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Torque Recommendations

Values assume zinc plated steel mating units and thread engagement of 0.875 x screw diameter or standard nuts.

 

Recommended Torque Range  (min-max, zinc plated steel fasteners)

Fastener Size Nominal Size Material Properties Minimum Thread Engagement Metric English % of Proof Load
Inch Fasteners mm (inch) Grade (Inch) / mm (inch) N-m in-lb
#2-64 2.2 (.086) 1 1.9  (.075) 0.17 - 0.23 1.5 - 2 56/74
#4-40 2.8 (.112) 1 2.5 (.098) 0.34 - 0.45 3 - 4 61/82
#6-32 3.5 (.138) 1 3.1 (.121) 0.7 - 1.1 6-  10 67/111
#8-32 4.2 (.164) 1 3.6  (.144) 1.1 - 1.7 10 - 15 60/90
#10-32 4.8 (.190) 1 4.2 (.166) 1.8 - 2.7 16 - 24 58/87
1/4-20 6.4 (.25) 1 5.6 (.219) 4 - 5.2 35 - 46 61/80
1/4-20 6.4 (.25) 2 5.6 (.219) 6.4 - 8.7 57 - 77 59/80
5/16-18 7.9 (.3125) 2 6.9 (.273) 13 - 18 119 - 158 60/80
3/8-16 9.5 (.375) 2 8.3 (.328) 23 - 31 205 - 274 58/78
7/16-14 11.1 (.4375) 2 9.7 (.383) 38 - 51 338 - 451 60/80
1/2-13 12.7 (.5) 2 11.1 (.438) 58 - 78 515 - 686 60/80
Metric Fasteners mm (inch) Property Class (Metric) mm (inch) N-m in-lb
M2 x .4 2 (.079) 4.8 1.75 (.069) 0.17 - 0.23 1.5 - 2 60/82
M2.5 x .45 2.5 (.098) 4.8 2.2 (.086) 0.34 - 0.45 3 - 4 59/78
M3 x .5 3 (.118) 4.8 2.6 (.103) 0.7 - 1.1 6 - 10 68/107
M3.5 x .6 3.5 (.138) 4.8 3.1 (.121) 1 - 1.5 8.5 - 13 62/93
M4 x .7 4 (.157) 4.8 3.5 (.138) 1.5 - 2 13 - 18 63/84
M5 x .8 5 (.197) 4.8 4.4 (.172) 2.8 - 3.8 25 - 34 58/79
M6 x 1 6 (.236) 4.8 5.3 (.207) 5 - 6.2 45 - 55 61/75
M6 x 1 6 (.236) 8.8 5.3 (.207) 9 - 11.3 80 - 100 57/71
M8 x 1.25 8 (.315) 4.8 7 (.276) 11 - 14.7 97 - 130 55/74
M8 x 1.25 8 (.315) 8.8 7 (.276) 23 - 31 205 - 274 60/80
M10 x 1.5 10 (.394) 8.8 8.8 (.344) 46 - 61 406 - 542 60/80
M12 x 1.75 12 (.472) 8.8 10.5 (.413) 80 - 107 708 - 945 60/80

Torque Calculation

Torque (metric)

 

            T = K * D * W * % where:

 

            T = torque (N-m)

            K = coefficient of friction (0.22 for zinc plated fastners)

            D = nominal diameter (m)

            W = clamp force (N) = As x PL

            As = stress area (mm**2)

            PL = proof load stress (Mpa)

            % = desired percent of proof load

 

Torque (Inch units)

 

            T = K * D * W * % where:

 

            T = torque (inch lbs.)

            K = coefficient of friction (0.22 for zinc plated fastners)

            D = nominal diameter (inches)

            W = clamp force (lbs) = As x PL

            As = stress area (in**2)

            PL = proof load stress (psi)

            % = desired percent of proof load

 

Stress Area

 

            As =  (pi/4)*((d2+d3)/2)**2

 

            pi = 3.1415927……

            d1 = basic minor diameter

            d2 = basic pitch diameter

            d3 = d1 – (H/6)

            H = height of fundamental thread triangle = 0.8660250P

            P = pitch

Inch Fastener Data

Basic Dimensions for Coarse Thread Series Parts (UNC/UNRC)
(measured in inches)
Nominal Size Major Diameter Threads/inch Basic Pitch Diameter Minor Diameter Lead Angle  Height of Fundamental Triangle  Tensile Stress Area
at Basic Pitch Diameter
          (Degrees) (Min)   (square inches)
#1 0.073 64 0.063 0.056 4 31 0.01353 0.003
#2 0.086 56 0.074 0.067 4 22 0.01547 0.004
#3 0.099 48 0.086 0.076 4 26 0.01804 0.005
#4 0.112 40 0.096 0.085 4 45 0.02165 0.006
#5 0.125 40 0.109 0.098 4 11 0.02165 0.008
#6 0.138 32 0.118 0.104 4 50 0.02706 0.009
#8 0.164 32 0.144 0.13 3 58 0.02706 0.014
#10 0.19 24 0.163 0.145 4 39 0.03608 0.018
#12 0.216 24 0.189 0.171 4 1 0.03608 0.024
4-Jan 0.25 20 0.218 0.196 4 11 0.0433 0.032
16-May 0.313 18 0.276 0.252 3 40 0.04811 0.052
8-Mar 0.375 16 0.334 0.307 3 24 0.05413 0.078
16-Jul 0.438 14 0.391 0.36 3 20 0.06186 0.106
2-Jan 0.5 13 0.45 0.417 3 7 0.06662 0.142
16-Sep 0.563 12 0.508 0.472 2 59 0.07217 0.182
8-May 0.625 11 0.566 0.527 2 56 0.07873 0.226
4-Mar 0.75 10 0.685 0.642 2 40 0.0866 0.334
8-Jul 0.875 9 0.803 0.755 2 31 0.09623 0.462
1 1 8 0.919 0.865 2 29 0.10825 0.606
1 1/8 1.125 7 1.032 0.941 2 31 0.12372 0.763
1 1/4 1.25 7 1.157 1.095 2 15 0.12372 0.969
1 3/8 1.375 6 1.267 1.195 2 24 0.14434 1.155
1 1/2 1.5 6 1.392 1.32 2 11 0.14434 1.405
1 3/4 1.75 5 1.62 1.534 2 15 0.17321 1.9
2 2 4 1/2 1.856 1.759 2 11 0.19245 2.5
2 1/4 2.25 4 1/2 2.106 2.009 1 55 0.19245 3.25
2 1/2 2.5 4 2.338 2.229 1 57 0.21651 4
2 3/4 2.75 4 2.588 2.479 1 46 0.21651 4.93
3 3 4 2.838 2.729 1 36 0.21651 5.97
3 1/4 3.25 4 3.088 2.979 1 29 0.21651 7.1
3 1/2 3.5 4 3.338 3.229 1 22 0.21651 8.33
3 3/4 3.75 4 3.588 3.479 1 16 0.21651 9.66
4 4 4 3.838 3.729 1 11 0.21651 11.08
 
(standards set by American Society of Mechanical Engineers)
Basic Dimensions for Fine Thread Series Parts (UNF/UNRF)
(measured in inches)
Nominal Size Major Diameter Threads/inch Basic Pitch Diameter Minor Diameter Lead Angle  Height of Fundamental Triangle  Tensile Stress Area
at Basic Pitch Diameter
          (Degrees) (Min)   (square inches)
#0 0.06 80 0.052 0.047 4 23 0.01083 0.002
#1 0.073 72 0.064 0.058 3 57 0.01203 0.003
#2 0.086 64 0.076 0.069 3 45 0.01353 0.004
#3 0.099 56 0.087 0.08 3 43 0.01547 0.005
#4 0.112 48 0.099 0.089 3 51 0.01804 0.007
#5 0.125 44 0.11 0.1 3 45 0.01968 0.008
#6 0.138 40 0.122 0.111 3 44 0.02165 0.01
#8 0.164 36 0.146 0.134 3 28 0.02406 0.015
#10 0.19 32 0.17 0.156 3 21 0.02706 0.02
#12 0.216 28 0.193 0.177 3 22 0.03093 0.026
4-Jan 0.25 28 0.227 0.211 2 52 0.03093 0.036
16-May 0.313 24 0.285 0.267 2 40 0.03608 0.058
8-Mar 0.375 24 0.348 0.33 2 11 0.03608 0.088
16-Jul 0.438 20 0.405 0.383 2 15 0.0433 0.119
2-Jan 0.5 20 0.468 0.446 1 57 0.0433 0.16
16-Sep 0.563 18 0.526 0.502 1 55 0.04811 0.203
8-May 0.625 18 0.589 0.565 1 43 0.04811 0.256
4-Mar 0.75 16 0.709 0.682 1 36 0.05413 0.373
8-Jul 0.875 14 0.829 0.798 1 34 0.06186 0.509
1 1 14 0.946 0.903 1 36 0.07217 0.663
1 1/8 1.125 12 1.071 1.035 1 25 0.07217 0.856
1 1/4 1.25 12 1.196 1.16 1 16 0.07217 1.073
1 3/8 1.375 12 1.321 1.285 1 9 0.07217 1.315
1 1/2 1.5 12 1.446 1.41 1 3 0.07217 1.581

Material Properties for Inch Fasteners

Steel Grade  Material & Treatment  Proof Load Stress  Yield Strength  Tensile Strength  Core Hardness, Rockwell  Standards Authority
    ksi (1000 lbs/sq inch) Min.  ksi (1000 lbs/sq inch) Min.  ksi (1000 lbs/sq inch) Min.     
Low-carbon grade 2 Low/medium carbon steel, cold-forged 55 57 74 B70-B100 Society of Automotive Engineers
Grade A Low/medium carbon steel 90-100 95-105 60 B69-B100 American Society for Testing & Materials
Grade B Low/medium carbon steel 70-133 76-139 60-100 B69-B95 American Society for Testing & Materials
Grade 5 Medium carbon steel, quenched & tempered 74-85 81-82 105-120 C19-C34 Society of Automotive Engineers
Grade 8 Medium carbon alloy steel, quenched & tempered 120 130 150 C33-C39 Society of Automotive Engineers
Grade C Medium carbon steel 144 154 N/A B78-C38 American Society for Testing & Materials
2-H Medium carbon steel 144 154 N/A B78-C38 Society of Automotive Engineers

Metric Fastener Data

THREAD DATA CHART: Metric Thread -- Coarse Pitch
Nominal Thread Form Type Major Pitch Root Pitch Minor Minor Thread Thread Tap
Size Diameter mm Radius Diameter Diameter Diameter Height Height Drill
ISO M mm p mm mm Male Thd. Female Thd. Male Thd. Female Thd. Diameter
  d=D   r d2=D2 d3 D1 h3 H1 mm
                     
1 M 1 0.25 0.036 0.838 0.693 0.729 0.153 0.135 0.75
1.1 M 1.1 0.25 0.036 0.938 0.793 0.829 0.153 0.135 0.85
1.2 M 1.2 0.25 0.036 1.038 0.893 0.929 0.153 0.135 0.95
1.4 M 1.4 0.3 0.043 1.205 1.032 1.075 0.184 0.162 1.1
1.6 M 1.6 0.35 0.051 1.373 1.171 1.221 0.215 0.189 1.25
1.8 M 1.8 0.35 0.051 1.573 1.371 1.421 0.215 0.189 1.45
2 M 2 0.4 0.058 1.74 1.509 1.567 0.245 0.217 1.6
2.2 M 2.2 0.45 0.065 1.908 1.648 1.713 0.276 0.244 1.75
2.5 M 2.5 0.45 0.065 2.208 1.948 2.013 0.276 0.244 2.05
3 M 3 0.5 0.072 2.675 2.387 2.459 0.307 0.271 2.5
3.5 M 3.5 0.6 0.087 3.11 2.764 2.85 0.368 0.325 2.9
4 M 4 0.7 0.101 3.545 3.141 3.242 0.429 0.379 3.3
4.5 M 4.5 0.75 0.108 4.013 3.58 3.688 0.46 0.406 3.8
5 M 5 0.8 0.115 4.48 4.019 4.134 0.491 0.433 4.2
6 M 6 1 0.144 5.35 4.773 4.917 0.613 0.541 5
7 M 7 1 0.144 6.35 5.773 5.917 0.613 0.541 6
8 M 8 1.25 0.18 7.188 6.466 6.647 0.767 0.677 6.8
9 M 9 1.25 0.18 8.188 7.466 7.647 0.767 0.677 7.8
10 M 10 1.5 0.217 9.026 8.16 8.376 0.92 0.812 8.5
11 M 11 1.5 0.217 10.026 9.16 9.376 0.92 0.812 9.5
12 M 12 1.75 0.253 10.863 9.853 10.106 1.074 0.947 10.2
14 M 14 2 0.289 12.701 11.546 11.835 1.227 1.083 12
16 M 16 2 0.289 14.701 13.546 13.835 1.227 1.083 14
18 M 18 2.5 0.361 16.376 14.933 15.394 1.534 1.353 15.5
20 M 20 2.5 0.361 18.376 16.933 17.294 1.534 1.353 17.5
22 M 22 2.5 0.361 20.376 18.933 19.294 1.534 1.353 19.5
24 M 24 3 0.433 22.051 20.319 20.752 1.84 1.624 21
27 M 27 3 0.433 25.051 23.319 23.752 1.84 1.624 24
30 M 30 3.5 0.505 27.727 25.706 26.211 2.147 1.894 26.5
33 M 33 3.5 0.505 30.727 28.706 29.211 2.147 1.894 29.5
36 M 36 4 0.577 33.402 31.093 31.67 2.454 2.165 32
39 M 39 4 0.577 36.402 34.093 34.67 2.454 2.165 35
42 M 42 4.5 0.65 39.077 36.479 37.129 2.76 2.436 37.5
45 M 45 4.5 0.65 42.077 39.479 40.129 2.76 2.436 40.5
48 M 48 5 0.722 44.752 41.866 42.857 3.067 2.706 43
52 M 52 5 0.722 48.752 45.866 46.587 3.067 2.706 47
56 M 56 5.5 0.794 52.428 49.252 50.046 3.374 2.977 50.5
60 M 60 5.5 0.794 56.428 53.252 54.046 3.374 2.977 54.5
64 M 64 6 0.866 60.103 56.639 57.505 3.681 3.248 58
68 M 68 6 0.866 64.103 60.639 61.505 3.681 3.248 62
THREAD DATA CHART: Metric Thread -- Fine Pitch
Nominal Thread Major Pitch Root Pitch Minor Minor Thread Thread Tap
Size Form Diameter