The influence of magnetic fields on watches
To understand why magnets have such a strong effect on mechanical watches, we will briefly go into the functioning of these watches. Particularly important here is the wafer-thin hairspring, which, together with the balance, forms the “heart” of the watch and ensures that a mechanical watch ticks correctly. If the movement is now exposed to a magnetic field and the hairspring is made of a ferromagnetic material such as iron or nickel, the balance spring is magnetized. Depending on the strength of the magnetic field, this then has smaller or larger effects on the accuracy of a watch. The spectrum here ranges from deviations of several minutes to several hours per day! With particularly strong magnetic fields, a watch can even stop completely. This is due to the fact that a magnetized balance spring can become “stuck” and thus no longer oscillates as “roundly” as a non-magnetized balance spring.
Before we get to watches that are insensitive to magnetic fields, let’s take a brief look at the history of the anti-magnetic watch.
The history of the anti-magnetic watch
The history of anti-magnetic watches began over 100 years ago. As early as 1915, the first watch of this type was developed. It was a pocket watch.
In fact, the development of anti-magnetic watches was necessary at the beginning of the 20th century, because already then mechanical watches were negatively affected by magnetic fields. For example, the electric motors of locomotives or the magnetic deflection coils of radar screens in airplanes interfered with the accuracy of the watches.
The first wristwatch series with magnetic field protection was produced in 1930, and in the 1940s the first watch model came onto the market that protected the movement from magnetic fields by means of the principle of the so-called Faraday cage or soft iron cage.