ISO 10684 Specification

Surface areas of bolts, screws and nuts

General

This annex gives guidance for the evaluation of the surface areas of bolts, screws and nuts which are needed for the determination of the batch average thickness according to 8.3.

NOTE The surface areas given in Tables D.1 and D.2 apply only if agreed upon between the parties concerned.

Bolts and screws

To obtain the total surface area of a bolt or screw, the following parameter values are necessary(see Figure 0.1):

the surface area, A1, of a length of 1 mm of the threaded shank of the bolt or screw;

the surface area, A2, of a length of 1 mm of the unthreaded shank of the bolt or screw;

the surface area, A3, of the head (including surface of the end face).

The total surface areas, A, is then calculated as follows:
A = A1 x thread length + A2 x shank length + A3

DIN 3570 U Bolts

a) Total surface area of the head including surface area of the end face, seed.
b) Surface area of the shank of 1 mm length.
c) Surface area of the threaded part of 1 mm length. d) Surface area of the end face is included in the surface area of the head (A3).

Surface area


If the thread is cut, the unthreaded shank will be approximately equal to the basic major diameter (nominal diameter). If the thread is rolled, the unthreaded shank will be approximately equal to either the pitch diameter (reduced shank) or the basic major diameter (full shank).
Table below gives values for the surface areas A1, A 2 and A3 for different shanks and hexagon head.

Surface areas of bolts and screws
Thread size(coarse thread) Surface area per millimetre length Surface area of head, A3
Treaded shank, A 1(coarse thread) Unthreaded Shank, A2 Hexagon head
Full shank Reduced shank
(coarse thread)
M8 38.48 25.15 22.43 541.3
M10 48.31 31.42 28.17 905.8
M12 58.14 37.63 33.98 1 151
M14 67.97 43.99 39.45 1523
M16 78.69 50.27 45.67 1830
M18 87.63 56.54 50.88 2 385

Note For the time being, values for bolts and screws with sizes> M18 or with fine pitch thread are not available and should be calculated as appropriate.
Nuts

Table below gives the surface areas of hexagon nut style 1.
NOTE When evaluating the surface area of a hot dip galvanized nut, the surface area of the thread is not taken into consideration since the nut is tapped after hot dip galvanizing.

Surface areas of hexagon nuts style 1
Thread size Surface area
A
M8 536
M10 892
M12 1169
M14 1522
M16 1877
M18 2424

NOTE:-For the time being values for nuts with sizes > M18 and nuts of style 2 are not available and should be calculated as appropriate.