Requirements of Steel for the Watch Making Industry

disassembled watch movement

There are various types of watch making steel. In principle, one differentiates between parts for movements and parts which are used for the watch case and its parts (as well as watch straps). The parts have the highest demands on precision, the materials require a fine structure. Hardenable carbon steels are usually not corrosion-resistant. Therefore, corrosion-resistant, hardenable steels are used for the medium- and high-price segments for all moving parts. Achievable hardness 600 HV. Non-moving parts are made of brass and / or copper nickel alloys (nickel silver).

Watch case steel requires the best corrosion resistance, as well as the highest demands on the polishing ability. A point that’s becoming more and more important today is the clock’s non-magnetism, as the influence of electronic devices in our environment increasingly adversely affect the clock’s accuracy.

A quantum leap for the production of steel parts necessary in the watch or clockwork industry is the use of stainless steel produced by a technique called powder metallurgy. In this process the steel is melted and after pushed through a nozzle under high pressure, after cooling the “steel haze” becomes a very fine steel powder. The powder is melted again and this results in a steel quality with an extremely homogeneous and fine structure.

tourbillon with gears

LAW 100 X®, a watchmaking steel with excellent qualities

One of the most suitable steels for the manufacturing of parts for clockworks or watches is the unalloyed, lead free LAW 100 X®. This new generation of watchmaking steel is produced with the technique of powder metallurgy. Due to its extremely fine structure, no lead has to be added, and thus the LAW 100 X® also meets the criteria of environmental friendliness.

It has an extremely low distortion and is suitable for the manufacturing of even the smallest precision parts and instruments.

At the reworks such as tempering/hardening, coating or polishing of parts, spectacular results are obtained. Because of its high wear resistance it is ideal to use for parts which are constantly in motion and therefore highly qualified in the watch making industry. Moving parts such as pivots, axles, pinions and gears are made from LAW 100 X®.

The use of LAW 100 X® is not limited to the watchmaking industry, it is also used in the automotive industry and for the production of heavily stressed parts for tool making machines.

Chronifer® M-15 X, high-quality steel for watch making

One excellent steel for the manufacture of clockwork parts or precision parts for watches is the Chronifer® M-15 X. It is a stainless hardenable martensitic steel which is produced by vacuum melting (Micro-Melt®) and a special powder metallurgic process.

Martensitic stainless steel is extremely tough and strong and shares some similar characteristics with ferritic steel, but it has a higher carbon content. Therefore it can be hardened and tempered, its corrosion resistance is similar to that of an AISI 304.

By this manufacturing process a finer and more homogeneous material structure is achieved. This results in higher corrosion resistance, more regular workability and lower distortion after hardening. Furthermore, it is characterized by better polishing ability and fatigue resistance. Due to its excellent properties Chronifer® M-15 X is especially qualified for pulling smallest tolerances and for the very economical production of small precision parts. In the watchmaking industry it is used for the production of pivots, bridges, pinions, plates and other clockwork parts.

The use of this steel is not limited to the watch making field, it is also used in the medical industry for manufacturing of medical instruments.

L. Klein SA, is trader and distributor of watchmaking steel. Thanks to their many years of experience and specialization they can give advice which material is suitable for the different parts and precision moving parts of watches. They have high quality watch making steel available on stock and deliver worldwide even in small quantities and units.

Rolex Winding Crown

Image with Gold Rolex triplock Crown

When it comes to water resistance, the bullet-proof case and solid crystal come after the winding crown. This essential part of the watch is not critical just because it serves for setting the time and other important features, but because this system defines the waterproofness of the timepiece. By using it you open the case and create an access point for dust and water, both of these outside factors are huge enemies of a high end mechanical self-winding movement. This is the reason why the winding crown needs to have its own sealing system, one that is capable of perfectly locking the case and keep its interior clean.




Rolex is one of the brands that pay great attention to this aspect. Its crowns feature two patented sealing systems called twinlock and triplelock. Both types imply a threaded screw-in crown that seals against a rubber gasket making the watch more water tight. In case you were wondering what’s the point of having two types of locking systems, let me clarify this right away. The water resistance required for a watch is what determines if the winding crown should be a twinlock or a triplelock one.

Rolex Twinlock and triplelock winding crown signs

The Twinlock crown is used for timepieces that are waterproofed to 100 meters/300 feet. You can easily recognize the type of system used by looking at the top of the stem. If it has the Rolex crown logo with a simple dash “-“ or two dots “..” then this means that the watch comes with a twinlock crown. The internals of this complex sealing system uses two rubber gaskets. One rubber o-seal is located inside the watch’s tube and the other one is at the interior of the actual gasket that presses against the threaded tube added to the watch’s case. By using these two gaskets system, water and dust are kept outside the case. A very interesting fact is that even if the crown is unscrewed, the gasket located inside the watch’s tube prevents water from entering the case.

The triplock crown system was designed to ensure waterproofness to depths of 300 meters/1000 feet. Rolex uses 10 different components for creating this system and four gaskets. You can recognize a Rolex watch that has the triplock stem by taking a closer look at the winding crown. This is larger than the Twinlock crown and has three dots under the small Rolex crown logo positioned on its top part. The architecture of the triplelock winding crown system implies four rubber o-ring seals and a bigger case tube. These manage to guarantee a higher level of water resistance. When the stem is unscrewed you can easily view the first gasket as it comprises the exterior of the winding tube, but is positioned just at the interior of the crown. Just like on the twinlock crown system, the second rubber gasket is located inside the crown and it presses against the tube of the case. The other two gaskets are at the interior of the case tube. The thicker threaded case tube and the four rubber seals offer a higher level of water resistance for those who are passionate by extreme diving.

There is nothing simple or ordinary about the patented Rolex twinlock and triplelock winding crown systems. These extremely complex and unique water resistance features have been developed and manufactured for those who need a reliable diving instrument for exploring the deepest parts of the ocean.