A Guide to Hairsprings

The hairspring is a flat, spiral spring that consists of 12 to 15 turns, weighs around 1 milligram, and is approximately 0.03 millimeters thick. Hairsprings serve a single purpose: when they coil and uncoil, hairsprings propel a balance wheel that spins around its axis. This balance is a flywheel and is meant to accumulate the energy provided by the hairspring. Both are made so this oscillation is as regular and repeatable as possible in order to become a stably recurring phenomenon. Because of the reliability of hairsprings, they are frequently used in watches and master clocks, which are used to measure time in very small increments. Wheels and pinions convert the oscillation into seconds, minutes, hours, and so on. Because hairsprings transform the energy they receive into information, it is considered a mechanical processor.

There are a variety of factors that a hairspring assembly must withstand in order to operate correctly. Years of progress in hairspring technology have strived to make them impervious to outside factors. Hairsprings must be stainless and resistant to magnetic fields, air pressure changes, and temperature variations. All of these factors have an effect on the shape, length, and properties of a hairspring, which alters the oscillation frequency and therefore interferes with timekeeping. The average hairspring will oscillate roughly 500 million times a year and is worn on a constantly-moving wrist as well. Hairsprings must be able to retain their shape and elasticity through any factors they may face.

The State of the Hairspring Industry

Modern hairsprings are made of iron-nickel alloys such as Nivarox, whose elasticity is nearly completely unaffected by temperature. Nivarox is an acronym for nicht variabel oxydfest (non-variable non-oxidizing). Hairsprings are manufactured through ultra-precise metal lamination techniques by a combination of advanced industrial precision and manual work. The process of turning a metal wire into a thin spring takes multiple days and successive steps. Tolerances are usually less than 0.1 microns, and the slightest variation can have a significant impact on a watch’s performance. For instance, a variation of just one micrometer in the thickness of a spring can change a watch by 30 minutes each day. Once the spring is created, it is shaped and coiled to obtain its spiral shape.

One of the first watchmakers to develop a fully in-house production facility for hairsprings was Rolex, who did so in order to be independent of other manufacturers. The first Rolex hairsprings entered production in the early 2000s. They are made from parachrom, an alloy of niobium and zirconium which is then coated in oxide. Two of the main advantages of parachrom are its non-magnetic properties and its accuracy when subjected to shock in comparison to ferromagnetic alloys. Since Rolex, other watchmakers such as Richemont began producing their own hairsprings. The most prolific manufacturers of hairsprings include companies such as Atokalpa, Concepto, Precision Engineering AG, Festina Group, and E20 innovation.

Though alloys are still the dominant material used for hairsprings, silicon has been disrupting the traditional watchmaking market. Silicon’s hard-wearing, light, durable, anti-magnetic, thermal stability, and excellent elasticity, make it a very attractive option for hairspring manufacturers. Though it is currently not widely available, the future of hairsprings could leave alloy behind.

For hairsprings and oscillator parts, look no further than NSN Fulfillment. Owned and operated by ASAP Semiconductor, we can help you find all types of hairspring assembly parts and deliver them with short lead times and competitive prices. Additionally, NSN Fulfillment has aerospace parts such as PB25685-3, PB25685-1, PB25685-1, L4647-01, HSC5074, from manufacturers like Honeywell International Inc and GE Aviation systems. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at sales@nsnfulfillment.com or call us at +1-714-705-4780. Our team of dedicated account managers is standing by and will reach out to you in 15 minutes or less.


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