Inside Seiko: P2/3: Shiojiri – cold forging, zaratsu and the 9F

Pinterest LinkedIn Tumblr +

We began our Media Experience 2018 trip report in autumn of 2018 last week with our impressions of the Tokyo HQ and the Morioka manufacture. Today, we continue with the Shiojiri manufacture.

Picking up where we left off last week, we journeyed across Japan in the Japanese high speed bullet train from Morioka and arrived at the city of Nagano. Here is a preview of the Shiojiri facilities in a Grand Seiko video:

The Seiko Epson Shiojiri plant is not far from the city of Nagano, and we were there swiftly. The plan is also self sufficient, being almost totally vertically integrated. We again saw rooms with rows upon rows of machinery to make all parts of watches. From cases, to movement components to dials, hands and indices.

Cold Forging

Including this machine used to forge the Grand Seiko and Credor cases. Not all cases are made equal, and the cold forging technique is reserved for the top of the line watches. One such example is the Grand Seiko SBGD001 8 Day Power Reserve.

Cold forging of cases. The machine press makes two passes. The first is at 30 tons of pressure and a second pass of 90 tons is made on the metal, causing it to be forged to the shape of the mould. The process also aligns the grains structure, making the case very strong.

Zaratsu finishing

On the shop floor, we also saw how the famous zaratsu finishing is achieved.

The machine is called Sallaz, which in German is pronounced phonetically as zarats. This machine was in common use in the Swiss watchmaking industry and the Japanese also started to use it. The Japanese transliteration is thus zaratsu.

The Sallaz machine is just a tool, which is rather generic, the final zaratsu polish lies in the hands of the skilled practitioner. Note the special holder used by this highly skilled operator. The operator fabricates the holder himself, so that it is suited to his particular working style.

The case is finished by polishing with the Sallaz machine. First a rough polish is done to buff out the surface, clearing it of any distortion so that when the final polish is applied, it will be a clear, distortionless mirror surface. A second fine polish is performed to achieve this mirror like surface, similar to black polishing. While this technique is possibly Swiss in its origins as is the machine to perform it, most of the technique is lost in the Swiss industry, and we only see a handful of Swiss manufactures who hand finish their cases use it. And it has more or less become the purvue of the twin Japanese watchmaking giants – Seiko and Citizen.

Other case finishing techniques like buffing, graining is also performed in the same shop floor.

Shinshu Studio

Shiojiri has its own assembly area with experts doing the final assembly, finishing and adjustment/regulation.

Where Morioka is the home of the Shizuku-Ishi Studios, Shiojiri is the home of the Shinshu Studio.

Here the Spring Drive and Quartz watches are made, finished and adjusted. The production is totally vertically integrated, from raw materials arriving at the purchasing department stores to the final watches being shipped out.

The 9F Quartz movement

We have reviewed and remain very imprssed with the Grand Seiko 9F quartz movement. As we eluded earlier, the 9F is designed and manufactured right here at the Shiojiri plant.

The prototypes for each phase of the quartz development. The Seiko Astron was the first commercially available quartz watch in December 1969, Seiko produced the world’s first commercial quartz wristwatch, the Seiko-Quartz Astron 35SQ.

As consistent with the vertical integration achieved at Shiojiro, the quartz crystals are grown in the facilities. The crystals are then cut into shape and inserted into circuitry which is also manufactured in-situ.

The Grand Seiko 9F is designed like no other quartz movement in the world. The entire mechanism is placed in a sealed cabin. This hermetic seal prevents contamination and moisture from entering the movement, resulting in a long service life. Battery change can be executed outside the sealed cabin, as seen in the movement photograph below. The system also allows the technician to adjust regulation by means of a screw.

The GS 9F movement. Finished and finely adjusted.

Next up: Micro Artist Studio

With this, we moved on to the Micro Artist Studio. Watch out for that report next week.


Comments are closed.