Nominal Tensile- Minor- Tensile- Minor￾Major Threads Stress Diameter Threads Stress Diameter Size Diameter per Inch Area At Area Ar per Inch Area At Area Ar Designation in N in2 in2 N in2 in2 0 0.0600 80 0.001 80 0.001 51 1 0.0730 64 0.002 63 0.002 18 72 0.002 78 0.002 37 2 0.0860 56 0.003 70 0.003 10 64 0.003 94 0.003 39 3 0.0990 48 0.004 87 0.004 06 56 0.005 23 0.004 51 4 0.1120 40 0.006 04 0.004 96 48 0.006 61 0.005 66 5 0.1250 40 0.007 96 0.006 72 44 0.008 80 0.007 16 6 0.1380 32 0.009 09 0.007 45 40 0.010 15 0.008 74 8 0.1640 32 0.014 0 0.011 96 36 0.014 74 0.012 85 10 0.1900 24 0.017 5 0.014 50 32 0.020 0 0.017 5 12 0.2160 24 0.024 2 0.020 6 28 0.025 8 0.022 6 1 4 0.2500 20 0.031 8 0.026 9 28 0.036 4 0.032 6 5 16 0.3125 18 0.052 4 0.045 4 24 0.058 0 0.052 4 3 8 0.3750 16 0.077 5 0.067 8 24 0.087 8 0.080 9 7 16 0.4375 14 0.106 3 0.093 3 20 0.118 7 0.109 0 1 2 0.5000 13 0.141 9 0.125 7 20 0.159 9 0.148 6 9 16 0.5625 12 0.182 0.162 18 0.203 0.189 5 8 0.6250 11 0.226 0.202 18 0.256 0.240 3 4 0.7500 10 0.334 0.302 16 0.373 0.351 7 8 0.8750 9 0.462 0.419 14 0.509 0.480 1 1.0000 8 0.606 0.551 12 0.663 0.625 11 4 1.2500 7 0.969 0.890 12 1.073 1.024 11 2 1.5000 6 1.405 1.294 12 1.581 1.521 *This table was compiled from ANSI B1.1-1974. The minor diameter was found from the equation dr d 1.299 038p, and the pitch diameter from dp d 0.649 519p. The mean of the pitch diameter and the minor diameter was used to compute the tensile-stress area. Table 8–2 Diameters and Area of Unified Screw Threads UNC and UNF*