Magnetism - the main reason automatic watches need service.
The proliforation of magnetic fields, founds in common objects that are now a part of our daily lives, can compromise and even stop an automatic watch. Watches are now exposed to magnetic fields from computer drives, speakers, iPad covers, iPhones and even refrigerator magnets.
ISO 764 - A REFRIGERATOR MAGNET?
Carbon Steel and Brass are ferromagnetic. In the presence of a magnetic field they will become magnetized as well. They will "remember" their magnetic history once the presence of the magnet is removed. This tendency to become magnetized is debilitating to automatic watches.
When a watch enters a magnetic field small components, such as the escapement and balance wheel, can become magnetized. The coils of the balance wheel will be attracted to each other and end up ‘sticking’ which will shorten the active length of the wheel and cause the watch to gain huge amounts of time and eventually stop.
In order to satisfy ISO 764, an automatic movement must run within a +/- 30 seconds per day deviation after experiencing a magnetic field of 4,800 A/m or 60 Gauss for 1 minute. Today, a magnetic field of 4,800 A/m is very common.
Small magnets, like those found in your iPad cover, a refrigerator magnet, stereo speakers or computer monitor, produce magnetic fields greater than 4,800 A/m. Even frequent high-altitude flying can magnetize a ISO 764 compliant watch.
ISO 764 standards fall short of protecting movements in modern times.
THE SEAHOLM SOLUTION
THE SEAHOLM WHITE PAPER
For more on SEAHOLM testing, methodology and performance, download the WHITE PAPER. The WHITE PAPER includes insight into design and testing methodology for shock resistance, water resistance and anti-magnetism.