FASTENER PROOF LOAD YIELD STRENGTH (Sy)
SIZE Fsp (kN)
Grade 8.8 Grade 9.8 Grade 10.9 MATERIAL Sy (MPa)
1 M3x0.5 2.9 3.2 4.1 1 1010 SAE Steel 200
2 M3.5x0.6 3.9 4.4 5.6 2 1020 SAE Steel 290
3 M4x0.7 5.1 5.7 7.2 3 1045 SAE Steel 414
4 M5x0.8 8.2 9.2 11.8 4 304-A SAE Stainless Steel 276
5 M6x1.0 11.6 13.1 16.7 5 1100-0 SAE Aluminum Alloy 31
6 M8x1.25 21.2 23.8 30.4 6 2024-T4 SAE Aluminum Alloy 296
7 M10x1.5 33.7 37.7 48.1 7 7075-0 SAE Aluminum Alloy 99
8 M12x1.75 48.9 54.8 70.0 8 7075-T6 SAE Aluminum Alloy 538
9 M14x2.0 66.7 74.8 95.5 9 HK31XA-0 SAE Magnesium Alloy 131
10 M16x2.0 91.0 102.0 130.0 10 HK31XA-H24 SAE Magnesium Alloy 214
11 M18 115.0 - 159.0 11 ABS Polymer 64 (ref)
12 M20x2.5 147.0 - 203.0 12 Polypropelene 36 (ref)

Load and Material Based Needed
Minumum Bearing Area

A

 mm2
Minimum Bearing Diameter db mm
Material Yield Strength(Sy) Sy Mpa
Fastener Proof Load Fsp kN
Fastener Service Load(or 20% of Fsp) Fsa kN
SAFTEY FACTOR (1.0 is Minimum) Sf
Hole Diameter Dh mm
formula

    SFSUR = (Sy * A) / (Fsp + Fsa)

   SFSUR >= 1 is a good joint.
Meaning load exerted by the bolt load in operation does not exceed the compressive strength of the joint.

 
Torque Needed

Tmax

 Nm Fastener Nominal Diameter D mm

Range

 Fastener Proof Load Fsp kN

Min

 Nm Fastener Coefficient of Friction u

Mid

 Nm formula
   T = KDF
   Torque = K-Factor * Nominal Dia * Proof Load
   NOTE:  As a general rule, use do not use more than 70% of maximum fastener proof load. For automotive applications, the K or nut factor is roughly the Coefficient of Friction (u) * 1.45
Bearing Area Needed

A

 mm2 Minimum Bearing Diameter db mm
Slot Width W mm
formula
    A = r2 ( a - sin a)
    a  = 2 arccos ( W / db )
Slot Width Needed

W

 mm Minimum Bearing Diameter db mm
Bearing Area A mm2
formula
    W = 2r Cos( a / 2 )

    a   = a0+(a1+(a2+(a4(a4+(a5+(a6z)z)z)z)z)z)
            where  z = A/r2
   aref = (a cosa - sin a - z) / (cos a - 1)
Minumum Bearing Diameter Needed

db

 mm Slot Width W mm
Bearing Area A mm2
formula

    db = W / Cos( a / 2)

    a   = a0+(a1+(a2+(a4(a4+(a5+(a6z)z)z)z)z)z)
                          or
   a     = (-6.334701512 * z ) * pi
            where  z =  sqr( W ) / 2A
   aref = (a*a*sin a + a - sin a + a cos a -
             cos a * sin a - z*a*a + 2*z*a*sin a -
             z + z * cos a * cos a ) / (a * sin a)