(Probably) the world's lightest mechanical watches

Out of our Special Projects Cave and several years in the making, we're proud to present what we believe are the world’s lightest mechanical wristwatches: the MING LW.01 Manual and LW.01 Automatic. They are a featherweight 8.8 and 10.8 grams respectively and for the watch head only.‍

The challenge‍

We wanted to push the envelope further than we – or any other brand – has ever done. Why? Because we wanted the challenge.

We set ourselves some ‘conventional’ constraints, though: the watch had to be a wearable size, and retain certain tactile qualities such as the texture and thermal transfer of metal. More importantly, it would have to be practically wearable and not technically compromised purely for the sake of lightness. As it turns out, it would take us a couple of years longer than expected and an exhaustive amount of metallurgy and testing.‍

Exotic solutions to chase numbers ‍

MT began by rethinking the entire case construction to minimize the amount of metal used, whilst retaining (and maximizing) rigidity. In a normal watch, the dial is fixed to the movement, which is in turn fixed to the caseband, with upper and lower bezels forming the front crystal and caseback respectively. The MING LW.01 has a combined “dial” ring and movement holder shaped like a hat, just 0.5mm thick in places but ribbed for strength. To prevent injury to the dial or disruption of the movement, this assembly is supported from the rear by a cage with 3D struts. It also caps and seals the entire assembly to the bezel, which despite being very narrow, is internally hollowed to save further weight.

There is no actual dial per se: the outer ring/background is the movement holder, and the central movement portion is occluded by a gradient print on the outer crystal – which also contains the index markings. 

We explored a wide range of ultralight materials including carbon fiber derivatives and hollow-core 3D printing, but ultimately found that AZ31 Magnesium-Aluminium-Zinc-Manganese alloy from Smiths High Performance was both lighter than carbon (1.77g/cc, vs ~2g/cc density), more consistent to produce than hollow 3D printing, and more importantly retained the feel of metal. It is further surface treated by plasmaelectrolytic oxidation by Keronite for corrosion resistance and biocompatibility, with a further composite protective layer. Material choices do not stop there: even the crystal is not sapphire, but instead Corning Gorilla Glass 6 via Knight Optical with an additional hardening treatment. At 2.40g/cc, it is significantly lighter than the 3.98g/cc of traditional sapphire whilst retaining 670 Vickers hardness and high impact resistance.

Every single component on the watch – down to the screws (in PEEK composite), hollowing of the bezel, and anglage of case buttressing – was optimised to hit the absolute balance of durability and weight. The crown is in anodised aluminium for durability of threading reasons. Finite element simulation was used to check overall torsional rigidity of the watch case. Fixed integral bars machined from the same billet as the case both contribute to rigidity and are lighter than steel springbars. 

The final result is a complete head weight of just 8.8 grams with manual winding, 10.8 grams with automatic winding, and an additional 0.6 grams for the matching AZ31 buckle, and 1.2 grams for the ‘record’ spec Alcantara strap. This puts a ready-to-wear watch at 10.6g or 12.6g.‍

Referencing details‍

The LW.01 has a several distinctive features that pay tribute to our earlier creations: the pulse seconds disc with an interference pattern as an evolution of MT’s own Ochs und Junior Simpleton of 2016; a shuriken hour hand from the 17.03, and the gradient and skeleton peripheral ring on the crystal from the 19 series. Indices are a visually ‘lighter’ skeletonized version of the 37 series. It also of course carries the same flared lugs and ergonomic crown of our other watches.‍

It takes an entire village‍

To machine AZ31 magnesium – let alone to the wall thicknesses and tolerances required – requires some special expertise. Reto Helfenstein of Helfenstein Mechanik was brought in on the recommendation of some mutual friends; his expertise with similar materials for the aerospace industry has proven invaluable. The raw AZ31 billet comes from Smiths High Performance in the UK, and Keronite handles the plasmaelectrolytic oxidation. Manufacture Jean-Rousseau created the single layer Alcantara straps that weigh just 1.2 grams, yet are soft and comfortable to wear without being floppy. Included with the watch are also a selection of other straps for a different feel. We also include a second buckle – in aluminium and in our tuck buckle design – by DBMF. Manufacture Schwarz-Etienne figured out which components within the ETA2000 could be removed or lightened to further save weight, and which had to remain untouched for reliability. Final assembly and testing are conducted at Schwarz-Etienne. ‍