ISO 16239-2013 pdf free download

ISO 16239-2013 pdf free download.Metric series wires for measuring screw threads Piges metriques pour mesurage des filetages.
3.1
best-size wire
wire that would touch an imaginary thread of zero lead angle at the pitch cylinder
Note ito entry: For symmetric threads, the diameter of a best-size wire is equal to P/(2 cos a/2), where PIs the pitch and a/2 is the flank angle.
4 Reference temperature
In accordance with ISO 1, the dimension of the wire shall be related to the standard reference temperature of 20 °C.
5 Material, hardness, and surface finish
The wires shall be made from alloy tool steel that has been stabilized to ensure dimensional stability.
The wires shall be free from cracks and other detrimental defects.
The hardness shall be (760 ± 50) HV5 over the measuring surface.
The roughness shall not exceed 0,4 urn Rz over the measuring surface.
6 Nominal diameters of best-size wires
6.1 Wires for ISO general purpose metric screw threads (M)
The nominal diameters of best-size wires and the allocation of pitches are given in Table 1.
8 Measurement methods for wires
8.1 Measuring the actual diameters of each wire
The actual diameters oteach wire should be measured in the three planes, l.1, E, anó 1, perpenaicular to the axis of the wire, and in each plane, two actual diameters should be measured in perpendicular directions (see Figure 1).
The direct measurement or comparison measurement (using gauge blocks) for the actual diameters of each wire should be chosen according to the measurement uncertainty required.
NOTE In some countries, the actual diameters of wires are measured in a deformed condition for Lhe correction of the measuring force.
8.2 Determination of the difference of the actual diameters around a wire
The difference of actual diameters around a wire should be determined by measuring the highest and the lowest points In a 600 groove, e.g. a ground thread plug gauge under a suitable measuring head (see Figure 2).
The measuring positions of a wire are in the three planes, El, E2, and E3 (see Figure 1).
When rotating the wire in a 600 groove, the difference between the maximum and minimum readings on the measuring instrument shall be taken and divided by 1,5. The calculated result shall not exceed the value of the maximum permissible difference specified.ISO 16239-2013 pdf free download.