Titanium hardening… Making something hard even harder!

Apr 26 2019

3 mins

Titanium hardening… Making something hard even harder!

We are already in full swing to make sure we can ship the Autark 10-years in time by end of June. Parts are already in the making and with this update, we want to talk about the hardening process used for all the Titanium parts in the Autark 10-years.

Way before the campaign we have been manufacturing the cases already. At this stage, the cases are more or less finished and then need to undergo the tricky process of hardening. Since many things can go wrong during this sophisticated process and since we want to keep out timeline we have started to load watch cases into the vacuum oven already. Just in case things go wrong we have some spare time to fix it… keep in mind in manufacturing always something can go wrong😉

UTARK Titanium grade 5 cases after hardening in Denmark

This hardening oven is located in Denmark and operated by our partner Expanite, who developed this specific gas-hardening process for grade 5 Titanium. In fact, this hardening technology is NOT a hardening in the sense of surface coating, or alternatively as it is often done with steel by using a combination of hot and cold liquids. It is a gas-based hardening process in which the material is heated to open the metal matrix and during this process infuse various gas molecules to strengthen the outer layer of the Titanium to a depth of approx. 40µm. This means the hardness does not sit outside on top of the Titanium, it much more has infiltrated the material itself.

Imagine while heating the material the metal matrix is opening up and gas molecules go in between atoms of the Titanium alloy and once the material is cooled back down, these gas molecules increase the strength because the tension in between the Titanium alloy matrix has been increased. More atoms of various properties squeezed in a smaller space. Kind of simple…

Why can things go wrong? If you do not understand the process flow and strictly stick to the recipe this increase in tension can twist parts and move things out of tolerance. Sometimes things like this happen and nobody knows why… There is a bit of "praying" involved that the parts come out as we wish them to be. It is highly recommended once the right formula has been found, to never change something again, especially not the material supplier...To further control these tensions, we must clamp the cases into special toolings to hold them together during the hardening process as you can see in the picture two.

This means besides manufacturing a regular watch case made of Titanium, there is a lot of additional work needed to do the hardening itself.

After that, we will send the parts to the finishing company which will give it the smooth-velvet-feeling. We will talk about this in the next update.