Nickel-plated brass was extensively used by early watchmakers, given that it was less expensive than precious metals and less corrosive than brass. For a long time, a movement’s mainspring was made out of either steel, which was difficult to cast uniformly, and, later, carbon steel, which could be very brittle and break easily.
By the 1960s, new and far sturdier and less brittle alloys comprised of cobalt, chromium, nickel, iron, molybdenum, and manganese had replaced carbon steel. These alloys were also rust- and corrosion-resistant.
The metals used in most movements today have altered even more dramatically. The new millennium has seen the development of alternatives to metal components used in watch movements.
For example, many watchmakers have replaced metal parts within watch movements with silicon, including the ultra-sensitive mainspring. This synthetic material has several advantages over metal for watchmaking purposes, including being:
- much lighter;
- temperature-resistant; and
Perhaps most importantly, silicon allows a movement to run at a higher frequency, which results in better time-keeping and, thus, a more accurate watch.
Titanium has also become more used in watchmaking, especially as it is very light. It is also as durable and corrosion-resistant as stainless steel. Titanium is used most often in dive watch models. However, it is also an expensive material, which explains why it is primarily used in the watch case.
The innovations in movement materials continue unabated. In 2018, a new alloy and alternative to silicon called Nivachron was developed in a partnership between Swiss giant the Swatch Group and Audemars Piguet. Being titanium-based means this alloy is as malleable as any metal alloy, while also being shock and temperature-resistant, as well as non-magnetic.