Dr. Ito's In-Depth Analysis of Mechanical Watches! Vol. 41 - Anti-Magnetic Countermeasures for Luxury Watches

Good evening everyone!

This column talks about mechanical watches from an engineer's perspective. This is the 41st installment.

"Magnetic protection for luxury watches"

I will be talking about this topic here.

Magnetism has always been one of the most common causes of malfunctions in luxury watches.

In today's world, where we are surrounded by electronic devices, there are many cases of watch maintenance being caused by magnetism. Some people may be wondering what actions are not allowed.

This time I would like to talk about this "magnetism."

What is magnetism?

As the name suggests, magnetization occurs when the internal parts of a watch become magnetized, adversely affecting its normal operation.

This is because some of the parts that make up the movement are made of metal, which is affected by magnetism. Metal has the property of sticking to magnets when exposed to magnetism, and this property is maintained even after the metal is removed from the source of the magnetic force.

In other words, magnetization in a wristwatch refers to a state in which magnetic properties remain in the parts inside the watch as a result of the watch being placed in close contact with a source of magnetic force.

So what kind of problems can occur if a watch becomes magnetized?

The most common symptom is poor accuracy. The balance spring, which controls the accuracy of a watch, is greatly affected by magnetization, so if it becomes magnetized (it takes on the properties of a magnet), the accuracy will be affected.

The balance spring is one of the components that make up the balance wheel, the heart of a watch, and its repeated expansion and contraction allows the watch to keep accurate time. However, if the watch becomes magnetized, this expansion and contraction is disrupted, preventing the balance wheel from keeping accurate time. This is a typical symptom of magnetization, which makes the watch more likely to lose accuracy.

We have previously explained the accuracy issues caused by magnetism using actual equipment on YouTube, so please take a look.

In addition, with automatic watches, the influence of magnetism can reduce winding efficiency or cause problems such as a feeling of resistance when manually winding the watch with the crown.

Once a mechanical watch has been magnetized, it cannot be restored to its original state unless it is demagnetized using a special demagnetizer.

What is an antimagnetic watch?

So, what measures have luxury watch manufacturers taken to combat this troublesome magnetism?

1. Magnetic shield

There are two main ways to make a watch anti-magnetic: the first is to house the movement in a magnetic shield.

"Soft iron," the mainstream magnetic shielding material, has soft magnetic properties, meaning that the rate at which magnetism remains is very small and magnetization does not persist after the external magnetic field is removed . While the use of a soft iron case to cover the movement has historically proven effective, it has the disadvantage of increasing the thickness of the case and making it impossible to use a transparent case back.

2. Use of non-magnetic materials

In order to eliminate the drawbacks of antimagnetic watches that use magnetic shields, manufacturers have been focusing on developing "non-magnetic materials" in recent years.

The problem of magnetism is often solved by using a highly non-magnetic material for the hairspring, such as silicon, Rolex's Parachrom alloy made of niobium and zirconium, or the silicon-based Syloxi hairspring.

Representative antimagnetic watches

1. Seamaster Aqua Terra

In 2013, Omega released the Aqua Terra Seamaster as the world's first fully antimagnetic watch. Gauss is a unit of magnetic flux density, and the Caliber 8508 movement installed in this model has been proven to withstand magnetic fields of up to 15,000 gauss, as confirmed by METAS testing. This high level of antimagnetic performance is due to the use of a silicon balance spring. Omega continues to use silicon balance springs to this day.

2. Rolex Milgauss

The Rolex Milgauss, which will cease production in 2023, is a watch named after the unit of magnetic flux density, "gauss." The first model, which appeared in the 1950s, featured a classic anti-magnetic design with a soft iron inner case. When it was re-released in 2007, it was equipped with the highly anti-magnetic Rolex Parachrom balance spring.

Although Rolex does not disclose the magnetic resistance figures, it is known to be far more resistant than the "1000 gauss" implied by its name.

3. IWC Ingenieur Automatic 40

The current IWC Ingenieur model, the Ingenieur Automatic 40, uses the same proven soft-iron inner case structure as in the 1950s. Therefore, while IWC usually prefers a see-through case back, this model has a closed case back.

summary

What did you think?

Magnetism is invisible and therefore always a cause for concern. It is the nemesis of luxury watches, but in recent years, many manufacturers have released models with improved anti-magnetic properties, so if you want to wear a watch without worrying about magnetism, these models might be a good choice.

We hope that this article has been useful to you and has sparked even a little interest in luxury watches! If you have any questions, please feel free to ask us directly and we will be happy to answer them. We look forward to your visit and inquiries.

Please look forward to the next one!