HERITAGE Swiss-Made Savoir-Faire, Chapter Two: Discover how our watch-cases are made

8 min

Join us for an in-depth exploration of the extraordinary savoir-faire that defines our Maison.

© TAG Heuer

Welcome to our ‘House’ – join us for an in-depth exploration of the extraordinary savoir-faire that defines our TAG Heuer Maison. In this series, we’re taking you behind the scenes, all the way into the very ateliers where horological marvels are born. From the first inkling of an idea, to the final polish on each perfected timepiece – via every careful step in-between. Already an expert on the art of watchmaking? Get ready to take your knowledge to the next level, with up-close-and-personal details sure to thrill even you masterminds of Swiss-Made magic. In Chapter Two, we’re examining the extraordinary case of our manufacture in Cornol, Switzerland, the Case-Makers Extraordinaire.

Cornol Manufacture, Switzerland © TAG Heuer

Back in 2009, the case-making company based in Cornol, Switzerland, was acquired by luxury maison LVMH.  This manufacturer now focusses about 90% of their work on TAG Heuer, creating watch-cases with extraordinary expertise that often ‘runs in the family’; many of the watchmakers at Cornol have grown up with horology in the blood, with parents who have worked in the industry before them. Sometimes arriving with the basics already under their belt, novice case-makers can then undergo a training program to develop the high-level skills and techniques they need to produce exceptional timepieces. 

So how exactly are watch-cases made? There are four basic stages to the process: stamping, machining, automatic and manual polishing, and assembly.  Let’s take a look at each of these steps in turn, to examine the superb savoir-faire required at every stage.

  • Stamping mould © TAG Heuer

Stamping © TAG Heuer

Stamping

Step one is stamping; case-making begins with selecting only the finest raw materials, whose purity and strength must be precisely tested to ensure high quality.  Stainless steel or titanium sheets in a variety of thicknesses are cut into rough metal case shapes that will be transformed over a multitude of steps. With up to 16 operations for our most complex pieces between the ‘raw bar’ and the basic shape, it’s not quite as simple as it looks.  Each metal disc is pounded with 70 tonnes of pressure to increase hardness, thinness, and resilience. After each press, the discs are heated and then cooled; known as ‘annealing’, this process smoothes and refines the metal that has been temporarily ‘damaged’ by the enormous pressure of stamping. 

With specialised washing machines in every workshop, the metal is cleaned using ecologically-friendly products, soaps, and technology that eliminate any remaining grease or impurities, without harming the environment. The waste products of this cleaning are then recycled to further increase the sustainability of our practices.  Because these mechanical processes are so highly specialised, the Cornol manufacture even develops its own tools to ensure absolute precision; 3D printers are utilised in addition to traditional means, to create tool-components unique to the making of each watch. 

Machining © TAG Heuer

Machining

Next, it’s time for step two: Machining. In the manufacture of Cornol’s unique machining workshop, you’ll find milling machines, turning tools specialised to different types of metal, and a 3D quality control check machine that can examine all necessary specifications. These machines cut the circular bars of steel, before the edges are washed and refined through ‘grinding’ to remove any metal fragments that remain.  Throughout production, quality checks are performed; up to 60 dimensions must be confirmed precisely.  Some checks are performed overnight – leaving only perfect specimens come morning. 

The automatic turning machine operates under a constant flow of oil to reduce heat and friction; these machines can rotate at a speed of up to 20,000 times per minute, and this process needs to be precisely calibrated to ensure safety and accuracy. Machine components are, once again, produced in-house to fit TAG Heuer’s unique designs, and quality-control checks every step of the way make sure each element is of the highest standard.

© TAG Heuer

Polishing

Polishing is our next step, though this stage comes with several separate ‘steps’ of its own. After an initial polish to some surfaces, we apply a colour-guide or ‘lacquer’ which serves two important purposes: first, it can protect the pre-polished surfaces and allow our craftspeople to see which areas still need work. It also acts as a guide during machine polishing, so we are able to see where the pigment has been removed in the process, accurately tracking the machine’s polishing ‘journey’. With between three and five ‘preparation’ steps before the final surface is created, we can, for example, increase shine, smoothness, or create different striations such as vertical or horizontal satin finishes.

  • Lacquer applied before polishing © TAG Heuer

The stone-polishing wheel is made up of a proprietary composite of sand, creating different grades a bit like sandpaper. Each stone variety is carefully tested for every model, to ensure we reach the right surface finish as efficiently as possible; it’s also developed to uniquely fit the shape of each product’s case. A polishing ‘belt’ is used for a final polish, especially for satin finishes – when it offers higher precision than the stone itself.

Manual polishing © TAG Heuer

The preparatory stage for manual polishing is perfection of the surface; robotic arms are directed by a specially-tailored program for each watch. The programming itself can take up to three months for a new model, or as little as two weeks for a design change in the same watch family. After this stage, we move on to manual polishing; guide colour is reapplied after an intermediary wash, and manually-operated scrubbing sponges are used to polish the case once more, under the watchful eyes of the case-makers. A final wash ensures that any dust or filaments are removed (once and for all), before moving on to the assembly process. 

Assembly and quality control © TAG Heuer

Assembly

Last but not least, we begin assembly.  The crafts-men and women who perform this step are highly skilled, some with many decades of experience behind them. Despite the incredibly detailed work on tiny parts, their hands can be seen moving quickly and surely across the workshop; it really is a sight to behold. We begin with a special glue used to attach the crown tube, and a heating procedure to seal these components together. 

Pushers are then added, using specially designed hand-held tools and steady movements.

Each person who works in the assembly workshop possesses different skills, and many can perform multiple tasks depending on the volume of their workload.  A pusher-applier might also, for instance, be able to apply the crystal faces or casebacks.  When closing the case by adding its rear backing, it’s essential to ensure absolute cleanliness; not a speck of dust can be allowed to remain! Compressed air is used to blast out even invisible flecks, and special protective gear is worn to eliminate any debris from clothes or shoes. 

Finally, we move on to waterproof-testing, pressure testing, and a final review of every potential opening into the watch case.  Even a fractional amount of humidity can interfere with a watch’s final functioning, and the case is the ultimate defense against the elements. A heating plate is used to perform condensation tests to ensure absolute protection.