BS ISO 764:2020 pdf free

BS ISO 764:2020 pdf free.Horology – Magnetic resistant watches.
The test apparatus used shall produce homogenentic and continuous direct current magnetic Melds of the test value according to the directions spediled In 5J. Admissible Variatkrns in magnetic fields strength during the magnetic resistance test shall be 0 % to +5 96.
5.3 Test procedure
5.3.1 General
Flowdijrts sunimari.ing tltec pruiedures (5.12 and 5.i3) are deccribed in AniwB.
53.2 Test procedure for mechanical watches
5.3.2.1 Preparation before magnetic resistance test
For mechanical watches, the ml lowing procedurec are performed before magnetic resistance test.
5.3.2.1.1 Demagnetization
A demagnetization of the watch is required in order to take into account a possible effect on the rate by repealed magnetizations and dernagnel iaI inns.
The watch shall be demagnetized in each of the three 311-911.611 12H and C11FH directions.
5.3.2.1.2 Wmding
At least I h before the initial rate measurement, the watch shall be completely winded up.
5.3.2.1.3 4lcasuremcntoIthc Initial rate Mijg
A measurement of the initial rare shall 1w carried out prior to applying any magnetic field.
Swtchable mechanisms shall be stopped and the hands, the date and other mechanisms shall be set up such to avoid any disturbance during the rate measurement.
The rate shall he measured during at least IKO s in CM position, according to ISO 3158. by using a rate measurement apparatus.
This duration shall he increased if necessary based on the stability and periodicity of the rate. The initial rate (Mji) is the average of instainaticous rates nicasuied for 180 s or loiiger.
5.3.2.2
Magnetic resistance test
Magnetic resistance tests shall be carried out as follows:
a) Switchable mechanisms shall be stopped and the hands, the date and other mechanisms shall be set up such to avoid any disturbance during the rate measurement and magnetic fields application.
b) Place the watch on the test apparatus so that the magnetic field is applied in the 3H 9H direction parallel to the watch face.
c) Increase progressively. at least 5 s, the strength of the magnetic field to the test value (in this case 4 800 A/m).